THE FIRST-TRIMESTER GROWTH-DISCORDANT TWIN - AN OMINOUS PRENATAL FINDING

Objective: To evaluate the clinical significance and the natural cours e of discordant twin growth found during the first trimester of pregna ncy. Methods: This was a retrospective survey between 1992-1993 of wom en presenting to the ultrasonographic unit with twin pregnancies in wh ich considerable interfetal size variation was noted in the first trim ester. Discordant embryonal growth was defined as a difference in crow n-rump length corresponding to 5 or more days in the estimated gestati onal age. Only cases that presented with continued viability of both t wins were reviewed. Cases were thoroughly followed by ultrasound exami nations throughout pregnancy. Neonatal records provided the outcome da ta. Results: Five cases with first-trimester discordant twin growth we re identified. All had complications of major congenital anomalies in the smaller twin, ie, diaphragmatic hernia, ventriculomegaly, schizenc ephaly, critical aortic atresia, and sacral agenesis. Conclusions: The first-trimester growth-discordant twin is at increased risk for conge nital anomalies. Meticulous sonographic search for congenital anomalie s is indicated when inter-twin size variation is evident in the first trimester.