Women having difficulty become pregnant may be invited to have their ‘tubes flushed’, a procedure which uses dye to show whether the fallopian tubes are blocked. It has been reported that women are more likely to become pregnant after this test, but no one knows why.

A Cochrane review has been updated with the best available evidence on tubal flushing and its effect on pregnancy and live birth rates. I asked obstetrician and gynaecologist Dr James Duffy to explain what the procedure, properly known as a hysterosalpingogram, involves:

“Hysterosalpingogram (HSG) is pronounced ‘he-ster-o-sal-ping-o-gram’, but fortunately most doctors call it HSG.  It is a common part of a work up for women having difficulty become pregnant. Normally eggs produced by the ovaries pass down fine, narrow tubes called fallopian tubes to reach the womb. A HSG can determine if these tubes are open or blocked. If either or both of these tubes are blocked then the chances of becoming pregnant are much reduced.

Patients will lie on an x-ray table, generally flat on their back. The procedure will start in the same way as a smear examination.  The doctor places a small tube called a catheter through the neck of the womb to inject dye.

Two kinds of dye are available: dyes which can be dissolved in water (water soluble) and dyes which cannot be easily dissolved in water (oil soluble). Commonly in the United Kingdom and United States doctors use a water soluble dye for HSG.”

If one sort of dye is better than another, this would be helpful to know. It’s also important to ask what evidence there is that tubal flushing improves pregnancy rates and live birth rates and whether this intervention is associated with any harms (adverse events), such as miscarriage.

Click here to read the full blog.