Ultrafiltration failure (UFF) can be diagnosed in a patient with clinical evidence of hypervolemia or from charts showing poor UF. Poor UF may be because of noncompliance, incorrect dialysis prescription, hypoalbuminemia, mechanical causes like leaks and catheter migration and “True UFF”. True UFF occurs in 10-40% of patients with poor UF and is an important cause of technique failure and switch to hemodialysis. True UFF can be diagnosed and characterized by doing a modified “Peritoneal equilibration test” and looking at “sodium sieving”. If UF is <400 mL after 4 hours’ dwell with 4.25% Dextrose, it is UFF.

There are 4 types of UFF – Type 1 as fast transporter seen usually after peritonitis; Type 2 associated with aquaporin loss; Type 3 seen in sclerosis or adhesions and Type 4 with increased lymphatic absorption. D/P creatinine and sodium sieving can differentiate between these types. Management depends on early identification and specific management of cause, if possible. The outcome of UFF is poor and most patients need shifting to hemodialysis.