Like other organs, organized contractions occur in the uterus. In the nonpregnant uterus, three patterns of contractility are typically encountered throughout the menstrual cycle.
First, under the influence of E2 during the late follicular phase, uterine contractions are mainly retrograde (displacement from cervix to fundus). These help to transport sperm toward the distal end of the fallopian tubes, where fertilization takes place. Characteristically, only the subendometrial layers of the myometrium are involved in the retrograde contractions of the late follicular phase. Women rarely perceive these contractions.
Second, under the influence of progesterone, the luteal phase is characterized by a state of relative uteroquiescence, possibly with some low amplitude bidirectional contractions. These may facilitate proper positioning of embryos for implantation and pregnancy.
Third, during the luteofollicular transition (i.e., menses), strong antegrade contractions occur in response to progesterone withdrawal. These uterine contractions, which involve all muscle layers of the uterus and are perceived by women, are instrumental in proper forward emptying of menstrual blood.
Abnormal patterns of uterine contractility have been associated with at least three medical entities: dysmenorrhea, endometriosis, and fecundity disorders . During menses, abnormal patterns of contractility will hamper proper forward emptying menstrual blood. This will cause menstrual blood to also exit the uterus by retrograde emptying through the fallopian tubes
Compared with controls, patients with endometriosis had uterine contractions with higher frequency (22.73 ± 5.66 osc/10 min vs. 11.09 ± 3.26 osc/10 min), amplitude (20.83 ± 3.94 mm Hg vs. 6.77 ± 2.83 mm Hg), and basal pressure tone (50.14 ± 16.30 mm Hg vs. 24.68 ± 6.14 mm Hg). Dysmenorrhea was scored as 4.09 ± 1.44 in patients with endometriosis and 0.86 ± 1.42 in controls. Retrograde bleeding was found in 73% of patients with endometriosis vs. 9% of controls, and only 45% of patients with endometriosis had viable endometrial cells in the culde-sac.1
https://www.sciencedirect.com/science/article/pii/S001502820203087X
- Characteristics of uterine contractility during menses in women with mild to moderate endometriosis
Author links open overlay panelCarlo Bulletti M.D. a, Dominique De Ziegler M.D. b, Valeria Polli M.D. a, Elena Del Ferro Ph.D. a, Simone Palini Ph.D. a, Carlo Flamigni M.D. c Fertility and Sterility Volume 77, Issue 6, June 2002, Pages 1156-1161