|Home | About | Journals | Submit | Contact Us | Français|
We highlight the importance of considering rarer causes of small bowel obstruction in patients presenting after extra-anatomical arterial bypass.
Our patient underwent a left common iliac-to-bifemoral bypass extra-anatomical graft for critical limb ischaemia. The patient developed mechanical small bowel obstruction on the 20th postoperative day. Emergency laparotomy revealed incarcerated, obstructed small bowel trapped in the graft tunnel. Recovery was satisfactory following small bowel resection.
To the best of our knowledge, small bowel herniation into an arterial bypass graft tunnel, with successful treatment outcome, has not been reported to date.
Bowel obstruction presenting after abdominal operations represents a diagnostic and therapeutic challenge. The most frequent dilemma is discriminating between functional ileus and mechanical obstruction. The difficulty is self-evident in the case of previous transcoelomic surgery.
We present a complication, not previously reported, of extra-anatomical arterial bypass involving the abdominal wall. Studies have reported on the local and general complications following iliofemoral and femorofemoral crossover bypass operations. These include infection, haematoma, superficial nerve injury, and ileus.1,2
We present a case of a 70-year-old man with a critically ischaemic left lower leg and necrotic left heel. Duplex scanning revealed left external iliac and right common iliac artery occlusion. He was deemed unfit for aortic surgery due to significant ischaemic heart disease. An extra-anatomical bypass procedure with left common ileo-bifemoral bypass utilising an 8-mm diameter expanded Dacron trouser graft was performed. The left common iliac artery was approached using an extraperitoneal route. The limbs of the graft were tunnelled to the groins using preperitoneal tunnels. The tunnels were formed by ‘blind’, blunt, digital dissection.
The patient remained in hospital, limited by immobility as a consequence of the heel ulcer and his poor general condition. On the 26th postoperative day, the patient developed clinical signs and symptoms of intestinal obstruction. A supine abdominal radiograph confirmed the presence of dilated, air-filled small bowel loops. He was treated non-operatively for several days because he was thought to have a functional ileus. His symptoms did not improve. Abdominal computed tomography (CT) with intestinal water-soluble contrast enhancement showed dilated small bowel loops with a transition point in the lower ileum anatomically close the bypass graft. On emergency laparotomy, the graft tunnel was identified in the sheath between the peritoneum and the inferior rectus and internal oblique muscles. The tunnelling process had created a breach of the peritoneum in the left lower quadrant. Through this hole, which was 3 cm in diameter, small bowel had been pulled into the tunnelling layer of the graft (Fig. 1). The dilated segment of incarcerated terminal ileum lay alongside the graft over a distance of 8 cm. The mechanism of how peritoneum had become involved in an extraperitoneal graft was surmised thus; during the process of tunnelling, the tip of the instrument perforated the peritoneum when it was pushed forward and hooked up a segment of small bowel. The segment of bowel was then carried forward with the instrument after it had been slightly repositioned and, thereby, the tip had been brought back into the extraperitoneal space.
The bowel was manually dislodged from the hernia cavity. There was no macroscopic intestinal perforation, only evidence of segmental venous infarction. Six centimetres of terminal ileum were resected and a side-to-side stapled ileo-ileostomy fashioned and oversewn by hand. The arterial graft was left in situ. It was exposed over a length of 5 cm and thoroughly rinsed with povidone iodine and 4% chlorhexidine solution. The bypass graft was extraperitonealised.
Histology of the specimen and culture of the peritoneal fluid showed no evidence of infection, inflammation or malignancy. The patient made a slow, but adequate, recovery. Discharge from hospital was on the 46th postoperative day.
An English language literature search using Medline and EmBase indicates that this is the first reported case of intestinal obstruction caused by herniation of small bowel into an arterial bypass tunnel. The reported mortality rates after crossover bypass vary, ranging from 2.7–27.8%,2,3 probably reflecting variable preoperative co-morbidity and indication for surgery (endovascular aneurysm repair, intermittent claudication, and critical ischaemia). The most commonly reported graft-related complications include haemorrhage, graft occlusion, graft infection, anastomotic false aneurysm and lymph fistula.1,2 Cases of visceral injury have been reported much less frequently.
The literature search identified similar reports involving small bowel obstruction, Read et al.4 retrospectively reviewed the complications associated with subcutaneous and preperitoneal graft placement. Nine of the 62 cases were preperitoneal, one of which developed small bowel obstruction attributable to the arterial graft 7 years after surgery. However, preperitoneal placement was associated with better primary prosthetic placement and less infection than the subcutaneous approach.4
Van Nieuwenhuizen et al.5 reported a case of unrecognised small bowel injury due to tunnelling of a femoro-femoral crossover bypass, which led to sepsis and death of the patient. Similarly, visceral organ damage following femoro-femoral bypass surgery has been alluded to in a study by Hinchliffe et al.3
In our case, we surmise that digital tunnelling of the left-to-right crossover graft limb stretched a pocket of peritoneum to create an internal hernia sac. The delayed presentation suggests that this sac was occupied by small bowel some weeks after it was created; small bowel obstruction ensued, fortunately without infarction or perforation. We attribute our patient’s survival and on-going graft function to the fact that the bowel was macroscopically intact. Nevertheless, the recognition of the true cause of postoperative bowel obstruction was delayed by initial consideration of the more common causes of the presentation, particularly functional ileus or adhesions secondary to previous inguinal hernia surgery. In the context of the extreme rarity of this presentation, the loop of small bowel trapped within the graft tunnel was initially overlooked on the CT scan.
This case serves as a timely reminder that blind tunnelling across the abdomen has the potential to injure viscera both directly and indirectly. This is of particular relevance as the frequency of the procedure is currently increasing as endovascular aneurysm repair gains popularity. It maybe useful that tunnels are formed under visual control, particularly in patients with abdominal scars that cross the intended tunnel path.
In the setting of intestinal obstruction following arterial bypass surgery involving the abdomen, visceral herniation into the graft tunnel should be considered in the differential diagnosis. This complication may be identifiable by CT scan if specifically considered. This complication may be further reduced by the use of refined techniques for tunnelling, such as the use of small calibre fibre-optic instruments for direct visualisation.