What is the cause of black residue in urine?

If you see black slag-like substances in urination, the possible reasons are as follows: 1. Urinary system stones, kidney stones, ureteral stones, bladder stones or recent urinary system stone lithotripsy or drug stone discharge treatment, black stone slag-like substances may be discharged. When touched by hand, the texture is relatively hard and rough. Most of them are discharged small stones. B-ultrasound examination of urinary system can be carried out to understand whether there are residual stones. If combined with urinary bleeding disease, the use of hemostatic drugs or self-coagulation can discharge black slag-like substances, mostly small blood clots. For example, acute hemorrhagic cystitis, bleeding gradually stops during treatment, coagulation in the bladder small clots discharged with urine, generally without pain. If there has been a history of infection or urinary system trauma bleeding in the past, the black residue discharged is mostly small blood clots. B-ultrasound or CT examination of urinary system can be further performed to rule out whether there is congestion or not completely healed.