Men with blood in the urine after sex is called hematuria, this situation is mostly due to genitourinary infection, stones, and even tumors and other factors. 1. Infection: unhygienic sex life, resulting in urinary tract infection can lead to bladder mucosal rupture bleeding, patients are often accompanied by frequent urination, urinary urgency, urinary pain symptoms. Urine routine examination will find that the white blood cells are obviously elevated. 2. Stones: Some patients themselves suffer from urinary stones, such as kidney stones, ureteral stones and so on. During sex, the stone position will move and damage the blood vessels, which may cause hematuria. 3. Tumor: older patients also need to consider the possibility of urinary system tumors, such as kidney cancer, bladder cancer, prostate cancer, etc., can cause hematuria. Overall, after sex, there are blood clots in urine, which need to be taken seriously, go to the hospital in time for examination, and carry out targeted treatment under the guidance of the doctor after the cause of the disease is clarified.