Fifty patients had residual urine measured by catheterisation immediat
ely before laparoscopic cholecystectomy. The median amount of urine in
the bladder was 100 ml (range 5-500 ml). This urine volume does not d
istend the bladder enough to risk inadvertant perforation during inser
tion of a subumbilical port. Urinary bladder catheterisation is unnece
ssary before laparoscopy especially if the bladder is impalpable.