The risks of early cordocentesis (12-21 weeks): analysis of 500 procedures.

Five hundred cordocenteses were performed between 12 and 21 weeks. The indications were thalassaemia (386), rapid karyotyping (97), feto-maternal allo-immunization (10), rubella (6), and toxoplasmosis (1). One hundred and ten pregnancies underwent termination on the basis of the result, while 20 of the 370 pregnancies intended to continue were lost to follow-up. Amongst these were 16 fetal losses (4.3 per cent) and 22 premature deliveries (5.9 per cent); no other complications were reported. Four adverse prognostic factors were identified: (a) cord bleeding; (b) fetal bradycardia; (c) prolonged procedure time; and (d) anterior insertion of the placenta. There was no 'obvious' difference in fetal loss rate with advancing gestation until 19-21 weeks, when the risk of fetal loss decreased to 2.5 per cent.