Bladder Exstrophy

Major congenital disorder resulting in abnormal development of the cloacal membrane with failure of fusion of the entire lower abdominal wall, including lower urinary tract, external genitalia, and symphysis pubis.

Incidence varies from 1:20,000 to 1:30,000 live births, with a prevalence of 3.3:100,000 live births and a male-to-female ratio of 2:1 to 3:1. The recurrence risk for sibs is approximately 1%, with a one in 70 recurrence risk for offspring of affected subjects.

Bladder exstrophy most likely is a multifactorially inherited anomaly. Only 20 cases of familial bladder exstrophy have been reported. One report of a pair of monozygotic twins—one with bladder exstrophy, the other with no congenital abnormalities—has been described. The authors of this report concluded that the condition was not purely genetically determined.

Abnormal development of cloacal membrane during the fifth and sixth weeks of embryonic life impedes normal mesodermal movement and prevents midline fusion of the musculoskeletal elements of the infraumbilical anterior abdominal wall.

Prenatal diagnosis using ultrasonography is the method of choice. A reliable diagnosis can be obtained before 20 weeks of gestation based on the absence of a bladder, normal kidneys, a semisolid mass protruding from the lower abdominal wall, and a low insertion of the umbilical cord into the abdomen. Clinical appearance and familial history (rare).

Prenatal diagnosis usually is made between 12 and 20 weeks of gestation. Failure of fusion of the cloacal membrane results in a complete lower anterior abdominal wall defect. This malformation is characterized by exstrophy of the bladder with a small bladder plate, lower urinary tract defect (urethra and bladder neck), abnormal external genitalia, open symphysis pubis, and nonfused lower abdominal wall. The kidneys are usually normal in appearance. The defect may involve the lower gastrointestinal tract and the spinal canal. Other anomalies can be associated. Most affected males develop severe sexual dysfunction because of a short penis and erection abnormalities.

Neonates require a full preoperative assessment to determine the extent of the bladder exstrophy and the presence of any other associated congenital abnormalities. Laboratory investigations should include a complete blood count, blood glucose, urea, and electrolytes, including calcium and phosphate. Renal and liver function tests, a clotting screen, and cross-matching of blood should be obtained. The cardiovascular status and state of fluid hydration should be assessed because the condition is associated with marked fluid losses prior to correction. Older children likely will have undergone several operations and will benefit from sedative premedication. Latex allergy may be a problem in children who have undergone several urologic or plastic reconstructive procedures. Use of a latex-free anesthesia and surgery equipment is recommended.

Standard preparation for all neonates undergoing major surgery, including arterial and central venous line. Repair of bladder exstrophy involves prolonged surgery with major blood loss and significant fluid requirements. Epidural analgesic techniques (caudal or lumbar approach) may be appropriate if the defect does not involve the spinal canal. Postoperatively, the neonate will require a period of ventilation and careful fluid management. Measures to maintain body temperature should be taken.

Perioperative prophylaxis with steroids and/or antihistaminics (H1 and H2 blocker) may be considered for patients with known latex allergy.

Exstrophy of the Cloaca Sequence: Most severe form of the exstrophy complex. Results from a developmental defect of the mesenchyme that causes a midline defect of the lower abdominal structures, exposing the bladder and a large portion of the bowel through the anterior abdominal wall. The patient usually presents with failed fusion of the symphysis pubis, often associated with incomplete development of the lumbosacral vertebrae leading to hydromelia. Omphalocele may coexist. In males, diphallus with bifid scrotum is usually present. Females often have duplication and occasionally vaginal atresia or agenesis. Other features include renal anomalies such as polycystic kidneys and renal agenesis.

OEIS Complex (Omphalocele-Exstrophy-Imperforate Anus-Spinal Defects): Inherited disorder resulting from an autosomal recessive trait. Patients present with an omphalocele, exstrophy-epispadias sequence, and pubic diastasis. An imperforated anus is often associated. Spinal defects because of failed fusion of vertebrae are always present. This rare complex is thought to be the most severe end of a spectrum of birth defects.