In men with sudden pain in the small abdomen, it is recommended to go to the hospital for an examination to identify the possible causes. First, urinary stones, commonly ureteral stones, can cause sudden and sharp pain in the small abdomen, which is often severe and may be accompanied by symptoms such as back pain, frequent urination, urinary urgency and hematuria. Further ultrasound of the urinary system is needed to rule out. Second, acute infection of the urinary system, such as acute cystitis, can cause sudden pain in the small abdomen, usually accompanied by obvious symptoms of urinary urgency and painful urination, and in severe patients, there can also be symptoms of blood in the eyes, and the patient may also have a combination of elevated body temperature changes, need to carry out routine urine, urine culture and other laboratory tests to further rule out the presence of infection. Third, non-urinary system diseases, such as acute appendicitis and acute intestinal cramps, can cause acute abdominal pain. It is necessary to go to a specialist for further examination, such as ultrasound of the appendix area and routine fecal laboratory tests.