Can B-ultrasound detect blocked fallopian tubes?

Ultrasound (B-ultrasound) usually cannot detect blocked fallopian tubes. The fallopian tubes are two very small ducts; ultrasound can reveal whether there is edema or cysts within the tubes. Normally, tubal blockage involves obstruction of the tubal lumen, which cannot be visualized by ultrasound. To determine whether the fallopian tubes are blocked, a hysterosalpingography (HSG) is required. During this procedure, a contrast agent is injected into the tubal cavity. If the tube is blocked, the contrast agent cannot pass through the fallopian tube into the pelvic cavity, but it can be visualized under X-ray. Therefore, in clinical practice, hysterosalpingography should be performed to make a definitive diagnosis of tubal patency.