Yes, a kidney stone can pass through a stoma, but it depends on the type of urinary diversion you have, where the stone is located, and how large it is. If your bladder was removed or bypassed and your urine now drains through a stoma, stones that form in your kidneys or ureters can potentially travel down through the diverted pathway and exit into your pouch or bag. Small stones sometimes pass on their own, while larger ones often need medical intervention.
How Stones Travel Through a Urinary Diversion
When you have a urostomy, urine flows from your kidneys through the ureters and into a surgically created conduit or reservoir, then out through the stoma. A kidney stone follows this same path. In an ileal conduit (the most common type), the conduit is a short segment of bowel that connects your ureters to the stoma opening on your abdomen. A stone small enough to pass through the ureter can travel through the conduit and drop into your external pouch.
With a continent diversion, urine collects in an internal reservoir that you drain periodically through the stoma using a catheter. Stones can form in the reservoir itself or travel there from the kidneys. In these cases, the stone sits inside the pouch rather than passing freely into an external bag, which often means it needs to be removed by a doctor.
The key difference from typical stone passage is that you no longer have a urethra. There’s no bladder squeezing the stone out, and the anatomy of the conduit or reservoir changes the route. Stones can also get trapped in mucosal folds inside the conduit or reservoir, making them harder to detect and pass naturally.
Why Stones Are More Common After Urinary Diversion
People with urinary diversions develop kidney stones at higher rates than the general population. In one long-term study of ileal conduit patients, 9% developed stones within the first five years after surgery. Among those who survived longer than 15 years, the rate climbed to 38%. Several factors drive this increase. The bowel tissue used in the diversion absorbs and secretes substances differently than the original urinary tract, which can change urine chemistry and promote crystal formation. Chronic urinary tract infections, which are common after diversion surgery, also contribute to stone development. Dehydration, mucus buildup in the conduit, and changes in urine acidity all play a role.
Signs a Stone May Be Present
Recognizing a kidney stone with a urostomy can be trickier than in someone with normal anatomy. You won’t feel the classic urge to urinate or burning during urination. Instead, watch for these signs:
- Reduced or stopped urine output from your stoma, which could mean a stone is blocking a ureter or the conduit itself
- Flank or back pain on one or both sides, similar to standard kidney stone pain
- Cloudy, dark, or foul-smelling urine in your pouch
- Blood in your urine, which may appear as pink or red-tinged output
- Fever, chills, nausea, or vomiting, which can signal an infection caused by a stone blocking urine flow
If you notice a small, hard fragment in your pouch, that may well be a stone that passed on its own. Save it if you can, as your doctor can analyze its composition to help prevent future stones.
When a Stone Won’t Pass on Its Own
Larger stones, or stones lodged in the kidney, ureter, or internal reservoir, typically require a procedure. The approach depends on where the stone is sitting and what type of diversion you have.
For stones in the kidney, a procedure called percutaneous nephrolithotomy is commonly used. A small puncture is made through the skin on your back directly into the kidney, and the stone is broken up and removed. This bypasses the stoma entirely and provides direct access to the stone. In a study of 20 patients with urinary diversions and stones, this was the most frequently used technique.
For stones inside a continent reservoir, doctors can sometimes pass a scope through the stoma to reach and break up the stone. This trans-stoma approach works best for smaller stones. With larger stone burdens, the risk of damaging the stoma’s continence mechanism or causing long-term narrowing (stomal stenosis) makes a percutaneous approach through the abdominal wall safer. In one case involving a reservoir stone measuring over 11 centimeters, open surgery was the only option.
Shock wave lithotripsy, which uses sound waves from outside the body to break stones into smaller pieces, is another option for some patients. However, the altered anatomy after diversion surgery can make targeting the stone more difficult, and the fragments still need to find their way out through the diverted system.
Protecting Your Stoma During and After a Stone
A stone passing through or near your stoma can irritate the tissue. Watch for redness, swelling, bleeding, or pain at the stoma site. If the skin around your stoma pulls back, develops sores, or starts draining unusual fluid, these need prompt attention.
Keep the skin around your stoma clean with warm water and dry it thoroughly before reattaching your pouch. Avoid alcohol-based skin products, which can worsen irritation, and skip oil-based products that interfere with pouch adhesion. Treating minor skin changes early prevents them from becoming bigger problems.
Staying well hydrated is one of the most effective ways to reduce your risk of future stones. With a urostomy, it’s easy to underestimate how much fluid you need since you don’t experience thirst cues the same way. Monitoring the color and volume of output in your pouch gives you a practical gauge. Pale, consistent output suggests good hydration. Dark, concentrated, or low-volume output means you need more fluids. Your care team can also test your urine chemistry periodically to catch stone-forming conditions before they produce symptoms.