* Director of Imaging Diagnosis Department, Maternal Tudu Hospital, 284 Cong Quynh St Dist 1, Hochimin City, Vietnam.
** Inner Vision Women"s Ultrasound, Nashville, Tennessee, USA; Department of Obstetrics and Gynecology, University Hospital Brno, Czech Republic.
Introduction
Exstrophy of the urinary bladder is a very rare congenital deformity in which the anterior bladder wall is absent and the posterior wall of the bladder is exposed externally into the amniotic cavity. This is caused by the incomplete closure of the anterior lower abdominal wall. It"s incidence is 0.25-0.5 to 10,000 births, more common in males in the ratio of 2:1. There usually other congenital anomalies present such as partial agenesis of the pubic bones, pubic bones diastasis, epispadia, absence of the urethra, clitoris, deformities of the vagina or uterus. Both genetic and environmental factors are involved in the etiology. Management is primarily surgical, with the aim of the anterior abdominal wall closure.
During the prenatal diagnosis we have to differentiate the bladder exstrophy from the other anterior abdominal wall defects, such as gastroschisis, omphalocele and cloacal exstrophy. Gastroschisis and omphalocele have both present urinary bladder which fills normally. In case, we can not visualize urinary bladder and there is an absence of oligohydramnios or other renal abnormalities, bladder exstrophy should always be considered as a differential diagnosis.
Color Doppler is also an useful tool in diagnostic of bladder exstrophy. Umbilical arteries normally run along the bladder wall on the transverse scan of the lower abdomen. In case of the bladder exstrophy they run along the anterior wall mass. On the opposite, in case of the omphalocele, the umbilical arteries run inferior to the herniated mass and the vein runs through the herniated liver. Fetal MRI is also helpful to differentiate the bladder exstrophy from other anterior abdominal wall defects.
Ultrasound findings
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Lower abdominal wall defect with protruding abdominal mass
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Absence of the normally filled urinary bladder
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No sign of oligohydramnios or other gross renal abnormalities
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Color Doppler shows umbilical arteries alongside the abdominal wall mass
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External genitalia malformation
Case report
We report a case of a 28 year old G1P0 who was referred to our hospital for the suspicion of the omphalocele diagnosed during the second trimester ultrasound scan. We scanned the patient at 24 weeks and diagnosed a bladder exstrophy. Apart of the lower abdomen mass, we also saw a anomaly of the genitalia. Patient opted for the pregnancy termination based on the ultrasound examination. Findings of the fetus confirmed our diagnosis. Unfortunatelly, there was no autopsy performed.
Images 1,2: Images show a transverse section of the lower abdomen. Note missing lower anterior abdominal wall and urinary bladder; anterior wall mass is indicated by arrow.