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