Q: 52 year old female with ESRD (End Stage Renal Disease) - on PD (Peritoneal Dialysis) for many years is admitted to ICU post-op after orthopedic surgery. Patient is requiring fair amount of narcotics for pain relief. Nurse call you to report outflow problem with her peritoneal dialysis catheter. What could be the most probable cause

Answer: Constipation

Constipation in peritoneal dialysis patient is a very common cause of outflow problem, particularly in patients who have otherwise  stabilized catheter (late complication). Use of laxatives to relieve constipation usually takes care of problem. Obviously, proper physical exam and other causes should be ruled out.