Retroperitoneal leakage is likely to arise from a tear or a gap in the peritoneum precipitated by an increase in intra-abdominal pressure associated with walking, coughing, straining, or using a high instilled volume (2.5 L or 3 L). Red flags may include history of hernia, pleuroperitoneal communication and large infusion volumes. The acute onset of ultrafiltration failure is another suggestive finding.