The difference between holding urine and not holding urine for an ultrasound is mainly in terms of having a gynecological ultrasound and having a prostate ultrasound. The difference between holding urine and not holding urine mainly lies in the following: 1. The intra-cavity ultrasound is clearer, especially for obese patients, and the image is clearer than the abdominal ultrasound. 2. Intracavitary ultrasound is significantly better than transabdominal ultrasound for fine lesions. 3. Transvaginal intracavitary ultrasound is contraindicated for virgins, and held urine gynecologic ultrasound is suitable for women of any age. 4. Intracavitary ultrasound shows poor far-field display, and for larger masses or masses with long tips and high locations, intracavitary ultrasound cannot show the full picture.