First trimester umbilical artery pulsatility index in fetuses presenting enlarged nuchal translucency

The aim of this prospective study was to evaluate an umbilical artery pulsa tility index (UAPI) in first trimester fetuses who present enlarged nuchal translucency (NT) measurements. UAPI was measured in 121 single fetuses wit h NT greater than or equal to 95th centile, from 10+3 to 13+6 weeks (crown- rump length (CRL) greater than or equal to 38 mm - less than or equal to 84 mm). In these fetuses there were 20 trisomy 21, and six other chromosomal a bnormalities (three trisomy 18 and three monosomy X). Eighty-nine cases had normal karyotype and delivered a baby without evidence of congenital malfo rmations. Five fetuses with normal karyotype assessed antenatally were excl uded from the comparison, because of evidence of congenital malformation. A fetus with normal karyotype that was spontaneously miscarried at 14 weeks' after chorionic villus sampling was also excluded. UAPI of fetuses with en larged NT was compared with those of 65 singleton fetuses with normal NT an d normal karyotype, which were used to establish our terms of reference (5t h centile, median and 95th centile). UAPI of 7/20 (35%) Down syndrome and 4 2/89 (47%) normal karyotype fetuses presenting enlarged NT were above the m edian, and respectively 2/20 (10%) and 14/89 (15.7%) were above 95th centil e of normal NT and normal karyotype fetuses. No significant differences wer e demonstrated in the UAPI values amongst normal karyotype fetuses with nor mal NT or normal karyotype fetuses with an enlarged NT or trisomy 21 fetuse s with an enlarged NT. Copyright (C) 2000 John Wiley & Sons, Ltd.