A review of problems following insertion of biliary stents illustrated by an unusual complication

Abstract

Introduction

The management of obstructive jaundice resulting from both benign and malignant causes relies heavily on minimally invasive techniques and particularly with the insertion of biliary endoprostheses. Migration of these biliary stents is a well-documented problem and can result in a variety of complications including perforation, intra-abdominal sepsis, fistulae formation, obstruction and appendicitis.

Methods

A literature search was performed using PubMed examining case reports, published abstracts and reviews to date (2009). In addition, we report a left groin abscess as a previously unreported complication following migration of a biliary endoprosthesis.

Findings

Stent migration can lead to serious complications and produce significant morbidity and mortality. Symptomatic patients especially those with other co-morbid abdominal pathologies such as colonic diverticulae, parastomal hernia or abdominal hernias may be at an increased risk of perforation especially when straight plastic stents are used.

The management of obstructive jaundice secondary to benign or malignant pathological processes in the liver, biliary tract or pancreas is frequently by the endoscopic insertion of biliary endoprostheses. This well-established and well-described, minimally invasive procedure was first described in 1980 by Soehendra and Reynders-Fredenix.^1–6 Over the past decade, the use of this modality has increased in prevalence and, with technological advances, the indications and potential therapeutic manoeuvres have widened.⁷ Generally, these procedures are conducted with low rates of morbidity although potential complications such as pancreatitis, haemorrhage, perforation, cholangitis occur in approximately 5–10% of cases producing morbidity and occasional mortality.^4,7 These complications occur immediately or shortly following the procedure but, in addition, there are long-term complications which are less predictable and more difficult to diagnose and manage. Stent occlusion requiring replacement is by far the most common but stent migration (either proximal or distal) is also recognised and is believed to occur in up to 10% of cases.^1,4,8,9 The majority of migrated stents remain within the bowel lumen and pass through the intestine without incident.¹ Very rarely, however, these stents can fail to pass and impact in the bowel wall leading to complications such as perforation, appendicitis, intra-abdominal sepsis, fistula formation (enterocutaneous, colovesical) and pelvic abscess formation.^1,4,7–9 The most common documented site for problems following migration of biliary stents is in the duodenum,^10–13 where endoscopic retrieval is usually possible and surgical intervention rarely necessary.^14,15 Complications involving other sections of the small bowel or colon are rare but they generally necessitate early surgical intervention to avoid serious or occasionally life-threatening problems.

Case history

A 79-year-old woman was admitted to hospital with a tender inflamed swelling in her left groin and a clinical diagnosis of a simple cutaneous abscess was made. One month previously, she had undergone an endoscopic retrograde cholangiogram pantcreatogram (ERCP) for biliary obstruction and a stent (straight 10-F 9 cm) had been inserted which had produced resolution of her jaundice. Past medical history included multiple ERCPs with stent changes for benign biliary stricture following an open cholecystectomy with common bile duct (CBD) exploration and ‘T’-tube insertion 6 years previously. At ERCP two months prior to her most recent procedure, it was felt that the stricture had resolved sufficiently to allow removal of the stents (the medical notes did not reveal whether these stents were retrieved following removal from the bile duct). In view of the recent ERCP, a plain abdominal X-ray was organised which confirmed the straight stent in the biliary tree. In addition, it was noticed that there was a straight stent in the left iliac fossa (LIF), in the region of the groin abscess with a further pigtail stent higher in the LIF (Fig. 1).

Figure 1.

Plain abdominal X-ray showing biliary stent in situ and migrated stents (straight and pigtail) in left iliac fossa.

The patient underwent exploration of the left groin and drainage of the subcutaneous abscess; the straight stent noted on the plain abdominal film was retrieved. A gastrograffin follow through was later organised which showed no communication of bowel with abscess cavity. A follow-up appointment 4 weeks later revealed the wound to have completely healed suggesting that the migrated stent had produced a fistula from the bowel (most probably through a colonic diverticulum) and that this had subsequently resolved.

At the follow-up appointment, a plain abdominal X-ray demonstrated a straight stent in the correct position in the CBD and a pigtail stent in the LIF (Fig. 2). The patient remained asymptomatic and a subsequent CT which was organised to assess the exact position of the stent confirmed that it was found in the lumen of proximal sigmoid colon and demonstrated the presence of the suspected diverticular disease (Fig. 3). A flexible sigmoidoscopy was arranged to remove this double pigtail stent.

Figure 2.

X-ray showing biliary stent in situ and migrated stent (double pigtail) in the left iliac fossa.

Figure 3.

CT scan showing migrated stent (double pigtail) in the sigmoid colon.

