Culdocentesis

The puncture and aspiration (withdrawal) of fluid from the cul-de-sac, the rectouterine pouch (the pouch of Douglas), an extension of the peritoneal cavity between the rectum and back wall of the uterus.

The word 'culdocentesis' is derived from 'cul-de-sac' which is a blind pouch or cavity that is closed at one end and, in a more specific sense, refers to the rectouterine pouch.

In French, 'cul-de-sac' literally is 'bottom of (a) sack.' As early as the 13th century, a cul-de-sac was a dead-end street (or a dead-end way), a blind alley.

A 'centesis' is a puncture (the Greek 'kentesis' = puncture), as in: abdominocentesis (am abdominal tap), amniocentesis (an amniotic fluid tap), etc.

Thus, the composite word 'culdocentesis' = a tap of the cul-de-sac.