Effects of colonoscopy on intracranial pressure: observation in a large animal model

Increased intra-abdominal pressure has been associated with increased intracranial pressure. Bowel insufflation during colonoscopy may increase the intra-abdominal pressure. It was hypothesized that colonoscopy may be associated with intracranial pressure elevation subsequent to an elevation in intra-abdominal pressure.

Colonoscopy was carried out in seven anesthetized pigs, and the colonoscope was advanced up to 60 cm from the anal verge. Insufflation was used to allow safe advancement of the colonoscope and to allow visualization of the colon, in the same way as in the procedure performed in humans. Intra-abdominal pressure was measured by determining the hydrostatic pressure in the urinary bladder. A subarachnoid screw was used to monitor intracranial pressure. The mean arterial blood pressure and intra-abdominal venous pressure were directly monitored via the femoral vessel access; all parameters were recorded before and during colonoscopy.

A statistically significant elevation in intracranial pressure was demonstrated during colonoscopy. The average increase in intracranial pressure was 3.1 mm Hg. The intra-abdominal pressure and intra-abdominal venous pressure were also significantly elevated during the procedure.

Colonoscopy may increase intracranial pressure due to an increase in intra-abdominal pressure. This may have clinical implications when colonoscopy is conducted in patients with brain pathology associated with high intracranial pressure.