The back swelling when having urine can be caused by pyelonephritis, urinary stones, prostatitis and other factors. 1. Pyelonephritis: When pyelonephritis occurs, there may be soreness in the lower back, and there may be discomfort such as the feeling of holding back urine, frequent urination, and pain in urination, and when the condition is serious, it may be accompanied by systemic symptoms such as chills and fever. 2. Urinary stones: bladder stones, kidney stones and other stones in the urinary system, can be in the urine when the symptoms of lumbar soreness, lumbar pain, can be frequent urination, urinary urgency, urinary pain and other irritating symptoms, the serious cases may also appear in the manifestation of the naked eye hematuria. 3. Prostatitis: Prostatitis and other diseases can appear to hold urine, in the urine can appear waist swelling and sleepy performance, but also can appear frequent urination, perineal area pain and other symptoms, the urethral opening can appear white secretion of prostate fluid. When you have to urinate on the waist, you should consult a doctor in time, under the guidance of a specialist doctor to actively perform appropriate treatment, which will help to alleviate the discomfort symptoms as soon as possible.