HSG Test: What It Shows and What a Normal Result Means

An HSG test — hysterosalpingography — is an X-ray that shows whether your fallopian tubes are open and whether the inside of your uterus is a normal shape. It is one of the first investigations offered when a couple has been trying to conceive without result, and it is the test patients most often arrive anxious about. This page explains what happens, what the report means, and what an abnormal finding does and does not imply.

On this page

• What an HSG test is
• When an HSG test is recommended
• How the procedure is done
• What a normal report says
• Abnormal findings and what they mean
• Pain, side effects and risks
• HSG test, HyCoSy or laparoscopy
• What happens after your HSG test
• Questions patients ask

What an HSG test is

A thin catheter is passed through the cervix and a water-soluble iodinated dye is injected slowly into the uterine cavity. X-ray images are taken as the dye fills the cavity, travels along both tubes and spills into the abdomen. The whole thing takes about ten minutes.

Two things are being read at once. The outline of the dye inside the uterus shows the shape of the cavity: polyps, submucous fibroids, adhesions and septa all appear as gaps or distortions. The thread of dye running out along each tube, and the free spill at the end, shows patency.

An HSG test does not show the outside of the tubes, the ovaries, or endometriosis. It answers a narrow question well and says nothing about the rest.

It helps to know what you are looking at when the images are handed to you. The uterine cavity appears as a small white triangle. From each upper corner a fine white line runs outwards — that is the tube. At the far end, if the tube is open, the dye disperses into a soft cloud. Two triangles, two lines, two clouds is what a clear study looks like.

When an HSG test is recommended

NICE advises tubal assessment for women with no history of pelvic infection, previous surgery or endometriosis using hysterosalpingography or a similar screening test, reserving laparoscopy with dye for those with such a history. In practice we suggest an HSG test when:

• You have been trying for twelve months, or six if you are over 35
• Ovulation and hormones look normal and the tubes are the remaining unknown
• You are being considered for intrauterine insemination, which requires at least one open tube
• There has been a previous ectopic pregnancy, pelvic surgery or appendicitis
• You are planning to stop contraception after a long gap and want the picture mapped first

How the procedure is done

Timing matters. The HSG test is scheduled between day 5 and day 10 of the cycle: after bleeding has stopped, so the view is clear, and before ovulation, so there is no chance of exposing an early pregnancy to X-rays.

You lie on an X-ray table with your knees bent. A speculum is placed, the cervix is cleaned, and the catheter is inserted. Dye goes in slowly over a minute or two while four to six images are taken. The catheter comes out, and you rest for fifteen to twenty minutes before going home. No anaesthetic is needed, and you can drive yourself afterwards.

We advise a simple painkiller such as ibuprofen an hour beforehand, and we ask you to eat normally. Antibiotic cover is given where there is a history of pelvic infection.

Bring a sanitary pad and someone to sit with you if you would rather not travel home alone. Tell us in advance about iodine or contrast allergy, asthma, thyroid disease or metformin use, since each changes how the contrast is handled. If there is any chance you are already pregnant, the HSG test is postponed. Our page on tubal assessment covers the practical arrangements in Chennai.

What a normal report says

A normal HSG test report describes a uterine cavity of normal size and outline, both tubes filling along their length, and free spill of dye into the peritoneal cavity on both sides. Some reports add “bilateral spillage seen” or “no filling defect”.

That is genuinely reassuring about the tubes. It is not a statement that you are fertile. Open tubes can still be damaged internally: the delicate cilia that move the egg cannot be seen on X-ray. Roughly a third of couples with unexplained infertility have entirely normal tubal imaging.

Abnormal findings and what they mean

No spill on one side. Often nothing. The muscle at the junction of tube and uterus can spasm when dye hits it, closing a healthy tube temporarily. Published series attribute a substantial share of proximal blocks — commonly quoted between 15% and 20% — to spasm rather than disease. A repeat study or a laparoscopy settles it.

No spill on either side. More meaningful, though still worth confirming. Bilateral proximal block on imaging is reproduced at laparoscopy in only about half of cases.

A dilated, sausage-shaped tube with no spill. This is a hydrosalpinx, and it does change the plan, because fluid in a blocked tube reduces implantation. See our page on fallopian tube problems.

Filling defects in the cavity. Polyps, submucous fibroids or adhesions. These are confirmed and usually treated at hysteroscopy.

An unusual cavity outline. A T-shaped, arcuate or septate cavity may be congenital. Only some of these matter, and imaging alone rarely settles which.

Pain, side effects and risks

Most women describe cramping like a strong period, lasting a few minutes while the dye goes in and easing quickly afterwards. A minority find it sharply painful. Tell the radiologist immediately if that happens rather than enduring it; slowing the injection usually helps.

Light spotting for a day or two is normal, as is a sticky discharge as dye drains. Serious problems are rare. Pelvic infection follows roughly 1–3% of procedures, concentrated almost entirely in women with previous pelvic inflammatory disease. Allergy to iodinated contrast and uterine perforation are both uncommon.

Radiation exposure is small: an HSG test delivers of the order of 1 millisievert, comparable to a few months of ordinary background radiation. Fever, heavy bleeding or worsening pain after twenty-four hours needs a same-day review.

HSG test, HyCoSy or laparoscopy

Three tests answer overlapping questions. HyCoSy and HyFoSy use ultrasound and a foam or saline contrast instead of X-ray, avoid radiation, and assess the ovaries at the same time; they depend more on operator skill. Laparoscopy with dye is definitive and also shows endometriosis and adhesions, but it is surgery under general anaesthetic.

For a woman with no risk factors, starting with an HSG test is proportionate. For a woman with a history of pelvic infection, severe pain or prior surgery, going straight to laparoscopy avoids a test that is likely to be equivocal.

What happens after your HSG test

You will usually have images and a report the same day. At Jananam both partners are evaluated before a plan is made, so tubal findings are read alongside ovarian reserve and the semen analysis, not on their own.

If both tubes are open and everything else is normal, timed attempts or intrauterine insemination remain reasonable. If both are blocked, or a hydrosalpinx is present, IVF bypasses the tubes and is the logical route. The NHS infertility overview sets out the same pathway, and the full NICE fertility guideline CG156 is publicly available.

One extra point worth knowing: flushing the tubes appears to have a modest therapeutic effect of its own. In a randomised trial of over a thousand women, ongoing pregnancy within six months occurred in 39.7% after oil-based flushing compared with 29.1% after water-based (Dreyer and colleagues, 2017).

Questions patients ask

Does an HSG test improve my chances of conceiving?

Modestly, for a few months afterwards, as the trial above suggests. It is a side benefit, not a reason to have the test.

Can I try to conceive in the same cycle?

Yes. Once bleeding has settled there is no reason to avoid intercourse in that cycle, and many clinicians actively encourage it.

What if one tube is blocked?

With one open tube, natural conception and insemination both remain possible. The blocked side is monitored rather than treated, unless it is dilated.

Do I need to repeat it?

Not routinely. A repeat is sensible only if the first study was technically poor, or if pelvic infection or surgery has occurred since.

Written and medically reviewed by Dr. Vani Sundarapandian, MD, DGO, FRCOG (UK) — founder and Medical Director, Jananam Fertility Centre, Chennai.