Unilateral macrocystic dysplasia and contralateral agenesis in a monoamniotic twin.

OBJECTIVE: We present a case report of a congenital malformation of the uropoetic tract in one of the monoamniotic twins. CASE REPORT: A 24-year-old primigravida with male monochorionic monoamniotic twins was dia-gnosed with congenital malformation in fetus A at 24 weeks of gestation. Ultrasound verified macrocystic dysplasia and contralateral renal agenesis. Planned caesarean section was performed after the observational management of the patient in the 34th gestational week. In fetus B, a physiological finding was confirmed on the postpartum ultrasonography. In fetus A, CT examination of the abdomen confirmed the finding of left kidney agenesis and polycystic degeneration of the right kidney. Exitus letalis was stated on the newborns 5th day. CONCLUSION: The occurrence of the described combination of congenital malformation in monoamniotic twins is rare. When dysplasia significantly affects the function of the parenchyma, renal agenesis with multicystic dysplasia of the other kidney is a condition incompatible with life. For the intrauterine survival of the affected fetus, the normal renal function of the twin was important and thus the normal volume of amniotic fluid was maintained. As a result, the fetus did not develop extrarenal symptoms of the Potter sequence in the described case - especially pulmonary hypoplasia and the newborn was able to ventilate spontaneously. The death was caused by the consequences of renal failure associated with anuria.