M.B. is a 24 year old woman who came for her first postnatal appointment. She delivered a healthy baby at a hospital 4 days prior to this visit. She says she has been unable to urinate since delivery. She does not appear to be in any discomfort. It does not seem possible that she has not urinated at all for 4 days, however, she repeatedly says that she has not been able to urinate 1 drop. She feels the urge to urinate but cannot. She looks like she is still pregnant. Could there be a twin? Ultrasound reveals a lot of watery liquid, no twin. So a catheter is placed into her bladder. 2 liters of urine is drained. And her abdomen visibly decreased as the urine came out. This shouldn’t be possible. 2 liters of urine! I looked up how much urine the bladder can hold. The answer: 500 milliliters for a woman. Her creatinine was normal, so kidney was functioning normally. We left the catheter in and had her come back 1 week later and removed the catheter. She hung out for awhile and drank some water but could not urinate. She had the urge to urinate, but nothing comes out. So the catheter was replaced and she came back to clinic again 1 week later. The catheter was removed and she could urinate normally. She came back to clinic 1 week later and was still urinating normally.