Culdocentesis is a medical procedure involving the extraction of fluid from the rectouterine pouch (pouch of Douglas)^[1] posterior to the vagina through a needle. It can be one diagnostic technique used in identifying pelvic inflammatory disease (in which case purulent fluid will be extracted) and ruptured ectopic pregnancies that cause hemoperitoneum.^[2]

Culdocentesis
Sagittal section of the lower part of a female trunk, right segment. (Pouch of Douglas labeled at bottom right.)
Specialty	gynaecology
ICD-9-CM	70.0
MedlinePlus	003919
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In the procedure, the rectouterine pouch is often reached through the posterior fornix of the vagina. The process of creating the hole is called colpotomy if a scalpel incision is made to drain the fluid rather than using a needle.