Congenital abnormalities in twins: selective termination.

Selective termination for an anomalous twin in discordant twin pregnancy has been a management option for nearly two decades. Using current conventional prenatal diagnostic techniques, the diagnosis of a twin gestation discordant for a congenital anomaly is commonly confirmed in the second trimester. Selective termination is thus usually a second-trimester procedure. The risks of second-trimester terminations as well as protocol choices, including indications and timing, have evolved over the years. Ethical issues regarding selective termination have developed significantly and continue to be debated.