When the signal of the muscle layer of the posterior wall of the rectum at about 3.0 cm from the anal opening is not uniform, the possibility of a lesion within the muscle layer of the posterior wall of the lower rectum should be considered. Under normal circumstances, ultrasonic endoscopy, the rectum of the muscle layer density uniformity, the entire rectum for the continuity of the low echo, in the case of lesions, due to the lesion of the tissue and rectal muscle tissue morphology, structure is not the same, and lesions within the structural disorders of the organization, lesions in the organization of the blood supply, ultrasonography, the performance of the limitation of the low-strong echogenicity. When ultrasound enteroscopy, suggesting that the posterior wall of the rectum muscle layer signal is not uniform, the need for specialists combined with the history, clinical symptoms and physical examination and other related matters, to understand the rectum with or without space-occupying lesions, and if necessary, also need to do a rectal magnetic resonance examination, to further clarify the diagnosis.