Is Pregnancy After an HSG More Likely?

How Tubal Flushing May Improve Your Odds of Conception

woman looking at a positive pregnancy test result after an HSG
An HSG may increase your odds of getting pregnant, but only in certain cases. PhotoAlto/Ale Ventura / PhotoAlto Agency RF Collections / Getty Images

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.

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.

So, are you more likely to get pregnant after an HSG?

Yes! Well, maybe. It depends.

A number of studies have found increased pregnancy rates after an HSG. But whether or not you will get that boost in odds will depend on the contrast used during your HSG and your particular cause of infertility.

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 x-ray.

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 was no increase in pregnancy rates when using water-soluble contrast or a combination of water and oil soluble contrasts.
  • There was an increase in pregnancy rates with oil-soluble contrast when compared to no intervention at all.

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

    How much did it increase pregnancy rates?

    Without any other interventions, couples with no other detected fertility problems had an estimated 17% 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%. 

    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 boosts 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.

    In 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.

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

    However, it's important to know that the increased chance of pregnancy after an HSG isn't that great.

    Doctors order an HSG for diagnostic reasons. It's rarely used as a treatment itself.


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