What is no free fluid in cul de sac?

"No free fluid in the cul de sac" refers to the absence of excess fluid in the rectouterine pouch (also known as the cul de sac of Douglas), which is the space between the uterus and the rectum in females. This finding is often noted during pelvic ultrasound or imaging studies and can suggest the absence of conditions such as pelvic inflammatory disease, ectopic pregnancy, or ruptured ovarian cysts. The presence of free fluid may indicate underlying pathology, so its absence is typically considered a normal finding.