What is the most appropriate investigation for Ulcerative Colitis?

The most appropriate investigation for Ulcerative Colitis is Flexible Sigmoidoscopy. This procedure allows for direct visualization of the rectum and the sigmoid colon, which are the areas primarily affected by Ulcerative Colitis.

Flexible Sigmoidoscopy is particularly useful in diagnosing and assessing the extent of inflammation in the lower part of the colon. It enables healthcare providers to take biopsy samples for histological analysis, which is crucial for confirming the diagnosis and ruling out other conditions.

While Colonoscopy, another endoscopic procedure, can also evaluate the entire colon and is often used in cases where more extensive assessment is needed, Flexible Sigmoidoscopy is the initial preferred method primarily when Ulcerative Colitis is suspected since it effectively assesses the most commonly involved segments of the colon with fewer risks compared to a complete colonoscopy.

Gastroscopy is designed for examining the upper gastrointestinal tract and therefore is not appropriate for diagnosing Ulcerative Colitis. A CT Scan, while useful in some gastrointestinal conditions, cannot replace direct visualization and biopsy capabilities provided by endoscopic procedures in the diagnosis of this specific condition.