Mechanisms of labor - Williams Obstetrics 23th Edition

Mechanisms of Labor

At the onset of labor, the position of the fetus with respect to the birth canal is critical to the route of delivery. Thus, fetal position within the uterine cavity should be determined at the onset of labor

Fetal Lie

The relation of the fetal long axis to that of the mother is termed fetal lie and is either longitudinal or transverse. Occasionally, the fetal and the maternal axes may cross at a 45-degree angle, forming an oblique lie, which is unstable and always becomes longitudinal or transverse during labor. A longitudinal lie is present in greater than 99 percent of labors at term. Predisposing factors for transverse lies include multiparity, placenta previa, hydramnios, and uterine anomalies

Fetal Presentation

The presenting part is that portion of the fetal body that is either foremost within the birth canal or in closest proximity to it. It can be felt through the cervix on vaginal examination. Accordingly, in longitudinal lies, the presenting part is either the fetal head or breech, creating cephalic and breech presentations, respectively. When the fetus lies with the long axis transversely, the shoulder is the presenting part and is felt through the cervix on vaginal examination

Cephalic Presentation

Such presentations are classified according to the relationship between the head and body of the fetus (Fig. 17-1). Ordinarily, the head is flexed sharply so that the chin is in contact with the thorax. The occipital fontanel is the presenting part, and this presentation is referred to as a vertex or occiput presentation. Much less commonly, the fetal neck may be sharply extended so that the occiput and back come in contact, and the face is foremost in the birth canal—face presentation (see Fig. 20-6). The fetal head may assume a position between these extremes, partially flexed in some cases, with the anterior (large) fontanel, or bregma, presenting—sinciput presentation—or partially extended in other cases, to have a brow presentation (see Fig. 20-8). These latter two presentations are usually transient. As labor progresses, sinciput and brow presentations almost always convert into vertex or face presentations by neck flexion or extension, respectively. Failure to do so can lead to dystocia

The term fetus usually presents with the vertex, most logically because the uterus is piriform or pear shaped. Although the fetal head at term is slightly larger than the breech, the entire podalic pole of the fetus—that is, the breech and its flexed extremities—is bulkier and more mobile than the cephalic pole. The cephalic pole is composed of the fetal head only. Until approximately 32 weeks, the amnionic cavity is large compared with the fetal mass, and there is no crowding of the fetus by the uterine walls. Subsequently, however, the ratio of amnionic fluid volume decreases relative to the increasing fetal mass. As a result, the uterine walls are apposed more closely to the fetal parts.

If presenting by the breech, the fetus often changes polarity to make use of the roomier fundus for its bulkier and more mobile podalic pole. As discussed in Chapter 24 (see Fig. 24-1), the incidence of breech presentation decreases with gestational age. It is approximately 25 percent at 28 weeks, 17 percent at 30 weeks, 11 percent at 32 weeks, and then decreases to approximately 3 percent at term. The high incidence of breech presentation in hydrocephalic fetuses is in accord with this theory, because in this circumstance, the fetal cephalic pole is larger than its podalic pole.

Fetal Attitude or Posture

In the later months of pregnancy the fetus assumes a characteristic posture described as attitude or habitus (see Fig. 17-1). As a rule, the fetus forms an ovoid mass that corresponds roughly to the shape of the uterine cavity. The fetus becomes folded or bent upon itself in such a manner that the back becomes markedly convex; the head is sharply flexed so that the chin is almost in contact with the chest; the thighs are flexed over the abdomen; and the legs are bent at the knees. In all cephalic presentations, the arms are usually crossed over the thorax or become parallel to the sides. The umbilical cord lies in the space between them and the lower extremities. This characteristic posture results from the mode of fetal growth and its accommodation to the uterine cavity.

Abnormal exceptions to this attitude occur as the fetal head becomes progressively more

extended from the vertex to the face presentation (see Fig. 17-1). This results in a prog

ressive change in fetal attitude from a convex (flexed) to a concave (extended) contour of the

vertebral column

Fetal Position

Position refers to the relationship of an arbitrarily chosen portion of the fetal presenting part to the right or left side of the birth canal. Accordingly, with each presentation there may be two positions—right or left. The fetal occiput, chin (mentum), and sacrum are the determining points in vertex, face, and breech presentations, respectively (Figs. 17-2, 17-3, 17-4, 17-5, and 17-6). Because the presenting part may be in either the left or right position, there are left and right occipital, left and right mental, and left and right sacral presentations, abbreviated as LO and RO, LM and RM, and LS and RS, respectively.

Approximately two thirds of all vertex presentations are in the left occiput position, and one

third in the right. In shoulder presentations, the acromion (scapula) is the portion of the fetus ar

bitrarily chosen for orientation with the maternal pelvis. One example of the terminology sometimes employed for this purpose is illustrated in Figure 17-7. The acromion or back of the fetus may be directed either posteriorly or anteriorly and superiorly or inferiorly (see Chap. 20, Transverse Lie). Because it is impossible to differentiate exactly the several varieties of shoulder presentation by clinical examination and because such differentiation serves no practical purpose, it is customary to refer to all transverse lies simply as shoulder presentations. Another term used is transverse lie, with back up or back down.

Diagnosis of Fetal Presentation and Position

Several methods can be used to diagnose fetal presentation and position. These include abdominal palpation, vaginal examination, auscultation, and, in certain doubtful cases, sonography. Occasionally plain radiographs, computed tomography, or magnetic resonance imaging may be used.

Abdominal Palpation—Leopold Maneuvers

Abdominal examination can be conducted systematically employing the four maneuvers described by Leopold in 1894 and shown in Figure 17-8. The mother lies supine and comfortably positioned with her abdomen bared. These maneuvers may be difficult if not impossible to perform and interpret if the patient is obese, if there is excessive amnionic fluid, or if the placenta is anteriorly implanted.

1. The first maneuver permits identification of which fetal pole—that is, cephalic or podalic—occupies the uterine fundus. The breech gives the sensation of a large, nodular mass, whereas the head feels hard and round and is more mobile and ballottable

2. Performed after determination of fetal lie, the second maneuver is accomplishe

d as the palms are placed on either side of the maternal abdomen, and gentle but deep pressure is exerted. On one side, a hard, resistant structure is felt—the back. On the other, numerous small, irregular, mobile parts are felt—the fetal extremities. By noting whether the back is directed anteriorly, transversely, or posteriorly, the orientation of the fetus can be determined

3. The third maneuver is performed by grasping with the thumb and fingers of one hand the lower portion of the maternal abdomen just above the symphysis pubis. If the presenting part is not engaged, a movable mass will be felt, usually the head. The differentiation between head and breech is made as in the first maneuver. If the presenting part is deeply engaged, however, the findings from this maneuver are simply indicative that the lower fetal pole is in the pelvis, and details are then defined by the fourth maneuver

4. To perform the fourth maneuver, the examiner faces the mother's feet and, with the tips of the first three fingers of each hand, exerts deep pressure in the direction of the axis of the pelvic inlet. In many instances, when the head has descended into the pelvis, the anterior shoulder may be differentiated readily by the third maneuver.

Vaginal Examination

Before labor, the diagnosis of fetal presentation and position by vaginal examination is often inconclusive because the presenting part must be palpated through a closed cervix and lower uterine segment. With the onset of labor and after cervical dilatation, vertex presentations and their positions are recognized by palpation of the various fetal sutures and fontanels. Face and breech presentations are identified by palpation of the facial features and the fetal sacrum, respectively.

