Is Diarrhea a Sign of Appendicitis?
Diarrhea is an uncommon but recognized symptom of appendicitis and should not exclude the diagnosis, particularly when accompanied by abdominal pain, fever, nausea, and vomiting. While classic appendicitis presents with periumbilical pain migrating to the right lower quadrant, anorexia, and low-grade fever, atypical presentations including diarrhea do occur and can lead to diagnostic delays 1.
Clinical Presentation Patterns
Classic vs. Atypical Presentations
Classic appendicitis symptoms include vague periumbilical pain, anorexia/nausea/intermittent vomiting, migration of pain to the right lower quadrant, and low-grade fever, which leads to diagnosis in approximately 90% of patients 1.
Diarrhea as a presenting symptom is less common but documented, and patients presenting with abdominal pain accompanied by diarrhea are actually more likely to have a missed diagnosis of appendicitis (adults: AOR 4.27; children: AOR 2.17) 2.
Certain bacterial infections that can mimic appendicitis, such as Yersinia enterocolitica and Campylobacter species, present with severe abdominal pain and diarrhea that may be indistinguishable from appendicitis 3.
High-Risk Scenarios for Missed Diagnosis
Women and girls presenting with diarrhea and abdominal pain are at significantly higher risk for missed appendicitis diagnosis (women with diarrhea: AOR 1.19; girls with diarrhea: AOR 1.80) 2.
Patients with comorbidities (Charlson index ≥2) presenting with diarrhea and abdominal pain have a 4-fold increased risk of missed appendicitis in adults and 2-fold increased risk in children 2.
Diagnostic Approach
Key Clinical Features to Assess
When evaluating a patient with diarrhea and abdominal pain for possible appendicitis, specifically assess for:
Fever presence and pattern: While fever is common in appendicitis, its absence does not exclude the diagnosis 1.
Pain characteristics: Severe, persistent abdominal pain that becomes localized (particularly to the right lower quadrant) despite diarrhea should raise suspicion 3.
Associated symptoms: The combination of nausea, vomiting, fever, and diarrhea warrants careful evaluation, as this symptom cluster can indicate complicated disease 3.
Imaging Recommendations
Computed tomography scanning at the initial emergency department visit significantly reduces the risk of missed appendicitis in adults presenting with diarrhea and abdominal pain (AOR 0.83) 2.
CT findings that support appendicitis diagnosis include:
- Appendiceal dilatation ≥7 mm
- Presence of appendicoliths
- Periappendiceal fat stranding 1
Important Clinical Pitfalls
Common Diagnostic Errors
Do not dismiss appendicitis based solely on the presence of diarrhea, as this is a documented factor associated with delayed diagnosis 2.
Patients with abdominal pain and constipation are actually at higher risk for missed appendicitis than those with diarrhea (adults: AOR 4.17; children: AOR 2.19), but diarrhea still represents a significant risk factor 2.
Rare but Documented Associations
Clostridium difficile colitis can coexist with appendicitis, presenting with watery diarrhea, diffuse abdominal pain that later localizes, and fever 4.
Plastron appendicitis (abscess formation after appendiceal perforation) can rarely present as chronic diarrhea lasting months, though this is an unusual presentation 5.
Clinical Decision-Making
When encountering a patient with diarrhea, abdominal pain, nausea, vomiting, and fever:
Maintain high clinical suspicion for appendicitis, particularly in women, children, and patients with comorbidities 2.
Obtain CT imaging in adults with persistent or localizing abdominal pain despite diarrhea, as this significantly reduces missed diagnoses 2.
Consider infectious etiologies that mimic appendicitis, including Yersinia, Campylobacter, and Shigella, which present with severe abdominal pain and diarrhea 3.
Serial examination and monitoring are essential if initial imaging is negative but symptoms persist or worsen 1.