Is Pregnancy After an HSG More Likely?

How Tubal Flushing May Improve Your Odds of Conception

HSG and increasing odds of conception

Verywell / Gary Ferster 

Pregnancy after an HSG may be more likely, depending on the cause of your infertility. At least one study found that an HSG with an oil-based contrast did significantly improve pregnancy rates in specific patients. The subsequent live birth rate was likewise significantly higher.

An HSG, or hysterosalpingogram, is a special kind of x-ray that involves administering an iodine dye via the cervix into the uterus and fallopian tubes, and then taking x-ray pictures. The test is intended to check the general uterine shape and to see if the fallopian tubes are clear.

Check out any fertility forum online, and you'll find women claiming they got pregnant one or two months after an HSG. Your doctor may even tell you that you're more likely to conceive after this fertility test.

So, are you more likely to get pregnant after an HSG? Yes! Well, maybe. It depends.

Oil or Water-Soluble Contrast?

An HSG can be done with a water-based or an oil-based contrast medium. (This is the dye that allows the technician to see your uterine shape and fallopian tubes on the x-ray.)

The contrast can also be used therapeutically for "tubal flushing." This is basically doing an HSG without the imaging.

While the contrast medium may not make a difference when it comes to the fertility test itself, it does seem to matter when looking at the post-HSG pregnancy boost.

Studies have compared pregnancy rates after:

  • tubal flushing with a water-soluble contrast media
  • tubal flushing with an oil-soluble contrast media
  • tubal flushing with both oil and water contrasts combined
  • no intervention at all

The studies found that:

  • There were boosts in pregnancy rates over six months using either oil-soluble contrast medium, or water. There was, however, more of an increase in pregnancy rates with oil-soluble contrast, compared with tubal flushing using water‐based contrast medium, or no intervention at all. This held true independent of the varied characteristics of the couples being studied.

If you hope to get the pregnancy boost, an oil-based contrast for HSG is your best bet. You can ask your doctor what they plan to use.

How much did it increase pregnancy rates?

In one analysis of thirteen randomized controlled trials, without any other interventions, couples with no other detected fertility problems had an estimated 17 percent chance of conceiving in any given month.

But, when these couples underwent tubal flushing with an oil-soluble contrast, their pregnancy odds increased to between 29 and 55 percent. This improvement in odds lasted for up to three months post-procedure.

Why Does It Boost Your Pregnancy Odds?

No one is entirely clear why tubal flushing or an HSG increases your pregnancy odds. There are some theories.

One theory is that the dye flushes out the fallopian tubes, clearing partial, minor blocks in some women. If this is the case, the HSG test result will show unblocked fallopian tubes. However, some contrast may seem to stop and then continue on the x-ray. This may be the dye breaking through very thin adhesions.

(In the case of a serious blockage, an HSG cannot repair or open up the tubes.)

Another possibility is that the dye solution enhances the endometrium (the lining of the uterus) in some way, making it easier for an embryo to implant successfully. It may have an anti-inflammatory effect.

And yet another theory is that the dye solution somehow affects the area surrounding the ovaries, enhancing ovulation.

There is another theory that just placement of the catheter into the cervical os boosts pregnancy rates in some women. When done therapeutically, this is known as endometrial scratching. While common, the practice is painful, expensive, and has side-effects.

Tubal flushing seems to have a greater impact on those with unexplained infertility, possible immunological fertility problems, and those with early stage endometriosis.

A Word From Verywell

You may be more likely to get pregnant in the three months after an HSG, but that depends on why you can't get pregnant and what kind of contrast the technician uses.

Doctors order an HSG for diagnostic reasons. It's rarely used as a treatment itself. If you go into the test thinking of it like a fertility treatment, you may feel disappointed if you don't conceive in the next few months. Instead, remember that the primary purpose is fertility assessment. Pregnancy afterward is just a possible bonus.

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Article Sources

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