Sonohysterogram (SHG)

During an SHG, sterile saline is introduced into the uterus through a thin catheter while transvaginal ultrasound creates detailed images of the uterine cavity and lining.

The procedure begins with a transvaginal ultrasound. A speculum is then placed so your provider can see the cervix, and a small catheter is passed through the cervix into the uterus. The speculum is removed, the ultrasound probe is repositioned, and saline is slowly introduced while your provider examines the uterine cavity in real time.

The test itself is typically completed in about 15 minutes, although your total appointment may be slightly longer for preparation and discussion.

For a more detailed walkthrough, read Illume’s guide to what to expect before, during, and after a saline sonogram.

Source: ACOG

An SHG can help identify structural abnormalities inside the uterine cavity, including endometrial polyps, submucosal fibroids, scar tissue or adhesions, and differences in uterine cavity shape.

Introducing saline gently separates the uterine walls, which makes abnormalities that project into or alter the cavity easier to see than with standard transvaginal ultrasound alone.

For more context on why uterine evaluation is included in the workup, explore Illume’s complete fertility testing process.

An SHG can cause cramping or discomfort, but the experience varies from person to person. Some patients feel only mild pressure, while others experience more noticeable menstrual-like cramping as the catheter is placed or saline enters the uterus.

It is also completely reasonable to feel nervous about the procedure. If pelvic exams have been painful for you in the past, you have a history of pelvic pain or trauma, or you are worried about discomfort for any reason, always tell your Care Team beforehand. They can explain what to expect, discuss pain-management options, and check in with you throughout the procedure.

Read Illume’s patient-focused SHG guide for more about the experience.

An SHG is usually performed after your menstrual period has ended but before ovulation. At Illume Fertility, SHG testing is typically scheduled on Cycle Days 5–10.

This timing allows the uterine lining to be evaluated when it is relatively thin and also helps avoid performing the procedure during an early pregnancy. Your Care Team will give you specific scheduling instructions based on your cycle.

If you are unsure which day counts as "Cycle Day 1," Illume defines it as the first day of full menstrual flow, not light spotting.

Most patients can return to their usual activities after an SHG. Mild cramping, light spotting, or watery vaginal discharge as the saline leaves the uterus can occur after the procedure.

These symptoms should generally improve rather than become more severe. Contact your Care Team if you develop fever, increasing or severe pelvic pain, heavy bleeding, or other symptoms that concern you.

Illume’s saline sonogram guide also provides more detail on what to expect after the procedure.

A standard SHG cannot reliably determine whether each individual fallopian tube is open. A hysterosalpingogram (HSG) is typically used to evaluate tubal patency.

Fluid seen outside the uterus during an SHG may suggest that at least one fallopian tube is open, but standard SHG does not reliably show which tube the fluid passed through.

ASRM distinguishes SHG as a detailed uterine-cavity test and HSG as a test used to document whether individual fallopian tubes are open or blocked.

Learn how Illume evaluates the fallopian tubes with an HSG test.

No. An SHG cannot diagnose endometriosis because it evaluates the inside of the uterine cavity, while endometriosis develops outside the uterine cavity.

A normal SHG therefore does not rule out endometriosis. If your symptoms or medical history raise concern for endometriosis, your fertility specialist may recommend a different evaluation based on your individual circumstances.

Learn more in Illume’s guide to endometriosis and fertility and ASRM’s endometriosis patient education booklet.

A normal SHG means no significant abnormality was identified within the uterine cavity. If the test identifies a structural finding, your physician will determine whether it needs further evaluation or treatment.

Not every abnormal finding will affect fertility or require intervention. Your physician will consider its size, location, appearance, your reproductive history, and your treatment plans before recommending next steps.

In some cases, hysteroscopy may be recommended. Unlike SHG, which creates ultrasound images of the cavity, hysteroscopy allows the physician to look directly inside the uterus and can also be used to treat certain abnormalities.

ASRM identifies hysteroscopy as the definitive method for diagnosing and treating intrauterine pathology. Read ASRM’s guidance on uterine cavity evaluation.

Learn more about hysteroscopy and other fertility surgeries offered at Illume.