Fluid-filled, distended fallopian tube

A hydrosalpinx is a dilated fallopian tube filled with fluid. A normal tube is not visible sonographically; however, when a tube becomes obstructed, it distends and fills with fluid, giving it a sausage-like appearance. Infection is a major cause of hydrosalpinx, also called pelvic inflammatory disease (PID), in which the tube fills with pus in the acute phase of the disease (pyosalpinx). In ectopic pregnancy, the tube can distend and fill with blood (hematosalpinx) and have a similar appearance to a pyosalpinx. Tubal torsion presents with acute pain and a tender, distended tube. Scarring and adhesions in the pelvis can obstruct the tubes and allow them to fill with fluid, but this is more often found in asymptomatic patients since it is not an acute process. This can also be seen in cases of severe endometriosis, or previous pelvic surgery. Rarely, tuberculosis and other infections can attack the pelvis and result in hydrosalpinx.

A hydrosalpinx has a typical sonographic appearance. Evaluation of the adnexa reveals a cystic, sausage-shaped, serpiginous, tubular mass. The distended tube often has a characteristic “spoke-wheel” pattern made up by the incomplete septae of the tube. The tube can become redundant and fold upon itself, giving the appearance of a multiseptate cystic mass. If the adjacent ovary is not clearly visualized, it is easy to suspect ovarian pathology. If the hydrosalpinx is the result of pelvic inflammatory disease, the tubal wall can occasionally be thick and irregular, making the correct diagnosis more difficult. In the study by Sokalska and colleagues (from the IOTA multicenter study), the sensitivity for the sonographic diagnosis of hydrosalpinx was 86%.