What is the appropriate approach to assess a suspected abdominal wall hernia, including history, physical exam, imaging, and management?

Assessment of Abdominal Wall Hernia

The assessment of a suspected abdominal wall hernia begins with a focused history and physical examination, followed by imaging when the diagnosis is unclear or complications are suspected, with ultrasound as the first-line imaging modality for diagnostic uncertainty and CT with contrast for suspected complications.

History Taking

Key Clinical Features to Elicit

• Document the presence of a visible or palpable bulge in the abdominal wall, particularly one that increases with Valsalva maneuver, coughing, or standing 1

• Assess for pain characteristics: localized tenderness at the hernia site versus diffuse abdominal pain, which may indicate complications 2, 1

• Inquire specifically about previous abdominal surgeries, as incisional hernias represent the most common long-term complication following laparotomy with incidence ranging from 2-40% 3

• Ask about symptoms suggesting complications:

  • Sudden onset of severe pain unresponsive to analgesics suggests strangulation 4, 3
  • Nausea, vomiting, inability to pass flatus or stool indicates possible bowel obstruction 5
  • Fever, tachycardia, or systemic symptoms suggest ischemia or infection 4, 5

Risk Factor Assessment

• Identify high-risk comorbidities including diabetes mellitus, chronic pulmonary disease, active smoking, obesity, and immunosuppression, all of which substantially elevate risk for hernia development and complications 3

• Document history of trauma, particularly in cases of suspected traumatic abdominal wall hernia following motor vehicle accidents or blunt abdominal trauma 6

Physical Examination

Systematic Inspection and Palpation

• Examine all potential hernia sites including inguinal regions, umbilicus, previous surgical incision sites, and the entire abdominal wall with the patient both supine and standing 4, 7

• Have the patient perform Valsalva maneuver or cough while palpating suspected hernia sites to detect reducible hernias that may not be apparent at rest 1

• Document the size, location, and reducibility of any palpable mass or bulge 1

Assessment for Complications

• Check vital signs carefully: tachycardia is the most sensitive early warning sign of surgical complications and should trigger urgent investigation 8

• Assess for peritoneal signs: guarding, rebound tenderness, or rigidity indicate possible bowel strangulation or perforation requiring emergency intervention 4, 8

• Auscultate bowel sounds: absent bowel sounds in a patient with suspected incarcerated hernia should raise immediate concern for bowel ischemia 5

• Perform digital rectal examination when bowel obstruction is suspected, as it provides crucial information about the position of herniated contents and extent of local injury 4

Laboratory Evaluation

When to Order Laboratory Tests

• Laboratory tests are unnecessary for uncomplicated, reducible hernias being evaluated for elective repair 4

• Order labs when complications are suspected, including:

  • Complete blood count to assess for leukocytosis suggesting strangulation 4, 5
  • Arterial lactate level ≥2.0 mmol/L, which predicts non-viable bowel with significant accuracy 4, 3
  • Metabolic panel to evaluate for dehydration and electrolyte abnormalities in bowel obstruction 5
  • C-reactive protein and procalcitonin if infection or sepsis is suspected 8

Imaging Studies

Ultrasound as First-Line Imaging

Ultrasound is the preferred initial imaging modality when the diagnosis of abdominal wall hernia is unclear on physical examination 1

• Ultrasound is accurate, non-invasive, relatively inexpensive, and readily available for confirming clinically suspected hernias 1

• Specific indications for ultrasound include:

  • Abdominal pain without a palpable hernia 1
  • A palpable mass of questionable etiology 1
  • Differentiating hernias from other abdominal wall masses such as tumors, hematomas, or abscesses 9

• Ultrasound can identify hernias in patients with pain alone where physical examination is negative, allowing for appropriate surgical referral or conservative management 1

• Ultrasound has 91% sensitivity and 84% specificity for detecting intestinal obstruction when hernia complications are suspected 5

CT Imaging for Complicated Hernias

Contrast-enhanced CT of the abdomen and pelvis is the imaging study of choice when complications are suspected 4, 3, 9

• CT provides exquisite anatomic detail of the abdominal wall, allowing accurate identification of hernias and their contents 9

• CT with contrast has >90% accuracy for diagnosing bowel obstruction and can identify signs of ischemia including abnormal bowel wall enhancement, mesenteric edema, and pneumatosis 5

• Specific indications for CT include:

  • Suspected bowel strangulation or ischemia 4, 3
  • Clinical signs of peritonitis or perforation 4
  • Hemodynamically stable patients with suspected perforation 4
  • Evaluation of post-operative complications including hernia recurrence, fluid collections, and mesh-related complications 9

• CT demonstrates 56% sensitivity and 94% specificity for predicting bowel strangulation based on reduced wall enhancement 4

Plain Radiography

• Plain X-rays have limited diagnostic value with sensitivity of only 50-60% and should not be routinely ordered for hernia assessment 5, 2

• Consider plain films only when looking for pneumoperitoneum in suspected perforation or when CT is not immediately available 4

Red Flags Requiring Urgent Intervention

Signs of Strangulation or Ischemia

• Severe pain out of proportion to physical findings suggests mesenteric ischemia and requires immediate surgical evaluation 8

• The combination of fever, tachycardia, and tachypnea predicts serious complications including strangulation or sepsis 8, 5

• Peritoneal signs (guarding, rebound tenderness, rigidity) indicate possible bowel necrosis or perforation requiring emergency surgery 4, 8

• Elevated lactate ≥2.0 mmol/L is a useful predictor of non-viable bowel strangulation 4, 3

Timing Considerations

• Delayed treatment beyond 24 hours in strangulated hernias is associated with significantly higher mortality rates 3

• Emergency hernia repair should be performed immediately when intestinal strangulation is suspected, as time from symptom onset to surgery is the most important prognostic factor 3

Common Pitfalls to Avoid

• Do not rely on normal laboratory values early in disease, as many tests are nonspecific and may be normal despite serious complications, especially in elderly patients 8

• Do not overlook hernias in obese patients where physical examination may be difficult—maintain a low threshold for ultrasound imaging 1

• Do not delay imaging in hemodynamically unstable patients with suspected perforation—proceed directly to surgical exploration 4

• Do not mistake incomplete bowel obstruction with watery diarrhea for gastroenteritis, as this can lead to dangerous delays in diagnosis 5

• Be aware that classic peritoneal signs may be absent in patients with chronic hernias despite established ischemia, as chronic distension can mask examination findings 8