Low-grade urethral swelling may be caused by diseases such as urethritis, genital inflammation, and low-grade uroepithelial cancer. 1. Urethritis: usually associated with infection with gonococcus or non-gonococcus bacteria. Repeated stimulation of urethral tissues by pathogenic bacteria may cause tingling and pain in the urethra with urethral swelling. 2. Genital inflammation: for example, prostatitis and glansitis in men; vaginitis and vulvitis in women may cause urinary tract swelling, which is related to the lack of attention to hygiene and the invasion of various pathogenic bacteria. 3. Low-grade uroepithelial carcinoma: it belongs to a kind of low-grade malignant tumor of uroepithelium, at the initial stage, painless hematuria may appear, and the condition will gradually aggravate, and the tumor will increase in size, which will lead to urethral swelling after causing obstruction, and it may be caused by other parts of the tumor invading into the urethral tissues. Low-grade urothelial swelling may also be caused by other factors, in order to clarify the cause of low-grade urothelial swelling, it is recommended to go to a regular hospital as soon as possible, to do routine urinalysis, urethroscopy, and pathological biopsy, to clarify the cause of the disease and then treatment, and strive for early recovery.