CT enhancement examination because of the need to inject iodine contrast agent, so there are certain dangers, as follows: 1, allergic reactions, including itching, rash, flushing, nausea, vomiting, edema, etc., and in severe cases, laryngeal edema, anaphylactic shock, etc., which can be life-threatening; 2, renal impairment, often transient, a very small number of patients, especially in renal insufficiency, may result in permanent renal impairment; 3, blood vessel Vagal reaction, mainly including pallor, weakness, sweating, nausea, vomiting, fainting, convulsions, urinary and fecal incontinence, etc.; 4, angina pectoris; 5, causing generalized feeling of heat, pain, and other discomforts; 6, bleeding, pain, bruising at the site of puncture, leakage of contrast medium, swelling and other phenomena.