Introduction

Intestinal obstruction is a common indication for abdominal surgery in dogs. A variety of causes of intestinal obstruction have been documented and commonly include foreign body obstruction, strictures, adhesions, torsion/volvulus, and masses involving the intestinal wall.¹ Mural lesions of the intestine reported to cause obstruction include certain neoplastic and pyogranulomatous lesions. In humans, mural pyogranulomatous lesions are most often infectious in nature; however, mural pyogranulomatous lesions resulting in intestinal obstruction have been reportedly associated with foreign bodies in dogs.²

Treatment for intestinal obstruction is surgical intervention. Depending on the cause of the obstruction and health of the bowel, an enterotomy may be performed, or a resection and anastomosis (RNA) may be needed to remove the obstructive lesion. Intestinal surgery has traditionally been performed via a xiphoid to umbilicus celiotomy approach; however, laparoscopic-assisted intestinal surgery is becoming increasingly common in veterinary medicine. Postoperative complications of intestinal surgery include dehiscence, stricture formation, adhesion formation, peritonitis, or abscess formation. Suture material used to close a previous enterotomy or anastomosis has rarely been reported to become entangled in foreign objects in the intestinal lumen.^3,4 The purpose of this paper is to document a novel complication following intestinal foreign body removal in a dog, which resulted in an intramural abscess and obstruction at the site of the previous enterotomy closed with unidirectional barbed suture^a.

Case Report

A 2 yr old male castrated mixed-breed dog presented to the James L. Voss Veterinary Teaching Hospital Urgent Care service for bilateral mucopurulent nasal discharge and vomiting. On abdominal palpation, the abdomen was soft and nonpainful with no organomegaly or other abnormalities detected. Abdominal radiographs performed revealed an empty stomach and superimposed loops of bowel containing soft tissue opacity material in the mid-abdominal region. There was no radiographic evidence of pathologic distension of bowel. It was unclear whether the material was foreign material or ingesta. A complete blood count was performed, which showed no abnormalities other than a mild monocytosis (1.1 × 10³ cells/uL, reference range 0.2–1.0 × 10³ cells/uL). Given the dog had no radiographic signs of obstruction and had no abdominal discomfort, the owners elected conservative management consisting of subcutaneous fluids, omeprazole 1.2 mg/kg per os (PO) q 24 hr, and doxycycline 6 mg/kg PO q 12 hr. The dog was not fed while monitored by the owners overnight, and the owners were instructed to return the dog to the Urgent Care service if gastrointestinal signs persisted or recurred.

Intermittent vomiting continued overnight, and the dog was re-presented to the Urgent Care service. At that time, the dog was reactive to palpation in the mid-caudal abdomen, and a firm tubular structure could be palpated. Abdominal radiographs with pneumocolonogram were performed, which indicated that the suspected foreign material was in the small intestine and had not moved. More aggressive medical management was elected, and the patient was hospitalized for IV fluid therapy; Plasmalyte A and 20 mEq KCl/L were administered at a rate of 70 mL/hr. Abdominal palpation performed the following morning showed no changes from the previous day. Orthogonal radiographs showed that the suspected intestinal foreign material had not changed location, and there was progressive evidence of small intestinal dilatation, suggesting ensuing obstruction. Abdominal exploration was recommended, and the owners elected a minimally invasive approach to remove the suspected intestinal foreign body.

The dog was placed under general anesthesia, and a laparoscopic abdominal exploration was performed through a laparoscopic instrument port^b.⁵ Cefoxitin 22 mg/kg IV was administered once at the start of the procedure. A large, cylindrical mass was localized to the mid-jejunum. The entire intestinal foreign body site appeared grossly viable. The jejunum in the area of the foreign body was exteriorized through the laparoscopic instrument port site, a 3 cm enterotomy was made over adjacent healthy bowel, and the foreign body (a sock) was removed. The enterotomy site was closed with 4-0 barbed^a suture taking 3 mm full-thickness bites in a simple continuous pattern. The suture line was anchored in the tissue in a standard fashion for barbed suture using the loop in the proximal end and two 180° passes beyond the edge of the enterotomy at the distal end. The barbed suture in question has an absorption profile of 90–110 days with a tensile strength of 90% at 7 days and 75% at 14 days.⁶ Three simple interrupted 4-0 glycomer 631^c sutures were placed to close several gaps in the simple continuous suture line. The abdominal wall, subcutaneous tissue, and skin were closed routinely. The patient recovered with no complications and was discharged the following day with tramadol 4.5 mg/kg PO q 8-12 hr for pain control.