In attempting to determine presentation and position by vaginal examination, it is advisable to pursue a definite routine, comprising four movements:

1. The examiner inserts two fingers into the vagina and the presenting part is found. Differentiation of vertex, face, and breech is then accomplished readily

2. If the vertex is presenting, the fingers are directed posteriorly and then swept forward over the fetal head toward the maternal symphysis (F

ig. 17-9). During this movement, the fingers necessarily cross the sagittal suture and its course is delineated

3. The positions of the two fontanels then are ascertained. The fingers are passed to the most anterior extension of the sagittal suture, and the fontanel encountered there is examined and identified. Then, with a sweeping motion, the fingers pass along the suture to the other end of the head until the other fontanel is felt and differentiated (Fig. 17-10)

4. The station, or extent to which the presenting part has descended into the pelvis, can also be established at this time (see Cervical Examination). Using these maneuvers, the various sutures and fontanels are located readily

Mechanisms of Labor with Occiput Anterior Presentation

In most cases, the vertex enters the pelvis with the sagittal suture lying in the transverse pelvic diameter. The fetus enters the pelvis in the left occiput transverse (LOT) position in 40 percent of labors and in the right occiput transverse (ROT) position in 20 percent (Caldwell and associates, 1934). In occiput anterior positions—LOA or ROA—the head either enters the pelvis with the occiput rotated 45 degrees anteriorly from the transverse position, or subsequently does so. The mechanism of labor in all these presentations is usually similar.

The positional changes in the presenting part required to navigate the pelvic canal constitute the mechanisms of labor. The cardinal movements of labor are engagement, descent, flexion, internal rotation, extension, external rotation, and expulsion (Fig. 17-11). During labor, these movements not only are sequential but also show great temporal overlap. For example, as part of engagement, there is both flexion and descent of the head. It is impossible for the movements to be completed unless the presenting part descends simultaneously. Concomitantly, uterine contractions effect important modifications in fetal attitude, or habitus, especially after the head has descended into the pelvis. These changes consist principally of fetal straightening, with loss of dorsal convexity and closer application of the extremities to the body. As a result, the fetal ovoid is transformed into a cylinder, with the smallest possible cross section typically passing through the birth canal

Engagement

The mechanism by which the biparietal diameter—the greatest transverse diameter in an occiput presentation—passes through the pelvic inlet is designated engagement. The fetal head may engage during the last few weeks of pregnancy or not until after labor commencement. In many multiparous and some nulliparous women, the fetal head is freely movable above the pelvic inlet at labor onset. In this circumstance, the head is sometimes referred to as "floating." A normal-sized head usually does not engage with its sagittal suture directed anteroposteriorly. Instead, the fetal head usually enters the pelvic inlet either transversely or obliquely.

Asynclitism

Although the fetal head tends to accommodate to the transverse axis of the pelvic inlet, the sagittal suture, while remaining parallel to that axis, may not lie exactly midway between the symphysis and the sacral promontory. The sagittal suture frequently is deflected either posteriorly toward the promontory or anteriorly toward the symphysis (Fig. 17-12). Such lateral deflection to a more anterior or posterior position in the pelvis is called asynclitism. If the sagittal suture approaches the sacral promontory, more of the anterior parietal bone presents itself to the examining fingers, and the condition is called anterior asynclitism. If, however, the sagittal suture lies close to the symphysis, more of the posterior parietal bone will present, and the condition is called posterior asynclitism. With extreme posterior asynclitism, the posterior ear may be easily palpated.

Moderate degrees of asynclitism are the rule in normal labor. However, if severe, the condition is a common reason for cephalopelvic disproportion even with an otherwise normal-sized pelvis. Successive shifting from posterior to anterior asynclitism aids descent.

Descent

This movement is the first requisite for birth of the newborn. In nulliparas, engagement may take place before the onset of labor, and further descent may not follow until the onset of the second stage. In multiparous women, descent usually begins with engagement. Descent is brought about by one or more of four forces: (1) pressure of the amnionic fluid, (2) direct pressure of the fundus upon the breech with contractions, (3) bearing-down efforts of maternal abdominal muscles, and (4) extension and straightening of the fetal body.

Flexion

As soon as the descending head meets resistance, whether from the cervix, walls of the pelvis, or pelvic floor, then flexion of the head normally results. In this movement, the chin is brought into more intimate contact with the fetal thorax, and the appreciably shorter suboccipitobregmatic diameter is substituted for the longer occipitofrontal diameter

Internal Rotation

This movement consists of a turning of the head in such a manner that the occiput gradually moves toward the symphysis pubis anteriorly from its original position or less commonly, posteriorly toward the hollow of the sacrum (Figs. 17-15, 17-16, and 17-17). Internal rotation is essential for the completion of labor, except when the fetus is unusually small.

Calkins (1939) studied more than 5000 women in labor to the time of internal rotation. He concluded that in approximately two thirds, internal rotation is completed by the time the head reaches the pelvic floor; in about another fourth, internal rotation is completed very shortly after the head reaches the pelvic floor; and in the remaining 5 percent, anterior rotation does not take place. When the head fails to turn until reaching the pelvic floor, it typically rotates during the next one or two contractions in multiparas. In nulliparas, rotation usually occurs during the next three to five contractions.

Extension

After internal rotation, the sharply flexed head reaches the vulva and undergoes extension. If the sharply flexed head, on reaching the pelvic floor, did not extend but was driven farther downward, it would impinge on the posterior portion of the perineum and would eventually be forced through the tissues of the perineum. When the head presses upon the pelvic floor, however, two forces come into play. The first force, exerted by the uterus, acts more posteriorly, and the second, supplied by the resistant pelvic floor and the symphysis, acts more anteriorly. The resultant vector is in the direction of the vulvar opening, thereby causing head extension. This brings the base of the occiput into direct contact with the inferior margin of the symphysis pubis

With progressive distension of the perineum and vaginal opening, an increasingly larger portion of the occiput gradually appears. The head is born as the occiput, bregma, forehead, nose, mouth, and finally the chin pass successively over the anterior margin of the perineum (see Fig. 17-17). Immediately after its delivery, the head drops downward so that the chin lies over the maternal anus.

External Rotation

The delivered head next undergoes restitution (see Fig. 17-11). If the occiput was originally directed toward the left, it rotates toward the left ischial tuberosity. If it was originally directed toward the right, the occiput rotates to the right. Restitution of the head to the oblique position is followed by completion of external rotation to the transverse position. This movement corresponds to rotation of the fetal body and serves to bring its bisacromial diameter into relation with the anteroposterior diameter of the pelvic outlet. Thus, one shoulder is anterior behind the symphysis and the other is posterior. This movement apparently is brought about by the same pelvic factors that produced internal rotation of the head

Expulsion

Almost immediately after external rotation, the anterior shoulder appears under the symphysis pubis, and the perineum soon becomes distended by the posterior shoulder. After delivery of the shoulders, the rest of the body quickly passes

Mechanisms of Labor with Occiput Posterior Presentation

In approximately 20 percent of labors, the fetus enters the pelvis in an occiput posterior (OP) position. The right occiput posterior (ROP) is slightly more common than the left (LOP) (Caldwell and associates, 1934). It appears likely from radiographic evidence that posterior positions are more often associated with a narrow forepelvis. They also are more commonly seen in association with anterior placentation (Gardberg and Tuppurainen, 1994a).

