Saline Sonogram, Hysterosalpingogram, and Sonohysterosalpingogram to Detect Uterine Abnormalities
Physical abnormalities, such as blocked fallopian tubes and uterine abnormalities — including fibroids, polyps, scar tissue, and uterine septa — can be structural causes of infertility.
If fallopian tubes are blocked, sperm is unable to reach an egg for fertilization and eggs can't move from the ovaries to the uterus. When a fertilized embryo is unable to travel through the fallopian tube into the uterus, this results in an ectopic pregnancy.
Abnormalities in the uterus can prevent an embryo (fertilized egg) from implanting in the uterine lining.
There are several ways to evaluate tubal and uterine anomalies, each with its benefits and drawbacks.
Saline Sonogram (SIS)
Also known as a saline infusion sonogram or a sonohysterogram, a SIS is a transvaginal ultrasound test that is performed while a sterile saline solution is gently infused into the uterus.
What it detects: uterine abnormalities such as endometrial polyps, fibroids, or uterine scars
How it works: The saline solution distends the uterus and neatly outlines the inside lining of the uterus, which provides more detail than a conventional ultrasound.
Benefits: This procedure takes less than 10 minutes and provides your doctor with important information regarding any obstacles that could prevent an embryo from implanting into the uterus.
Drawbacks: It does not provide any information about the fallopian tubes.
A hysterosalpingogram is an X-ray that looks at the uterus and fallopian tubes.
What it detects: blockages in the fallopian tubes, abnormalities in the uterus such as an abnormal shape or structure, polyps, fibroids, or adhesions.
How it works: A radiologist or someone trained in radiographic imaging injects a radiographic dye into your uterus, which fills with the dye. The radiologist will take pictures using a fluoroscopy (a continuous X-ray beam), to track the dye from the uterus into the fallopian tubes. If your fallopian tubes do not contain a blockage, the dye will spill into your abdominal cavity.
Benefits: It can tell you information about the fallopian tubes as well as the uterine cavity. If there's blockage within the fallopian tubes, the HSG will also show where the blockage is located — at the junction of the tube and uterus (proximal) or at the end of the tubes (distal).
Drawbacks: HSG involves a low dose of radiation, can be uncomfortable, and does not provide as much detailed information about the uterine cavity as a transvaginal ultrasound.
Sonohysterosalpingogram
A sonohysterosalpingogram is a newer, non-radiologic method that can provide valuable information about the fallopian tubes as well as the uterine cavity, with results that are comparable to HSG.
What it detects: Similar to an HSG, a sonohysterosalpingogram assesses fallopian tubes and uterine shape.
How it works: A sonohysterosalpingogram uses sterile saline and air or contrast, which is passed through the cervix into the uterus and visualized by transvaginal ultrasound.
Benefits: Unlike the HSG, this test does not require any exposure to radiation and can be done in your fertility doctor's office.
Drawbacks: This test hasn't been as well-studied as the HSG and is not as widely available.
Dr. Sydney Chang is a Fellow in Reproductive Endocrinology and Infertility at the Icahn School of Medicine at Mount Sinai/Reproductive Medicine Associates of New York.  She earned her Bachelor of Arts in Human Biology at Stanford University, where she graduated with Honors and Distinction. She went on to complete her medical school education at Duke University School of Medicine. She completed her residency in Obstetrics, Gynecology, and Women's Health at the Albert Einstein College of Medicine, where she served as an administrative chief resident.