Diverticulitis with coloenteric fistula mimicking gangrenous appendicitis with perityphlitic abscess. An uncommon presentation of a common disease – A case report

Abstract

Introduction

Diverticulitis is a common gastrointestinal disease usually presenting with a typical clinical picture depending on the stage of the disease. In complicated cases, the clinical presentation may be untypical, thus delaying diagnosis and treatment.

Presentation of case

We present a case of a young patient who was initially treated for obscure intraabdominal abscesses presumably due to gangrenous appendicitis; however, intraoperative exploration revealed a normal appendix and a coloenteric fistula resulting from an unknown and untreated perforated diverticulitis.

Discussion

A patient with a perityphlitic abscess was initially managed with primary non-operative management (NOM) in accordance with the current Jerusalem guidelines, but surgery was eventually necessary due to failure of NOM. Intraoperative findings revealed a sigmoido-ileal fistula, a rare but potentially detectable complication of diverticulitis through colonoscopy. This case highlights the challenges in diagnosing and treating common surgical diseases with uncommon clinical presentations, emphasizing the importance of a detailed patient history and not relying solely on imaging studies.

Conclusion

Intraabdominal abscesses require prompt treatment with non-operative management, while intestinal fistulae associated with diverticulitis are a rare consequence of chronic inflammation, often asymptomatic and often detected incidentally during surgery. In most cases simple fistulous tract resection is usually sufficient as first line therapy.

Keywords: Unusual presentation, Diagnostic challenges, Complicated diverticulitis, Intestinal fistula, Elective sigmoid resection, Case report

Introduction

Colonic diverticulitis is one of the most common clinical conditions encountered by surgeons in Western countries. It is classified into uncomplicated diverticulitis and complicated diverticulitis based on the presence of perforation, abscess and/or fistula formation [1]. Uncomplicated diverticulitis is usually managed conservatively, while complicated diverticulitis is a surgical disease. Colovesical, colocutaneous and colovaginal fistulae are the most common type of fistula associated with diverticulitis, while an intestinal fistula formation is a rare complication, occurring in about 3 % of complicated diverticulitis cases [2]. We discuss a case of a coloenteric, more specifically sigmoido-ileal fistula, due to complicated diverticulitis with an intraabdominal abscess mimicking a perforated appendicitis that necessitated surgical intervention.

This work has been reported in line with the SCARE criteria [3].

Presentation of case

A 42-year-old male patient with no past medical and surgical history was referred to the surgical emergency department with lower abdominal pain and fever for a week. Physical examination revealed abdominal tenderness in the right lower quadrant. The lab results showed an elevated white blood cell count of 16,2 G/l and an elevated C-reactive protein of 18mg/dl. The outpatient abdominal MRI demonstrated an intraabdominal abscess in the right hemiabdomen, with no visible appendix vermiformis (Fig. 1), and showed no other pathological findings, including in the sigmoid colon (Fig. 2).

Fig. 1 MRI scan of the patient's abdomen demonstrating an intraabdominal abscess in the right hemiabdomen (arrow).

Fig. 2 MRI scans (two transverse, T2-weighted and a coronal, T1-weighted with intravenous contrast) of the patient's abdomen showing no pathological findings in the sigmoid colon.

A diagnosis of perityphlitic abscess following untreated gangrenous appendicitis was made. Non-operative management (NOM) with intravenous antibiotics was initiated, and the abscess was drained via CT-guided percutaneous drainage.

However, after a few days, stool was seen in the drainage, and surgical exploration was indicated, hinting insufficiency of the appendiceal stump. Laparoscopic exploration surprisingly revealed an unremarkable appendix vermiformis and a sigmoido-ileal fistula that resulted from a perforated sigmoid diverticulum (Fig. 3). The fistulous tract was resected, and a simultaneous appendectomy was performed.

Fig. 3 Intraoperative findings revealing an unremarkable appendix and a sigmoido-ileal fistulous tract (arrow) that resulted from a perforated sigmoid diverticulum.

Due to the unexpected intraoperative findings a detailed patient history was repeated postoperatively, revealing that the patient had indeed experienced characteristic symptoms of diverticulitis three months earlier.

The postoperative course was uneventful. Histopathologic workup of the resected specimens showed no malignancy. The patient was scheduled for a follow-up colonoscopy 8 weeks after the surgery to assess the extent of diverticulitis and to rule out colonic stenosis and colonic neoplasm. According to the Classification of Diverticular Disease (CDD), the final diagnosis was a complicated diverticulitis type 3c [1].

