Why Does a Stent in the Bile Duct Have to Be Removed?

Bile duct stents are temporary devices by design because they inevitably clog, and a clogged stent can trigger a life-threatening infection of the bile ducts called cholangitis. Plastic stents typically stay open for only a few months before bacterial buildup and sludge choke off the channel, while metal stents last somewhat longer but face their own failure modes. The fact that these devices degrade in performance over a predictable window is the central reason they need to come out or be swapped, and understanding how and why that happens matters if you or someone you know has one.

What a Bile Duct Stent Actually Does

A biliary stent is a small tube placed inside the bile duct to hold it open when something is blocking the normal flow of bile from the liver to the small intestine. The blockage might be a gallstone wedged in the duct, a tumor pressing on or growing into it, scar tissue from prior surgery, or inflammation from chronic pancreatitis. Stent placement effectively relieves both benign and malignant bile duct strictures, and the procedure is usually done endoscopically during a procedure called ERCP, where a flexible scope passes through the mouth, stomach, and into the upper small intestine to reach the bile duct opening.¹

Once in place, bile flows through the stent’s hollow center and drains normally. Jaundice fades, itching resolves, and liver enzymes start to improve. For many patients, the relief is dramatic within days. But the stent is a foreign object sitting in a warm, bacteria-rich environment bathed in digestive fluids, and that environment is hostile to anything that stays put for long.

How Stents Fail Over Time

The interior of a bile duct stent starts accumulating material almost immediately after placement. Chemical analysis of this buildup shows calcium bilirubinate, calcium palmitate, and mucoproteins, essentially a thick sludge made of bile salts, calcium, and protein.² On top of that chemical deposition, bacteria from the gut colonize the stent surface and form a biofilm, a sticky, layered community of microbes that progressively narrows the stent’s open channel.³ Some of these bacteria also produce enzymes that break down bile components into insoluble compounds, accelerating sludge formation. The process is self-reinforcing: as the opening shrinks, bile flow slows, giving bacteria and sludge more time to accumulate.

For plastic stents, this clogging process means functional life spans of roughly three to six months on average.⁴ Metal self-expanding stents, which have a wider diameter, tend to stay open longer, with mean patency of about eight to twelve months.⁴ But metal stents face additional problems: tumor tissue can grow through the mesh of uncovered stents (tumor ingrowth) or extend past the stent’s edges (tumor overgrowth), both of which re-block the duct.⁵ One comparative study found that plastic stents had a median patency of about ten weeks versus roughly twenty-two weeks for metal stents, confirming the trade-off between cost and longevity.⁶

None of these stents, whether plastic or metal, covered or uncovered, last indefinitely. That limited window of function is why scheduled removal or exchange is part of the treatment plan from the start.

What Happens If a Stent Is Left Too Long

The consequences of a forgotten or retained stent range from inconvenient to dangerous. Between a third and three-quarters of plastic stents become occluded within twelve months, and roughly one in five patients with a biliary stent shows up with occlusion and infection before their next planned procedure. The major risk is cholangitis, a bacterial infection of the bile ducts that can escalate to sepsis if untreated. Standard blood tests that flag stent obstruction, like rising liver enzymes, tend to be lagging indicators that only become abnormal once the stent is nearly completely blocked and infection risk is already elevated.

In one review of patients with forgotten long-term biliary stents, cholangitis was by far the most common complication, occurring in nearly 95% of cases.⁷ A separate study found that among 127 patients with previously placed plastic stents, about 35% ended up with retained stents, kept in place for a median of roughly five months but in some cases for years. About 20% of those patients developed cholangitis, while smaller numbers developed bile duct stones, abscesses, or septicemia.⁸ The fact that many of those patients were technically asymptomatic does not make the situation safe; a clogged stent is a ticking clock even when the patient feels fine.

Stent Migration

Clogging is not the only problem. Stents can physically move from their intended position, either sliding deeper into the bile duct (proximal migration) or slipping out into the intestine (distal migration). A study of 51 migrated stents found that all patients with stents that migrated upward into the bile duct were symptomatic, and more than half of those with stents that migrated downward also had symptoms. Risk factors included a dilated common bile duct and certain stent sizes.⁹

A stent that migrates distally and gets stuck in the intestine rather than passing naturally can cause intestinal perforation and peritonitis, a surgical emergency. Patients with prior abdominal surgery, hernias, extensive adhesions, or colonic diverticula are at higher risk for this complication, and in those cases the placement of a plastic stent may itself be more risky.¹⁰ Migration problems are another reason stents need monitoring and timely removal: the longer one sits, the more opportunity it has to shift.

How Stent Removal and Exchange Work

Removing a plastic biliary stent is usually straightforward. During a repeat ERCP, the endoscopist grabs the stent with forceps or a snare and pulls it out through the scope. If the underlying problem has been resolved (say, a stone was cleared or a stricture has healed), no replacement is needed. If drainage is still necessary, the old stent comes out and a fresh one goes in during the same session. This exchange resets the clock on clogging.

