Incidence of Enterocutaneous Fistula in Ruptured Appendicitis
Enterocutaneous fistula formation after ruptured appendicitis is rare, occurring in approximately 0.13% of open appendectomies overall, though it accounts for 10% of postoperative morbidity when complications do occur. 1
Baseline Risk in Standard Appendicitis
- Post-appendectomy enterocutaneous fistula is an uncommon but serious complication, with an incidence of 0.133% after open appendectomy 1
- When fistulas do develop, they represent a significant proportion (10%) of overall postoperative morbidity 1
- The complication is recognized as a major surgical problem in systematic reviews, though specific percentages for ruptured appendicitis are not separately quantified 2, 3
Risk Factors That Increase Fistula Formation
The risk of enterocutaneous fistula formation increases substantially in specific clinical scenarios:
- Severe appendicitis (suppurative, gangrenous, or perforated) was present in 21 of 22 cases (95%) of post-appendectomy fistulas in one series 1
- Technically difficult appendectomy was noted in nearly all fistula cases 1
- Atypical appendix location was present in approximately one-third of fistula cases 1
- Drainage placement at the time of appendectomy was performed in 77% of cases that subsequently developed fistulas 1
Special Population: Crohn's Disease
A critical pitfall involves unrecognized Crohn's disease:
- Appendectomy of a macroscopically normal appendix in the presence of terminal ileitis carries an elevated risk of intra-abdominal septic complications and fistulas 4
- Isolated Crohn's disease of the appendix occurs in 0.2-1.8% of cases and is associated with ileocecal Crohn's in 25% of ileal and 50% of cecal disease 5
- Performing appendectomy alone in unsuspected ileocecal Crohn's disease significantly increases the risk of postoperative enterocutaneous fistula 5
Clinical Presentation and Timing
- Fistulas typically manifest around day 14 postoperatively 1
- Diagnosis is often made based on the character of drainage fluid when drains are present (14 of 22 cases) 1
- The complication carries significant morbidity, with a 50% reoperation rate and 7% mortality in contemporary series 3, 1
Key Clinical Caveat
When encountering an unexplained enterocutaneous fistula following appendectomy, maintain a high index of suspicion for underlying ileocecal Crohn's disease, as this requires definitive ileocecal resection rather than simple fistula management alone 5. The presence of a history of general ill health or altered bowel habits prior to the acute appendicitis presentation should heighten this suspicion 5.