Ovarian Cyst Rupture: This is a common cause of free fluid in the pelvis, especially in women of reproductive age. The rupture of an ovarian cyst can lead to a significant amount of fluid accumulation in the pelvic cavity.

Pelvic Inflammatory Disease (PID): PID can cause inflammation and fluid accumulation in the pelvis due to infection.
Ectopic Pregnancy: Although less common, an ectopic pregnancy can rupture and cause moderate to severe free fluid in the pelvis.
Endometriosis: In some cases, endometriosis can lead to fluid accumulation in the pelvis, especially if there are endometriotic cysts that rupture.
Diverticulitis: Diverticulitis, especially if it involves the sigmoid colon, can cause fluid to leak into the pelvis.

Ruptured Ectopic Pregnancy: Although mentioned earlier, it's crucial to emphasize that a ruptured ectopic pregnancy is a medical emergency that requires immediate attention.
Appendicitis with Rupture: If the appendix ruptures, it can spill infectious material and fluid into the pelvis, leading to severe consequences if not promptly treated.
Bowel Perforation: Any perforation of the bowel can lead to leakage of bowel contents into the pelvis, which is a serious condition requiring urgent surgical intervention.

Malignancy: Certain pelvic malignancies can cause fluid accumulation due to tumor rupture or necrosis, although this is less common.
Tuberculosis: Pelvic tuberculosis can cause fluid accumulation and adhesions in the pelvis, though it is relatively rare in many parts of the world.
Lymphatic Fluid Leak: A rare condition where there is a leak from the lymphatic system, leading to the accumulation of lymphatic fluid (chyle) in the pelvis.