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At a glance

A major congenital disorder resulting in abnormal development of the cloacal membrane with failed 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 male-to-female ratio of 1 to 3:1. The recurrence risk for sibs is approximately 1%, with a 1:70 recurrence risk for offsprings of affected subjects. Infants of Caucasians ethnicity are significantly more likely to present with Bladder Exstrophy (BE) than nonCaucasians.

Genetic inheritance

BE is most likely an inherited, but multifactorial anomaly. Only around 20 cases of familial bladder exstrophy have been described. The authors of one report describing a pair of monozygotic twins, one with bladder exstrophy, the other without congenital abnormalities, concluded that the condition was not purely genetically determined. One study identified higher maternal age and body weight as potential risk factors for BE.

Pathophysiology

Abnormal development of the 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.

Diagnosis

Based on the clinical appearance. Prenatal diagnosis using ultrasonography is the method of choice. A reliable prenatal diagnosis is usually possible between 15 and 20 weeks of gestation and based on absent bladder/bladder filling, normal kidneys, widening of the pubic rami, a semisolid mass protruding from the lower abdominal wall and a lower than normal insertion of the umbilical cord into the abdomen. Despite these clues, only about 25% of patients are diagnosed antenatally.

Clinical aspects

The failure of cloacal membrane fusion is characterized by exstrophy of the bladder with a small bladder plate, lower urinary tract (urethra and bladder neck) and reproductive tract defects, abnormal external genitalia, open symphysis pubis (pelvic/pubic diastasis), and open lower abdominal wall. The osseous pelvic anomalies can be quite variable and complex and are not limited to pubic diastasis. Acetabular retroversion with compensatory femoral anteversion, shortening of the pubic rami, and external rotation of the posterior and anterior pelvic segments are frequently seen. While some of these anomalies improve spontaneously with age, pubic diastasis tends to worsen over time if left untreated. The kidneys are usually normal in appearance and function with anomalies occurring in less than 3% of BE patients (eg, complete duplication of the collecting system, absent/hypoplastic/ectopic kidney, multicystic dysplastic kidney). The defect may however involve the lower gastrointestinal tract and the spinal canal. Other anomalies can be associated (eg, small omphalocele, spinal anomalies, orthopedic problems), but in over 90% of cases, BE is an isolated malformation. Most affected males develop severe sexual dysfunction due to a short penis (significantly shorter and thinner corporal body) and erectile abnormalities. In females, vaginal shortening, stenotic vaginal orifice, bifid ...

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