In most occiput posterior presentations, the mechanism of labor is identical to that observed in the transverse and anterior varieties, except that the occiput has to internally rotate to the symphysis pubis through 135 degrees, instead of 90 and 45 degrees, respectively (see Fig. 17-17).

With effective contractions, adequate flexion of the head, and a fetus of average size, most posteriorly positioned occiputs rotate promptly as soon as they reach the pelvic floor, and labor is not lengthened appreciably. In perhaps 5 to 10 percent of cases, however, rotation may be incomplete or may not take place at all, especially if the fetus is large (Gardberg and Tuppurainen, 1994b). Poor contractions, faulty flexion of the head, or epidural analgesia, which diminishes abdominal muscular pushing and relaxes the muscles of the pelvic floor, may predispose to incomplete rotation. If rotation is incomplete, transverse arrest may result. If no rotation toward the symphysis takes place, the occiput may remain in the direct occiput posterior position, a condition known as persistent occiput posterior. Both persistent occiput posterior and transverse arrest represent deviations from the normal mechanisms of labor and are considered further in Chapter 20

Caput Succedaneum

In vertex presentations, the fetal head changes shape as the result of labor forces. In prolonged labors before complete cervical dilatation, the portion of the fetal scalp immediately over the cervical os becomes edematous (see Fig. 29-12). This swelling known as the caput succedaneum (Figs. 17-18 and 17-19). It usually attains a thickness of only a few millimeters, but in prolonged labors it may be sufficiently extensive to prevent the differentiation of the various sutures and fontanels. More commonly, the caput is formed when the head is in the lower portion of the birth canal and frequently only after the resistance of a rigid vaginal outlet is encountered. Because it develops over the most dependent area of the head, one may deduce the original fetal head position by noting the location of the caput succedaneum

Molding

The change in fetal head shape from external compressive forces is referred to as molding. Possibly related to Braxton Hicks contractions, some molding develops before labor. Most studies indicate that there is seldom overlapping of the parietal bones. A "locking" mechanism at the coronal and lambdoidal connections actually prevents such overlapping (Carlan and colleagues, 1991). Molding results in a shortened suboccipitobregmatic diameter and a lengthened mentovertical diameter. These changes are of greatest importance in women with contracted pelves or asynclitic presentations. In these circumstances, the degree to which the head is capable of molding may make the difference between spontaneous vaginal delivery and an operative delivery. Some older literature cited severe head molding as a cause for possible cerebral trauma. Because of the multitude of associated factors, for example, prolonged labor with fetal sepsis and acidosis, it is impossible to link molding to any alleged fetal or neonatal neurological sequelae. Most cases of molding resolve within the week.

Characteristics of Normal Labor

The greatest impediment to understanding normal labor is recognizing its start. The strict definition of labor—uterine contractions that bring about demonstrable effacement and dilatation of the cervix—does not easily aid the clinician in determining when labor has actually begun, because this diagnosis is confirmed only retrospectively. Several methods may be used to define its start. One defines onset as the clock time when painful contractions become regular. Unfortunately, uterine activity that causes discomfort, but that does not represent true labor, may develop at any time during pregnancy. False labor often stops spontaneously, or it may proceed rapidly into effective contractions.

A second method defines the onset of labor as beginning at the time of admission to the labor unit. At the National Maternity Hospital in Dublin, efforts have been made to codify admission criteria (O'Driscoll and colleagues, 1984). These criteria at term require painful uterine contractions accompanied by any one of the following: (1) ruptured membranes, (2) bloody "show," or (3) complete cervical effacement.

In the United States, admission for labor is frequently based on the extent of dilatation accompanied by painful contractions. When a woman presents with intact membranes, a cervical dilatation of 3 to 4 cm or greater is presumed to be a reasonably reliable threshold for the diagnosis of labor. In this case, labor onset commences with the time of admission. This presumptive method obviates many of the uncertainties in diagnosing labor during earlier stages of cervical dilatation

1º stage of labor:

1. During the preparatory division, although the cervix dilates little, its connective tissue components change considerably (see Chap. 6, Phase 2 of Parturition: Preparation for Labor). Sedation and conduction analgesia are capable of arresting this division of labor.

2. The dilatational division, during which dilatation proceeds at its most rapid rate, is unaffected by sedation or conduction analgesia.

3. The pelvic division commences with the deceleration phase of cervical dilatation. The classic mechanisms of labor that involve the cardinal fetal movements of the cephalic presentation—engagement, flexion, descent, internal rotation, extension, and external rotation—take place principally during the pelvic division. In actual practice, however, the onset of the pelvic division is seldom clearly identifiable

As shown in Figure 17-20, the pattern of cervical dilatation during the preparatory and dilatational divisions of normal labor is a sigmoid curve. Two phases of cervical dilatation are defined. The latent phase corresponds to the preparatory division, and the active phase, to the dilatational division. Friedman subdivided the active phase into the acceleration phase, the phase of maximum slope, and the deceleration phase (Fig. 17-21).

Latent Phase

The onset of latent labor, as defined by Friedman (1972), is the point at which the mother perceives regular contractions. The latent phase for most women ends at between 3 and 5 cm of dilatation. This threshold may be clinically useful, for it defines cervical dilatation limits beyond which active labor can be expected

Prolonged Latent Phase

Friedman and Sachtleben (1963) defined this by a latent phase exceeding 20 hours in the nullipara and 14 hours in the multipara. These times corresponded to the 95th percentiles. Factors that affected duration of the latent phase included excessive sedation or epidural analgesia; unfavorable cervical condition, that is, thick, uneffaced, or undilated; and false labor. Following heavy sedation, 85 percent of women progressed to active labor. In another 10 percent, uterine contractions ceased, suggesting that they had false labor. The remaining 5 percent experienced persistence of an abnormal latent phase and required oxytocin stimulation. Amniotomy was discouraged because of the 10-percent incidence of false labor

Active Labor

As shown in Figure 17-22, the progress of labor in nulliparous women has particular significance because these curves all reveal a rapid change in the slope of cervical dilatation rates between 3 and 5 cm. Thus, cervical dilatation of 3 to 5 cm or more, in the presence of uterine contractions, can be taken to reliably represent the threshold for active labor. Similarly, these curves provide useful guideposts for labor management

Turning again to Friedman (1955), the mean duration of active-phase labor in nulliparas was 4.9 hours. But the standard deviation of 3.4 hours is large; hence, the active phase was reported to have a statistical maximum of 11.7 hours. Indeed, rates of cervical dilatation ranged from a minimum of 1.2 up to 6.8 cm/hr. Friedman (1972) also found that multiparas progress somewhat faster in active-phase labor, with a minimum normal rate of 1.5 cm/hr. His analysis of active-phase labor concomitantly describes rates of fetal descent and cervical dilatation (see Fig. 17-20). Descent begins in the later stage of active dilatation, commencing at 7 to 8 cm in nulliparas and becoming most rapid after 8 cm.

