Origin of peritoneal fluid in women: an ovarian exudation product.

The volume of peritoneal fluid was measured after laparoscopic aspiration in 303 women. Contamination with blood was estimated at 4.2 per cent by haemoglobin assay. In 120 women with regular menstrual cycles, the volume of peritoneal fluid increased progressively during the follicular phase, was highest during the early luteal phase (20.0 +/- 6.3 ml) and declined thereafter. In 89 women with moderate and mild endometriosis the amounts of peritoneal fluid were similar, but 9 women with severe endometriosis had lower (P less than 0.05) volumes during the luteal phase. Women with inactive ovaries had uniformly low amounts of peritoneal fluid: 4.2 +/- 2.3 ml in 31 women taking combined oral contraceptive pills; 4.7 +/- 5.8 ml in 17 women taking 5 mg of lynoestrenol daily and 1.2 +/- 1.9 ml in 20 postmenopausal women with an inactive endometrium. In contrast, two postmenopausal women with proliferative endometrium had 7 and 10 ml of peritoneal fluid. Women with active ovaries, 5 with absent or distally occluded Fallopian tubes and 7 without a uterus had normal amounts of peritoneal fluid. The volume of peritoneal fluid was not affected by pelvic varicose veins, a visible corpus luteum or an ovulation stigma. Peritoneal fluid appears to be predominantly an ovarian exudate, neither an exudate from the pelvic peritoneum nor a tubal secretion.