Fetal cloacal anomalies: prenatal sonographic findings and differential diagnosis.

Serial sonographic findings are presented in three cases of cloacal anomalies. The following sonographic signs were noted: transient fetal ascites, bicystic intra-abdominal structure arising from the fetal pelvis, and oligohydramnios and impaired interval growth. This sequence of sonographic findings may help clarify the natural history of the developing cloacal anomaly: In the early state of its formation, urine enters the abdominal cavity via the fallopian tubes, causing ascites; later, chronic urinary and meconium irritation of tubal mucosa may cause tubal obstruction, which in turn may lead to the formation of genitourinary tract distention, hydronephrosis, and oligohydramnios. Timely diagnosis of cloacal anomalies improves the outcome of pregnancies (delivery in the tertiary care center, early operative correction).