Information on difficulty passing urine, including symptoms like slow flow, straining, and incomplete emptying, potential causes like blockage or bladder weakness, and diagnostic tests. There are four stages of passing a kidney stone: formation, moving into the ureter, reaching the bladder, and exiting the body in urine. Kidney stones form when urine becomes concentrated, allowing crystals to develop. Passing urine happens when your brain tells your bladder muscle to tighten to squeeze your pee out. Your brain then tells your sphincter muscles surrounding your urethra to relax. Most men struggle to pass urine because the prostate has enlarged (benign prostatic hyperplasia), a urinary tract infection has caused swelling, or medicines are blocking bladder nerves. Acute urinary retention causes sudden inability to pass urine, often with pain and bloating. Chronic urinary retention may have no symptoms or cause frequent urination and discomfort. Frequent urination with an abnormally large amount of urine is often an early symptom of both type 1 and type 2 diabetes as the body tries to rid itself of unused glucose through the urine. Learn about the causes and signs of being unable to pass urine, a serious condition known as Acute Urinary Retention.