Rectouterine

Rectouterine refers to the rectum and uterus, most often designating the rectouterine pouch, also known as the pouch of Douglas. This peritoneal space is the posterior cul-de-sac between the uterus and the rectum in females and is the deepest part of the peritoneal cavity when a person is upright.

Anatomy: The rectouterine pouch is formed by peritoneum reflecting from the posterior surface of the uterus onto the anterior surface of the rectum. It lies posterior to the uterus and anterior to the rectum and extends laterally into the pararectal fossae. Its superior limit is near the uterus and its inferior extent near the rectum, with communication to the rest of the peritoneal cavity around the pelvic brim.

Clinical significance: Because it is the lowest point of the female peritoneal cavity, the rectouterine pouch can accumulate fluid such as blood or pus in disease or injury. It has historical use in culdocentesis to sample intraperitoneal bleeding. Modern imaging, including ultrasound, CT, and MRI, can detect fluid in this pouch; fluid collections may indicate conditions such as ectopic pregnancy rupture, pelvic inflammatory disease, endometriosis, or ascites.

Other terms: The space is also called the rectouterine pouch, pouch of Douglas, or posterior cul-de-sac. In males, there is no rectouterine pouch; the analogous spaces are the rectovesical pouches between the rectum and bladder.