Ultrasound is one of the most commonly used imaging modalities in gynecology. It utilizes sound waves to create images of the internal structures of the pelvis. There are two main types of ultrasound used: transabdominal ultrasound and transvaginal ultrasound. Transabdominal ultrasound involves placing a probe on the abdomen, while transvaginal ultrasound involves inserting a probe into the vagina. Ultrasound is particularly useful for evaluating the uterus, ovaries, and early pregnancy.