HSG Test: Can It Boost Pregnancy Odds?

Up to 38 % more live births were reported in women who had a hysterosalpingogram—an HSG. Infertility affects millions in the United States, and every step toward understanding your options matters. HSG is a common diagnostic tool that checks if your fallopian tubes are open and your uterus is healthy—key factors in conception.

Recent research shows that HSG may do more than diagnose; it can also increase your chances of getting pregnant, especially when oil-based contrast is used. Studies have found that people under 40 who undergo HSG with oil-based contrast see higher pregnancy and live birth rates compared to those who do not have the test or use water-based contrast. The fertility-boosting effect is most pronounced in the first year after the procedure, and the benefits are seen across different causes of infertility, including unexplained and endometriosis-related cases.

You are not alone in seeking answers or feeling hopeful about the potential of HSG. Understanding the evidence can help you make informed, empowered decisions about your next steps.

What exactly is an HSG test and why is it part of a fertility work-up?

A hysterosalpingography (HSG) test is a specialized X-ray procedure that examines your uterus and fallopian tubes. During the test, a healthcare provider gently inserts a thin tube through your cervix and injects a contrast dye. This dye outlines your uterus and fallopian tubes on X-ray images, helping to identify blockages, structural issues, or other abnormalities that could affect your fertility.

HSG is a key part of the fertility work-up because it provides crucial information about two major causes of infertility: tubal blockages and uterine problems. About 25-35% of infertility cases are linked to tubal factors, and HSG is one of the most effective ways to detect these issues early in your evaluation. The test is cost-effective, widely available, and can guide your next steps—whether that means further testing, treatment, or reassurance that your tubes are open.

Key facts:

• The procedure lasts about 15 minutes and uses less radiation than a chest X-ray.
• Most patients feel cramping similar to period pain that resolves within an hour.
• Up to 30 % of tubes that look “blocked” at first are simply in spasm and open during the test.
• HSG is a standard piece of the broader Fertility Workup after 6–12 months of trying to conceive (TTC).
• Beyond diagnosis, the same dye flush can have a mechanical “cleaning” effect that interests anyone hoping to boost pregnancy odds.

You may experience mild discomfort or cramping during the procedure, but it is usually brief. According to the American College of Obstetricians and Gynecologists (ACOG), HSG is considered safe, though rare risks include infection or allergic reaction to the dye. As Dr. Nitin Ghonge, MD, DNB, Professor of Radiology, notes: “HSG remains a valuable diagnostic tool in current clinical practice, offering crucial insights into the endometrial cavity, fallopian tubes, and adjoining pelvic structures”. If you are undergoing a fertility evaluation, HSG can be a vital step in understanding your reproductive health and planning your path forward.

How could a simple dye flush from an HSG actually boost fertility?

A hysterosalpingography (HSG) test can boost fertility through several possible mechanisms. When the dye is flushed through your uterus and fallopian tubes, it may physically clear minor blockages or mucus plugs that could be preventing sperm from reaching the egg. This “tubal flushing” effect is especially pronounced with oil-based contrast dyes, which have been shown to increase pregnancy rates compared to water-based dyes and no HSG at all. In a large study, couples with unexplained infertility who underwent HSG had a 6% higher pregnancy rate within six months than those who did not, regardless of the dye used.

Beyond the mechanical clearing, oil-based dyes may also change the immune environment in your pelvis. Research suggests these dyes can help balance immune cells, such as dendritic cells and regulatory T cells, making the environment more favorable for embryo implantation. Additionally, HSG has been shown to increase levels of leukemia inhibitory factor (LIF), a protein crucial for embryo implantation, in the uterine lining. The iodine in oil-based dyes may also play a role, as increased iodine levels after HSG have been linked to higher pregnancy rates, especially in those with mild iodine deficiency…First Transvaginal Ultrasound.

The fertility-boosting effect of HSG is most noticeable in the first year after the procedure and gradually decreases over time. Overall, HSG offers both diagnostic and potential therapeutic benefits for those seeking to grow their families

What does the research show about pregnancy rates after HSG?

