Ultrasound, also known as sonography, uses a small transducer (probe) and ultrasound gel to create high-frequency sound waves. Echoes produced by the sound waves are recorded and displayed as real-time, visual images. Ultrasound is commonly used in obstetrics as well as breast, thyroid, renal, liver, scrotum, vascular, and other pelvic and abdominal imaging. Additionally, several biopsy procedures are done under ultrasound guidance. No ionizing radiation is involved in ultrasound imaging making it is safe for pregnant women and children.