Investigations for Symptomatic Hernia in Adults
Clinical Assessment
For most symptomatic hernias, physical examination alone is sufficient for diagnosis, and imaging is rarely warranted unless complications are suspected or the diagnosis is uncertain. 1
Essential Physical Examination Components
Perform inspection and palpation at the suspected hernia site with the patient both standing and supine, incorporating a Valsalva maneuver to reveal reducible hernias. 2
Assess immediately for signs of complications: peritonitis, tachycardia, fever, hypotension, and abdominal wall rigidity—these indicate potential strangulation requiring urgent intervention. 3
For groin hernias specifically: Examine for a bulge or impulse while the patient coughs or strains; note that the bulge may disappear when prone. 1
Laboratory Testing Strategy
Routine laboratory tests are NOT recommended for uncomplicated hernias. 2
Laboratory investigations are indicated ONLY when complications are suspected (strangulation, incarceration, or bowel ischemia): 3, 2
- Complete blood count (CBC)
- Serum lactate
- Inflammatory markers (C-reactive protein, procalcitonin)
- Serum creatinine
- Creatine phosphokinase (CPK)
- D-dimer
Critical timing consideration: Symptomatic periods lasting longer than 8 hours significantly affect morbidity, and delays beyond 24 hours increase mortality risk. 3 Early detection of progression from incarceration to strangulation is difficult by clinical or laboratory means alone. 3
Imaging Investigations
First-Line Imaging Based on Hernia Type
For abdominal wall and inguinal hernias:
- Ultrasonography is the first-line imaging modality, particularly useful for women and when the diagnosis is unclear. 2, 4
- Physical examination alone suffices in the majority of cases with appropriate signs and symptoms. 1, 5
For diaphragmatic hernias:
- Start with anteroposterior and lateral chest X-ray as the first diagnostic study in patients without trauma history presenting with respiratory symptoms. 3, 6
- Critical caveat: Normal chest X-rays do NOT exclude diaphragmatic hernias, with false negatives occurring in 11-62% of cases. 6, 2 If clinical suspicion persists, proceed directly to CT scan.
Advanced Imaging: CT Scan Indications
Contrast-enhanced CT scan of the abdomen and pelvis with intravenous contrast is the gold standard and imaging modality of choice when: 7, 4
- Complications are suspected (strangulation, bowel ischemia, obstruction, perforation)
- Internal hernias are suspected (these cannot be diagnosed clinically and require both IV and oral contrast) 7
- Diagnosis remains uncertain after physical examination and initial imaging
- Recurrent hernia is present 1
- Patient is hemodynamically stable with suspected diaphragmatic hernia and perforation 3
Essential CT technical requirements: 7
- Scan BOTH abdomen and pelvis (not just abdomen) to capture the full extent
- Use multiplanar reconstructions to increase accuracy
- IV contrast is essential to assess vascular perfusion and detect ischemia/strangulation
Key CT findings indicating urgent surgical intervention: 7
- Bowel wall thickening with target enhancement (suggests ischemia)
- Absence of bowel wall contrast enhancement (indicates strangulation)
- Pneumatosis intestinalis or portal venous gas (signifies bowel necrosis)
- "Whirlpool sign" (indicates mesenteric volvulus with internal hernia)
- Clustered/crowded dilated bowel loops with engorged mesenteric vessels
Special Imaging Scenarios
For athletes without palpable impulse or bulge: Ultrasonography or MRI can help diagnose occult hernias. 1
For pregnant patients with suspected diaphragmatic hernia: Use ultrasound first, followed by MRI if necessary to limit radiation exposure. 7
Fluoroscopic herniography: Reserved for patients with groin pain where hernia is suspected but cannot be identified on physical examination—this is a sensitive investigation for occult hernias. 4
Critical Decision Point: When to Skip Imaging
In hemodynamically unstable patients with suspected complicated hernia, do NOT delay surgical treatment to perform imaging investigations. 3 Proceed directly to operative intervention when peritonitis or hemodynamic instability is present. 2
Common Pitfalls to Avoid
Do not rely on normal imaging to exclude hernia: Chest X-rays miss diaphragmatic hernias in up to 62% of cases; negative CT should not rule out internal hernias in post-bariatric surgery patients. 6, 2
Do not underestimate the "golden period": The elapsed time from symptom onset to surgery is the most important prognostic factor, with delays beyond 24 hours significantly increasing mortality. 3
Do not miss femoral hernias in women: These have higher complication rates and are best evaluated with laparoscopic approach to avoid missing them. 5