Densitometry as an aid in amniotic fluid gel acetylcholinesterase analysis.

We have performed gel acetylcholinesterase analysis blindly on 1,300 consecutive amniotic fluid samples sent to our laboratory for alpha-fetoprotein measurement. Faint acetylcholinesterase bands were identified in nine of 1,300 samples, and all of these were associated with pregnancies free of major fetal malformations. Dense acetylcholinesterase bands were identified in four samples, and all were associated with major fetal malformations. Densitometric analysis of acetylcholinesterase bands provided additional objectivity in classifying band density.