Research consistently shows that pregnancy rates increase after a hysterosalpingography (HSG) test, especially when oil-based contrast is used. In a large randomized trial, women who underwent HSG with oil-based dye had an ongoing pregnancy rate of 80% and a live birth rate of 74.8% over five years, compared to 75% and 67.3% respectively for those who received water-based dye. Natural conception was also more common and occurred sooner in the oil-based group. Another study found that women under 40 who had HSG with oil-based contrast achieved a 49% pregnancy rate within six months, while those over 40 had lower rates (16%) 1.

For individuals with endometriosis-related infertility, HSG with oil-based contrast led to clinical pregnancy rates of 51.4% and live birth rates of 31.5%, both significantly higher than with non-oil-based contrast. Even with water-based contrast, HSG was linked to higher pregnancy rates compared to other diagnostic methods. The fertility-enhancing effect is most pronounced in the first year after HSG and gradually decreases over time, but the overall benefit remains significant for many patients 2 3.

A post-hoc analysis of over 4,500 couples with unexplained infertility found that HSG increased the chance of natural conception by 6% within six months, regardless of the type of dye used. These findings support the use of HSG not only as a diagnostic tool but also as a potential fertility-boosting procedure, especially for those under 40 and those with unexplained or endometriosis-related infertility 4 5.

Couples considering IUI can leverage this high-yield window by following our step-by-step IUI Roadmap.

Who gains the most and when is the “fertility window” after an HSG?

You are most likely to benefit from a hysterosalpingography (HSG) if you are under 40 years old and have unexplained infertility or mild tubal issues. Research shows that women under 40 who undergo HSG with oil-based contrast have significantly higher pregnancy and live birth rates compared to those over 40, with pregnancy rates of 49% for those under 40 versus 16% for those 40 and older. The fertility-boosting effect is also more pronounced in those with mild iodine deficiency, as the iodine in the oil-based dye may help correct this and further improve your chances.

The “fertility window” after HSG is strongest in the first year following the procedure. Most pregnancies occur within the first 6 to 12 months, with the benefit gradually decreasing over the next two years and returning to baseline by year three. For example, the odds of pregnancy are highest in the first month (odds ratio 1.54), and while the advantage persists for up to a year, it becomes less pronounced over time.

If you have secondary infertility due to tubal factors, you may also see greater benefit from HSG, as this group is more likely to have blockages that the dye flush can help clear. In summary, the greatest gains are seen in younger individuals, those with unexplained or tubal infertility, and especially in the first year after the HSG procedure.

Every five-year increase in female age trims the post-HSG pregnancy lift by roughly 7 %. Many clinics schedule HSG in cycle 1 and add timed intercourse or Clomid vs. Letrozole in cycles 2–4 to ride the wave.

Is an oil-based or water-based HSG better—and can you choose in the U.S.?

Oil-based contrast is generally more effective than water-based contrast for boosting fertility after a hysterosalpingography (HSG) test. Large, high-quality studies and meta-analyses show that oil-based HSG leads to higher pregnancy and live birth rates. For example, one major randomized trial found ongoing pregnancy rates of 80% and live birth rates of 74.8% with oil-based contrast, compared to 75% and 67.3% with water-based contrast over five years. Natural conception was also more common and occurred sooner with oil-based dye. Meta-analyses confirm these findings, showing a 29–51% higher chance of pregnancy with oil-based contrast, without an increase in miscarriage or ectopic pregnancy risk.

Oil-based HSG is also linked to better image quality and less abdominal pain or vaginal bleeding for many patients. However, water-based contrast may have a slightly lower risk of rare complications like intravasation (dye entering the bloodstream), but both types are considered safe for most people.

In the U.S., water-based contrast is more commonly used, but oil-based options are available at some fertility centers. You can ask your provider about the type of contrast they use and discuss whether oil-based HSG is right for you. As one recent review notes, “oil-based contrast medium enhances fertility outcomes compared with the water-based contrast medium in patients receiving HSG”. If maximizing your pregnancy chances is your priority, oil-based HSG may offer a meaningful advantage.

What risks, side effects, and myths should you know about HSG?

Hysterosalpingography (HSG) is generally safe, but you should be aware of its risks, side effects, and common myths.

