The pouch of Douglas is the lowest area of the peritoneal cavity in women. It is a small extension of the peritoneal cavity which lies between the uterus and the rectum. This structure is named after Dr. James Douglas, a Scottish physician who worked in the 18th century and was especially interested in this area of the anatomy. Several other anatomical features are named for Dr. Douglas, recognizing his contributions to the understanding of human anatomy.
Terms such as “rectouterine pouch” and “cul de sac” are sometimes used to refer to the pouch of Douglas. The structure is long and narrow, open at the top and closed at the bottom. Because of its position at the bottom of the peritoneal cavity, it can serve as a drainage point for fluids in the cavity. This can lead to medical problems; malignant growths may spread to the pouch of Douglas, and women can experience discomfort if the pouch of Douglas fills with fluid, pus, and other materials.
Due to concerns about the fact that the pouch of Douglas can act as a collection point for materials in the peritoneal cavity, a doctor may recommend examination of the area if a woman has a medical issue which involves the peritoneal cavity. The examination can be used to determine whether or not the pouch of Douglas has become involved, and to identify emerging complications which could threaten reproductive health, such as infections which could penetrate the uterine wall.
In a procedure known as peritoneal dialysis which is sometimes used to treat kidney failure, the peritoneal cavity is regularly bathed with a dialysate solution which may be introduced through the pouch of Douglas in women. In this case, a catheter is placed into the structure and is used as a semi-permanent port to introduce dialysate fluid and to allow for drainage of the fluid.
In a procedure known as culdoscopy, an endoscope is introduced to the pouch of Douglas through the vagina for the purpose of examining the interior. This may be done for the purpose of preparing for a procedure such as a fluid drainage, or to look for signs of abnormalities which could be involved in a medical diagnosis. The structure can also be visualized with a medical imaging study such as an MRI scan if a doctor suspects that a woman has endometriosis, adhesions, or other abnormalities inside the pouch of Douglas.
How To Identify Pouch of Douglas Malignancies
While many of these symptoms overlap with other issues that lay beyond the peritoneal cavity that are so common to women’s reproductive health, nonetheless, one should remain vigilant and question whether or not there is a need to have the pouch of Douglas examined.
Symptoms vary but include:
- Abdominal pain and distension
- Abnormal uterine bleeding
- Introitus lump
- Reduced stool caliber
Too often, these symptoms are mistakenly attributed solely to pathologies of the uterus or ovaries due to their similarity in appearance via imaging technology. In many cases, examination of the rectouterine pouch is ignored in favor of searching for causality in these two most common offenders, glossing over potential complications specific to the peritoneal cavity.
What Malignancies Are Specific to the Pouch of Douglas?
Listed below are the three primary malignancies specific to the Pouch of Douglas, seen in both men and women.
Mullerian Adenosarcomas: Extragenital
The rarity of primary peritoneal cavity issues makes literature on the subject quite scarce, and this is partly why they are misdiagnosed based on ultrasound and MRI scans. Usually, they are unintentionally characterized as having a uterine or ovarian origin regarding legion metastases. In short, the result is that doctors may accidentally attribute the source to various forms of ovarian cancer. It is important to note that sometimes, these issues are concurrent.
However, non-ovarian lesions have sparked intense study, relegated to the peritoneal cavity. Researcher Ker Yi Wong wrote about Mullerian adenosarcoma in their collaborative article surrounding the primary pouch of Douglas malignancies. They stated that malignant stromal (sarcomatous) and benign epithelial components, which typically arise from the uterus, make up the mixed neoplasms seen in Mullerian adenosarcoma. Location is vital in understanding their behavior regarding one’s health.
While uterine adenosarcomas have great prognosis, extragenital adenosarcomas typically have higher rates of occurring more than once and mortality in comparison. Unfortunately, these pouch of Douglas lesions are rare enough that, at this point in time, there is no agreement yet on the best treatment for them. Surgery and chemotherapy have been endorsed, with about a 50% effectiveness rate.
Pouch of Douglas Hernias
A hernia occurs when fatty tissue or an organ, like the intestines, slips through a spot in the weakened connective tissue or muscle surrounding it. In accordance with documentation by doctors John Bunni and James Berstock in the attached article, it is understood that peritoneal cavity hernias are an unusual form of pelvic hernia that appears to manifest predominantly in elderly, multiparous women, as well as those who have undergone previous pelvic surgery in their lifetime.
Hernias of the rectouterine pouch are classified as perineal hernias and are very rare. It is generally accepted that pelvic hernias as a unit are not at all commonplace, so treatment of them is somewhat obscure and still in its nascent stages. Surgery is presented as the best option, as is the resolution for the patient featured in the case study presented in detail upon which the article is founded.
Men vs. the Pouch of Douglas
The discussion thus far on the cul-de-sac has centered on its implications for women’s reproductive health and the potential threats to this region pathologically, due to its proximity to the uterus and ovaries. Males also possess this anatomical space dubbed the rectovesical pouch.
The lowest part of the peritoneal cavity is known as the rectovesical pouch. It typically has loops of the sigmoid colon or the small bowel. It is a space for potential fluids to collect in males due to its close relation to the anal margins. It is directly analogous to the rectouterine pouch in females and is otherwise still collectively known as the pouch of Douglas.
Just as it can cause problems in women, men are not immune to the consequences of amassing materials in the peritoneal cavity due to its location. It is a receptacle for extraneous fluids, puss, and even blood, and an infection in this area may pose significant harm to the rectum and prostate of the one affected.
Being informed can allow an individual to take precautions to maintain their longevity. Though it is often overlooked by doctors searching for causality regarding lower abdominal abnormalities, here is a short list of associated pathologies of the rectovesical pouch.
Related Pathologies
- Ascites (hydroperitoneum): an abnormal amount of intraperitoneal fluid in the peritoneal cavity.
- Haemoperitoneum: the presence and accumulation of blood within the peritoneal cavity.
