Exstrophy of the bladder has been recognized for centuries, but it was not until the 19th century that surgical correction was first attempted (Hall et al., 1953). The first attempts at diversion of urine into the colon were made in 1850, and the first successful closure of bladder exstrophy was performed in 1862 (Canning et al., 1996). In contrast to patients with cloacal exstrophy that have other unrelated abnormalities, infants with bladder exstrophy have defects confined to the bladder, abdominal wall, perineum, genitalia, and bony pelvis.

At birth the diagnosis of bladder exstrophy is easily made by the presence of characteristic findings. The bladder plate protrudes immediately beneath the umbilical cord (Figure 65-1). The rectus muscles are divergent due to separated pubic bones. There is an outward rotation of the innominate bones and eversion of the pubic rami (Sponsellor et al., 1991). The phallus is short, with a dorsal urethral plate, splayed glans, and dorsal chordee. In females, the mons pubis, clitoris, and labia are separated and the vaginal orifice may be displaced anteriorly. Bilateral inguinal hernias are commonly seen at birth because of the large internal and external inguinal ring caused by the splaying of the rectus musculature and lack of obliquity of the inguinal canal. Hussman et al., (1990) reported that 56% of males and 15% of females have inguinal hernias. In a report by Peppas et al., (1995) in patients presenting with hernia within one year of primary closure, 10%–53% of the hernias were incarcerated.

In bladder exstrophy the umbilical cord inserts low on the abdomen and the anus and scrotum tend to be more anteriorly placed than normal (see Figure 65-1). Although the rectus abdominis muscles insert normally at the pubic tubercles, the diastasis of the pubic symphysis and lateral displacement of the iliac bones causes splaying of the rectus muscles. This lateral displacement of the rectus muscles widens the inguinal canal, predisposing to indirect inguinal hernias in these patients (Connor et al., 1989; Hussman et al., 1990; Stringer et al., 1994). Because the bladder is external, the peritoneal reflection is deeper in the pelvis than normal and the ureters course deeply through the pelvis and enter the bladder with almost no submucosal tunnel, which predisposes them to vesicoureteral reflux (Nisonson and Lattimer, 1968).

The penis in males with bladder exstrophy is short and broad because of pubic bone separation, which prevents the midline joining of the corpora cavernosa. Figure 65-1 illustrates the appearance of the female infant with bladder exstrophy. The overall length of the corpora cavernosa is shortened but reasonable length may be obtained with epispadias repair from the deep corporal bodies (Woodhouse and Kallett, 1984). There is usually a marked dorsal chordee and the penile curvature is compounded by shorter dorsal tunica albuginea. Females with bladder exstrophy (Figure 65-1) have a hemiclitoris on each side of the bladder and the vaginal orifice may be duplicated and displaced anteriorly (Damario et al., 1994). The uterus may be duplicated, but the fallopian tubes and ovaries are usually normal.

All patients with bladder exstrophy have some degree of pubic diastasis, with the hips rotated outward. Many patients have a waddling gait in early childhood, but long-term hip or gait problems are rare.

In normal development the cloacal membrane occupies the infraumbilical position of the abdominal wall, and this bilaminar membrane is infiltrated by mesenchyme to form the lower abdominal musculature. The genital folds fuse superiorly to form the genital tubercle. The most widely accepted theory for the cause of exstrophy is based on the work of Muecke, (1964), in chick embryos. In this model, overgrowth or persistence of a thickened cloacal membrane results in truncated mesenchymal migration. Later rupture of the membrane without the mesenchymal reinforcement results in exstrophy. Bladder exstrophy results if the rupture occurs after the descent of urorectal septum. If rupture occurs in the absence of the urorectal septum, then cloacal exstrophy occurs. The prenatal sonographic observation by Langer et al. of an intact cloacal membrane that subsequently ruptured during the second trimester suggests that the presence or absence of the urorectal septum and not timing of membrane rupture distinguishes bladder exstrophy from cloacal exstrophy (Langer et al., 1992).

