A hysterosalpingogram, commonly called an HSG, is an X-ray procedure that uses contrast dye to create images of your uterus and fallopian tubes. It’s one of the first tests ordered during a fertility workup because it can reveal whether your fallopian tubes are open and whether the shape of your uterus is normal. The entire procedure takes about 15 to 30 minutes and is done in a radiology suite, not an operating room.
What an HSG Can Tell You
The primary purpose of an HSG is to check whether your fallopian tubes are open (a term doctors call “patent”). During the test, contrast dye is slowly injected through the cervix into the uterus. If the tubes are open, the dye flows through them and spills out into the pelvic cavity, which shows up clearly on X-ray. If the dye stops at any point, that indicates a blockage.
Blockages can occur at different locations. In one study of women with tubal occlusion, 40.5% had blockages near the uterus (proximal), 35.1% had blockages near the ends of the tubes (distal), and 13.5% had a combination of both. This distinction matters because the location of the blockage influences which treatments are most likely to help.
Beyond the tubes, the HSG also outlines the interior shape of the uterus. It can detect congenital uterine abnormalities like a septum dividing the cavity, polyps, fibroids that project into the uterine lining, and scar tissue (adhesions) that may interfere with implantation.
How the Procedure Works
An HSG is scheduled during the first half of your menstrual cycle, typically between days 1 and 14. This timing serves two purposes: it reduces the chance you could be pregnant, and the uterine lining is thinner at this point, making the images easier to read. You’ll be asked to avoid intercourse before the test to further rule out early pregnancy.
You’ll lie on an exam table with your feet in stirrups, similar to a pelvic exam. The doctor inserts a speculum, then threads a thin catheter through the cervix and into the lower uterine cavity. A small balloon on the catheter inflates to hold it in place and create a seal. Once the speculum is removed for your comfort, the imaging begins.
The doctor slowly injects contrast dye through the catheter while a fluoroscopy machine (a real-time X-ray) captures images. You’ll typically be repositioned slightly so the radiologist can get straight-on and angled views. The images are taken at several stages: as the dye first enters the uterus, after the uterine cavity is fully outlined, as dye moves through the fallopian tubes, and finally as it spills into the surrounding pelvic space. If one tube doesn’t appear to fill, medication can be given through an IV to relax the tube muscles, since spasm can mimic a true blockage.
What It Feels Like
Most women describe the HSG as uncomfortable rather than painful. The sensation is similar to strong menstrual cramps, particularly when the dye is being injected. Pain tends to be brief, lasting mainly during the injection itself and easing quickly once the catheter is removed.
Your doctor will likely recommend taking an over-the-counter anti-inflammatory painkiller about an hour before the procedure. Clinical studies have tested various pain relief approaches and found that an oral anti-inflammatory combined with a local numbing agent applied to the cervix provides the most effective relief. Some clinics also prescribe a short course of antibiotics beforehand as a precaution against infection.
Recovery After the Test
You can return to normal activities immediately after an HSG. Light spotting for one to two days is common and not a cause for concern. Some doctors recommend avoiding intercourse for a few days. Heavy bleeding, fever, or increasing pelvic pain after the procedure is not typical and should prompt a call to your doctor.
Risks Are Low
Serious complications from an HSG are rare. A large nationwide survey of over 5,000 procedures found that pelvic infection occurred in only 0.3% to 0.4% of cases, regardless of which type of contrast dye was used. Allergic reactions to the iodine-based contrast were even rarer, occurring in 0.03% to 0.1% of cases, and no anaphylactic reactions were reported at all.
The test is not performed if you are pregnant, have an active pelvic or genital tract infection, have recently had uterine or tubal surgery, have active vaginal or uterine bleeding, or have a severe allergy to iodine-based contrast.
The Surprising Fertility Benefit
One of the most interesting aspects of an HSG is that it may actually improve your chances of getting pregnant, not just diagnose why you haven’t. Flushing dye through the tubes appears to have a therapeutic effect, possibly by clearing minor debris or mucus plugs.
A landmark trial published in the New England Journal of Medicine compared pregnancy rates in over 1,100 women and found a significant difference depending on the type of contrast used. Among women who received oil-based contrast, 39.7% achieved an ongoing pregnancy within six months, compared to 29.1% of women who received water-based contrast. The live birth rate followed the same pattern: 38.8% with oil-based dye versus 28.1% with water-based. That 10-percentage-point difference means that for roughly every 10 women who receive oil-based contrast during their HSG, one additional woman becomes pregnant who otherwise would not have.
This doesn’t mean an HSG replaces fertility treatment, but it does mean the test itself can be more than just diagnostic. If you’re having an HSG and your clinic offers a choice of contrast type, this is worth discussing with your doctor.
How It Fits Into a Fertility Workup
An HSG is typically one of the earlier tests in an infertility evaluation, alongside blood work to check hormone levels and a semen analysis for the male partner. It’s considered a first-line screening tool for tubal problems because it’s relatively quick, doesn’t require anesthesia, and is far less invasive than surgical alternatives like laparoscopy. If the HSG shows a clear abnormality, your doctor may recommend further evaluation or move directly to treatments like IVF, which bypasses the fallopian tubes entirely.