Endoscopic drainage of the biliary tract is a well-established treatment both in cases of benign and malignant strictures, either temporary or permanent. Metallic stents are typically used in malignant strictures as a permanent solution, whereas plastic stents are used mostly in benign strictures or as a temporary preoperative procedure, though this varies according to patient needs and medical issues. Stent placement is not free from complications. In the short term, bleeding, pancreatitis, cholangitis, and intestinal perforation may occur, with subsequent occlusion, stent migration, and potential intestinal perforation [1].

Approximately 5–14% of plastic biliary stents migrate [1–3]. Distal migration is more frequent than proximal migration (5.9% vs. 4.9%, respectively) [4]. Most stents pass through the small bowel without causing any symptoms. In less than 1% of cases, they cause hollow viscera perforation [3,5]. The duodenum is the most common perforation site in this extremely rare complication (92%),⁶ with a poor prognosis and high mortality rate (50%) [50], perhaps because it has a thinner wall than the rest of the small bowel [3,7]. Stents occasionally migrate distally and reach the small bowel or colon, where they cause complications, especially in patients with diverticulosis, previous abdominal surgery, or hernia [1,2,8]. In these patients, plastic stents could be contraindicated [4,6]. Retroperitoneal perforations are more frequent than intraperitoneal perforations, but the latter are more severe [5,7]. Migration can occur during the procedure, days or even weeks later, but it is extremely rare in the first hours [5].

Stent migration risk factors include presence of benign biliary stricture, use of a plastic stent, placement of a single stent, and < 3 months since procedure [5,7–9]. In addition, shorter stents tend to migrate proximally, whereas longer ones usually migrate distally [5]. In our case study, the patient experienced distal migration within 8 hours of placing a single, long, plastic stent. A large angle (≥30º) between the distal side of the stent and the central line of the patient’s body is another risk factor of perforation due to distal stent migration [7].

Clinical signs are highly variable. Some patients experience no symptoms or mild discomfort, some present with abscesses in retroperitoneal perforations, and some experience acute abdomen with pain, fever, nausea, vomiting, and other symptoms [2,5,10]. Because these symptoms also occur frequently in patients with pancreatitis following ERCP, early differential diagnosis is key to avoid treatment delays. Laboratory findings are highly unspecific, though amylase levels and liver function testing could show increases [9]. Consequently, imaging tests prove highly useful for diagnostic purposes. Various classifications of duodenal perforation following ERCP have been suggested. Stapfer et al. established four types in descending order of severity, according to production mechanism and perforation location and including treatment implications [13].

Ultrasonography has been proven helpful in terms of diagnosis and assessing retroperitoneal air removal in conservatively treated patients [10]. However, contrast-enhanced abdominal CT scan remains the diagnostic tool of choice because it detects very low volumes of intraperitoneal and retroperitoneal air and fluid [11,12]. Additionally, in patients with a retained stent and no symptoms, CT scan allows monitoring of progress and potential complications [8]. Furthermore, simple X-ray shows normal results in about 50% of perforation cases [10].

All patients undergoing biliary stent placement require close follow-up [2]. Advances in interventional radiology, endoscopy, and laparoscopy have improved treatment scope and reduced treatment morbidity in perforation secondary to biliary stent migration therapies, both for conservative and surgical treatments [14]. Management remains controversial, but early diagnosis and treatment are key. A delay of 24 hours or more has a negative impact on survival and quality of life [11,14]. Treatment options vary according to patient condition, perforation size and type, and the physician in charge [3].

Conservative antibiotic treatment with bowel rest and parenteral nutrition may be attempted in more stable patients [9], in patients with symptom-free retroperitoneal perforations, in elderly patients with multiple comorbidities, or in the presence of advanced malignant neoplasia [10]. A comprehensive description of patients that may benefit from this treatment is key [9]. For smaller perforations that are endoscopically accessible, stent removal and intestinal wall defect closure with clips or loops is the treatment of choice [12,15]. However, in cases of endoscopic treatment failure, diagnostic hesitation, unstable patients, or patients with clinical signs of acute abdomen or radiological evidence of widespread peritonitis, surgery is required [1]. Surgical options include stent removal and primary closure alone, defect closure with drainage and abdominal cavity lavage, and in severe cases with significant peritonitis and intestinal wall inflammation, pyloric exclusion [10].

In our case, due to the difficulty of previous ERCP attempts and the clinical signs of acute abdomen, a surgical treatment was selected. Considering the early diagnosis achieved through abdominal CT scan and the patient’s age and quality of life, a simple duodenal suture sufficed.