Saline-Infused Sonography

WHY is this test done?

Saline-Infused Sonography (SIS) is also known as a sonohysterogram.

A standard ultrasound uses sound waves to image the shape of the uterus and other pelvic organs.  A sonohysterogram is an ultrasound that goes one step further by using sterile water to distend the uterine cavity to obtain more accurate information about fibroids, polyps, or the lining of the uterus. 

On a standard ultrasound, fibroids are visible, but if a fibroid is protruding from the wall into the cavity, it is not always obvious since the uterine walls are collapsed together. By doing a sonohysterogram and filling the potential space in the uterine cavity with water, one can determine with great accuracy how much a fibroid is pushing into the cavity of the uterus.

In addition, SIS is useful to detect an endometrial polyp. Polyps are non-cancerous growths in the lining of the uterus that frequently cause spotting or bleeding. Polyps are often undetected on standard ultrasound, but are clearly visible when surrounded by water.

In short, a sonohysterogram allows a two-dimensional image to be seen three-dimensionally and yields results that are more accurate than standard ultrasound. An SIS is not necessary in every situation. Your doctor will let you know if it is appropriate for you.

WHAT to expect during the procedure

In the ultrasound suite, you will lie on the table and place your heels in the stirrups. Transvaginal ultrasound involves a thin condom-covered wand (probe) that is inserted in the vagina. The gel is placed in the condom, not in your vagina. Generally, you can place the probe yourself with the help of the technician.

After the ultrasound is complete, the vaginal probe will be removed. Your doctor will insert a speculum, just like for a Pap smear, and cleanse the cervix with a betadyne soap solution. A thin catheter (tube) will then be inserted into your cervical canal to enter the uterine cavity. Some women feel a slight cramp during this part of the procedure. A tiny balloon will be inflated to hold the catheter in position. This may also cause a mild cramp. Your doctor will then remove the speculum and insert the vaginal transducer. A small amount of sterile saline will then be instilled through the catheter in order to fill the uterine cavity. There may be slight cramping during this time. Once the pictures are taken, the balloon is deflated and the catheter and vaginal probe removed. If there is cramping, it usually lasts about 10-20 seconds and then subsides. The entire SIS generally takes less than five minutes.

WHAT to expect after the procedure

Some women have slight cramps for a few hours and have a light pink discharge for a day or two. A watery discharge is expected. You may use a tampon or pad. In most cases, there are no after-effects and you can return to your normal activities immediately.


Our technician will digitally send the ultrasound to the radiologist at Northwestern Memorial Hospital who will interpret the ultrasound and prepare a preliminary report. The doctors who interpret our ultrasounds are experts who read ONLY obstetric and gynecologic ultrasounds. We generally have a written report within 20 minutes. We recommend that when you schedule your ultrasound/SIS, you also schedule an appointment with your doctor immediately following the ultrasound. She can then sit down with you and review your results.


What if the final report is different from the original report?
This rarely occurs, but in the case that the final report has new or different information, your doctor will contact you within a week.

If I don't have an SIS scheduled, but during my ultrasound it is determined that I need one, can it be done while I am there or will I need to return on another day?
If it is determined at your ultrasound that an SIS is needed, we will do our best to accommodate you on that day. If there is no availability, you may need to return on another day.

Can I request an SIS when I make my appointment if I am concerned about something, even if I have not seen my doctor yet and haven’t been advised to have one?
If you think you may need an SIS as part of your visit, call or email us prior to your visit and let us know why you need one.

Can I bring someone with me?
An adult friend or relative may accompany you, but small children are not permitted in the ultrasound suite.

What if I have my period or am bleeding?
An ultrasound can be performed if you are bleeding. Please remove your tampon in the bathroom before you enter the ultrasound suite. The medical assistant or ultrasound tech will provide a pad if you need one. You can reinsert your tampon immediately following the exam. An SIS is ideally performed when you are not bleeding, but sometimes this is not practical or possible. Let us know prior to your appointment if you are bleeding, and, depending on the circumstances, we will proceed or reschedule.