A hysterosonogram, also called a sonohysterogram or saline infusion sonography, is an imaging test that uses sterile saltwater and ultrasound to get a detailed view of the inside of your uterus. It takes less than 30 minutes, is done in an office setting, and gives your provider a much clearer picture of the uterine lining than a standard ultrasound alone. The saline gently fills and expands the uterine cavity, separating the walls so that growths, scarring, or structural problems show up on the ultrasound screen.
Why It’s Ordered
The most common reason for a hysterosonogram is abnormal uterine bleeding, whether that means unusually heavy periods, bleeding between periods, or unexpected bleeding after menopause. It’s also a go-to test during fertility evaluations. If you’ve had trouble getting pregnant, experienced repeated miscarriages, or are preparing for an IVF cycle, this test helps rule out structural problems inside the uterus that could interfere with implantation or pregnancy.
Specifically, the test is used to look for:
- Polyps: small, usually benign growths on the uterine lining
- Fibroids: noncancerous muscle tumors, particularly those that bulge into the uterine cavity
- Scar tissue (adhesions): bands of tissue inside the uterus, sometimes from prior surgery
- Congenital abnormalities: structural differences in uterine shape present from birth, such as a septum dividing the cavity
- Endometrial abnormalities: thickening or irregular areas of the lining that may need further evaluation, including for cancer
Sometimes the test is ordered simply because a standard transvaginal ultrasound couldn’t show the uterine lining clearly enough, and the provider needs a better look.
What Happens During the Procedure
The procedure follows a straightforward sequence. You lie on your back with your feet in stirrups, similar to a pelvic exam. A speculum is placed in the vagina, and the cervix is cleaned. A very thin, flexible catheter (roughly the width of a piece of spaghetti) is threaded through the cervical opening into the uterus. A tiny balloon at the catheter’s tip is inflated with a small amount of saline to hold it in place.
The speculum is then removed, and a transvaginal ultrasound probe is inserted alongside the catheter. Warm sterile saline is slowly pushed through the catheter to fill the uterine cavity, typically around 40 mL total, though the amount varies based on how much your uterus needs to expand and how you’re feeling. As the saline flows in, the ultrasound captures images of the lining from multiple angles. The provider sweeps the probe from side to side to view the entire cavity and confirm there are no abnormalities hiding in any corner. After imaging is complete, the catheter and probe are removed.
A negative pregnancy test is required before the procedure begins.
When to Schedule It
Timing matters. The best window is after your period ends but before you ovulate, usually days 6 through 11 of your cycle. At this point, the uterine lining is at its thinnest, which makes it much easier for your provider to spot anything abnormal. A thicker lining can obscure small polyps or other subtle findings.
If you’re menopausal, taking a continuous birth control pill, or have a hormonal IUD, the lining stays consistently thin, so the test can be scheduled at any time.
How It Feels and What to Expect After
Most people describe the sensation as mild to moderate cramping, similar to menstrual cramps, particularly when the saline is being instilled. The discomfort is usually brief and eases quickly once the catheter is removed. Taking an over-the-counter pain reliever about an hour beforehand can help take the edge off.
Afterward, you may experience cramping, bloating, light spotting, or watery discharge for up to 24 hours. None of this is cause for concern. There are no activity restrictions, so you can go back to your normal routine right away.
Risks and Contraindications
A hysterosonogram is considered very safe. The saline is sterile, there’s no radiation involved (unlike X-ray-based tests), and serious complications are rare. The most notable risk is pelvic infection, which is why the procedure is not performed if you have an active pelvic infection or signs of a sexually transmitted infection. It’s also not done during pregnancy.
How It Compares to an HSG
A hysterosonogram is sometimes confused with a hysterosalpingogram (HSG), but they serve different purposes. An HSG uses X-ray and a contrast dye to evaluate both the uterine cavity and the fallopian tubes. It’s the standard test for checking whether the tubes are open, which is a key part of many fertility workups.
A hysterosonogram, on the other hand, uses ultrasound and saline and focuses exclusively on the uterine cavity. It doesn’t show the fallopian tubes, but it does a better job of visualizing what’s happening inside the uterus itself. Research comparing the two found that sonohysterography is more sensitive, specific, and accurate than HSG for detecting problems within the uterine cavity, such as polyps, fibroids, and adhesions. In practice, many fertility evaluations include both tests: an HSG to check the tubes and a hysterosonogram to examine the uterine lining in detail.
How It Compares to a Standard Ultrasound
A regular transvaginal ultrasound can show the general size and shape of the uterus, but the two walls of the uterine cavity sit pressed against each other, making it difficult to distinguish a small polyp from normal lining tissue. The saline in a hysterosonogram acts like a contrast agent, pushing the walls apart so that anything attached to the lining stands out clearly against the dark fluid background. Think of it like inflating a deflated balloon to see if anything is stuck to the inside surface. This is why providers often order a hysterosonogram as a follow-up when a standard ultrasound shows something ambiguous or when the lining couldn’t be seen well enough to make a confident diagnosis.