Eliminating waste from the body, known as defecation, is a natural and necessary physiological function. While the body is designed for timely waste expulsion, delaying the urge becomes temporarily necessary when a restroom is unavailable. Understanding how the body manages this urge provides context for why timely elimination is generally best for digestive well-being.
Anatomy of Delay: How the Body Controls the Urge
The rectum, the final section of the large intestine, acts as a temporary storage area for waste before expulsion. As mass movements from the colon push fecal matter into the rectum, the walls of this organ stretch, activating special sensory receptors. These receptors send a signal to the brain, which is interpreted as the desire to defecate.
This initial signal triggers an involuntary response known as the rectoanal inhibitory reflex (RAIR). The RAIR causes the smooth muscle of the internal anal sphincter to relax, preparing for potential passage of stool. The internal sphincter is made of involuntary muscle.
The ability to delay is due to the external anal sphincter, which is composed of skeletal muscle and is under voluntary control, innervated by the pudendal nerve. When the internal sphincter relaxes, the external sphincter consciously contracts to override the involuntary reflex and keep the anal canal closed. By voluntarily tightening this external muscle, a person can suppress the urge, which allows the rectal walls to relax and the stool to move slightly backward into the lower colon, temporarily reducing the pressure sensation.
If the urge is successfully delayed, the fecal matter remains stored in the rectum or lower colon until the next mass movement occurs. During this period of retention, the body continues to absorb water from the stool.
Immediate Strategies for Temporary Suppression
When the urge to defecate arrives at an inconvenient time, the most immediate strategy involves consciously engaging the external anal sphincter. This voluntary action of squeezing the pelvic floor muscles helps to keep the anal canal sealed and counteract the reflex relaxation of the internal sphincter. A sustained, submaximal contraction of these muscles for about 60 to 90 seconds can often signal the internal sphincter to re-contract, effectively shutting down the immediate urge.
Adjusting posture is another physical tactic that can reduce the pressure promoting elimination. Avoiding sitting or squatting positions is recommended, as these naturally straighten the anorectal angle and facilitate the passage of stool. Standing or lying down helps to maintain the natural kink between the rectum and the anal canal, which acts as a shut-off valve.
Employing techniques to calm the nervous system can also assist in temporary suppression. Taking a few deep, diaphragmatic breaths can help to relax the overall tension in the body, which may inadvertently lessen the intensity of the bowel urgency.
Why Habitual Retention is Detrimental to Health
While occasionally delaying defecation is harmless, making a habit of ignoring the body’s signal can lead to a cascade of negative health outcomes. One of the most common consequences is the development of chronic constipation. When stool is held back, the colon continues to absorb water from the waste, causing the fecal matter to become progressively drier and harder, making it significantly more difficult to pass.
Regularly suppressing the urge can eventually impair the body’s natural signaling system. The nerves and muscles in the rectum may become less sensitive to the distention caused by stool, leading to a diminished or absent feeling of the need to defecate.
The difficulty of passing hardened stool often leads to excessive straining, which dramatically increases pressure in the abdominal and rectal areas. This repeated straining can cause the veins around the anus and rectum to swell, resulting in painful hemorrhoids. In addition, the passage of hard stools can cause small, painful tears in the tissue around the anus, known as anal fissures.
In severe cases, prolonged retention can lead to fecal impaction, where a large, solid mass of stool becomes completely stuck and cannot be expelled, sometimes requiring medical intervention. Beyond localized issues, chronic constipation has been linked to broader systemic health concerns. Infrequent bowel movements and hard stool consistency are associated with an increased risk for cardiovascular disease, chronic kidney disease, and all-cause mortality.