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fertility

HSG Test: What It Is, What It Detects & How to Prepare

A hysterosalpingogram (HSG) is an outpatient X-ray procedure in which contrast dye is guided through the cervix to outline the uterine cavity and fallopian tubes. It shows whether the tubes are open or blocked and whether the uterus has an unusual shape. Most women experience mild to moderate cramping; the procedure typically takes under 30 minutes.

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What does an HSG actually show?

The dye flows through the inside of the uterus and then into each fallopian tube. On the X-ray images, the clinician can see:

  • Tubal patency: whether each tube is open and the dye spills freely into the pelvis
  • Tubal blockage: a point where the dye stops moving, suggesting a partial or complete obstruction
  • Uterine cavity shape: whether there are polyps, fibroids pressing into the cavity, a uterine septum, or other structural issues

An HSG does not directly show the outside of the uterus, ovarian function, or egg quality. It is one piece of a broader fertility evaluation 1, typically ordered alongside ovarian reserve testing and a semen analysis as part of a standard infertility workup.

Who is usually referred for an HSG?

A reproductive endocrinologist or gynecologist may recommend an HSG as part of a standard fertility workup, particularly if:

  • You have been trying to conceive without success and your clinician is evaluating all possible contributing factors 1
  • There is a history of pelvic infection (chlamydia, gonorrhea, or pelvic inflammatory disease), which can scar the tubes
  • You have a history of ectopic pregnancy
  • Prior imaging suggested a uterine abnormality
  • You are preparing for intrauterine insemination (IUI) or in vitro fertilization (IVF) and the clinician wants to confirm the cavity is clear

The procedure is generally performed between days 7 and 10 of a menstrual cycle, after bleeding has stopped but before ovulation.

How painful is an HSG, and how should you prepare?

Pain varies widely. Many women describe a sensation similar to strong menstrual cramping during the 2-3 minutes the dye is introduced. For most, this peaks and then eases quickly. A smaller number find it more uncomfortable, particularly if a tube is blocked and the dye creates pressure.

Preparation steps commonly recommended:

  • Take an over-the-counter anti-inflammatory (such as ibuprofen) 30-60 minutes before the procedure, as your clinician advises
  • Arrange for someone to drive you home if you are concerned about cramping afterward
  • Some clinics prescribe a short antibiotic course before the procedure as a precaution against infection
  • Bring a pad; light spotting for a day or two afterward is normal
  • Mild cramping for several hours after the procedure is common

Always follow the specific instructions given by the clinic performing your test — their protocols may differ.

What happens during and after the procedure?

You lie on an X-ray table as you would for a pelvic exam. A speculum is placed, the cervix is cleansed, and a small flexible catheter is inserted through the cervical opening into the uterus. A small balloon may be inflated to keep the catheter in place. Contrast dye is then introduced slowly while X-ray images (fluoroscopy) are taken in real time.

The entire procedure from setup to completion is typically 15-30 minutes, though you may be in the facility longer for check-in and recovery. Most women are able to return to normal activity the same day.

After the HSG: - Light spotting for 1-2 days is expected - Mild cramping for a few hours is common - Contact your clinician if you develop fever, heavy bleeding, or worsening pelvic pain — these require prompt evaluation

Can an HSG improve fertility?

This is a well-studied question. Some research has shown that tubal flushing with oil-based contrast during HSG is associated with higher live birth rates compared with water-based contrast. A 2020 long-term follow-up of a randomized trial (the H2Oil study) found live birth rates of 74.8% in the oil-contrast group versus 67.3% in the water-based group over five years, with more natural conceptions and shorter time to pregnancy in the oil group 2.

The mechanism isn't fully understood — hypotheses include flushing of mild tubal debris or local immune effects. Most HSGs in the U.S. use water-based iodine contrast, so the fertility-enhancing effect observed in these studies may not apply equally to all HSG procedures. The HSG remains a diagnostic test first; any fertility-enhancing effect should be considered a possible secondary benefit, not a guaranteed outcome. Discuss this with your reproductive specialist.

What do the results mean, and what comes next?

Your clinician will review the images with you. A normal result — dye flowing freely through both tubes and a smooth uterine cavity — is reassuring but does not rule out all causes of infertility.

If a blockage is found: - Proximal blockage (close to the uterus): sometimes caused by temporary spasm rather than a true structural block; can occasionally be re-evaluated or treated through a procedure called selective salpingography - Distal blockage (at the far end of the tube): more often represents scarring and is associated with a condition called hydrosalpinx

The HSG result guides next steps — which might be additional imaging, laparoscopy, or moving forward with IVF depending on the full clinical picture 1.

Common questions

Can an HSG increase my chances of getting pregnant?

Some research has suggested that the passage of dye through the tubes may have a small fertility-enhancing effect in certain cases, possibly by flushing mild debris. However, this is not the primary purpose of the test, and results are mixed. Your clinician can put this in context for your situation.

Is an HSG the same as a sonohysterogram?

No. A sonohysterogram (also called a saline infusion sonogram or SIS) uses ultrasound and saline rather than X-ray and iodine-based contrast. Both assess the uterine cavity, but only an HSG evaluates tubal patency with direct imaging of tube anatomy.

What if I am allergic to contrast dye or iodine?

Tell your clinician and the facility before the procedure. Alternatives may be available, such as a sonohysterogram or direct laparoscopic evaluation. Your safety team will determine the safest path.

How long does it take to get HSG results?

Because the images are taken in real time during the procedure (fluoroscopy), your clinician often can give you a preliminary interpretation immediately or at your follow-up appointment the same week. A written radiologist report may follow.

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When to contact your clinician or seek care after an HSG

  • —Fever above 100.4°F (38°C) within 48 hours of the procedure
  • —Heavy vaginal bleeding (soaking a pad in under an hour)
  • —Severe or worsening pelvic pain not relieved by ibuprofen
  • —Foul-smelling vaginal discharge
  • —Feeling faint, shortness of breath, or signs of allergic reaction during or shortly after the procedure

For severe symptoms, call 911 or go to the nearest emergency room. For concerning but non-emergency symptoms, contact the clinic that performed your HSG.

This article is for general education only. It does not replace the advice of a licensed clinician who knows your full medical history. Always follow the instructions provided by your own care team.

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 as a standard component of the female fertility evaluation; tubal patency assessment as part of the systematic infertility workup
  2. 2.van Rijswijk J, et al. (2020). Tubal flushing with oil-based or water-based contrast at hysterosalpingography for infertility: long-term reproductive outcomes of a randomized trial. Fertility and Sterility. doi:10.1016/j.fertnstert.2020.03.022 ✓Oil-based contrast at HSG was associated with higher 5-year live birth rates (74.8% vs 67.3%) and more natural conceptions compared with water-based contrast in a randomized trial of 1,107 couples

2 sources, numbered by first appearance. General health information, not medical advice — synthetic demonstration content.