Anatomical Variations of Rouviere’s Sulcus and Importance of R4U Line During Laparoscopic Cholecystectomy: A Prospective Observational Study

Abstract

Background: Laparoscopic cholecystectomy (LC) is the gold standard for symptomatic cholelithiasis, but bile duct injuries (BDIs) remain a significant complication. Rouviere's sulcus (RS) and the R4U line are proposed anatomical landmarks to minimize BDIs. This study aims to evaluate their utility in LC.

Methods: A prospective observational study was conducted on 350 patients undergoing LC at Sharda Hospital from March 2024 to November 2025. Intraoperative findings regarding RS, the R4U line, and dissection relative to the R4U line were recorded. Postoperative BDIs were assessed.

Results: RS was present in 85.7% of patients, with the open type being most common (85.33%). The R4U line was determinable in 85.7% of patients. Dissection was above the R4U line in 93.33% of cases. Two patients experienced intraoperative BDIs. One BDI occurred in a patient with absent R4U line, and the other occurred in a patient with dissection below the R4U line. A significant association was found between dissection below the R4U line and the occurrence of BDIs (p=0.02).

Conclusion: Rouviere's sulcus is a frequently identifiable landmark during LC. Dissection below the R4U line is associated with a significantly increased risk of bile duct injuries. The R4U line is a valuable landmark for safe dissection during laparoscopic cholecystectomy.