The dog’s appetite returned the day following surgery, and the owners noted the dog was bright and alert when sutures were removed at 2 wk. There were no further gastrointestinal signs until 26 days after the original surgery, when the dog was re-presented to the Urgent Care service for an acute episode of vomiting and lethargy. The dog was hospitalized overnight for monitoring, and given IV fluids. Initial radiographs showed suspected foreign material in the small bowel, but there was no evidence of mechanical obstruction. Abdominal radiographs repeated 6 hr later showed progressive bowel dilatation with no movement of the suspected foreign material, suggesting intestinal obstruction. Abdominal exploration was recommended through a standard celiotomy approach. Cefoxitin 22 mg/kg IV was given twice, once at the start of the procedure and then 90 min later, consistent with hospital protocols.⁷

During exploration, a dilated loop of jejunum filled with firm material was isolated at the level of the previous enterotomy. There were numerous firm adhesions at the previous enterotomy site to adjacent jejunum and several adhesions of the omentum to this site. On palpation, there was a fluctuant mass that appeared to be within the wall of the aboral dilatated bowel, and firm intraluminal material was palpable immediately orad to the mass. The adhesions were carefully broken down with electrotomy. Because the obstructive lesion appeared to be within the intestinal wall, the lesion was removed with 3–5 cm of normal jejunum on either side. The intestine was anastomosed using a previously described simple continuous closure method.⁸ The abdomen was closed routinely.

After surgery, the resected intestinal segment was carefully incised along its antimesenteric border to determine the cause of the mural obstruction and for biopsy sampling. Impacted intestinal contents was found orad to the mural lesion. A 2 cm mural mass containing purulent material extending 270 degrees around the jejunum was found, causing blockage of the intestinal lumen (Figure 1). No obvious foreign material was observed within the mass. Gross inspection of the abscess by the pathologist found the presence of suture material from the previous intestinal anastomosis. Histopathology of the resected intestinal segment showed moderate-to-severe, chronic-active multifocal mural abscesses of various sizes, with dystrophic mineralization and mild suppurative enteritis. One cross section of the resected intestine showed a mural abscess partially lined with mature mucosal tissue and a tract of submucosal tissue through the muscularis layer connecting the luminal mucosa with the mucosa surrounding the abscess (Figure 2).

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The dog recovered from anesthesia with no complications and was discharged the following day with tramadol 3 mg/kg PO q 6–8 hr. There were no gastrointestinal signs, such as vomiting, diarrhea, or anorexia, and the patient was comfortable on abdominal palpation at suture removal. The dog has recovered fully from the surgery and remains in good health 4 mo following mural abscess excision.

Discussion

After intestinal surgery, early postoperative complications (defined as those occurring prior to suture removal) related to the intestinal repair include dehiscence, peritonitis from necrosis or leakage at the surgical site, ileus, or short-bowel syndrome if a significant amount of small bowel is removed. Dehiscence has been reported to occur in 3–16% of cases of hand-sewn small bowel anastomoses.^8,9 For anastomosis techniques that use staples, localized, nonobstructive abscesses within the staple line have been reported to occur up to 4% of the time.^10,11 In a study performed by Jardell et al., an abscess was identified 3 days after RNA surgery using staples during postoperative ultrasound monitoring, and the abscess was successfully removed in a second surgery. During surgical exploration, it was discovered that the abscess formed outside of a region of the anastomosis that had excessively everted mucosa.¹⁰

Late postoperative complications, occurring after suture removal for RNA or enterotomy, have been reported to be stricture formation at the anastomosis site and adhesion formation.¹ There are also reports of entanglement of foreign material in nonabsorbable suture from a previous enterotomy.³ Entanglement of an intestinal trichobezoar in the exposed intraluminal portions of staples has also been documented.⁴ Although not considered a late postoperative complication, reobstruction from another foreign body is also not uncommon in dogs and would be considered one of the possible causes of the clinical signs.¹² The authors report a novel late postoperative complication following an enterotomy. Recurrence of intestinal obstruction from an intramural abscess at the previous surgical site has not been documented to the authors’ knowledge in either human or veterinary medicine.

