Myoelectrical activity in the human oviduct with tubal pregnancy.

Myoelectrical activity and progesterone (P) and 17 beta-estradiol (E2) concentrations were measured in 12 human oviducts with tubal pregnancy. Spikes were frequently superimposed on a single, smooth, slow wave. The region above a large conceptus (P dominance) was inactive in eight of 10 oviducts. The myoelectrical activity spread toward these conceptuses from both sides, apparently holding the conceptus in place. In three cases with small placentas, the spread of weak activity tended to push the conceptus out of the oviduct. A steep decline of P and E2 levels distally in both directions from the conceptus was coincident with frequency of peaks.