Incisional hernia

Background

• An incisional hernia is a protrusion of abdominal contents through a defect in the abdominal wall fascia at the site of a previous surgical incision
• Most common type of ventral hernia; occurs after 10–23% of abdominal surgeries
• Majority develop within the first 3 years after surgery, though they may appear years to decades later
• Midline incisions carry the highest risk; non-midline (lateral, subcostal, Pfannenstiel, trocar site) hernias are less common but do occur
• Risk factors for development:
  • Surgical: midline incision, wound infection, emergency surgery, re-operation, improper fascial closure technique
  • Patient: obesity, smoking, chronic cough/COPD, diabetes, malnutrition, corticosteroid use, connective tissue disorders, immunosuppression, increased intra-abdominal pressure (ascites, pregnancy)
• Natural history is progressive enlargement over time
• The primary concern in the ED is incarceration and strangulation:
  • Reducible: Hernia contents return to the abdominal cavity with manual pressure or spontaneously
  • Incarcerated: Contents cannot be reduced — may cause bowel obstruction; surgical emergency
  • Strangulated: Blood supply to the herniated contents is compromised → bowel ischemia, necrosis, perforation; life-threatening emergency
• Smaller hernia defects are at higher risk for incarceration/strangulation than large defects (narrow neck traps contents more readily)
• Emergency hernia repair carries significantly higher morbidity (20%) and mortality (3%) compared to elective repair

Clinical features

Uncomplicated (reducible)

• Visible or palpable bulge at the incision site — more prominent with Valsalva, coughing, standing
• May be asymptomatic or cause mild discomfort, pulling sensation, or intermittent pain
• Positive cough impulse on palpation
• Bulge reduces spontaneously or with gentle pressure when supine

Incarcerated

• Bulge that cannot be reduced
• Increasing pain at the hernia site
• Nausea, vomiting (if bowel is obstructed)
• Abdominal distension, obstipation (if complete bowel obstruction)
• The hernia may be firm, tender, and slightly swollen

Strangulated (surgical emergency)

• Severe, constant pain at the hernia site — often out of proportion to exam early on
• Skin changes: Erythema, warmth, or dusky/violaceous discoloration overlying the hernia — highly concerning for vascular compromise
• Signs of systemic toxicity: fever, tachycardia, hypotension
• Peritoneal signs (rebound, guarding) if bowel perforation has occurred
• Leukocytosis, elevated lactate
• Obstipation and complete absence of flatus

Key clinical pearl

• Do NOT attempt reduction if strangulation is suspected (skin changes, systemic toxicity, prolonged incarceration) — reducing necrotic bowel into the abdomen can lead to perforation, peritonitis, and sepsis
• Richter hernia: Only the anti-mesenteric border of the bowel wall herniates — may strangulate without complete bowel obstruction; can be missed clinically because obstructive symptoms may be absent

Differential diagnosis

• Seroma or hematoma at the incision site
• Wound infection / incisional abscess
• Rectus sheath hematoma
• Other ventral hernias (Umbilical hernia, Epigastric hernia, Spigelian hernia)
• Inguinal hernia
• Small bowel obstruction from other causes (adhesions, Internal hernia)
• Desmoid tumor or other abdominal wall mass
• Incarcerated inguinal hernia
• