Uterine contractility and plasma progesterone levels in the nonpregnant woman

Abstract

Thirty-three uterine contractility recordings were obtained in four nonpregnant patients, covering 16 cycles. A modification of the sponge-tip catheter method was used. Plasma progesterone concentration at the time of the recordings was measured and correlated with the contractility patterns observed. All the recordings were done in the presence of intrauterine Silastic capsules, which were empty during the first two cycles and replaced by identical capsules filled with progesterone for the next two menstrual cycles. The observed patterns of uterine contractility failed to show a consistent relation to the plasma progesterone levels or to the phase of the cycle. The local administration of progesterone via the Silastic capsules did not affect uterine contractility. Breakthrough bleeding in one patient was associated with “labor-like” contractions, which did not coincide with abdominal cramps. Strong frequent contractions were observed with the urge to urinate.