MANAGEMENT OF TWIN PREGNANCIES WITH FETAL TRISOMIES

Objective To examine options of management and outcome of twin pregnan cies affected by fetal trisomies. Design Retrospective study. Setting Research Centre for Fetal Medicine. Population Twenty-seven twin pregn ancies affected by fetal trisomy. Methods A computer search was made o f our database for twin pregnancies concordant or discordant for triso mies. The data were reviewed for gestation at diagnosis of the chromos omal abnormality management and pregnancy outcome. Main outcome measur es Pregnancy management and outcome in relation to type and gestation at diagnosis of the trisomies. Results There were seven cases where bo th fetuses were trisomies and in these the parents opted for terminati on of pregnancy; termination was also performed in another pregnancy w here one fetus had trisomy 18 and the chromosomally normal co-twin had a major facial cleft. In 19 cases one fetus had either trisomy 21 (n = 14) or trisomy 18 (n = 5) and the other was normal. Selective fetoci de was carried out in 13 of 14 pregnancies discordant for trisomy 21 a nd in one of the five with trisomy 18. In the four cases discordant fo r trisomy 18 that were managed expectantly, the trisomic baby died in utero or in the neonatal period, whereas the normal co-twin was livebo rn at 33 to 40 weeks (median 37). In the 14 cases of selective fetocid e, the chromosomally normal co-twin was live born at 24 to 41 weeks of gestation (median 38), and there was a nonsignificant inverse correla tion between the gestation at fetocide and gestation at delivery. Conc lusions In twin pregnancies discordant for fetal trisomies the main de terminant in deciding whether to perform selective fetocide or adopt e xpectant management is the degree of lethality of the chromosomal defe ct.