Sonohysterogram is a special type of ultrasound evaluation. A sonohysterogram (SHG) is used to look for abnormalities of the uterine lining or endometrium. The procedure involves using a small sterile tube called a catheter that is inserted through the cervix to introduce sterile water into the uterine cavity while an ultrasound is performed over the abdomen. The water outlines any abnormal structures in the uterine lining such as polyps or fibroids. Risks are uncommon, including bleeding, infection, and puncturing the uterus or cervix during the procedure. Sometimes an SHG is accompanied by an endometrial biopsy.