A sonohysterogram is an ultrasound procedure used to determine if there are any abnormalities in the uterine cavity that may be interfering with pregnancy. The procedure is performed by placing a small catheter in the uterus and injecting a small amount of saline, allowing Dr. Allen to visualize the uterine cavity. The procedure is simple and relatively painless and can be performed in the office during the first or second week of your menstrual cycle.