Risks:

• Infection: Rare, but possible, especially in those with a history of pelvic infections.
• Allergic reaction: Uncommon, but can occur due to iodine-based contrast media.
• Intravasation: Oil-based contrast has a higher risk of dye entering blood vessels, but this is usually not dangerous and resolves on its own.
• Uterine perforation or heavy bleeding:** Extremely rare complications.
• Temporary changes in thyroid function: Iodinated contrast can cause a transient reduction in thyroid hormone synthesis, which may affect neurodevelopment if conception occurs soon after HSG, though more research is needed.
• Contrast-induced nephropathy: Very rare, but possible in those with pre-existing kidney issues.

Side Effects:

• Pelvic pain or cramping: Most common side effect, affecting about 20% of patients; usually mild and short-lived.
• Vaginal bleeding or spotting: Mild and typically resolves within a day or two.
• Abdominal discomfort: More common with water-based contrast; oil-based contrast may cause less pain and bleeding.
• Interstitial reflux: Dye leaking into surrounding tissues, usually mild and self-limited.
• No significant association between pain and age or BMI; pain is generally manageable and brief.

Myths:

• HSG causes infertility or birth defects: No evidence supports this; studies show no increased risk of miscarriage, ectopic pregnancy, or harm to future children from HSG or the contrast used.
• HSG is unbearably painful: While discomfort is common, most people tolerate the procedure well, and pain is usually brief and manageable.
• Radiation exposure is dangerous: The dose from HSG is very low and not considered a significant risk for future pregnancies or cancer.
• Iodine in contrast always harms thyroid or child development: While transient thyroid changes can occur, long-term harm is not established, but monitoring may be warranted if conception occurs soon after HSG.

For comparison, see the procedure risks outlined in IVF Made Easy. Taking 600 mg of ibuprofen one hour before the test can cut pain scores by roughly one-third.

How can you maximize your chances of conceiving after an HSG?

To maximize your chances of conceiving after an HSG, consider the following strategies:

• Opt for oil-based contrast if possible: Oil-based HSG is consistently linked to higher pregnancy and live birth rates compared to water-based HSG, especially in women with unexplained or endometriosis-related infertility.
• Time intercourse or fertility treatments soon after HSG: The fertility-enhancing effect is strongest in the first 6–12 months after the procedure, with the greatest benefit in the first few months.
• Address underlying health factors: If you are under 40, your chances of conceiving after HSG are higher. Treating mild subclinical hypothyroidism with levothyroxine and correcting iodine deficiency may further improve outcomes, especially after oil-based HSG.
• Follow up on abnormal findings: If HSG reveals tubal or uterine abnormalities, discuss further evaluation or treatment (such as hysteroscopy or surgery) with your doctor, as addressing these can improve fertility.
• Consider your infertility type: Women with secondary infertility or tubal factors may benefit more from HSG, so personalized follow-up is important.
• Manage pain and stress: While HSG can be uncomfortable, using pain relief strategies and stress reduction techniques may improve your overall experience and willingness to pursue timely conception attempts.
• Consult your provider about timing: Early HSG (as part of the initial fertility work-up) does not necessarily increase live birth rates compared to delayed HSG in women with a good prognosis, so discuss the best timing for your situation.
• Monitor thyroid function if using oil-based contrast: While most effects are mild and temporary, monitoring is especially important if you plan to conceive soon after the procedure.
• Try right away: Begin TTC once spotting stops; ovulation tracking or Follicle Scans help you hit the fertile window.
• Streamline next moves: Use our Telehealth Tips to review results quickly with your care team.

By combining these approaches—choosing oil-based contrast, timing conception efforts, addressing health factors, and following up on any abnormalities—you can maximize your chances of conceiving after an HSG.

Your top questions, answered

Can I get pregnant the same month as my HSG?
Yes, it is possible to conceive in the same month as your HSG. Studies show that the chance of pregnancy increases soon after the procedure, especially within the first few months, regardless of whether oil- or water-based contrast is used.

Does an HSG help women with PCOS?
HSG is used to check if your fallopian tubes are open, but it does not specifically treat PCOS. For women with PCOS, HSG is as effective as other imaging methods (like saline infusion sonohysterography, SIS) for confirming tubal patency, and the choice between HSG and SIS does not affect pregnancy rates.

Will insurance cover the test?
Insurance coverage for HSG varies by provider and plan. Many insurance plans cover HSG when it is ordered for infertility evaluation, but you should check with your insurer to confirm your specific benefits and any out-of-pocket costs.