Discussion

Due to the clinical picture of a perityphlitic abscess, our patient was treated with primary NOM in accordance with the current Jerusalem guidelines [4]. Early appendectomy in perityphlitic abscess was shown to significantly increase the risk of a more extensive operation (ileocecal resection or right-sided hemicolectomy) compared to primary NOM with interval appendectomy, based on a study by Akingboye et al. published in 2021. However, NOM fails in approximately 6 %, ultimately requiring appendectomy [5]. When stool was seen in the drainage of our patient, failure of NOM was suspected, which is why surgical exploration was indicated. Surprisingly, intraoperative findings revealed a sigmoido-ileal fistula as a result of a complicated diverticulitis (CDD type 3c) [5]. Generally, for differential diagnosis intestinal fistula formation occurs rarely (3 %) in complicated diverticulitis, more commonly it is found in Crohn's disease or malignancy [6,7]. Intestinal fistula complicating diverticular disease of the sigmoid colon has first been described in 1972 by Colcock et al. [8]. No specific symptoms suggestive of a coloenteric fistula have been observed. Most patients with coloenteric fistula had multiple recurrences of diverticulitis and a history of sepsis. Woods et al. in 1988 retrospectively observed diarrhea and an abdominal mass in physical examination as the only symptom and sign in these patients [9]. All coloenteric fistulae were detected at operation and all patients with a coloenteric fistula formation involved the terminal ileum, probably because of the natural adjacence of ileum and sigma. Earlier detection of a coloenteric fistula than during surgery may be achieved during colonoscopy, as reported by Ahmad et al. in 2016 [2].

The younger age in our reported patient supported the initial diagnosis of a complicated appendicitis, yet there is an increasing number of younger patients with complicated diverticulitis due to the increasing unhealthy lifestyle in Western societies. Ünlü et al. took a closer look at younger age (<50 years) in diverticulitis patients and underlined that it is neither associated with a more severe disease course nor with a higher incidence of recurrence or poor outcomes [10], concluding diverticulitis should be treated independently of the patient's age. Diverticulitis' surgical therapy needs to be individualized and should be reserved for cases where NOM fails [2]. Santos et al. recently presented a new approach trying to individualize the treatment decision of patients suffering from abdominal complaints following their first episode of diverticulitis. Using the GIQLI-score (GIQLI = Gastro-Intestinal-Quality-of-Life-Index) as the primary outcome parameter, the so-called LASER study, a randomized clinical trial comparing elective sigmoid resection versus NOM in patients after their first episode of diverticulitis, demonstrated a higher gastrointestinal quality of life in patients with CDD type 3c undergoing elective sigmoid resected compared to continuous NOM [11]. Ultimately, the risk of surgical morbidity must be weighed against the benefits. The surgical therapy of 106 diverticulitis-associated fistula cases following elective sigmoid resection in laparoscopic technique have been evaluated 2018 by Martinolich et al. 15 patients presented with a coloenteric fistula, ten patients could be operated laparoscopically, but in five patients conversion to laparotomy, due to bleeding, failure to progress and difficulty with fistula division was necessary [12]. Laparoscopy is an excellent surgical approach. However, conversion to open surgery and a strategical flexibility needs to be present since the initial laparoscopic appendectomy as for our reported patient is often performed by young surgeons. In summary, the treatment of choice in patients with a diverticulitis associated coloenteric fistula is a sigmoid resection to cure both, fistula and diverticulitis. In our patient only fistula resection was performed since diverticulitis was unknown and inactive and the patient was not informed about an extension of surgery apart from an appendectomy.

The patient did not present with perforation and generalized peritonitis, which indicated that emergency sigmoid resection was unnecessary. Furthermore, the patient had not provided consent for sigmoid resection prior to the surgery, and the intraoperative findings were unexpected. According to the 2021 AWMF S3-guideline for diverticular disease and diverticulitis, elective sigmoid resection can be considered in CDD type 3c [13]. We thoroughly discussed these recommendations with the patient after the surgery.

Conclusion

In conclusion, this case provides an excellent example of the pitfalls, delaying diagnosis and treatment of common surgical diseases like diverticulitis and appendicitis presenting with an uncommon clinical picture, the importance of a detailed and sophisticated patient history as well as the over-reliance on imaging studies. Intraabdominal abscesses occur in acute complicated diseases as appendicitis and diverticulitis, are symptomatic and necessitate acute therapy, primarily by NOM. Intraabdominal fistulae are a consequence of a chronic inflammation, rare, usually asymptomatic and therefore often an incidental finding during surgery masked by an intraabdominal abscess. In most cases simple fistulous tract resection is usually sufficient as first line therapy.

Consent

Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Funding

No sources of funding.

Ethical approval

Patient approval has been given. This study is exempt from ethical approval in our institution (Medical University Innsbruck).

CRediT authorship contribution statement

Jessica Singh – Conceptualization, Data curation, Writing - Original Draft.

Felix Krendl – Conceptualization, Writing - Review & Editing.

Silvia Gasteiger - Data curation, Writing - Review & Editing.

Stefan Schneeberger - Supervision, Writing - Review & Editing.

Alexander Perathoner – Conceptualization, Supervision, Writing - Review & Editing.

All - approval of final manuscript.

Guarantor

Alexander Perathoner.

Declaration of competing interest

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. The authors have no competing interests to declare.