PRENATAL-DIAGNOSIS OF CLOACAL DYSGENESIS SEQUENCE - DIFFERENTIAL-DIAGNOSIS FROM OTHER FORMS OF FETAL OBSTRUCTIVE UROPATHY

Cloacal dysgenesis sequence (CDS) is a rare cause of fetal obstructive uropathy (FOU). The prenatal differentiation of CDS from other FOU is important because CDS is not amenable to in utero surgical interventi on in the form of vesicoamniotic shunts. We evaluated the prenatal cha racteristics of 8 fetuses with CDS, including a pair of monozygotic tw ins concordant for CDS, in order to identify features that would enabl e differentiation from other forms of FOU. Pathologic examination in e ach of the 8 fetuses confirmed characteristic features of absent anal, genital, and urinary orifices associated with a smooth perineum and a bnormal phallic development. Associated abnormalities included dysplas tic kidneys in 6, hydroureters in 5, intraluminal colonic calcificatio ns in 2, and hypoplastic lungs in 5. Five of these fetuses initially p resented as posterior urethral valve syndrome. Six fetuses had megacys tis, and 4 underwent vesicocenteses to evaluate urinary electrolytes, all of which were in the 'poor-risk' category. Six fetuses were male a nd 2 female, contradicting earlier claims that CDS occurs only in fema les. Evaluation of candidates for in utero surgical intervention shoul d include fetal karyotype, and CDS should be suspected in cases of FOU in whom the karyotype reveals a male fetus and sonographic evaluation demonstrates colonic calcifications or abnormal phallic development. Diagnostic microendoscopy may be of benefit in such cases.