Bladder exstrophy results from defective development of the anterior bladder and lower abdominal walls, leaving the posterior bladder wall lying exposed on the abdomen.
Epidemiology: 3.3 cases per 100,000 live births. Male to female ratio is >2:1. Increased risk in offspring of affected patients and with younger maternal age and increased parity.
Embryology: An embryological malformation results in the abnormal overdevelopment of the cloacal membrane, which prevents in-growth of lower abdominal tissues. The cloacal membrane normally perforates to form the urogenital and anal openings, but in exstrophy there is premature rupture resulting in a triangular defect below the umbilicus. The timing of this rupture determines the type of defect (bladder exstrophy, cloacal exstrophy, or epispadias).
Associated anomalies- Bone defects Diastasis (widening) of the symphysis pubis due to outward rotation of the pelvic bones along the sacroiliac joints.
- Musculofascial defects Umbilical hernias, inguinal hernias, abnormal pelvic floor.
- Genital defects Males: short, broad penis with lateral splaying of the corporal cavernosa, short urethral plate. Females: bifid clitoris, stenotic vaginal orifice, short vaginal canal, vaginal prolase.
- Urinary tract defects Majority suffer vescioureteric reflux (VUR) due to lateral displacement of the ureteric orifices.
- GIT defects Anteriorly displaced anus, rectal prolapse, abnormal anal sphincter contributes to incontinence.
Investigation
Typical features seen on prenatal ultrasound scan include a lower abdominal wall mass; absent bladder filling; low-set umbilicus; small genitalia; abnormal iliac crest widening. Diagnosis can help planning of delivery in a centre with facilities to perform early surgical correction.
Treatment
At birth, cover the bladder with plastic film and irrigate regularly with sterile saline. Trauma to the bladder mucosa can result in squamous metaplasia, cystitis cystica, or adenocarcinoma and squamous cell carcinoma after chronic exposure.
- Selected cases are suitable for one-stage repair, but most require a three stage procedure:
- Newborn pelvic osteotomy (cutting bone to correct deformity) with external fixation with closure of bladder, abdominal wall, and posterior urethra.
- 6 12 months epispadias repair.
- 4 5 years bladder neck reconstruction (Young Dees Leadbetter procedure) and anti-reflux surgery (ureteric reimplantation) is performed when there is adequate bladder capacity and children can participate in voiding protocols. Where bladder capacity is too small, bladder augmentation or urinary diversion is required.
As the child gets older, they may find that their bladder is too small to cope as they take in larger amounts of fluid. In this case, a bladder enlargement (augmentation or cystoplasty) may be necessary. This is usually done by using a piece of the intestine, and often coincides with a reconstruction of the bladder neck, and the formation of a "continent catheterisable channel" from the bladder onto the abdominal wall - sometimes called a mitrofanoff.
There will be scars from the operations, but these will fade with time, and some will become covered with pubic hair at puberty.
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