A colonoscopy is a medical procedure used to examine the entire length of the large intestine, also known as the colon and rectum. This examination involves inserting a long, flexible tube with a camera, called a colonoscope, into the rectum and advancing it through the colon. The procedure serves as a diagnostic tool for various lower gastrointestinal symptoms and is a widely accepted screening method for detecting and preventing colorectal cancer by identifying and removing polyps.
The Standard Starting Position
Patients undergoing a colonoscopy begin the procedure lying on their left side. This is referred to as the left lateral decubitus position. The individual lies on their left side with their knees bent towards their chest. This position helps to align the lower part of the colon, specifically the rectum and sigmoid colon, with the natural entry point for the colonoscope.
Why This Position is Used
The left lateral position is used due to anatomical considerations that facilitate the insertion and advancement of the colonoscope. When a patient lies on their left side, gravity helps move the contents of the colon, allowing for better visualization of the intestinal lining. This positioning also straightens the sigmoid colon, often the most challenging segment to navigate due to its curves and loops. Entering the colon in this position can help reduce looping of the scope, making the procedure smoother. It may also improve distension of the right side of the colon, aiding in polyp detection in that area.
Positional Adjustments During the Procedure
While a colonoscopy begins with the patient on their left side, the medical team frequently adjusts the patient’s position throughout the examination. These changes are a routine part of the procedure, assisting the physician in navigating the entire colon. For instance, a patient might be asked to turn onto their back (supine position) to help straighten the transverse colon, or onto their right side to improve visualization of the splenic flexure and descending colon. Such positional changes, including turning onto the stomach (prone position), can help redistribute gas and fluid within the colon and flatten folds, enhancing the visibility of the mucosal lining and aiding in polyp detection. These adjustments contribute to the effectiveness and safety of the colonoscopy.