What are the major causes of hydrosalpinx and hematosalpinx, and what are their imaging features on US and MRI?
A hydrosalpinx is a dilated fluid-filled fallopian tube; it is most commonly due to prior pelvic inflammatory disease (PID) and less commonly due to endometriosis, prior pelvic surgery with adhesions, fallopian tube cancer, or ectopic pregnancy. On US, a tubular adnexal cystic lesion separate from the ovary is seen, sometimes with visualization of a characteristic “waist” sign due to indentation of the opposing walls or with a “cog-wheel” or “beads-on-a-string” appearance due to polypoid protrusions of the mucosa into the lumen. On MRI, low T1-weighted and very high T2-weighted signal intensity fluid contents are observed within a tubular adnexal cystic lesion, along with characteristic incomplete longitudinal folds representing mucosal plicae.
A hematosalpinx is a dilated hemorrhage-filled fallopian tube and is most commonly due to endometriosis in a nonpregnant female. Other causes include ectopic pregnancy, adnexal torsion, fallopian tube cancer, and retrograde menstruation in the setting of hematometrocolpos. On US, low-level echoes or laying echogenic material may be seen within the fallopian tube lumen. On MRI, high T1-weighted and variable T2-weighted signal intensity hemorrhagic fluid is observed.