The HSG Procedure and Infertility
Hysterosalpingography, or HSG, is the first line of investigation when seeking an accurate diagnosis for the cause of infertility in women. The procedure is part of a routine infertility evaluation. Because obstruction of one or both of the fallopian tubes is one of the most common causes of infertility in women, diagnosis starts with checking this part of the reproductive system.
The HSG Procedure
In HSG, a thin tube is threaded through the vagina and cervix. The opening of the uterus is gently blocked and a substance called “contrast material” or “contrast media” is injected into the uterus. The contrast media gradually fills up the uterine cavity and the fallopian tubes, eventually spilling out into the pelvic cavity where the body resorbs it.
During this process, x-rays are taken. The contrast media appears white in the x-ray shows if the media flows freely out of the fallopian tubes… or not. It can also reveal if there is an abnormality in the shape of the uterus through the outline of the contrast media.
Accuracy and Effectiveness of the HSG Procedure
In general, HSG Procedures have a high accuracy of “true positives” and “true negatives” on both unilateral and bilateral blockage of the fallopian tubes. This makes it a reliable indicator of tubal occlusion. A 2017 study published in the New England Journal of Medicine showed that 155 of 552 women had successful pregnancies within six months of undergoing an HSG procedure with water-based contrast media. It is thought that the simple act of “flushing out” the fallopian tubes is responsible for the increase in successful pregnancies, although it’s important to remember that clinical data on this is still being gathered and HSG is not in itself a treatment for infertility.
HSG is most often used to help diagnose abnormal uterine bleeding, endometriosis, endometritis, and other ailments. In lieu of an invasive laparoscopy, the HSG procedure lets medical professionals see into the body in real time. This allows them to quickly detect whether the uterus has an abnormal shape that may be hindering fertility, and to check for possible interference from fibroids, polyps, or scar tissue inside the uterine cavity.
Limitations of the HSG Procedure
Studies show that the HSG procedure’s accuracy declines after a patient has undergone surgeries such as tubal reanastomosis or distal salpingostomy. The HSG procedure is reliable for assessing possible blockage following reanastomosis, but not so much after distal salpingostomy. A research study by G.S. Letterie et al. emphasizes that, “…clinicians should be aware of HSG’s limitations when interpreting any HSG findings in infertile patients who had tubal surgery.”