Although adhesions commonly form on intestinal repair sites, barbed suture may have contributed to formation of the firm adhesions we observed. There are increasing reports in the human literature of adhesions resulting in intestinal obstruction following gastrointestinal surgery in which barbed suture is utilized.^13,14 These adhesions are thought to form at the exposed suture tail, which can irritate adjacent viscera and even become entangled with opposing intestines. Barbed sutures have also resulted in intestinal obstruction by causing small tears in the adjacent mesentery from the exposed barbs moving during normal peristaltic movement. This results in a window in the mesentery through which the small bowel can enter and became entrapped.¹⁵ More serious adhesions from exposed sections of barbed suture have resulted in full-thickness serosal injury and small bowel volvulus.¹⁶ However, it should be noted that there are also many case series reports with greater than 100 individuals in human surgery documenting the safety of barbed suture in intestinal surgery, although barbed suture in human gastrointestinal surgery is primary used in laparoscopic Roux-en-Y gastric bypass.^17,18 To the authors' knowledge, there are no large case series documenting complications related to barbed suture when used solely for intestinal repair.

The inciting cause or causes of the intramural abscesses in this case study cannot be identified. An intramural abscess could have formed from a focal area of mucosal damage caused by the foreign body that was removed during the first surgery. Bacterial contamination from the intestinal lumen could have entered deeper layers of the bowel wall through a defect in the mucosa created by the enterotomy and subsequent suturing, and when the mucosa sealed, an abscess formed. Perhaps there was delamination of the bowel wall layers (mucosa separating from the submucosa), and during suturing, mucosal tissue and ingesta became trapped inside the intestinal wall, contributing to abscess formation. Bacterial culture of the abscesses could have helped to identify the source of the bacteria; however, it was not performed in this case because during biopsy sampling of the mural mass, fecal contamination occurred. A fine needle aspirate could have been performed to collect a sample for bacterial culture if the mass causing the obstruction was known to be an abscess prior to biopsy sampling.

The barbed suture material used in the original enterotomy closure may have also contributed to intramural abscess formation. The barbs within the suture line may have caught and invaginated mucosal tissue within the bowel wall. This could explain why one mural abscess was lined with mature mucosa, with a tract through the muscularis muscle layer connecting the mural abscess and intestinal lumen (Figure 2). Barbed sutures allow for knotless placement of suture by engaging the tissues with unidirectional barbs, preventing the suture from sliding backward within the tissue. During peristalsis, the presence of the barbs within the friable mucosa may have eroded the mucosa, resulting in penetration of contaminated fluid into the deeper layers of the bowel wall. The barbs may have also caught small pieces of foreign material and introduced them within the suture line inside the bowel wall. In a case series of four dogs with small intestinal obstruction, pyogranulomatous intramural lesions containing microscopic traces of plant matter have been documented.² Increased tension on the suture line due to loss of “backsliding” between needle bites (which occurs to some degree during tensioning with smooth suture materials) may have also created areas of ischemia, resulting in mucosal necrosis, delamination of the bowel wall, and subsequent abscess formation.

Surgeons should be aware of the possibility of intramural abscess formation as a cause of late obstruction after enterotomy. An intramural intestinal abscess can be challenging to diagnose. In human medicine, computed tomography scans are used to diagnose intramural lesions resulting in obstruction from Crohn’s disease and tuberculosis.^19,20 We achieved the diagnosis of a mural abscess causing obstruction via exploratory laparotomy, but if there is doubt as to the cause of an obstruction, computed tomography imaging could prove useful in small animals. A complete cure can be achieved with successful resection and anastomosis of intramural lesions. As laparoscopic surgery and the use of barbed suture grow in popularity, surgeons should be aware of the emergence of new complications and recommendations or limitations regarding the use of barbed suture in abdominal surgery. At this time in human surgery, the use of barb sutures in laparoscopic procedures within the peritoneal cavity is considered “off-label.”^21,22 An intramural abscess at the site of a previous enterotomy is an extremely rare cause for reobstruction. Although adhesions like the ones found during the second exploratory surgery rarely cause intestinal obstructions in small animals, they have been documented to cause serious complications such as entrapment, volvulus, and strangulation.²³

Conclusion

This is the first documented case of an intramural abscess resulting in intestinal obstruction at the site of a previous enterotomy. Surgeons should be aware of this new late complication when a dog presents recurrence of gastrointestinal signs of obstruction after intestinal surgery. Surgeons should also be aware of the possible complications when using barbed suture in abdominal visceral repair.