Differential Diagnosis for Mild Free Fluid on Pelvic US
- Single Most Likely Diagnosis
- Ovulation: Mild free fluid in the pelvis can be a normal finding, especially in women of reproductive age, due to ovulation. The rupture of the follicle during ovulation can release a small amount of fluid into the pelvic cavity.
- Other Likely Diagnoses
- Pelvic Inflammatory Disease (PID): An infection of the female reproductive organs can cause inflammation and lead to the accumulation of fluid in the pelvis.
- Ovarian Cyst Rupture: A ruptured ovarian cyst can release fluid into the pelvic cavity, which may be detected on ultrasound.
- Miscarriage or Ectopic Pregnancy: In early pregnancy, mild free fluid can be a sign of a miscarriage or an ectopic pregnancy.
- Do Not Miss Diagnoses
- Ruptured Ectopic Pregnancy: Although less common, a ruptured ectopic pregnancy is a life-threatening condition that requires immediate medical attention. The presence of free fluid can indicate internal bleeding.
- Appendicitis: In some cases, a ruptured appendix can cause free fluid to accumulate in the pelvis, which may be visible on ultrasound.
- Ovarian Torsion: Torsion of the ovary can cut off blood supply and lead to the release of fluid into the pelvic cavity.
- Rare Diagnoses
- Endometriosis: Although not typically associated with free fluid, severe endometriosis can cause inflammation and lead to the accumulation of fluid in the pelvis.
- Malignancy: Certain types of cancer, such as ovarian cancer, can cause the accumulation of fluid in the pelvis, known as ascites.
- Tubal Pregnancy or Rupture: A rare condition where the embryo implants in the fallopian tube, which can rupture and cause free fluid in the pelvis.