A broad range of incidences have been reported for bladder exstrophy, from 1 in 3000 to 1 in 50,000 livebirths (Lattimer and Smith, 1996; Sanders, 1996). Rickham estimated the incidence of bladder exstrophy at 1 in 10,000 livebirths (Rickham, 1960). The International Clearinghouse for Birth Defects Monitoring Systems estimated the incidence of bladder exstrophy at 3.3 in 100,000 livebirths (Lancaster, 1987). All reports have consistently shown a male predominance, which, derived from multiple series, averages 2.3:1 (Bennett, 1973; Harvard and Thompson, 1951; Higgins, 1962; Jeffs et al., 1982). Individual reports exist that describe a male predominance as high as 5:1 or 6:1 (Ives et al., 1980; Lancaster, 1987). There are no estimates available for the prenatal incidence of bladder exstrophy.

While no definite teratogenic effect has been demonstrated, there is a slightly increased risk of bladder exstrophy with maternal progestin use (Blickstein and Katz, 1991). Also, a single case of bladder exstrophy has been reported in the child of a user of lysergic acid diethylamide. A slightly increased risk of bladder exstrophy has been observed in mothers less than 20 years of age (Lancaster, 1987).

The prenatal sonographic diagnosis of bladder exstrophy is based on the association of several findings, including inability to visualize the bladder, normal amniotic fluid volume, presence of a mass on the anterior abdominal wall in the suprapubic region, small penis with an anteriorly displaced scrotum, low umbilical cord insertion, splayed iliac crests, umbilical arteries situated alongside the bulging mass protruding from the lower abdominal wall, malformation of the external genetalia (Barth et al., 1990; Bronshtein et al., 1993; Gearhart et al., 1995a; Jaffe et al., 1990; Lee et al., 2003: Meizner and Bar-Ziv, 1986; Mirk et al., 1986; Pinette et al., 1996; Richards et al., 1992). The fetal bladder is most easily identified between the umbilical arteries, using color Doppler sonography. If completely empty, the bladder may not be seen, but since it normally fills and empties every 5– 15 minutes, persistent observation should identify the normal bladder (Gearhart et al., 1995a). However, the normal bladder may not be imaged if there is a lack of urine production, either due to bilateral renal agenesis or bilateral multicystic dysplastic kidneys. The use of 3-D ultrasound may be particularly useful in identifying the lower abdominal mass in bladder exstrophy (Evangelidis et al., 2004). Similarly, ultrafast fetal MRI may be useful as an adjunct to ultrasound if the diagnosis is not clear as a result of technical limitations of ultrasound such as fetal position or maternal body habitus.

All of the features of bladder exstrophy may not be seen in every patient. In the report by Gearhart et al., (1995a), in 17 fetuses with prenatal sonographic examinations in whom a retrospective diagnosis of bladder exstrophy could be made, not every feature was present. In 71% of cases there was persistent nonvisualization of the fetal bladder. In only 47% of cases were a persistent lower abdominal wall mass or bulge seen. A very small penis with an anteriorly displaced scrotum was seen in 57% of fetuses. Even less commonly appreciated was the low umbilical cord insertion (29%) and abnormal widening of the iliac crests (18%).

In a female, the clitoris is bifocal and there are widely separated labia, but this may be difficult to discern sonographically.

The differential diagnosis of bladder exstrophy includes cloacal exstrophy, persistent urachus, omphalocele, and gastroschisis. However, the lower abdominal wall bulge with low cord insertion immediately cephalad to the exstrophied bladder usually allows its identification. The kidneys are usually normal in bladder exstrophy. In contrast, in cloacal exstrophy, unilateral renal agenesis is common, as is hydronephrosis. In addition, there is often prolapse of the ileum through the cloaca to form the “elephant trunk” deformity (see Chapter 64). Myelomeningocele and omphalocele are also commonly associated with cloacal exstrophy. Rarely, a small omphalocele may be seen in bladder exstrophy (Gearhart et al., 1989b). The lower abdominal wall bulge or soft tissue mass in cloacal exstrophy is usually larger and more heterogeneous than in bladder exstrophy (Pinette et al., 1996). A persistent urachus may resemble the normal bladder and complicate the diagnosis. However, prolonged observation demonstrates the structure to be constant in size and shape lacking any voiding episodes excluding the possibility of a normal bladder (Goldstein et al., 2001, see Table 65-1).