Persistent elevation of amniotic fluid alpha-fetoprotein with a normal fetus

Amniocentesis was performed at 13 weeks gestation on a woman with a history of one child with multiple deformities. The fluid was brown-green with no red cells. It had an elevated alpha fetoprotein (AFP) level of 480 mg/1, but a normal acetylcholinesterase level of 9.4 U/l. Two subsequent amniocenteses at 16 and 19 wk had a similar appearance and AFP levels of 290 and 120 mg/l respectively. Acetylcholinesterase was normal in each case. Therapeutic abortion was done but examination of the foetus revealed no open neural tube defect, cxomphalos, renal disease, or alimentary tract atresia. The placenta showed a considerable area of old infarction of the decidual bed and a focal area of placental sclerosis consistent with partial placental separation.