CHANGES IN VOLUME, TOTAL PROTEIN AND OVARIAN STEROID CONCENTRATIONS OF PERITONEAL FLUID THROUGHOUT THE HUMAN MENSTRUAL CYCLE

Abstract

SUMMARY Peritoneal fluid was aspirated during laparoscopy from normal women at various stages of the menstrual cycle. The volume of the fluid was found to be influenced by the stage of the cycle, rising from an early proliferative mean value of 0·8 ml to a mean volume of 18·7 ml after ovulation and decreasing again to a mean volume of 5·4 ml in the late secretory phase. The mean volume of peritoneal fluid obtained from women using the contraceptive pill was 0·8 ml, whereas only negligible amounts of fluid were aspirated at laparotomy from the peritoneal cavity of men. Despite marked changes in volume, the total protein content of the peritoneal fluid (± 60% of the concentration measured in plasma) remained fairly constant throughout the cycle, although a slightly, but significantly, lower value was found in the late proliferative phase. After ovulation the concentration of oestradiol and progesterone in the peritoneal fluid was higher than in plasma in the majority of cases, suggesting that some follicular fluid had drained into the peritoneal cavity at that time. Progesterone, in contrast to oestradiol, was also found in higher concentrations in peritoneal fluid than in plasma before ovulation. These results suggest that the volume and ovarian steroid concentration of peritoneal fluid are influenced by cyclic ovarian activity. At least two mechanisms may account for these observations: changes possibly effected by oestradiol in vascular permeability leading to a change of inflow and outflow equilibrium at the level of the peritoneal membranes and ovarian–peritoneal transfer of fluid after and possibly also before follicular rupture.