A colonoscopy is a medical procedure used to examine the entire length of the large intestine, or colon. The primary purpose is to screen for colorectal cancer by identifying and removing precancerous growths called polyps, or to diagnose the source of other intestinal symptoms. A long, flexible tube equipped with a camera, called a colonoscope, is gently inserted through the rectum to visualize the inner lining of the bowel wall. Understanding patient positioning helps demystify the experience and reduce anxiety.
Initial Patient Positioning
The initial position for a colonoscopy is nearly always the Left Lateral Decubitus position, meaning the patient lies completely on their left side. This is the standard starting point before the endoscopist begins inserting the scope. In this position, the patient’s left arm is stretched out or placed behind them, and the knees are drawn up toward the chest in a fetal-like posture.
The medical team ensures the patient is comfortable, often utilizing padding to support the knees, ankles, head, and neck while the patient is under sedation. This physical setup optimizes the initial path of the scope into the lower part of the large bowel, allowing the endoscopist the best possible access and alignment for the colonoscope.
Anatomical Reasons for Positioning
The choice of the left lateral decubitus position is based on the specific anatomy of the lower digestive tract. Lying on the left side utilizes gravity to assist in straightening the sigmoid colon, a particularly challenging segment. The sigmoid colon is the S-shaped final curve of the large intestine before the rectum, often difficult to navigate due to its natural loops and tortuosity.
When the patient is on their left side, gravity pulls the mobile loops of the sigmoid colon downward, significantly reducing acute angles and slack in the bowel. This straightening effect allows the colonoscope to advance smoothly without excessive pressure or looping, improving the chances of a complete examination. The position also helps pool any residual fluid and stool residue away from the rectum and the entry point, aiding in clearer visualization at the start of the procedure.
Positional Adjustments During the Procedure
The patient does not remain in the initial position for the entire duration of the colonoscopy; the medical team often requests small changes to facilitate the scope’s passage. These positional adjustments are a common and effective technique used by endoscopists to navigate the colon’s major bends, which are known as flexures. When the scope encounters a difficult turn, such as the splenic flexure near the spleen or the hepatic flexure near the liver, the patient may be asked to roll slightly.
Rolling the patient onto their back, known as the supine position, or onto their right side (right lateral decubitus), uses gravity to alter the shape and angle of these flexures. This action transforms a sharp, acute angle into a more obtuse, open angle, allowing the scope to pass more easily toward the next segment of the colon. For example, rolling to the supine position is often helpful when approaching the splenic flexure, while a right lateral roll can assist in negotiating the hepatic flexure. These dynamic movements, which are performed while the patient is monitored and sedated, are a routine way to ensure the entire colon is successfully examined.