Prenatal diagnosis of megacystis-microcolon-intestinal hypoperistalsis syndrome in one fetus of a twin pregnancy.

Megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS) is a rare genetic disorder that affects the muscle tone in the intestinal and urinary tract systems. Prenatal diagnosis is difficult because an identifiable genetic locus is absent and there are no specific ultrasound findings. We present an interesting case of this syndrome diagnosed prenatally in one fetus of a twin pregnancy. A 26-year-old white woman gravida 4, para 2103, at 11 weeks' gestation was diagnosed with a dichorionic diamniotic twin pregnancy. The patient's history was significant for having a previous female infant diagnosed with MMIHS. During a follow-up ultrasound at 26 weeks, one of the twins had multiple anomalies including: a pelvic cystic structure with a keyhole appearance, enlarged stomach, dilated bowel, and prominent renal pelves. Prenatal diagnosis of MMIHS can be possible on ultrasound findings with a positive family history.