When is a catheter necessary (during surgery) and when not please?

Sometimes: Urinary catheters are needed for long procedures or ones that anticipate blood loss. Otherwise the bladder could become over distended. We also place them if we want to monitor urine output or watch for signs of blood in the urine when working close to the urinary tract. On average though we have cut way back on catheter use in the past 5 years as we know it reduces urinary infections.