Myometrial activity and endometrial blood flow in an ectopic pregnancy.

Myometrial activity and endometrial blood flow were recorded in a patient with uterine haemorrhage and lower abdominal pain, who turned out to have a tubal pregnancy. The uterine contractions had an amplitude sometimes exceeding 400 mmHg and a duration up to 3.5 min. Thus, strong uterine contractions can appear during pregnancy without the presence of a gestational sac within the uterus. This is contrary to the assumption that processes in the foetal membranes initiate the sequence of events leading to abortion or labour.