Diagnostic dilemma with elevated level of alpha-fetoprotein in an undiagnosed twin pregnancy with a small discordant holoacardius acephalus.

We report a case of a patient who had highly elevated levels of alpha-fetoprotein when she was first examined and a positive acetylcholinesterase test result in amniotic fluid. Despite repeated ultrasonographic screening, pathologic findings were not detected and the holoacardius acephalus twin was not identified. After termination of pregnancy the histopathologic findings demonstrated a twin pregnancy with a holoacardius acephalus.