Sonohysterography (SHG) is an ultrasound-monitored procedure similar to a hysterosalpingogram (HSG), and is used to detect abnormalities of the uterus and fallopian tubes or tubal blockage. The indications for its use overlap with those for an HSG.
Sonohysterography can be performed as an office procedure. It usually involves

The placement of a speculum into the vagina through which a catheter is positioned in the uterus

A saline solution is injected into the uterine cavity

At the same time, a transvaginal ultrasound is being performed. There is no radiation and no iodinated contrast material involved.

Sonohysterography can be used to evaluate the endometrium and Fallopian tubes. For endometrial evaluation, SHG plays a role in an infertility workup. The injection of saline into the endometrial canal (uterine cavity) acts to separate the two sides of the endometrium and improve the visualization of masses, such as polyps. In addition, the saline acts as a contrast medium, which can make abnormal intraluminal structures, such as synechiae (adhesions), visible. Submucus myomas (fibroids which displace the endometrium) may be better evaluated when an SHG is performed.

An SHG can also be employed to evaluate the Fallopian tubes for patency. When the saline is injected, some of it may be seen flowing from the tubes into the pelvis, a finding that confirms patency.

Sonohysterography is an excellent procedure for evaluation of the endometrium and tubal patency. It has the added advantages of no radiation exposure, no iodinated contrast injection (which can be associated with increased discomfort and allergic reactions), and the potential for fewer complications. SHG also offers the advantage that ultrasound of the uterus, ovaries and pelvis can be performed at the same time. Thus, uterine masses and other abnormalities may be discovered which would have been missed during a conventional HSG. However, to evaluate the Fallopian tubes for more than just patency the HSG gives better information.