A hysterosalpingogram (HSG) is a short X-ray procedure that checks whether your fallopian tubes are open and whether the inside of your uterus looks normal. The whole test takes about 15 to 30 minutes and is done in a radiology suite or your fertility clinic, not an operating room. It’s one of the first tests ordered during a fertility workup, and understanding what happens at each stage can make the experience far less intimidating.
When the Test Is Scheduled
Your clinic will ask you to come in during a specific window of your menstrual cycle. The ideal timing is 7 to 10 days after the first day of your period, which places the test after your period has ended but before ovulation. This minimizes the chance you could be pregnant during the procedure. If your cycles are irregular, your doctor may confirm timing with a pregnancy test beforehand.
The test should not be performed if you are pregnant, if you have an active pelvic infection, or if you have an untreated allergy to iodine-based contrast dye. If you have a known iodine or shellfish allergy, let your doctor know ahead of time so they can prescribe premedication.
How to Prepare
Preparation is minimal. The most helpful thing you can do is take a pain reliever before you arrive. Johns Hopkins Medicine recommends 400 milligrams of ibuprofen or 500 milligrams of acetaminophen about 30 minutes before the procedure. This helps take the edge off cramping during and after the test. You can take another dose about an hour afterward if needed.
You don’t need to fast, and you won’t receive sedation. Wear comfortable clothing that’s easy to change out of. Some clinics provide a gown. Bring a pad for light spotting afterward, since most facilities won’t have one on hand.
Step by Step: What Happens During the Test
You’ll lie on an X-ray table in the same position as a pelvic exam, with your feet in stirrups. The radiologist or gynecologist performing the test will insert a speculum to visualize your cervix, just like during a Pap smear. They’ll clean the cervix, then thread a thin, flexible catheter through the cervical opening into the uterus. Some providers use a small balloon on the tip of the catheter to hold it in place.
Once the catheter is positioned, the speculum is removed and the clinician slowly injects a contrast dye through the catheter. This dye is visible on X-ray and fills your uterine cavity first, then travels through your fallopian tubes. A series of X-ray images are taken as the dye flows, showing the shape of the uterine cavity and whether each tube is open. If the tubes are clear, the dye spills freely out the ends into the pelvic cavity, which confirms they aren’t blocked.
The entire injection and imaging sequence typically takes just a few minutes. The catheter is then removed, and you’re done.
What It Feels Like
Most people experience mild to moderate cramping that feels similar to period cramps. This usually lasts about 5 to 10 minutes, though some people have cramps that linger for several hours afterward. The cramping tends to be strongest at two moments: when the catheter passes through the cervix and when the dye is injected. If a tube is blocked, the pressure from the dye trying to push through can cause sharper discomfort on that side.
The procedure is uncomfortable, but it’s brief. Most people describe it as tolerable, especially with the pre-procedure pain reliever on board. Deep, slow breathing during the injection can help you stay relaxed and may reduce cramping.
What the Results Show
Your doctor reviews the X-ray images to check two things: the uterine cavity and the fallopian tubes.
- Uterine cavity: The dye outlines the interior shape of the uterus, revealing abnormalities like polyps, fibroids pushing into the cavity, scar tissue (adhesions), or a uterine septum (a wall of tissue dividing the cavity). These can interfere with implantation.
- Fallopian tubes: If dye flows through a tube and spills out the far end, the tube is open. If dye stops partway through or the tube appears swollen and distended (a sign of fluid buildup called hydrosalpinx), that tube may be blocked. Blockages can occur near the uterus, at the middle of the tube, or at the far end.
Results are often available the same day or within a day or two. A normal HSG doesn’t guarantee fertility, but it rules out some of the most common structural problems. If a blockage or abnormality is found, your doctor will discuss next steps, which might include further imaging, a procedure to look inside the uterus directly, or surgical evaluation of the tubes.
Oil-Based vs. Water-Based Contrast Dye
Not all HSG dyes are the same. Clinics use either an oil-based or water-based contrast, and the choice can matter beyond just getting a clear picture. A meta-analysis published in the Turkish Journal of Obstetrics and Gynecology found that pregnancy rates were significantly higher in women who received oil-based contrast compared to water-based, with roughly 51% greater odds of conceiving. Live birth rates were also higher in the oil-based group.
The exact reason isn’t fully understood, but researchers believe the oil-based dye may have mild antibacterial properties and help break up thin debris or mucus inside the tubes, essentially flushing them in a way that creates a more favorable environment for conception. This is why some fertility specialists describe the HSG itself as mildly therapeutic, not just diagnostic. If you have a choice, it’s worth asking your clinic which type of contrast they use.
Recovery and What to Expect After
You can go home right after the procedure. Most people return to normal activities the same day, though you may want to take it easy for the rest of the afternoon if cramping persists. Light spotting or a small amount of watery discharge (from residual dye) is normal for a day or two.
The risk of infection following an HSG is low, ranging from about 1.4% to 3.4%. Signs to watch for in the days after include fever, increasing pelvic pain, or unusual vaginal discharge with a strong odor. These are uncommon but warrant a call to your clinic. For most people, the HSG is a one-and-done test that provides answers quickly with very little downtime.