Systems and methods for laxative-free colonoscopy include an ultrasound transducer housing positioned at or near the operable end of the flexible tube, the housing including an ultrasound transducer to generate ultrasound energy. The flexible tube with ultrasound transducer is inserted into a gastrointestinal tract. A water flow channel delivers water to the gastrointestinal tract. The ultrasound energy and water liquefy stool in the gastrointestinal tract, and the liquefied stool is removed from the gastrointestinal tract.