Is HyCoSy the same as HSG?
No, HyCoSy (hysterosalpingo-contrast sonography) and HSG (hysterosalpingography) are different tests. HSG uses X-rays and a contrast dye, while HyCoSy uses ultrasound and a different type of contrast. Some studies suggest HSG may be more effective for predicting pregnancy outcomes, but both are used to assess tubal patency.

Should I repeat the test if I’m still not pregnant?
Repeating HSG can be helpful in some cases, especially if your first test showed blocked tubes or if your fertility situation changes. Studies show that some women achieve tubal patency and pregnancy after a repeat HSG, but the decision should be made with your doctor based on your individual circumstances.

Bottom line: Can an HSG move the needle on your fertility journey?

HSG can indeed “move the needle” on your fertility journey, especially if you have unexplained infertility or endometriosis. Large, high-quality studies show that HSG—particularly when performed with oil-based contrast—significantly increases pregnancy and live birth rates compared to water-based contrast or no HSG at all, with the greatest benefit seen in the first 6–12 months after the procedure. Even water-based HSG appears to improve the chance of conception compared to not having the test, though oil-based contrast offers the strongest fertility boost. The effect is most pronounced in women under 40 and in those with tubal or endometriosis-related infertility. HSG also provides valuable diagnostic information about your tubes and uterus, helping guide further treatment if needed. While not a cure-all, HSG is a proven, cost-effective step that can both diagnose and, in many cases, enhance your chances of getting pregnant.

References

1. Comparative analysis of hysterosalpingography and hysterosalpingo-contrast sonography for assessing tubal patency in women with endometriosis-related infertility: a propensity score-matched study… Archives of gynecology and obstetrics. https://doi.org/10.1007/s00404-025-08008-4

2. Hystero-Salphingography in current clinical practice-old flames, die hard!. Abdominal radiology. https://doi.org/10.1007/s00261-024-04456-9

3. Evaluation and perspectives on hysterosalpingography (HSG) procedure in infertility: a comprehensive study… European review for medical and pharmacological sciences, 27 15, 7107-7117. https://doi.org/10.26355/eurrev_202308_33284

4. The therapeutic effect of hysterosalpingography in couples with unexplained subfertility: a post-hoc analysis of a prospective multi-centre cohort study… Reproductive biomedicine online, 38 2, 233-239. https://doi.org/10.1016/j.rbmo.2018.11.005

5. Oil-Soluble Contrast Medium (OSCM) for Hysterosalpingography Modulates Dendritic Cell and Regulatory T Cell Profiles in the Peritoneal Cavity: A Possible Mechanism by Which OSCM Enhances Fertility. The Journal of Immunology, 198, 4277 - 4284. https://doi.org/10.4049/jimmunol.1600498

6. Fertility-enhancing effect of oil-based contrast agents during hysterosalpingography and the variation of this effect within a 3-year follow-up period in infertile patients. Frontiers in Medicine, 9. https://doi.org/10.3389/fmed.2022.948945

7. Oil-Based Hysterosalpingography ?mproves Leukaemia ?nhibitory Factor Expression ?n Endometrial Flushing Samples. Gynecology & Reproductive Health. https://doi.org/10.33425/2639-9342.1204

8. Fertility Outcome and Safety of Ethiodized Poppy Seed Oil for Hysterosalpingography in 1,053 Infertile Patients: A Real-World Study. Frontiers in Medicine, 9. https://doi.org/10.3389/fmed.2022.804494

9. Evaluation and perspectives on hysterosalpingography (HSG) procedure in infertility: a comprehensive study… European review for medical and pharmacological sciences, 27 15, 7107-7117. https://doi.org/10.26355/eurrev_202308_33284

10. A meta-analysis of fertility and adverse outcomes in oil- and water-based contrast for hysterosalpingography. Turkish Journal of Obstetrics and Gynecology, 20, 64 - 73. https://doi.org/10.4274/tjod.galenos.2023.67750

11. Comparison of fertility outcomes between oil‑based and water‑based contrast media during hysterosalpingography: A meta‑analysis. Experimental and Therapeutic Medicine, 26. https://doi.org/10.3892/etm.2023.12148