What investigations should be performed prior to surgery for large bowel obstruction?

Performing a CT scan prior to surgery for a large bowel obstruction is critical for several reasons. Firstly, a CT scan provides detailed images of the abdominal structures, which can help identify the specific site and cause of the obstruction, such as tumors, strictures, or diverticular disease. This imaging modality is particularly valuable because it can also help differentiate between true bowel obstruction and pseudo-obstruction, which can significantly affect surgical decision-making.

Additionally, a CT scan can reveal complications associated with obstruction, such as bowel perforation, ischemia, or abscess formation, enabling the surgeon to plan a more effective surgical approach. By excluding pseudo-obstruction or identifying the underlying pathology, the CT scan supports a thorough pre-operative assessment, ensuring that appropriate surgical strategies are deployed and potential risks are managed.

The other options, while they may have some applications in specific scenarios, do not provide the comprehensive information necessary for the pre-operative evaluation of a large bowel obstruction. For instance, ultrasound may not offer sufficient detail for identifying an obstruction's cause, and plain X-rays may not adequately visualize the whole bowel, leading to a potential misdiagnosis. Barium enemas, on the other hand, can help visualize colonic issues but are generally not recommended in acute settings due