pararectal fossa pararectal fossa in the male, the peritoneum encircles the sigmoid colon, from which it is reflected to the posterior wall of the pelvis as a fold, the sigmoid mesocolon. it then leaves the sides and, finally, the front of the rectum, and is continued on to the upper ends of the seminal vesicles and the bladder; on either side of the rectum it forms a fossa, the pararectal fossa, which varies in size with the distension of the rectum. pararectal fossathe peritoneum of the male pelvis. (pararectal fossa visible at center left.)female pelvis and its contents, seen from above and in front. (pararectal fossa labeled at bottom left.)detailsidentifierslatinfossa pararectalista98a10.1.02.514ta23728fma19749anatomical terminology