Hysterosalpingogram (HSG): procedure, indications and pain

What is a hysterosalpingogram used for?

A hysterosalpingogram (often called an "HSG" or "tube test") shows:

• the fallopian tubes: the doctor checks that the dye flows through them and spills into the abdomen, which means they are open;
• the cavity of the womb: its shape and size, and whether there is a polyp, a fibroid, scar tissue (adhesions, or synechiae) or a malformation;
• the cervical canal.

It is one of the first-line tests in a couple's fertility work-up. The 2022 guidelines of the French College of Gynaecologists and Obstetricians (CNGOF) recommend checking whether the tubes are open either by HSG or by HyFoSy, an ultrasound scan performed with a contrast foam. The tubes can be damaged by a past pelvic infection, surgery or endometriosis.

The test is not only used for fertility investigations. It may also be requested to examine the womb cavity before surgery, to look for a cause of recurrent miscarriage (a uterine malformation or adhesions), or to check the womb and tubes after certain operations. It does not replace a pelvic ultrasound, which remains the basic test for looking at the womb and ovaries.

HSG or HyFoSy: what is the difference?

The choice between the two depends on your medical history, any iodine allergy and which technique is available locally. Both tests are scheduled under the same conditions: first half of the cycle, no pregnancy and no infection.

When in my cycle should I have an HSG?

The test is booked in the first half of the cycle, usually between the end of your period and ovulation. Scheduling instructions are provided by the radiology practice.

This timing makes sure there is no early pregnancy and gives clearer images of the womb cavity. If there is any doubt, a pregnancy test is requested. You are advised to avoid unprotected sex between the start of your period and the test, following the radiologist's instructions.

If your cycles are irregular, mention it when you book: the timing will be adjusted, and a pregnancy test may be done on the day. If you are bleeding, the test cannot always be performed in good conditions.

What happens during a hysterosalpingogram?

1. Positioning: you lie on the X-ray table in the same position as for a smear test.
2. A speculum is inserted and the cervix is cleaned.
3. A thin cannula or a small soft catheter is placed in the cervix.
4. The iodine-based contrast dye is injected slowly while several X-ray images are taken.
5. End of the test: the instruments are removed, and a final image is sometimes taken a few minutes later.

The whole procedure takes about 15 minutes. The X-ray dose is low. The radiologist often comments on the images at the end; the report is then discussed with your gynaecologist.

Before the test, tell the team about

• an allergy to iodine-based contrast dye;
• a possible pregnancy;
• unusual discharge, pelvic pain or fever in recent days;
• a history of tubal infection or a swollen, fluid-filled tube (hydrosalpinx).

Depending on your history, the doctor may prescribe a painkiller to take beforehand, or an antibiotic.

After the test, wear a sanitary pad for any dye leaking out. You can shower the same day; most women return to their usual activities the next day.

Is a hysterosalpingogram painful?

Most women feel cramps similar to period pain when the dye is injected. They usually last a few minutes. The pain can be stronger when a tube is blocked, because the dye builds up under pressure.

To reduce discomfort:

• take any prescribed painkiller about one hour beforehand;
• say if it hurts during the test: the injection can be slowed down;
• plan to rest for a while afterwards and, if possible, have someone with you.

What do HSG results mean?

Pregnancy sometimes occurs in the months after a normal HSG. A Dutch randomised trial published in the NEJM in 2017, in 1,119 women, found an ongoing pregnancy rate at six months of 39.7% after a test with an oil-based dye, compared with 29.1% with a water-based dye. A Cochrane review (2020) supports this trend with low-quality evidence, and notes that harmless passage of dye into the blood vessels is more common with oil-based dyes. The choice of dye depends on the centre and on the patient.

What are the risks of an HSG and when should I seek urgent care?

Afterwards, light discharge stained with dye or blood and mild cramps are common for one or two days. Complications are rare:

• upper genital tract infection (salpingitis), especially if you have had a tubal infection before;
• allergic reaction to the iodine-based dye;
• fainting (vasovagal reaction) during or just after the test.

See a doctor promptly, or call 15 or 112 in France, or your local emergency number, if symptoms are severe, if in the following days you have:

• a fever (38 °C or higher);
• lower abdominal pain that gets worse instead of better;
• foul-smelling or pus-like discharge;
• heavy bleeding;
• difficulty breathing, swelling of the face or a widespread rash.

Who should not have an HSG, and what are the alternatives?

The test is not performed during pregnancy, with an active genital infection or with heavy bleeding. A severe allergy to iodine-based dye leads to discussing another technique.

The alternatives are:

• HyFoSy (ultrasound with a contrast foam), with no X-rays and no iodine, which the CNGOF places on the same level as HSG for assessing the tubes;
• laparoscopy with a dye test, under general anaesthesia, reserved for situations where surgery is planned anyway;
• saline infusion sonography or hysteroscopy, which examine the womb cavity but not whether the tubes are open.

Frequently asked questions

General information article: it does not replace a medical consultation. In an emergency, call 15 or 112 in France, or your local emergency number.