Which Uterus Evaluation Procedure Should You Get?

I’m 35 and just saw a fertility doctor after trying to get pregnant for six months without success. The first step is to do a bunch of testing, one of which includes an evaluation of the uterus. There are two options to do this, hysterosalpingography (HSG) and sonohysterography (SHG). HSG has the benefit of also flushing the fallopian tubes, which can increase your chances of getting pregnant, but has the con of being much less specific, accurate, and sensitive in diagnosing uterine issues. As a first step in my fertility testing, is HSG or SHG the better choice?

—Anonymous

This is a great question, and the answer is individualized based on the patient’s specific clinical picture.

The HSG (hysterosalpingogram) and the SHG (sonohysterography, also known as a saline infusion sonogram, or SIS) are performed similarly but look at different parts of your reproductive tract.

Both procedures use a small, flexible catheter to put fluid into the uterus. With the HSG, the fluid has contrast dye, so that x-ray images can be taken to examine the fallopian tubes. With an SHG, the fluid is sterile saline, and 2D or 3D ultrasound is used to examine the endometrial cavity, or the space within the uterus where a pregnancy would implant and develop.

There are pros and cons with each procedure. The HSG requires contrast dye as well as radiation (though it’s a very small amount — about 10% of that of an abdominal pelvic CT scan). It is also not as useful for identifying lesions like endometrial polyps or fibroids. On the plus side, there are some studies that demonstrate an increased pregnancy rate in the months following an HSG. This may be because it removes excess mucus and debris blocking the fallopian tubes. However, the research is mixed, and this has not been confirmed in other studies.

On the other hand, with the SHG, there is no contrast or radiation, but it is truly focused on the endometrial cavity, and so has limited ability to assess the fallopian tubes. The SHG can identify lesions such as polyps, fibroids, and adhesions, as well structural defects like a uterine septum. There is the additional benefit of being able to assess defects in the wall of the uterus surrounding the endometrial cavity (like fibroids or adenomyosis), particularly if your physician uses 3D ultrasonography.

Both studies carry a small risk of infection, since we are putting a catheter into the uterus and flushing fluid up into the uterus and fallopian tubes. With the HSG, if your physician finds dilated fallopian tubes or evidence of a damaged tube, they may prescribe a short course of antibiotics to prevent infection.

So which one is right for you?

Traditionally, the general recommendation is HSG as the first step because we think tubal blockage has a big impact on chance of conception (i.e. if both tubes are blocked or damaged, the chance of conception is extremely low). It’s not as well established how lesions like polyps and fibroids impact implantation and ongoing pregnancy.

But the “general” recommendation doesn’t make sense for all patients. For instance, patients who have not previously conceived, especially those with risk factors for fallopian tube damage, are best served by an HSG. These risk factors include prior history of endometriosis, pelvic surgery, ectopic pregnancy, or certain sexually transmitted diseases including gonorrhea, chlamydia, and pelvic inflammatory disease. Any of these issues can cause scarring of one or both of the fallopian tubes, leading to tubal blockage or tubal dilation and rendering the tubes non-functional.

For patients who have a suspected uterine issue such as fibroids, polyps, or adhesions, the SHG or SIS may be recommended. The SHG or SIS is also important for those with recent pregnancy (delivery or loss), a history of uterine surgery, or any procedure where a surgical instrument is introduced into the uterus (such as a D&C or hysteroscopy), or evidence of a structural defect such as a uterine septum.

Patients with the rare but complex diagnosis of recurrent pregnancy loss or recurrent implantation failure (typically classified as two or more losses) may benefit from having both studies done.

It is important to discuss with your doctor which study makes sense to start with based on your own clinical history and the treatment options you are considering. For example, if intrauterine insemination (IUI) is planned, then an HSG makes sense to ensure that the tubes are open before you spend time and money on the insemination process. If you are planning to start with IVF (which, by definition, bypasses the tubes), then the HSG is less important. The last thing to keep in mind when deciding what to do is that the definition of some infertility diagnoses requires that certain tests have been done. One example is “unexplained infertility,” which requires at least one open fallopian tube, a normal semen analysis, and regular periods. Definitely make sure to check on your insurance plan, as many require specific tests on file before they will cover any fertility treatment.