The Hysterosalpingogram (HSG) is an X-ray based procedure which is usually done in the department of radiology by a radiologist.
The person is placed on an X-ray table. The cervix is visualized by placing a speculum. The cervix is cleansed and grasped. A metal tube is place in the cervix and radio-opaque fluid is flushed through the uterus and fallopian tubes. If the tubes are open, the dye will spill into the abdomen.
The test can be painful and there is a slight chance of either infection or an allergic reaction to the dye. The value of the test lies in the ability of the test to determine abnormal pathology. If there are abnormal structures in the cavity of the uterus they will show on the X-ray.
The test is accurate in determining if the fallopian tubes are open. However, the test is far less accurate if it says the tubes are blocked. If the test says the tubes are blocked, the accuracy is only 40-50 %, meaning half the time the test suggested the tubes are abnormal when in fact the anatomy is normal.
Furthermore, commonly the test will say one tube is blocked just as the tube leaves the uterus, called a proximal, unilateral obstruction. Unless there is other evidence for an anatomic problem, this finding does not suggest a reduction in fertility rates.
Before the introduction of ultrasonography, the course of action was to do a HSG and if normal, follow that with a diagnostic laparoscopy. Today, that course has been replaced with the use of ultrasonography.