Diagnostic Approach for Suspected Incisional Hernia
Clinical examination demonstrating a bulge at the previous incision site is typically sufficient for diagnosis, but contrast-enhanced CT scanning should be obtained when complications such as incarceration or strangulation are suspected, or when clinical findings are equivocal. 1
Initial Clinical Assessment
The diagnosis of incisional hernia begins with identifying key clinical features:
- Ask the patient directly if they see or feel a lump or bulge at the surgical scar site, as patient self-identification has 95% sensitivity for detecting incisional hernia 2
- Examine for a visible or palpable bulge that increases with Valsalva maneuver, coughing, or standing 1
- Assess for pain at the scar site, though pain alone has modest correlation with hernia presence 2
- Document the defect size and location through physical examination, as these guide surgical planning 3
Red Flag Signs Requiring Urgent Imaging
Certain clinical presentations mandate immediate CT evaluation rather than relying on physical examination alone:
- Inability to reduce the hernia (incarceration) 4
- Overlying skin erythema, warmth, or tenderness suggesting strangulation 5
- Abdominal pain with systemic signs: fever ≥38°C, tachycardia ≥110 bpm, or hypotension 4
- Signs of bowel obstruction: nausea, vomiting, abdominal distension, or obstipation 4
Laboratory Markers for Suspected Strangulation
When strangulation is suspected based on clinical presentation, obtain:
- Arterial lactate level: ≥2.0 mmol/L predicts non-viable bowel with significant accuracy 4
- White blood cell count: elevation is moderately predictive of strangulation 4
- Fibrinogen level: elevated levels predict increased morbidity in incarcerated hernias 4
Imaging Strategy
When CT is Indicated
Contrast-enhanced CT is the diagnostic study of choice in the following scenarios 4, 1:
- Any suspicion of incarceration, strangulation, or bowel obstruction
- Equivocal physical examination findings
- Obese patients where physical examination is unreliable
- Planning for complex hernia repair requiring detailed anatomic assessment
CT findings that predict bowel strangulation include reduced bowel wall enhancement (56% sensitivity, 94% specificity) 4
When Clinical Diagnosis Alone is Sufficient
For uncomplicated incisional hernias in non-obese patients with:
- Clear bulge visible and palpable on examination
- Easily reducible hernia
- No pain or systemic symptoms
- No signs of obstruction
Imaging is not mandatory and the patient can proceed directly to surgical consultation 2
Critical Timing Considerations
Do not delay surgical evaluation when strangulation is suspected, as treatment beyond 24 hours is associated with significantly higher mortality 1. Time from symptom onset to surgery is the most important prognostic factor 1.
Common Diagnostic Pitfalls
- Failing to examine the patient standing and with Valsalva: Small hernias may only be apparent with increased intra-abdominal pressure 1
- Relying on plain radiography: Abdominal X-rays have limited diagnostic value for incisional hernias and should not delay CT when complications are suspected 4
- Dismissing patient-reported symptoms: Patient self-identification of a bulge has excellent sensitivity and should prompt thorough evaluation 2
- Delaying imaging in post-bariatric surgery patients: These patients may have atypical presentations with unreliable physical examination due to excess skin and flaccid abdominal wall 4