An HSG, or hysterosalpingogram, is an X-ray test that checks whether your fallopian tubes are open and your uterus is shaped normally. It’s one of the first tests ordered during a fertility workup because structural problems with the uterus and fallopian tubes contribute to up to 60% of infertility cases. The test takes about 15 to 30 minutes, involves injecting a special dye through the cervix, and can sometimes improve your chances of conceiving in the months that follow.
How the Test Works
During an HSG, you lie on an X-ray table while a thin catheter is inserted through your cervix into the uterus. A contrast dye flows through the catheter, filling your uterine cavity and traveling into your fallopian tubes. As the dye moves, a series of X-ray images capture its path in real time using fluoroscopy. If the tubes are open, the dye spills out the far ends near the ovaries. If a tube is blocked, the dye stops at the point of obstruction, showing exactly where the problem is.
The entire process happens in a radiology suite or your fertility clinic. You’re awake throughout, and no anesthesia is required, though pain management options exist (more on that below). Most people are able to go home shortly after the test is finished.
When It’s Scheduled
HSG is typically performed 7 to 10 days after the first day of your period. This window falls before ovulation, which minimizes the chance you could be pregnant during the test. Your clinic will confirm you’re not pregnant beforehand, since the X-ray radiation and dye injection could pose risks to an early pregnancy.
What the Results Mean
A normal HSG shows dye flowing freely through both fallopian tubes and spilling into the pelvic cavity, confirming the tubes are open (patent). The images also reveal the shape of the uterine cavity, which can identify abnormalities like polyps, fibroids, or a uterine septum that might interfere with implantation.
Abnormal results generally fall into two categories:
- Tubal blockage. If both tubes are blocked (bilateral occlusion), there’s no natural path for egg and sperm to meet. In this case, IVF is typically the recommended next step. If only one tube is blocked, the open tube can still allow natural conception, and your doctor may suggest less invasive treatments first.
- Hydrosalpinx. This is a specific type of blockage where the far end of a tube is sealed shut and fluid accumulates inside, causing the tube to swell. It’s most commonly caused by a prior pelvic infection. A hydrosalpinx can reduce IVF success rates, so surgical repair or removal of the affected tube is often recommended before starting treatment.
How Accurate Is It?
HSG is good at confirming what it finds, but it isn’t perfect. For detecting whether both tubes are open or both are blocked, the test has a sensitivity of about 92% and a specificity of about 86%, meaning it correctly identifies the situation in the vast majority of cases. However, when one tube is open and one is blocked, accuracy drops considerably, with specificity falling to roughly 53%. For this reason, if results are ambiguous or don’t match your clinical picture, your doctor may recommend a laparoscopy for a more definitive look.
What the Pain Actually Feels Like
The most common concern about HSG is the pain, and it’s worth being honest: for many women, the dye injection is genuinely uncomfortable. In studies measuring pain at each step of the procedure, the moment when contrast dye is pushed into the uterus and tubes consistently ranks as the most painful phase. Women who took only an anti-inflammatory painkiller beforehand rated this step around 7 out of 10 on a pain scale.
The discomfort is typically described as intense menstrual-type cramping that peaks during the injection and fades within minutes. Taking an over-the-counter anti-inflammatory about an hour before the appointment helps, but research shows that adding a local anesthetic (like a numbing cream applied to the cervix) drops pain scores significantly, to roughly 4 out of 10. If you’re concerned about pain, it’s reasonable to ask your clinic what they offer beyond a standard painkiller.
The other steps of the procedure, including speculum insertion and catheter placement, tend to cause much milder discomfort similar to a Pap smear.
After the Procedure
Light spotting and mild cramping are normal for a day or two following an HSG. Some women notice a small amount of watery discharge as residual contrast dye leaves the body. You can use a pad but should avoid tampons for a short period to reduce infection risk. Most people return to normal activities the same day or the next morning.
Serious complications are rare. The risk of developing a pelvic infection after HSG runs between 1.4% and 3.4%. Antibiotics before the test aren’t routinely recommended unless you have a history of pelvic inflammatory disease or the test reveals dilated tubes. Contact your doctor if you develop a fever, worsening pain, or unusual discharge in the days following the procedure.
The Fertility Boost After HSG
One of the more surprising aspects of HSG is that the test itself may improve your chances of getting pregnant. This isn’t just anecdotal. A large randomized trial published in the New England Journal of Medicine compared over 1,100 women undergoing HSG and found that those who received oil-based contrast dye had a 39.7% ongoing pregnancy rate in the months after the test, compared to 29.1% for those who received water-based dye. Live birth rates showed the same pattern: 38.8% with oil-based contrast versus 28.1% with water-based.
Roughly three-quarters of these pregnancies in both groups were conceived naturally, without any additional fertility treatment. The leading theory is that the dye may flush out minor debris or mucus from the tubes, or that the oil-based contrast has some effect on the uterine lining that makes implantation more favorable. Whatever the mechanism, the effect is real enough that some clinics specifically use oil-based contrast when performing HSG.
This means HSG serves a dual purpose: it diagnoses structural problems and may simultaneously give fertility a measurable boost. If your tubes turn out to be open and your uterus looks normal, your doctor will likely suggest trying to conceive naturally for a few cycles before moving on to other interventions, since the months immediately following HSG appear to carry improved odds.
What Comes Next Based on Your Results
Your HSG results shape the rest of your fertility plan. If everything looks normal, your workup continues with other tests, including hormone levels, ovulation tracking, and semen analysis for your partner. A normal HSG rules out a major category of infertility but doesn’t explain all possible causes.
If a blockage is found, the path depends on whether one or both tubes are affected. Bilateral blockage generally leads to IVF, since there’s no open route for natural conception. Unilateral blockage leaves more options on the table, including timed intercourse, ovulation-stimulating medications, or intrauterine insemination timed to ovulation from the side with the open tube.
If the uterine cavity shows an abnormal shape or a structural issue like a polyp or fibroid, a follow-up procedure (often a hysteroscopy, which uses a small camera inserted through the cervix) may be recommended to confirm the finding and potentially correct it at the same time.