CASE REPORT Antenatal Diagnosis of Bilateral Renal Agenesis in One of a Twin Pair

Bilateral renal agenesis (BRA) was diagnosed antenatally in one of like-sexed (probably monozygotic) twins. This is the first report of such a diagnosis. The difficulties of certain sonographic diagnosis of BRA are outlined and are possibly compounded in twin pregnancy in the presence of growth retardation/oligohydramnios of one of the twins. Recent evidence suggests that BRA is inherited in an autosomal dominant pattern with reduced penetrance and variable expressivity. The discordance for BRA in twins, even mono.zygotic twins, has been relatively frequent suggesting a possible role of environmental influences in the expression of the anomaly. Genetic counseling should include renal evaluation of asymptomatic parents and siblings and early detailed ultrasound evaluation of fetal kidneys in all subsequent pregnancies. Key words: Bilaternal renal agenesis, antenatal diagnosis, sonographic diagnosis, twins. Bilateral renal agenesis (BRA) is a rare complica-tion of pregnancy occuring in only 0.23 to 0.34 per 1000 deliveries. 1 The condition is fatal. Antenatal diagnosis of BRA utilizing sonography has been reported.2 • 3 Sonographic findings consistent with the diagnosis include severe oligohydramnios,,_. and the inability to see the bladder and the kidneys. 1 • 3 Fetal growth retardation is also associated with this anomaly. 1 •'•'The case we are presenting is unusual in that BRA was antenatally diagnosed in only one of a twin pair. This is the first report of such a diagnosis. Case report A 23 year old primigravida was referred for evaluation of a 34 weeks twin pregnancy in which discordant fetal growth was appreciated. The patient denied any vaginal discharge or leakage of fluid. Sh