Abnormalities in this labor phase are common. Sokol and co-workers (1977) reported that 25 percent of nulliparous and 15 percent of multiparous labors were complicated by an active-phase abnormality. Friedman (1972) subdivided active-phase problems into protraction and arrest disorders. He defined protraction as a slow rate of cervical dilatation or descent, which for nulliparas was less than 1.2 cm dilatation per hour or less than 1 cm descent per hour. For multiparas, protraction was defined as less than 1.5 cm dilatation per hour or less than 2 cm descent per hour. He defined arrest as a complete cessation of dilatation or descent. Arrest of dilatation was defined as 2 hours with no cervical change, and arrest of descent as 1 hour without fetal descent.

The prognosis for protraction and arrest disorders differed considerably. Friedman found that approximately 30 percent of women with protraction disorders had cephalopelvic disproportion, compared with 45 percent of women in whom an arrest disorder developed. Factors contributing to both protraction and arrest disorders were excessive sedation, epidural analgesia, and fetal malposition. In both protraction and arrest disorders, Friedman recommended fetopelvic evaluation to identify cephalopelvic disproportion. Recommended therapy for protraction disorders was expectant management, whereas oxytocin was advised for arrest disorders in the absence of cephalopelvic disproportion.

Second Stage of Labor

This stage begins when cervical dilatation is complete and ends with fetal delivery. The median duration is approximately 50 minutes for nulliparas and about 20 minutes for multiparas, but it is highly variable (Kilpatrick and Laros, 1989).

Duration of Labor

Our understanding of the normal duration of labor may be clouded by the many clinical variables that affect conduct of labor in modern obstetrical units. Kilpatrick and Laros (1989) reported that the mean length of first- and second-stage labor was approximately 9 hours in nulliparous women without regional analgesia, and that the 95th percentile upper limit was 18.5 hours. Corresponding times for multiparous women were a mean of 6 hours with a 95th percentile maximum of 13.5 hours. These authors defined labor onset as the time when a woman recalled regular, painful contractions every 3 to 5 minutes that led to cervical change

Admission Procedures

Pregnant women should be urged to report early in labor rather than to procrastinate until delivery is imminent for fear that they might be experiencing false labor. Early admittance to the labor and delivery unit is important, especially if during antepartum care the woman, her fetus, or both have been identified as being at risk

Among 768 women studied at Parkland Hospital, active labor defined as cervical dilatation 4 cm was diagnosed within 24 hours in three fourths of women with 12 or more contractions per hour. Bailit and colleagues (2005) compared labor outcomes of 6121 women who presented in active labor defined as uterine contractions plus cervical dilatation 4 cm with those of 2697 women who presented in the latent phase. Women admitted during latent-phase labor had more active-phase arrest, need for oxytocin labor stimulation, and chorioamnionitis. It was concluded that physician interventions in women presenting in the latent phase may have been the cause of subsequent labor abnormalities

+management of 1º stage

As discussed in Chapter 18, Electronic Fetal Monitoring, electronic fetal heart rate monitoring is routinely used for high-risk pregnancies commencing at admission. Some investigators recommend monitoring women with low-risk pregnancies upon admission as a test of fetal well-being—the so-called fetal admission test.

Most often, unless there has been bleeding in excess of bloody show, a vaginal examination is performed. The gloved index and second fingers are then introduced into the vagina while avoiding the anal region (Fig. 17-23). The number of vaginal examinations correlates with infection-related morbidity, especially in cases of early membrane ruptura.

The woman should be instructed during the antepartum period to be aware of fluid leakage from the vagina and to report such an event promptly. Rupture of the membranes is significant for three reasons. First, if the presenting part is not fixed in the pelvis, the possibility of umbilical cord prolapse and compression is greatly increased. Second, labor is likely to begin soon if the pregnancy is at or near term. Third, if delivery is delayed after membrane rupture, intrauterine infection is more likely as the time interval increases. A pH above 6.5 is consistent with ruptured membranes.

Cervical Examination

The degree of cervical effacement usually is expressed in terms of the length of the cervical canal compared with that of an uneffaced cervix. When the length of the cervix is reduced by one half, it is 50-percent effaced. When the cervix becomes as thin as the adjacent lower uterine segment, it is completely, or 100-percent, effaced

Cervical dilation

The position of the cervix is determined by the relationship of the cervical os to the fetal head and is categorized as posterior, midposition, or anterior. Along with position, the consistency of cervix is determined to be soft, firm, or intermediate between these two.

The level—or station—of the presenting fetal part in the birth canal is described in relationship to the ischial spines, which are halfway between the pelvic inlet and the pelvic outlet. When the lowermost portion of the presenting fetal part is at the level of the spines, it is designated as being at zero (0) station. In the past, the long axis of the birth canal above and below the ischial spines was arbitrarily divided into thirds by some and into fifths (approximately 1 cm) by other groups. In 1989, the American College of Obstetricians and Gynecologists adopted the classification of station that divides the pelvis above and below the spines into fifths. Each fifth represents a centimeter above or below the spines. Thus, as the presenting fetal part descends from the inlet toward the ischial spines, the designation is –5, –4, –3, –2, –1, then 0 station. Below the spines, as the presenting fetal part descends, it passes +1, +2, +3, +4, and +5 stations to delivery. Station +5 cm corresponds to the fetal head being visible at the introitus. If the leading part of the fetal head is at 0 station or below, most often the fetal head has engaged—thus, the biparietal plane has passed through the pelvic inlet. If the head is unusually molded or if there is an extensive caput formation or both, engagement might not have taken place although the head appears to be at 0 station.

When the woman is admitted in labor, most often the hematocrit or hemoglobin concentration should be rechecked. We obtain a urine specimen for protein determination in hypertensive women only.

Management of the First Stage of Labor

This is discussed in detail in Chapter 18. Briefly, the American Academy of Pediatrics and American College of Obstetricians and Gynecologists (2007) recommend that during the first stage of labor, in the absence of any abnormalities, the fetal heart rate should be checked immediately after a contraction at least every 30 minutes and then every 15 minutes during the second stage.

Uterine Contractions

Although usually assessed by electronic monitoring as also discussed in Chapter 18, contractions can be both quantitatively and qualitatively evaluated manually. With the palm of the hand resting lightly on the uterus, the time of contraction onset is determined. Its intensity is gauged from the degree of firmness the uterus achieves. At the acme of effective contractions, the finger or thumb cannot readily indent the uterus during a "firm" contraction. The time at which the contraction disappears is noted next. This sequence is repeated to evaluate the frequency, duration, and intensity of uterine contractions.

Maternal Vital Signs

Food should be withheld during active labor and delivery

IV fluids??? Shrivastava and associates (2009) noted shorter labors in nulliparas delivering vaginal who were provided an intravenous normal saline (NS) with dextrose solution compared with those given NS solution only

Any maternal position

Bladder distension should be avoided because it can hinder descent of the fetal presenting part and lead to subsequent bladder hypotonia and infection. During each abdominal examination, the suprapubic region should be inspected and palpated to detect distension. If the bladder is readily seen or palpated above the symphysis, the woman should be encouraged to void. At times, she can ambulate with assistance to a toilet and successfully void, even though she cannot void on a bedpan. If the bladder is distended and she cannot void, catheterization is indicated

Management of the Second Stage of Labor

With full cervical dilatation, which signifies the onset of the second stage, a woman typically begins to bear down. With descent of the presenting part, she develops the urge to defecate. Uterine contractions and the accompanying expulsive forces may now last 11/2 minutes and recur at an interval no longer than 1 minute. As discussed in Second Stage of Labor, the median duration of the second stage is 50 minutes in nulliparas and 20 minutes in multiparas, although the interval can be highly variable

