Fertility & conception

Saline Sonogram vs. HSG: Which Test Shows What

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A saline sonogram uses ultrasound and saline to show the shape of the uterine cavity, spotting polyps or fibroids. An HSG uses X-ray dye and also reveals whether the fallopian tubes are open. Tubes point to an HSG; cavity questions often point to a saline sonogram, and some workups use both.

Last updated: July 2026

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What does each test actually look at?

An HSG uses X-ray and contrast dye to show both the fallopian tubes and the uterine cavity, while a saline sonogram, also called a sonohysterogram or SIS, uses ultrasound and sterile saline to show the cavity alone. Both are quick outpatient tests, usually done in the first half of the menstrual cycle before ovulation.

According to the American Society for Reproductive Medicine, imaging of the uterus and tubes is a core part of the infertility evaluation, often begun after 12 months of trying, or 6 months at age 35 or older 1. Our guide to what to expect during an HSG walks through that specific test.

When would a clinic order a saline sonogram?

A saline sonogram is often chosen when the main question is the shape and lining of the uterine cavity. Filling the cavity with a small amount of saline makes polyps, fibroids that bulge inward, and bands of scar tissue stand out clearly on ultrasound.

It uses no radiation and no iodine-based dye, which can matter for people with certain allergies. Polyps, submucosal fibroids, and scar tissue are among the uterine-cavity findings that can interfere with implantation, and knowing whether they distort the cavity changes fertility planning 2. Our overview of uterine fibroids and their treatment explains why cavity involvement matters.

When is an HSG the better test?

An HSG is the test of choice when tubal patency, whether the tubes are open, is the question, because a standard saline sonogram cannot reliably show the length of the tubes. Contrast dye that spills freely from the ends of the tubes on X-ray confirms they are open, while dye that stops short suggests a blockage.

Since tubal factors are a common and treatable cause of infertility, this information is often decisive 1. About 1 in 6 people of reproductive age face infertility, and identifying a blocked tube early can direct treatment 3. Our guide to blocked fallopian tubes explains the options that follow.

How do comfort, radiation, and timing compare?

Both tests are brief, typically taking about 10 to 15 minutes, and both are scheduled in the first half of the cycle to avoid an early pregnancy. Both can cause cramping and light spotting afterward.

The clearest differences are that an HSG involves a small dose of X-ray radiation and iodine-based dye, while a saline sonogram uses neither. Because both are done while people are actively trying to conceive, they belong to the reproductive years rather than adolescence or the postmenopausal stage. Blood tests often run alongside imaging; our guide to fertility blood tests explains what those add.

When a uterine or tubal test needs a specialist

Choosing between a saline sonogram and an HSG is a decision a fertility specialist makes with the full picture in view. A reproductive endocrinologist or gynecologist weighs your history, symptoms, and earlier results to order the test that answers the most useful question first, and sometimes both are needed.

If results are unclear, further tests such as hysteroscopy may follow. Gale can help you prepare for that conversation and keep your results organized.

Common questions

No. A saline sonogram uses ultrasound and saline to show the uterine cavity, with no radiation. An HSG uses X-ray and contrast dye and can also show whether the fallopian tubes are open. They answer different questions and are sometimes both used.

Both can cause cramping when the cervix is passed and the cavity is filled. Discomfort varies from person to person, and neither is reliably worse. Over-the-counter pain relief beforehand is a common approach for both.

A standard saline sonogram focuses on the cavity and cannot reliably confirm the tubes are open. A specialized version using contrast can assess tubes in some clinics, but the HSG remains the common test for tubal patency.

Sometimes. If both the cavity and the tubes are in question, a clinician may order both, or start with one and add the other based on what it shows. The order depends on your history and symptoms.

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When symptoms after a uterine or tubal test need a call

  • —A fever or chills after either test can signal a pelvic infection and is a reason to seek same-day clinician review.
  • —Pelvic pain that worsens over the days after the test, rather than easing, is a reason to contact your clinician promptly.
  • —Heavy bleeding, such as soaking a pad within an hour, is a reason to seek urgent medical care.
  • —Foul-smelling discharge or feeling generally unwell afterward is a reason to arrange a prompt clinician review.

Fever, worsening pelvic pain, or heavy bleeding after a saline sonogram or HSG can signal a pelvic infection. Contact your clinician the same day or go to urgent care. Call 911 for fainting or bleeding you cannot control.

This article is general health education, not medical advice. Which test is right for you is a decision to make with a gynecologist or reproductive endocrinologist who knows your history.

References

  1. 1.Practice Committee of the American Society for Reproductive Medicine (2021). Fertility evaluation of infertile women: a committee opinion. Fertility and Sterility. doi:10.1016/j.fertnstert.2021.08.038 ✓HSG and saline sonohysterography as core imaging tests in the infertility evaluation; the HSG assesses tubal patency, which a standard saline sonogram cannot; timing thresholds for the workup.
  2. 2.MedlinePlus (National Library of Medicine) (2025). Female Infertility. MedlinePlus, U.S. National Library of Medicine (NIH). link ✓Uterine-cavity findings such as polyps and fibroids as causes of female infertility.
  3. 3.World Health Organization (2025). Infertility (fact sheet). World Health Organization (WHO). link ✓Infertility affects about 1 in 6 people of reproductive age.

3 sources, numbered by first appearance. General health information, not medical advice. AI-assisted editorial content — every citation independently verified. Editorial policy

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