Megacystis-Microcolon-Intestinal Hypoperistalsis Syndrome: A Rare Case Report

Abstract

Megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS) is an extremely rare congenital disorder characterized by an enlarged bladder without renal obstruction, decreased intestinal motility, and microcolon. This genetic disease is challenging to diagnose prenatally because of its nonspecific ultrasonographic findings and low incidence. In a case study, a 36-year-old nullipara who was at 24 weeks of gestation and referred to Asan Medical Center with a chief complaint of fetal enlarged bladder. Fetal ultrasonography showed megacystis without definite renal obstruction, normal female genitalia, and a normal amniotic fluid index. Follow-up ultrasonography at 30 weeks of gestation revealed worsening bladder distention accompanied by hydronephrosis. At 34 weeks of gestation, ultrasonography showed dilatation of the stomach and small bowel and polyhydramnios. The final prenatal diagnosis was megacystis associated with hydronephrosis and additional small bowel obstruction. Thus, MMIHS was prenatally suspected. The patient underwent an elective cesarean section at 37 weeks of gestation. A female newborn was delivered, with a birth weight of 2,300 g, and was admitted to the neonatal intensive care unit. No urethral obstruction was confirmed by Foley catheter insertion; however, on neonatal abdominal ultrasonography, a long segment of the microcolon was observed. The newborn failed to defecate and urinate, and genetic testing was performed, which was ultimately diagnosed with MMIHS with an ACTG2 (actin gamma 2, smooth muscle) gene mutation. While MMIHS was once a fatal disease, treatments such as intestinal rehabilitation and transplantation have improved the survival rate. Therefore, prenatal diagnosis is crucial for counseling, early postnatal diagnosis, and treatment.