An HSG 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? It depends.
HSG Increases Pregnancy Success
During HSD, a water-based or oil-based contrast medium is placed in the uterus and fallopian tubes. This fluid contains a dye that makes your uterine shape and fallopian tubes visible on an x-ray screen. The contrast can also be used therapeutically for “tubal flushing.” This is basically doing an HSG without 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. Researchers compared the effectiveness of tubal flushing with different contrast media—oil-based, water-based, a combination, and no tubal flushing—in women with infertility. They found boosts in pregnancy rates over six months using both oil-based or water-based contrast media, though there was more of an increase in those using oil-based contrast medium. This held true independent of the varied characteristics of the couples being studied.
Chances of Pregnancy After HSG
One analysis compared 13 randomized controlled trials. They found that among subfertile women with a 17% chance of conceiving in any given month (without intervention), the rate will increase to between 29% and 55% if they undergo tubal flushing with an oil-soluble contrast medium. This improvement in odds lasted for up to three months post-procedure.
Why Does HSG Increase Pregnancy Success?
No one is entirely clear why tubal flushing or an HSG increases your pregnancy odds, but there are some theories. One theory is that the dye flushes out the fallopian tubes, clearing minor blocks in some women. (Though HSG cannot repair or open the serious blockages.) 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. 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. 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 cases. When done therapeutically, this is known as endometrial scratching. While common, the practice is painful, expensive, and has side effects.
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 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.