Expulsive Efforts

In most cases, bearing down is reflexive and spontaneous during second-stage labor. Occasionally, a woman may not employ her expulsive forces to good advantage and coaching is desirable. Her legs should be half-flexed so that she can push with them against the mattress. When the next uterine contraction begins, she is instructed to exert downward pressure as though she were straining at stool. In a randomized study from Istanbul, Yildirim and Beji (2008) reported that open-glottis pushing while breathing out was superior to the closed-glottis breath-held Valsalva-type pushing. The former method resulted in a shorter second stage and better cord acid-base values. A woman is not encouraged to push beyond the completion of each contraction. Instead, she and her fetus should be allowed to rest and recover. During this period of actively bearing down, the fetal heart rate auscultated immediately after the contraction is likely to be slow but should recover to normal range before the next expulsive effort

They found that the supported upright position had no advantages over the recumbent one. As the head descends through the pelvis, feces frequently are expelled by the woman. With further descent, the perineum begins to bulge and the overlying skin becomes stretched. Now the scalp of the fetus may be visible through the vulvar opening. At this time, the woman and her fetus are prepared for delivery.

Spontaneus delivery- delivery of the head. With each contraction, the perineum bulges increasingly. The vulvovaginal opening is dilated by the fetal head (Fig. 17-24), gradually forming an ovoid and, finally, an almost circular opening (Fig. 17-25). This encirclement of the largest head diameter by the vulvar ring is known as crowning. Unless an episiotomy has been made as described later, the perineum thins and especially in nulliparous women, may undergo spontaneous laceration. Slow delivery of the head while instructing the mother not to push may decrease lacerations according to Laine and co-workers (2008). The anus becomes greatly stretched and protuberant, and the anterior wall of the rectum may be easily seen through it.

Ritgen Maneuver

When the head distends the vulva and perineum enough to open the vaginal introitus to a diameter of 5 cm or more, a towel-draped, gloved hand may be used to exert forward pressure on the chin of the fetus through the perineum just in front of the coccyx. Concurrently, the other hand exerts pressure superiorly against the occiput (Fig. 17-26). This maneuver is simpler than that originally described by Ritgen (1855), and it is customarily designated the modified Ritgen maneuver

They preferred the "hands-poised" method, in which the attendant did not touch the perineum during delivery of the head. This method had similar associated laceration rates as the modified Ritgen maneuver, but with a lower incidence of third-degree tears.

Most often, the shoulders appear at the vulva just after external rotation and are born spontaneously. If delayed, immediate extraction may appear advisable. The sides of the head are grasped with two hands, and gentle downward traction is applied until the anterior shoulder appears under the pubic arch (Fig. 17-29). Some prefer to deliver the anterior shoulder prior to suctioning the nasopharynx or checking for a nuchal cord to avoid shoulder dystocia. Next, by an upward movement, the posterior shoulder is delivered. Hooking the fingers in the axillae should be avoided. This may injure the nerves of the upper extremity and produce a transient or possibly permanent paralysis. Traction, furthermore, should be exerted only in the direction of the long axis of the neonate. If applied obliquely, it causes bending of the neck and excessive stretching of the brachial plexus.

Clear the nasopharinx

Nuchal Cord

Following delivery of the anterior shoulder, a finger should be passed to the fetal neck to determine whether it is encircled by one or more coils of the umbilical cord (Fig. 17-30). A nuchal cord is found in approximately 25 percent of deliveries and ordinarily causes no harm. If a coil of umbilical cord is felt, it should be slipped over the head if loose enough. If applied too tightly, the loop should be cut between two clamps and the neonate promptly delivered

Clamping the Cord

The umbilical cord is cut between two clamps placed 4 to 5 cm from the fetal abdomen, and later an umbilical cord clamp is applied 2 to 3 cm from the fetal abdomen. A plastic clamp that is safe, efficient, and fairly inexpensive, such as the Double Grip Umbilical Clamp

Timing of Cord Clamping

If after delivery the newborn is placed at or below the level of the vaginal introitus for 3 minutes and the fetoplacental circulation is not immediately occluded by cord clamping, an average of 80 mL of blood may be shifted from the placenta to the neonate (Yao and Lind, 1974). This provides approximately 50 mg of iron, which reduces the frequency of iron-deficiency anemia later in infancy. At the same time, however, increased bilirubin from the added erythrocytes contributes further to hyperbilirubinemia (see Chap. 29, Hyperbilirubinemia). In their recent Cochrane Database review of randomized trials, McDonald and Middleton (2008) reported that delaying cord clamping until 1 minute after birth increased the newborn hemoglobin concentration 2.2 g/dL compared with clamping within the first 60 seconds. At the same time, early clamping reduced the risk of phototherapy by 40 percent.

Our policy is to clamp the cord after first thoroughly clearing the airway, all of which usually requires approximately 30 seconds. The newborn is not elevated above the introitus at vaginal delivery or much above the maternal abdominal wall at the time of cesarean delivery

Management of the Third Stage of Labor

Immediately after delivery of the newborn, the size of the uterine fundus and its consistency are examined. If the uterus remains firm and there is no unusual bleeding, watchful waiting until the placenta separates is the usual practice. Massage is not employed, but the fundus is frequently palpated to make certain that it does not become atonic and filled with blood from placental separation.

Signs of Placental Separation

Because attempts to express the placenta prior to its separation are futile and possibly dangerous, the clinician should be alert to the following signs of placental separation:

1. The uterus becomes globular and as a rule, firmer

2. There is often a sudden gush of blood

3. The uterus rises in the abdomen because the placenta, having separated, passes down into the lower uterine segment and vagina. Here, its bulk pushes the uterus upward

4. The umbilical cord protrudes farther out of the vagina, indicating that the placenta has descended.

These signs sometimes appear within 1 minute after delivery of the newborn and usually within 5 minutes. When the placenta has separated, it should be determined that the uterus is firmly contracted. The mother may be asked to bear down, and the intra-abdominal pressure may be adequate to expel the placenta. If these efforts fail or if spontaneous expulsion is not possible because of anesthesia, then after ensuring that the uterus is contracted firmly, pressure is exerted with the hand on the fundus to propel the detached placenta into the vagina, as depicted and described in Figure 17-31. This approach has been termed physiological management as later contrasted with active management of the third stage .

