The saline infusion test is a medical procedure used to assess the function of the uterus and fallopian tubes. During the test, a sterile saline solution is injected into the uterus through a catheter. This helps to visualize the uterine cavity and check for any abnormalities, such as fibroids or polyps. The procedure is often performed in conjunction with hysterosalpingography (HSG) or sonohysterography (SHG) to provide a clearer picture of reproductive health. It is typically done in an outpatient setting and may cause mild discomfort, but it is generally considered safe and effective for evaluating infertility issues.