Discussion

Endoscopic biliary tract stenting is well established as a routine treatment for obstructive jaundice secondary to benign or malignant strictures.^1,16 It is also valuable for the treatment of postoperative biliary leaks reducing dramatically the need for surgical intervention.^2,3 A variety of prostheses can be used and differ in size, design and material.^17,18 They are generally classified into two types – plastic and metal stents, which describes the material from which they are constructed.¹⁹

Complication rates range between 8–10% with a mortality below 1%.²⁰ A review of the literature indicates that proximal and distal stent migration occurs in about 10% of treated biliary strictures (previous studies report 3.1–4.9% of proximal and 3.6% of distal stent migration).^{17,21,23–26} This was recently analysed by Arhan et al.,²¹ who found a rather lower rate with 4.58% of proximal and 4.0% of distal stent migration. Distal stent migration into the intestinal tract leads to spontaneous passage of the stent in most cases^17,20 and the majority of stents which migrate and do not pass (or where migration is detected prior to passage) can be retrieved endoscopically and fluoroscopy.^20,27–29 Price et al.³⁰ reported a successful retrieval rate of 78% which is consistent with results from other retrospective studies that showed a retrieval rate of 80% and 75% for main and dorsal pancreatic duct stents, respectively.³¹

The migration of self-expandable metal stents occurs rarely, with a frequency of less than 1%, because the surrounding tissue grows through the interstices of the stent and produces fixation, although the same process is believed to lead to occlusion eventually.^32–35 It is also believed that the shortening that occurs following placement aids security.³⁶ The significantly more frequent migration of plastic stents at approximately 10%^{17,32,34,37,38} led Johanson et al.¹⁷ to analyse various stent characteristics and clinical factors that may contribute to proximal and distal stent migration. They reported that papillary stenosis is the only risk factor clearly associated with distal stent migration.¹⁷ Other studies, however, suggest that omission of a sphincterotomy may be a contributory cause.^16,39 It has also been noted that distal migration of stents is more common in benign than malignant strictures.^{16,17,33,40–42} The possible explanation for this phenomenon being that benign stenosis is less tight, due to resolution of inflammation and mucosal oedema and also that the tumour growth in malignant strictures may help to anchor the stent and prevent migration.³²

Arhan et al.,²¹ however, reported that stent migration is less frequent following treatment of strictures following cholecystectomy compared to other benign aetiologies possible due to the tight fibrotic nature of these strictures. Different stent properties and designs have been introduced to reduce the displacement risk including double pigtail stents, side-flaps and barbs.⁴³ It has also been shown that diameter and length play a role in the migration of stents with shorter stents tending to migrate proximally and larger stents distally in benign disease,²¹ although this relationship with length and migration does not seem to hold true for malignant strictures.^17,21 Multiple stents are associated with a decreased frequency of migration possibly due to the fact that they will be held more tightly within the stricture and there may be increased friction between the stents (particularly when they have been placed for any length of time and the surface becomes irregular).^21,32

Migration of biliary stents can lead to impaction in the distal bowel and the commonest cause is an extrinsic fixation or irregularity of the bowel wall such as the ligament of Trietz,⁷ parastomal hernias, abdominal hernias, adhesions, colonic diverticulae⁴ and, rarely, in the orifice of the appendix.⁸ The complications that result following stent migration and impaction have been broadly classified into penetration, perforation, intra-abdominal sepsis and obstruction of the intestine,^41,44,45 fistula formation (duodenocolic,⁴⁶ colovesical,⁴⁷ enterocutaneous,^16,42 duodenoscrotal⁴⁸), appendicitis,⁸ perforation of colonic diverticulum⁴⁹ and necrotizing fasciitis.⁵⁰ Rarely, other cavities or organs such as pleura or pancreas can be effected^14,15 and, as reported by ourselves, very rarely groin abscess. A review of the literature reveals 11 cases of colonic perforation and six cases of small bowel perforation.^1,4 Although we were unable to demonstrate the site of perforation in our case (due to the complete resolution of the fistula), with the presence of diverticular disease colonic perforation seems most likely. With these provisos this is the first reported case of colonic perforation producing a groin abscess requiring only an incision and drainage as treatment due to the lack of an obvious fistula tract.

Review of the literature reveals that the majority of complications associated with stent migration and perforation are seen with straight stents as in our patient.^{15,32,45,48–51} This may be due to the side flaps or barbs which cause entrapment of the stent in the bowel wall which is followed by pressure necrosis and perforation. After the diagnosis of stent migration has been made, patients with known risk factors such as adhesions, diverticular disease and hernias should be followed up carefully and stents retrieved if possible. In addition, every possible effort should be made to retrieve stents when new endoprostheses are placed and the old prostheses should not be discarded into the lumen of the duodenum or into the stomach.

Conclusions

Endoscopic placement of endoprostheses has an important role in the short- and long-term treatment of biliary obstruction, drastically reducing the need for surgical intervention and, consequently, the associated morbidity. In cases where long-term stent therapy is required, although stent migration is rare life-threatening complications can occur. To reduce the incidence to a minimum, removal of migrated stents should be attempted in all cases and surgical intervention should be considered at an early stage for all symptomatic patients. Use of double pigtail stents should also be encouraged as these are associated with less secondary complications than migrated straight stents.