The relation between maternal serum alpha-fetoprotein levels and fetomaternal haemorrhage.

Spontaneous fetomaternal haemorrhage at 14 to 20 weeks gestation resulted in raised serum alpha-fetoprotein (AFP) levels in 13 of 150 patients attending a genetic counselling clinic. In all 13 patients, the placenta was anterior or fundal in position. By allowing for a rise in serum AFP levels of 4 microgram/l for each fetal cell seen in 30 high power fields (Kleihauer test), a 62.5 per cent reduction in the number of patients selected for amniocentesis because of raised serum AFP levels would have been achieved. The occurrence of fetomaternal haemorrhages at the time of amniocentesis can be detected by either the Kleihauer technique or the measurement of maternal serum AFP levels.