Passing a small amount of stool when you pee is common, and it usually comes down to anatomy: your bladder and rectum share the same set of muscles and nerves, so relaxing one system often nudges the other. About 1 in 12 adults worldwide experience some degree of accidental bowel leakage, so you’re far from alone in noticing this.
Your Bladder and Bowel Share the Same Controls
The pelvic floor is a hammock of muscles that stretches across the bottom of your pelvis, supporting your bladder, rectum, and reproductive organs. When you sit down to urinate, your brain sends a signal to relax these muscles so urine can flow. But the same group of muscles also wraps around your anal canal. When they let go to open the urinary sphincter, the anal sphincter loosens too.
This isn’t a design flaw. Both your bladder and your bowel are controlled by nerves that originate from the same small segment of your spinal cord, specifically the sacral nerves at levels S2 through S4. The pudendal nerve, which branches from this cluster, directly controls both your external urinary sphincter and your external anal sphincter. So when your nervous system sends a “relax” signal for urination, that signal can partially reach the muscles holding stool in place. If there’s stool sitting low in your rectum, a small amount may slip out.
When It’s Normal and When It’s Not
Occasional, tiny amounts of stool during urination are generally harmless, especially if you were already close to needing a bowel movement. The fuller your rectum, the more likely relaxation during urination will push a bit out. This is particularly common first thing in the morning, when stool has had all night to move into the lower rectum.
It becomes worth paying closer attention if it happens frequently, if the leakage is more than a small smear, or if you notice you can’t control it at all. Persistent accidental bowel leakage affects roughly 5% of adults under 60 and over 9% of adults 60 and older. Women experience it slightly more often than men (about 9% versus 7%), partly because pregnancy and childbirth can stretch or injure pelvic floor muscles and nerves.
Common Causes of Frequent Leakage
If this is happening regularly rather than once in a while, a few things could be contributing.
Weak pelvic floor muscles. Aging, childbirth, chronic straining during bowel movements, heavy lifting, obesity, and surgery in the pelvic area can all weaken these muscles over time. When the pelvic floor can’t maintain enough tension around the anal canal, even the mild relaxation that comes with urination is enough to let stool escape.
Chronic constipation. This one is counterintuitive. When large, hard stool gets stuck in the rectum, softer or liquid stool higher up can leak around the blockage. The medical term is overflow incontinence. If you’re frequently constipated and also noticing leakage, the constipation itself may be the root problem.
Nerve damage. Diabetes, multiple sclerosis, spinal injuries, and even long-term straining can damage the nerves that coordinate your sphincters. When the nerves can’t send precise signals, the muscles don’t contract and relax with the right timing.
Muscle or sphincter injury. Previous surgery near the anus or rectum, trauma, or tears during childbirth can directly damage the anal sphincter. Even small injuries that healed years ago can gradually worsen with age.
A Rare but Serious Warning Sign
In very rare cases, sudden loss of both bladder and bowel control signals a condition called cauda equina syndrome, where the bundle of nerves at the base of your spine gets compressed. This is a medical emergency. The key difference is that it comes on suddenly and is accompanied by other symptoms: severe low back pain, numbness in the groin and inner thighs (the area that would touch a saddle), weakness in one or both legs, or difficulty walking. If you experience this combination, get to an emergency room immediately. Isolated, minor stool leakage during urination without these other symptoms is not cauda equina syndrome.
How to Reduce Leakage
For most people, a few practical changes can make a noticeable difference.
Pelvic floor exercises. Kegel exercises aren’t just for urinary issues. Strengthening the pelvic floor improves anal sphincter control too. The goal is to practice both sustained squeezes (holding for several seconds) and quick contractions. Consistency matters more than intensity. If you’re not sure you’re doing them correctly, pelvic floor physical therapists use biofeedback, a sensor-based tool that shows you in real time how strongly you’re contracting the right muscles. This guided approach helps people learn to exercise more effectively and can also retrain the coordination between your internal and external sphincters.
Fiber, but the right kind. Not all fiber works the same way. Psyllium husk, a soluble fiber found in products like Metamucil, has been shown to reduce leakage episodes by roughly half in some people. It works by forming a gel in the stool, making it firmer and more cohesive so it’s less likely to seep out. In one clinical trial, people who started with loose, unformed stools shifted to soft but formed consistency after taking psyllium. Other fiber types don’t have the same benefit. Carboxymethylcellulose, a synthetic fiber found in some supplements, actually increased leakage frequency in the same study. If you’re adding fiber, psyllium is the better choice for this particular problem.
Address constipation. If hard, backed-up stool is part of the picture, resolving the constipation often resolves the leakage. Adequate water intake, regular physical activity, and fiber all help. The goal is soft, formed stools that pass easily and completely, leaving less residual stool in the rectum to leak later.
Timing your bathroom habits. Going to the toilet at regular, predictable times, especially after meals when your digestive system is naturally more active, can help empty the rectum more completely. If there’s less stool sitting low in the rectum when you urinate, there’s less to leak out.
What a Doctor Can Check
If lifestyle changes aren’t enough, a specialist can run specific tests to pinpoint the problem. Anorectal manometry measures the pressure your anal sphincter generates, how well your rectum senses fullness, and whether your reflexes are working correctly. Electromyography (EMG) of the sphincter muscles checks for underlying nerve damage. These are diagnostic tests done in an office, not surgical procedures, and they help determine whether the issue is muscular weakness, nerve dysfunction, or a coordination problem, each of which calls for a different approach to treatment.