There are many reasons why the right side of the bladder is distended without pain, such as cystitis, bladder stones, bladder tumors, diseases of neighboring organs and other reasons. 1. Cystitis: Inflammation of the bladder caused by invasion of pathogenic bacteria may cause the symptoms of right bladder distension without pain, and most of them will be accompanied by urinary tract irritation signs such as frequent urination and urinary urgency. 2. Bladder stones: Kidney stones and ureteral stones may be dislodged into the bladder and irritate the bladder wall, which may cause the right side of the bladder to swell without pain. 3. Bladder tumors: For example, benign and malignant tumors of the bladder may cause the right side of the bladder to swell without pain due to the compression of the tumor. 4. Diseases of neighboring organs: for example, prostatitis and hyperplasia in men, pelvic inflammatory disease in women, right salpingitis, ovarian inflammation and other diseases may also lead to the feeling of swelling and pain on the right side of the bladder. There may be other reasons for the pain and swelling of the right side of the bladder, so it is recommended that you go to the hospital first to check the cause of the problem.