Tubal patency testing (HSG / HyCoSy)

The fallopian tubes are where the egg and the sperm meet. If they are blocked or damaged, natural conception becomes difficult or impossible. That is why tubal patency testing is a core part of the infertility work-up.

Two tests are mainly used: hysterosalpingography (HSG) with fluoroscopy and contrast, and the ultrasound-based method HyCoSy/HyFoSy. Both check whether the tubes are open — and they have some interesting, less well-known properties.

What is hysterosalpingography (HSG)?

In HSG, a contrast fluid is injected through the cervix into the uterus and tubes while X-ray images are taken. If the fluid passes through the tubes and spills into the peritoneal cavity, the tubes are patent.

The test is done in the first half of the cycle, after the period ends. It can cause cramping, so a simple painkiller beforehand is often advised.

What is HyCoSy / HyFoSy?

HyCoSy (hysterosalpingo-contrast-sonography) and its newer version HyFoSy (using foam) check tubal patency with transvaginal ultrasound instead of X-rays. A special ultrasound medium is injected into the uterus and its flow through the tubes is watched.

The main advantage is that radiation and iodinated contrast are avoided, while the uterine cavity and the ovaries are also assessed at the same time. Many women find it less uncomfortable than HSG.

Which method is more accurate?

For assessing tubal patency, HSG and HyCoSy/HyFoSy are considered comparable in accuracy. The ESHRE guideline on unexplained infertility states that the two methods are comparable to laparoscopy with dye testing, which remains the reference standard but is invasive.

Neither is perfect: a transient spasm at the tubal opening can give the false impression of a blockage. That is why an abnormal result is always interpreted within the whole clinical picture.

Is it true the test can increase the chance of pregnancy?

Yes, and this is one of the most interesting findings. “Flushing” the tubes during HSG appears to have a mild, temporary favourable effect on fertility, especially when oil-based contrast is used.

In the large randomized H2Oil trial, women who had HSG with oil-based contrast had a significantly higher pregnancy rate within six months compared with water-based contrast (about 40% versus 29%). The benefit applies mainly to couples with unexplained infertility.

Is the test dangerous or painful?

Both tests are generally safe and take a few minutes, without anaesthesia. The most common discomfort is period-type cramping during the injection of fluid, which usually settles quickly. There may be mild spotting for a day or two.

Serious complications, such as infection, are rare. In women with a history of pelvic inflammatory disease, antibiotics may be given prophylactically. The test is avoided if there is an active infection or a chance of pregnancy.

When is the test needed and when not?

Tubal patency testing is important when natural conception or insemination is planned, since these options require at least one open tube.

But when IVF is decided from the outset — for example because of a severe male factor or advanced age — tubal patency is no longer a prerequisite, since IVF bypasses the tubes. The decision is individualized.

Summary

Tubal patency is checked either with hysterosalpingography (HSG, using X-rays and contrast) or the ultrasound-based HyCoSy/HyFoSy; the two methods are comparable in accuracy. Beyond diagnosis, flushing the tubes — especially with oil-based contrast, as the H2Oil trial showed — can temporarily raise the chance of pregnancy in unexplained infertility. The test is essential when natural conception or insemination is planned, but not when proceeding directly to IVF.

⚕ Medically reviewed by Prof. Stratis Kolibianakis · Thessaloniki Medical Association Reg. No. 16340

ARTICLE 16 · INFERTILITY & DIAGNOSIS