Amniotic fluid alpha fetoprotein (AFAFP) and maternal serum alpha fetoprotein (MSAFP) in abdominal pregnancies: correlation with extent and site of placental implantation and clinical implications.

The hypotheses are evaluated that in abdominal pregnancies 1) elevated MSAFP is due to an altered maternal-placental interface, and 2) differences in MSAFP levels may reflect placental location within the peritoneal cavity. A review of 1,193 ectopic pregnancies from 1983-1993 identified three cases of advanced abdominal pregnancy. All three had undergone second trimester genetic amniocentesis for amniotic fluid alpha fetoprotein (AFAFP) and karyotype. The clinical course was reviewed (including presentation and surgical findings). MSAFP was elevated in two of the three cases (3.63 and 4.88 MoM). AFAFP and fetal karyotype were normal in all three cases. Elevated MSAFP values were associated with more extensive visceral implantation, longer surgical operative time, greater blood loss and transfusion requirements. Abdominal pregnancies with elevated MSAFP appear to have more extensive placental involvement of the abdominal viscera; this would, in fact, account for the elevated MSAFP values given the normal AFAFP.