Delivery of the Placenta

Expression of the placenta should never be forced before placental separation lest the uterus becomes inverted. Traction on the umbilical cord must not be used to pull the placenta out of the uterus. Uterine inversion is one of the grave complications associated with delivery, and it constitutes an emergency requiring immediate attention (see Chap. 35, Inversion of the Uterus). As downward pressure toward the vagina is applied to the body of the uterus, the umbilical cord is kept slightly taut (see Fig. 17-31). The uterus is then lifted cephalad with the abdominal hand. This maneuver is repeated until the placenta reaches the introitus (Prendiville and associates, 1988b). As the placenta passes through the introitus, pressure on the uterus is stopped. The placenta is then gently lifted away from the introitus (Fig. 17-32). Care is taken to prevent the membranes from being torn off and left behind. If the membranes start to tear, they are grasped with a clamp and removed by gentle teasing (Fig. 17-33). The maternal surface of the placenta should be examined carefully to ensure that no placental fragments are left in the uterus

Manual Removal of Placenta

Occasionally, the placenta will not separate promptly. This is especially common in cases of preterm delivery (Dombrowski and colleagues, 1995). If there is brisk bleeding and the placenta cannot be delivered by the above technique, manual removal of the placenta is indicated, using the safeguards described in Chapter 35, Technique of Manual Placental Removal. It is unclear as to the length of time that should elapse in the absence of bleeding before the placenta is manually removed (Deneux-Tharaux and co-workers, 2009). If induction analgesia is still intact, some obstetricians practice routine manual removal of any placenta that has not separated spontaneously by the time they have completed delivery of the newborn and care of the cord. Proof of the benefits of this practice, however, has not been established, and most obstetricians await spontaneous placental separation unless bleeding is excessive. The American College of Obstetricians and Gynecologists (2003b) has concluded that there are no data to either support or refute the use of prophylactic antimicrobials when manual removal is performed

Management of the Third Stage

Uterine massage following placental delivery is recommended by many to prevent postpartum hemorrhage. We support this but note that evidence for this practice is lacking (Hofmeyr and associates, 2008). Oxytocin, ergonovine, and methylergonovine are all employed widely in the normal third stage of labor, but the timing of their administration differs in various institutions. Oxytocin, and especially ergonovine, given before delivery of the placenta will decrease blood loss (Prendiville and associates, 1988a). If they are given before delivery of the placenta, however, they may entrap an undiagnosed, undelivered second twin. However, Jackson and colleagues (2001) randomly assigned 1486 women to infusions of 20 units of oxytocin diluted in 500 mL normal saline begun before or after placental delivery and found no differences in outcomes.

If an intravenous infusion is in place, our standard practice has been to add 20 units (2 mL) of oxytocin per liter of infusate. This solution is administered after delivery of the placenta at a rate of 10 mL/min (200 mU/min) for a few minutes until the uterus remains firmly contracted and bleeding is controlled. The infusion rate then is reduced to 1 to 2 mL/min until the mother is ready for transfer from the recovery suite to the postpartum unit. The infusion is usually then discontinued

Oxitocin: Mean pulse rate increased 28 bpm, mean arterial pressure decreased 33 mm Hg, and electrocardiogram changes of myocardial ischemia as well as chest pain and subjective discomfort were noted. These hemodynamic changes could be dangerous for women hypovolemic from hemorrhage or those with cardiac disease. Thus, oxytocin should not be given intravenously as a large bolus. Rather, it should be given as a dilute solution by continuous intravenous infusion or as an intramuscular injection in a dose of 10 USP units. In cases of postpartum hemorrhage, direct injection into the uterus, either transvaginally or transabdominally, following a vaginal birth or cesarean delivery has proven effective.

The use of nipple stimulation in the third stage of labor also has been shown to increase uterine pressures and to decrease third-stage duration and blood loss (Irons and associates, 1994). Indeed, results were similar to those achieved using the combination of oxytocin (5 units) and ergometrine (0.5 mg).

Prostaglandins

Analogs of prostaglandins are not used routinely for management of third-stage labor. Villar and colleagues (2002) reviewed prophylactic use of misoprostol to prevent postpartum hemorrhage and concluded that oxytocin or oxytocin-ergot preparations are more effective

First-degree lacerations involve the fourchette, perineal skin, and vaginal mucous membrane but not the underlying fascia and muscle (Fig. 17-34). These included periurethral lacerations, which may bleed profusely. Second-degree lacerations involve, in addition, the fascia and muscles of the perineal body but not the anal sphincter. These tears usually extend upward on one or both sides of the vagina, forming an irregular triangular injury. Third-degree lacerations extend farther to involve the anal sphincter. A fourth-degree laceration extends through the rectum's mucosa to expose its lumen.

Perineal tears may follow any vaginal delivery, but Combs and associates (1990) identified factors associated with an increased risk of third- and fourth-degree lacerations. These include midline episiotomy, nulliparity, second-stage arrest of labor, persistent occiput posterior position, mid or low forceps, use of local anesthetics, and Asian race.

Haemolacria

Rockwood (Tennessee, USA): Calvino Inman had just stepped out of the shower one evening in May when a glimpse of his reflection in the mirror caused him to panic.

"I looked up and saw myself, and I thought I was going to die," says the 15-year-old from Rockwood, Tennessee. His eyes were streaming tears of blood.

Inman's mother, Tammy Mynatt, says she immediately rushed him to the emergency room, but by the time they arrived, the bleeding had stopped. Doctors couldn't see what the family was trying to explain.

They returned home completely perplexed. When the bloody tears returned a few days later while Inman was on a camping trip, he was rushed back to the hospital.

Mynatt hoped that once doctors finally witnessed the phenomenon, there would be answers. But that wasn't the case. "The people at the hospital said they had never seen anything like it," Mynatt recalls. She says her son underwent an MRI, a CT scan and an ultrasound, but none of the tests had abnormal results. "'We don't know how to stop it,'" Mynatt remembers being told by doctors. "It just has to run its course."

Dr. Barrett G. Haik, director of the University of Tennessee's Hamilton Eye Institute, says there is an answer, sort of. He says "crying blood," a condition called haemolacria, is common in people who have experienced extreme trauma or who have recently had a serious head injury. But a case such as Inman's is still a medical mystery. "What's really rare is to have a child like this," Haik says. "Only once every several years do you see someone with no obvious cause."

Haik and a team of researchers published a 2004 study in the Journal of the American Society of Ophthalmic Plastic and Reconstructive Surgery looking specifically at children who developed unexplained, spontaneous episodes of bloody tears between February 1992 and January 2003. Only four cases were recorded.

Because of the rarity of the condition, experts anticipate Inman will have multiple tests from a variety of specialists, including hematologists (blood specialists), ophthalmologists (eye specialists) and otolaryngologists (ear, nose and throat specialists).

Dr. James C. Flemming, also an ophthalmologist at the Hamilton Eye Institute, has been in touch with Mynatt and her son. He is reviewing Inman's medical records for possible treatment.

Flemming says complications to look for include blood clots, a growth or tumor near the eye, or even a simple infection. He also says the culprit could be something so tiny that none of the standard tests would pick it up. "It's a very hard thing to estimate," Flemming says. "You may have to watch expectedly for other symptoms to show up."

Inman's analysis would also include a psychological evaluation to rule out the possibility that the bloody tears were faked. "When you can't find an origin, you can't eliminate any of the possibilities" Haik explains. He says there have been cases where children seeking attention have found creative ways to simulate haemolacriatic symptoms.

Still, Mynatt and her son are relieved to at least have more guidance. In an interview with CNN affiliate WATE, Mynatt was near tears herself explaining her frustration: "I just truly want somebody to say they've seen this and they can help us."

And that's at least one reassurance Flemming and his team of experts at the Hamilton Eye Institute can offer. "We get more positive talk now than negative. It really feels like there's hope," Mynatt says, relieved.

But still, the possibility remains that after endless tests, the underlying cause may never be found. In all four cases Haik examined previously, the bleeding stopped on its own.

"As physicians, that's disconcerting, because we like to have the answers," Haik admits. Moreover, he says he knows from previous experience that the toll of not knowing is much worse for patients. "I could always see the fear in their faces because no matter what we studied, we couldn't find an answer."

