Differential diagnosis of free fluid in cul de sac (pouch of Douglas)
The cul-de-sac, also known as the pouch of Douglas or rectouterine pouch, is an extension of the postero-inferior reflection of the peritoneal fold between the uterus (anteriorly) and rectum (posteriorly). It is the most inferior aspect of the peritoneal cavity and therefore the first location where free fluid accumulates.
Evidence of fluid within the cul-de-sac is a common finding, and the underlying cause can be thought of as either physiological or pathological.
Physiological pelvic intraperitoneal fluid in women may be due to:
- ruptured follicles
- retrograde menstruation
- increase in ovarian permeability due to oestrogen influence
- 1. Nyberg DA, Laing FC, Jeffrey RB. Sonographic detection of subtle pelvic fluid collections. AJR Am J Roentgenol. 1984;143 (2): 261-3. doi:10.2214/ajr.143.2.261 - Pubmed citation
- 2. DeCherney AH, Minkin MJ, Spangler S. Contemporary management of ectopic pregnancy. J Reprod Med. 1982;26 (10): 519-23. Pubmed citation
- 3. Nakeer T, Shahid M, Ansari MA et-al. Hydatidiform mole presentation as a tubal ectopic pregnancy. J Coll Physicians Surg Pak. 2015;24 Suppl 2: S89-90. Pubmed citation