Small bowel obstruction caused by a fibrotic bow-string appendix: a consequence of non-operative management of acute appendicitis

Abstract

A 73-year-old woman presented with small bowel obstruction that failed to settle with conservative management. Over the previous 2 years she had presented twice with computed tomography scan-proven acute appendicitis with localised perforation of the appendix tip. In view of medical comorbidities, she was treated non-operatively with clinical and radiological resolution on each occasion, but on the third presentation laparoscopy was undertaken for non-resolving small bowel obstruction and the non-inflamed appendix itself was identified as a fibrous band causing compression of the distal ileum and complete small bowel obstruction. Following division and appendicectomy, the patient made an uneventful recovery. This case illustrates the potential consequence of repeated appendiceal inflammation and non-operative management and may be seen increasingly as this approach is widely adopted during the COVID-19 pandemic.

Background

Acute appendicitis (AA) is a common emergency presentation with a lifetime risk of around 8%.¹ Traditionally treated by appendicectomy, there has been renewed interest in non-operative management (NOM), particularly in the UK during the 2020 COVID-19 pandemic when there was a desire to reduce operative activity for fear of virus transmission during aerosol-generating procedures such as laparoscopic appendicectomy. NOM for uncomplicated appendicitis is associated with therapeutic success in the short term in the majority of patients for whom this approach is adopted,² although recurrent or persistent appendicitis requiring surgery approaches 30% and 40% at 1 and 5 years, respectively.³

NOM is less likely to be successful for complicated (that is, perforated) appendicitis. Nevertheless, this approach is feasible in patients with localised contained perforation in whom, for medical reasons, surgery may be best avoided. Indeed, complications such as abdominal abscess, wound infections and further unplanned procedures may be higher in this group than in those managed conservatively.⁴

The long-term consequences of NOM for complicated appendicitis are not well documented and the ultimate appendicectomy rate for this group is just one measure of outcome. A case is reported of one possible consequence of NOM of AA.

Case history

A 73-year-old woman with a past history of lacunar stroke, hypertension, chronic kidney disease stage 3 and hypothyroidism presented with a 3-day history of abdominal pain and distension. There was no history of abdominal surgery. On examination there was tenderness and guarding in the right iliac fossa. Blood tests revealed a white cell count of 21×10⁹/L and C-reactive protein of 326mg/L, and a computed tomography (CT) scan showed AA with tip perforation and localised abscess, causing a degree of small bowel obstruction (SBO) (Figure 1). A consensus decision was made for a trial of NOM with a nasogastric tube, intravenous fluids and antibiotics. Rapid improvement and resolution was observed, such that the patient was discharged home after 3 days on an extended course of antibiotics and at 6-week telephone follow-up the patient was symptom-free.

Figure 1 .

Axial and coronal contrast-enhanced computed tomography scans showing calcified appendicolith adjacent to an appendix tip perforation abscess cavity

The patient re-presented 10 months later during the UK’s ‘first wave’ COVID-19 pandemic with a 2-week history of diarrhoea and abdominal pain, a white cell count of 17 × 10⁹/L and C-reactive protein of 62mg/L. CT demonstrated recurrent perforated appendicitis and SBO. The patient again responded well to NOM with early discharge and an interval scan demonstrated complete resolution.

A third presentation ensued 6 months later, with abdominal pain, vomiting and signs of SBO. A CT scan demonstrated a complex fibrous band causing closed loop obstruction at the level of the terminal ileum without evidence of AA (Figure 2). At diagnostic laparoscopy, a thick fibrous band arising from the caecum was apparent compressing the distal ileum causing complete SBO. The band was divided, releasing the small bowel and allowing recovery; it was apparent that the band was the obliterated appendix itself with its tip buried in the distal ileal mesentery and the two parts were then removed (Figure 3). The patient made an uneventful recovery and was discharged after 3 days. Histopathological examination of the appendix confirmed fibrous obliteration with evidence of previous inflammation.

Figure 2 .

Axial and coronal contrast-enhanced computed tomography scan demonstrating small bowel obstruction with a transition point in the right iliac fossa

Figure 3 .

Image taken at the time of operation demonstrating a fibrous obliterated appendix causing small bowel obstruction

Discussion

This case highlights the potential consequence of NOM of AA. During the ‘first wave’ and lockdown period of the COVID-19 pandemic in the UK from 23 March 2020, NOM for AA was popular and the national COVID-HAREM study, analysing 500 adult patients from 48 sites, demonstrated high short-term success rates for NOM for complicated and uncomplicated AA, with only 10% of patients progressing to appendicectomy over the 2-month study period. Larger studies with longer follow-up, however, show that although patients may improve with antibiotics and not initially require surgery, the reported recurrence of AA at 2, 3, 4 and 5 years is 34%, 35.2%, 37.1% and 39.1%, respectively.³ Those requiring appendicectomy at a later presentation may be subject to higher rates of complications, a higher incidence of bowel resection⁵ and lower rates of satisfaction. The distinction between uncomplicated and complicated AA can only be ascertained by cross-sectional imaging, which assumes greater importance in diagnosis at all ages.

Conclusions

NOM of AA is relevant not only for the elderly or infirm for whom surgery may pose a considerable risk, but also to mitigate risk to healthcare workers during anaesthesia and surgery through aerosol-generating procedures, a significant concern expressed during the COVID-19 pandemic. The long-term consequences of large numbers of patients being managed by NOM are unknown, but may become evident over the next few years. Recurrent AA and missed pathology of the appendix or ileocaecum are legitimate concerns. This case illustrates the potential consequence of treated ‘burnt out’ AA in which not only may peri-appendiceal adhesions ensue, but the appendix itself, having healed by fibrosis, is rendered capable of acting as a thick adhesional band with potentially catastrophic consequences of SBO and ischaemia.