Tuberous sclerosis complex (Bourneville disease) - Merritt's Neurology Review

Tuberous Sclerosis Complex

Arnold P. Gold

Marc C. Patterson

Tuberous sclerosis complex (TSC) was first described by von Recklinghausen in 1863. In 1880, Bourneville coined the term sclérose tubéreuse for the potato-like lesions in the brain. In 1890, Pringle described the facial nevi, or adenoma sebaceum. Vogt later emphasized the classic triad of seizures, mental retardation, and adenoma sebaceum. TSC is called Pringle disease when there are only dermatologic findings, Bourneville disease when the nervous system is affected, and West syndrome when skin lesions are associated with infantile spasms, hypsarrhythmia, and mental retardation. TSC (MIM 191100) is a progressive genetic disorder characterized by the development in early life of hamartomas, malformations, and congenital tumors of the CNS, skin, and viscera.

GENETICS AND INCIDENCE

Tuberous sclerosis is inherited as an autosomal dominant trait, with a high incidence of sporadic cases and protean clinical expression. These features are attributed to modifier genes, for which the homozygous condition results in a phenotypically normal individual despite the presence of the gene for tuberous sclerosis; when heterozygous, the modifier gene results in a mildly affected patient. The defective gene has been mapped to chromosome 9q34 (TSC1) in some families and to chromosome 16p13.3 (TSC2) in others. TSC1 or TSC2 is mutated in 75% to 85% of TSC patients; no mutation is found in 15%. Hamartin is the gene product for TSC1, and tuberin is the gene product for TSC2. Children with TSC2 mutations tend to have more serious neurologic manifestations when compared with those with TSC1. Both are involved in the regulation of cell growth and are considered tumor suppressor genes. Hamartin and tuberin form a complex that functions as a negative regulator of the insulin receptor/phosphoinositide 3-kinase/S6 kinase pathway, which suppresses tumorigenesis. Understanding this pathway may lead to targeted drug therapies.

Incidence figures are considered minimal because milder varieties are often unrecognized. Autopsy data gave an incidence of 1 in 6,000 people; clinical surveys gave a prevalence between 1 in 10,000 and 1 in 170,000. Although all races are affected, the disease is thought to be uncommon in blacks, and there may be a greater frequency in males. Pulmonary lymphangiomyomatosis, progressive and often fatal, is present only in young women.

PATHOLOGY AND PATHOGENESIS

The pathologic changes are widespread and include lesions in the nervous system, skin, bones, retina, kidney, lungs, and other viscera. Tuberous sclerosis is a migrational disorder. Multiple small nodules often line the ventricles.

TSC is characterized by the presence of hamartias and hamartomas. Hamartias (from the Greek for “tragic flaw”) are malformations in which cells native to a tissue show abnormal architecture and morphology. These lesions do not grow disproportionately for the tissue or organ in which they are found. Hamartomas have the same characteristics, but grow excessively for their site of origin. This old concept is valuable in recognizing the proliferative potential of lesions found in TSC. Thus, cortical tubers are hamartias and do not grow excessively, whereas angiomyolipomas are hamartomas that grow disproportionately and may produce symptoms as a consequence.

The brain is usually normal in size, but variable numbers of hard nodules occur on the surface of the cortex. These nodules are smooth, round, or polygonal and project slightly above the surface of the neighboring cortex. They are white, firm to the touch, and of various sizes. Some involve only a small portion of one convolution; others encompass the convolutions of one whole lobe or a major portion of a hemisphere. In addition, there may be developmental anomalies of the cortical convolutions in the form of pachygyria or microgyria. On sectioning of the hemispheres, sclerotic nodules may be found in the subcortical gray matter, the white matter, and the basal ganglia. The lining of the lateral ventricles is frequently the site of numerous small nodules that project into the ventricular cavity (candle gutterings; Fig. 109.1). Sclerotic nodules are less frequently found in the cerebellum. The brain stem and spinal cord are rarely involved.

Histologically, the nodules are characterized by a cluster of atypical glial cells in the center and giant cells in the periphery. Calcifications are relatively frequent. Other features include heterotopia, vascular hyperplasia (sometimes with actual angiomatous malformations), disturbances in the cortical architecture, and, occasionally, development of subependymal giant cell astrocytomas. Intracranial giant aneurysm and arterial ectasia are uncommon findings.

The skin lesions are multiform and include the characteristic facial nevi (adenoma sebaceum) and patches or plaques of skin fibrosis, typically localized to the frontal area. The facial lesions are not adenomas of the sebaceous glands, but rather, small hamartomas arising from nerve elements of the skin combined with hyperplasia of connective tissue and blood vessels (Fig. 109.2). In late childhood, lesions similar to those on the face are found around or underneath the fingernails and toenails (ungual fibroma). Circumscribed areas of hypomelanosis or depigmented nevi are common in tuberous sclerosis and are often found in infants. Although these depigmented nevi are less specific than the adenoma sebaceum, they are important in raising suspicion for the diagnosis in infants with seizures. Histologically, the skin appears normal except for the loss of melanin, but ultrastructural studies show that melanosomes are small and have reduced content of melanin.

The retinal lesions are small congenital tumors (phakomas) composed of glia, ganglion cells, or fibroblasts. Glioma of the optic nerve has been reported.

Other lesions include cardiac rhabdomyoma; renal angiomyolipoma, renal cysts, and, rarely, renal carcinoma; cystic disease of the lungs and pulmonary lymphangioleiomyomatosis; hepatic angiomas and hamartomas; skeletal abnormalities with localized areas of osteosclerosis in the calvarium, spine, pelvis, and limbs; cystic defects involving the phalanges; and periosteal new bone formation confined to the metacarpals and metatarsals.

SYMPTOMS AND SIGNS

The cardinal features of tuberous sclerosis are skin lesions, convulsive seizures, and mental retardation. The disease is characterized by variability and expressivity of the clinical manifestations and is often age related: the symptomatic neonate with cardiac rhabdomyoma and heart failure; the infant with hypomelanotic macules and infantile spasms; preschool and school-age children with adenoma sebaceum, developmental delay, learning disability or retardation, and seizures; and adults with migrational dermatologic lesions, subungual fibromas, seizures, and often retardation.

CUTANEOUS FINDINGS

Depigmented or hypomelanotic macules are the earliest skin lesion (Fig. 109.3). They are present at birth, persist through life, and may be found only with a Wood lamp examination. The diagnosis is suggested if there are three or more macules measuring 1 cm or more in length. Numerous small macules sometimes resemble confetti or depigmented freckles. Most macules are leaf shaped, resembling the leaf of the European mountain ash tree and sometimes following a dermatomal distribution. Facial adenoma sebaceum (facial angiofibroma) is never present at birth but is clinically evident in more than 90% of affected children by age 4. At first, the facial lesion is the size of a pinhead and red because of the angiomatous component. It is distributed symmetrically on the nose and cheeks in a butterfly distribution. The lesions may involve the forehead and chin but rarely involve the upper lip. They gradually increase in size and become yellowish and glistening. Shagreen patches, connective tissue hamartomas, are also characteristic. Rarely present in infancy, the patches become evident after age 10. Usually found in the lumbosacral region, shagreen patches are yellowish-brown elevated plaques that have the texture of pigskin (from which the name originated in French). Other skin lesions include café au lait spots, small fibromas that may be tiny and resemble coarse gooseflesh, and ungual fibromas that appear after puberty.

