40w LaterGuide

Some people hear that pregnancy may be more likely after a hysterosalpingography (HSG) and wonder whether this is actually true.

The answer is: there is some medical evidence behind this idea.

HSG is primarily a diagnostic test used to check whether the fallopian tubes are open. During the procedure, contrast medium is introduced through the cervix and passes through the uterus and fallopian tubes.

Interestingly, this process may also have a temporary “tubal flushing” effect, and some studies have found higher pregnancy rates after HSG, particularly when an oil-based contrast medium is used.

Why might HSG improve fertility?

The exact reason is not known.

One possibility is that flushing the tubes may remove small amounts of mucus or debris that were interfering with tubal function. Other possible mechanisms involving immune responses or the environment of the uterine lining have also been proposed, but these remain uncertain.

So it is more accurate to say that HSG may have a fertility-enhancing effect in some women rather than that it physically “opens” every partially blocked tube.

Does the type of contrast medium matter?

It may.

A large randomized study found that women who underwent HSG with an oil-based contrast medium had higher ongoing pregnancy and live-birth rates over the following months than those who underwent HSG with a water-based contrast medium.

Current European fertility guidelines also state that, for couples with unexplained infertility, HSG using oil-soluble contrast may be preferred over water-soluble contrast after discussing the potential benefits and risks.

However, this does not mean that oil-based contrast is the best choice for everyone.

Are there any risks?

Both oil-based and water-based contrast media can be used for HSG, and each has advantages and disadvantages.

With oil-based contrast, there is a somewhat greater risk that contrast may enter blood or lymphatic vessels, a phenomenon known as intravasation. Serious complications are rare, but this is one of the reasons the choice of contrast medium should be individualized.

In summary

1. HSG is mainly a diagnostic test for checking the fallopian tubes, but it may also have a temporary fertility-enhancing effect.
2. The evidence is strongest for tubal flushing with oil-based contrast, particularly in some women with unexplained infertility.
3. The exact mechanism is not fully understood and may involve flushing mucus or debris from the tubes.
4. Oil-based contrast is not automatically suitable for everyone, so the type of contrast should be chosen with a healthcare professional after considering the benefits and risks.