Measurements of endometrial blood flow in anaesthetized ewes by xenon-133 clearance and microsphere techniques.

In six anaesthetized, non-pregnant ewes, uterine blood flow rates measured by monitoring the clearance of xenon (133Xe) from the lumen of the uterus were compared with estimates of endometrial and myometrial capillary blood flow obtained by the use of microspheres of 15 micron diameter (eleven comparisons). On analysis, seven of the 133Xe clearance curves indicated the occurrence of both a fast and a slow compartment of flow with flow rates approximating to the rate of capillary blood flow in the caruncular and inter-caruncular portions of the endometrium, respectively. In each of the remaining four curves which provided a single estimate of flow, the derived blood flow rate was similar to the rate of capillary blood flow in both the caruncular and inter-caruncular portions of the endometrium. No relationship existed between myometrial capillary blood flow and the flow rates derived from the 133Xe clearance curves.