Stents that have migrated proximally deeper into the bile duct are harder to retrieve but still usually manageable endoscopically. In one series of 44 such cases, 86% were successfully extracted using a variety of techniques: passing a guide wire through the stent and pulling, grasping with a wire basket or forceps, or using a balloon alongside the stent for traction.¹¹

Metal stents, especially those left in place for a long time, present a bigger challenge. Uncovered metal stents can become embedded in the bile duct wall as tissue grows through the mesh, making removal difficult or impossible without tearing the duct. Covered metal stents are designed to be removable, but even they can become embedded if left in too long. One rescue approach for embedded metal stents involves placing a second fully covered metal stent inside the first one, compressing the overgrown tissue for a few weeks, and then removing both together.¹² This technique has shown a technical success rate of about 77% overall, though outcomes vary depending on the anatomy involved.¹³

The Problem of Forgotten Stents

One of the more frustrating issues in biliary stent management is that stents get forgotten. A patient has an ERCP, a stent is placed, and then the follow-up appointment for removal never happens. The patient may move, change doctors, get lost in the healthcare system, or simply not realize a second procedure was needed. Some patients are elderly, have multiple medical issues, and the stent removal falls off the priority list.

This is more common than you would expect. One study found that 35% of patients with biliary plastic stents ended up with retained devices, with some stents staying in place for nearly nine years.⁸ Researchers have proposed several solutions: stent cards given to patients at discharge, digital tracking systems that flag upcoming removal dates, electronic reminders sent to both patients and providers, and even national computerized registries to ensure no stent goes untracked.⁸ Some centers already review all ERCP procedures at regular intervals and contact patients who have not returned for stent removal on schedule.¹⁴

If you have a biliary stent, the single most important practical takeaway is to make sure you have a clear follow-up date and to keep it. Ask your gastroenterologist exactly when the stent needs to come out or be checked, write it down, set a reminder, and do not assume the clinic will track you down.

A Parallel Example from Pancreatic Stents

Biliary stents are not the only ductal stents with a removal timeline. Small plastic stents are sometimes placed in the pancreatic duct during ERCP to prevent post-procedure pancreatitis. These prophylactic pancreatic stents are designed to fall out on their own, but they do not always cooperate. A multicenter trial compared scheduling removal at two weeks versus four weeks and found that the four-week group had a much lower rate of needing endoscopic removal: about 7% compared to 19% in the two-week group, largely because more stents had fallen out spontaneously by the four-week mark.¹⁵ Another study found that only about half of prophylactic pancreatic stents had cleared by four weeks.¹⁶

The principle is the same as with biliary stents: any device left inside a duct needs to be confirmed as gone or removed on schedule. The body does not tolerate foreign material in narrow, bacteria-adjacent channels indefinitely.

Why Not Just Make a Stent That Lasts Longer

Researchers have been working on this from two angles. The first is surface coatings that resist the buildup of biofilm and sludge. One experimental approach uses a lubricant-infused coating (given the acronym ELFS) that kept stents free of biofilm for over six months in animal models and maintained a fully open channel for two months in a rabbit bile duct. Uncoated stents in the same experiments became completely blocked, with the bile duct dilating to over four times its normal size and the liver showing enlargement and scarring.¹⁷ These coatings are still experimental, but if they can double or triple functional stent life, they would reduce the number of exchange procedures a patient needs.

The second, more ambitious approach is building stents that dissolve on their own once the duct has healed, eliminating the need for removal entirely. Biodegradable stents made from materials like polylactic acid (PLA) or polycaprolactone gradually break down inside the body. In one animal model, PLA stents remained unobstructed for about 26 weeks before degrading.¹⁸ A zinc alloy stent maintained structural integrity for three weeks in a rabbit bile duct, then degraded completely within eight weeks.¹⁹ The challenge is matching the degradation timeline to the healing timeline. If the stent dissolves too fast, the duct re-narrows. If it dissolves too slowly, it causes obstruction or stone formation, as happened with one experimental design where fragmentation led to bile duct blockage in an animal model.²⁰

These technologies could eventually solve the removal problem for many patients, particularly those with benign conditions where stenting is a bridge to healing rather than an ongoing need. For malignant obstructions, where the stent may need to function until the end of life, longer-lasting conventional stents or anti-fouling coatings are probably the more relevant innovations.

Monitoring a Stent Between Appointments

If you have a biliary stent and are waiting for your scheduled exchange or removal, certain symptoms should prompt an earlier call to your doctor. Fever, chills, worsening jaundice (yellowing of the skin or eyes), dark urine, pale stools, and new upper abdominal pain can all signal that the stent has clogged and bile is no longer draining. Cholangitis, the infection that follows stent occlusion, can escalate quickly: a case report described a 42-year-old woman who developed moderate cholangitis five months after a plastic biliary stent was placed while waiting for her definitive treatment.²¹

Standard blood work can detect rising liver enzymes and bilirubin, but these tend to elevate only after the stent is nearly fully blocked. Researchers are exploring more proactive monitoring tools, including miniaturized sensors embedded in the stent itself that could wirelessly signal when the channel is narrowing, potentially catching the problem before symptoms develop. For now, though, patient awareness remains the primary early-warning system. Knowing what to watch for is genuinely important, because stent occlusion is not a complication that rewards a wait-and-see approach.

The broader context for all of this is that biliary stents are among the most effective tools gastroenterologists have for restoring bile flow and relieving jaundice, but they work best as part of a monitored, time-limited treatment plan. The removal is not an afterthought or optional follow-up. It is an integral part of the therapy, built into the plan from the moment the stent goes in.