The R4U Planes for the Zonal Demarcation for Safe Laparoscopic Cholecystectomy.

Post-cholecystectomy bile duct injury is a serious complication. Usually, it results from structural misidentification and can be avoided by adopting the critical view of safety. The biliary, vascular, and other visceral injuries can also occur during the dissection to achieve the critical view of safety. To avoid such complication, identification of the safe area for dissection is important during laparoscopic cholecystectomy. It is imperative to start the dissection in a safe area and remain there during the procedure. Fixed anatomical landmarks can help in proper orientation to ascertain the surgical anatomy correctly during surgery. The Rouviere's sulcus is one of such anatomical landmarks. Utilizing this sulcus, we describe a technique of zonal demarcation based on the concept of one line (the R4U line), two planes (the R4U planes), and four zones to identify a "safe area" for dissection during laparoscopic cholecystectomy to perform the procedure safely.