Neurologic Findings

Seizures and mental retardation indicate a diffuse encephalopathy. Infantile myoclonic spasms with or without hypsarrhythmia are the characteristic seizures in young infants and, when associated with hypopigmented macules, are diagnostic of tuberous sclerosis. The older child or adult has generalized tonic-clonic or partial complex seizures. There is a close relationship between the onset of seizures at a young age and mental retardation. Mental retardation rarely occurs without clinical seizures, but intellect may be normal, despite seizures. Other than delayed acquisition of developmental milestones, intellectual impairment, or nonspecific language or coordinative deficiencies, the formal neurologic examination is typically nonfocal. TSC is a major cause of autism which is related to cortical and subcortical dysfunction.

Ophthalmic Findings

Hamartomas of the retina or optic nerve are observed in about 50% of patients. Two types of re tinal lesions are seen on fundoscopy: first, the easily recognized calcified hamartoma near or at the disc with an elevated multinodular lesion that resembles mulberries, grains of tapioca, or salmon eggs (Fig. 109.4), and second, the less distinct, relatively flat, smooth-surfaced, white or salmon-colored, circular or oval lesion located peripherally in the retina (Fig. 109.5). Nonretinal lesions may range from the specific depigmented lesion of the iris (Fig. 109.6) to nonspecific, nonparalytic strabismus; optic atrophy; visual-field defects; or cataracts.

Visceral and Skeletal Findings

Renal lesions include hamartomas (angiomyolipomas) and hamartias (renal cysts). Typically, both are multiple, bilateral, and usually innocuous and silent. Renal angiomyolipomas grow and occasionally bleed, but most can be followed with annual CT scans. Renal cell carcinoma is a rare complication in the older child or adult. In one series, there was a 50% incidence of tuberous sclerosis in patients with cardiac rhabdomyoma. Often asymptomatic, this cardiac tumor may be symptomatic at any age and in infancy can result in death.

Pulmonary hamartomas consisting of multifocal alveolar hyperplasia associated with cystic lymphangioleiomyomatosis occur in fewer than 1% of patients. These become symptomatic (often with a spontaneous pneumothorax) in women in the third or fourth decade and are progressive, often leading to death. Hamartomatous hemangiomas of the spleen and racemose angiomas of the liver are rare and usually asymptomatic. Sclerotic lesions of the calvarium and cystic lesions of the metacarpals and phalanges are asymptomatic. Enamel pitting of the deciduous teeth may aid in diagnosis.

LABORATORY DATA

Unless renal lesions are present, routine laboratory studies are normal. Renal angiomyolipomas are usually asymptomatic and rarely cause gross hematuria, but they may show albuminuria and microscopic hematuria. Sonography (Fig. 109.7), angiography, and CT are often diagnostic. Multiple or diffuse renal cysts may be associated with albuminuria or azotemia and hypertension. Intravenous pyelography is diagnostic.

Chest radiographs may reveal pulmonary lesions or rhabdomyoma with cardiomegaly. ECG findings are variable, but the echocardiogram is diagnostic.

Skull radiographs usually reveal small calcifications within the substance of the cerebrum (Fig. 109.8). The CSF is normal, except when a large intracerebral tumor is present. The EEG is often abnormal, especially in patients with clinical seizures. Abnormalities include slow-wave activity and epileptiform discharges such as hypsarrhythmia, focal or multifocal spike or sharp-wave discharges, and generalized spike-and-wave discharges. CT is diagnostic when calcified subependymal nodules encroach on the lateral ventricle (often in the region of the foramen of Monro); there may also be calcified cortical or cerebellar nodules (Fig. 109.9). A few nodules appear isodense on CT and are better visualized on MRI. Fluidattenuated inversion recovery (FLAIR) provides more accurate delineation of cortical and subcortical tubers. Calcified periventricular and cortical lesions have been visualized shortly after birth. The number of cortical tubers often correlates with the severity of cortical dysfunction. There is enough variation in clinical outcome that prognosis cannot be based on cortical tuber count alone. PET often reveals hypometabolic regions that are not noted on MRI, indicating a more extensive disturbance of cerebral function.

Diagnostic Criteria (2 majors or one major plus one minor criteria)

DIAGNOSIS

Clinical diagnosis is possible at most ages. In infancy, three or more characteristic depigmented cutaneous lesions suggest the diagnosis, and this is reinforced in the presence of infantile myoclonic spasms. In the older child or adult, the diagnosis is made by the triad of tuberous sclerosis: facial adenoma sebaceum, epilepsy, and mental retardation. Retinal or visceral lesions may be diagnostic. The disease, however, is noted for the protean manifestations, and the family history may be invaluable in establishing the diagnosis, which is often reinforced by CT or MRI lesions. Internatal diagnosis of TSC by fetal ultrasound and MRI is suggested by the presence of a cardiac rhabdomyoma and cortical tubers. Prenatal diagnosis is available for both TSC1 and TSC2.

The differential diagnosis includes other neurocutaneous syndromes that are differentiated by their characteristic skin lesions. Multisystem involvement may complicate the diagnosis of tuberous sclerosis. The National Tuberous Sclerosis Association has developed a classification of diagnostic criteria (Table 109.1), and the Tuberous Sclerosis Complex Consensus Conference (Table 109.2) provided an additional classification.

COURSE AND PROGNOSIS

Mild or solely cutaneous involvement often follows a static course, whereas patients with the full-blown syndrome have a progressive course with increasing seizures and dementia. The child with infantile myoclonic spasms is at great risk of later intellectual deficit. Brain tumor, status epilepticus, renal insufficiency, cardiac failure, or progressive pulmonary impairment can lead to death.

TREATMENT

There is no specific treatment. The cutaneous lesions do not compromise function, but cosmetic surgery may be indicated for facial adenoma sebaceum or large shagreen patches. Infantile myoclonic spasms respond to corticosteroid or corticotropin therapy; currently, vigabatrin is the drug of choice. Focal and generalized seizures are treated with anticonvulsants. Patients with unilateral seizures and minimal developmental delay may experience long-term seizure control following surgical resection of epileptogenic tubers. Oral rapamycin has been shown to cause regression of astrocytomas associated with TSC and may eventually be an alternative to operative therapy. Progressive cystic renal disease often responds to surgical decompression, but with renal failure, dialysis or renal transplantation may be necessary. Intramural cardiac rhabdomyoma and complicating congestive heart failure are managed medically with cardiotonics, diuretics, and salt restriction. Whole obstructive intracavity tumors and congestive heart failure require surgical extirpation of the tumor. Progressive pulmonary involvement is an indication for respiratory therapy, but response is poor and most patients die a few years after the onset of this complication.

Amyand's hernia

An 84-year-old man presented with a 5-day history of swelling and discomfort in the right inguinal region, which was followed by 24 hours of generalized abdominal pain, nausea, and vomiting. Computed tomographic imaging of the abdomen revealed an inflamed appendix within a right-sided indirect inguinal hernia (shown in a reconstructed coronal image). The edematous appendix measured 2.1 cm in diameter, contained an appendicolith (arrow), and was accompanied by a fluid collection extending from the inguinal canal into the scrotum. An inguinal hernia sac containing a vermiform appendix is known as Amyand's hernia. Claudius Amyand, sergeant-surgeon to King George II of England, is credited by some with performing the first documented successful appendectomy, in which he removed a perforated appendix from a right inguinal hernia sac in 1735. Our patient was initially treated with antibiotics and drainage of the right scrotal fluid collection. Five days later, he underwent successful appendectomy and hernia repair