Culdocentesis is a procedure that checks for abnormal fluid in the space just behind the vagina (cul-de-sac).

This procedure is done when you have pain in the lower abdomen and pelvis, and other tests suggest there is fluid in the cul-de-sac. This test may also be done when the doctor suspects a ruptured ectopic pregnancy or ovarian cyst.

The test is rarely done today because an ultrasound can usually detect fluid in the cul-de-sac.

First, you will have a pelvic examination. Then, the health care provider will grasp the cervix with an instrument and lift it slightly.

A long, thin needle is inserted through the wall of the vagina (just below the uterus). A sample is taken of any fluid found in the space. The needle is pulled out.

You may be asked to walk or sit for a short time before the test is done.

You may have an uncomfortable, cramping feeling when the cervix is grasped. There is a sharp, brief pain as the needle is inserted.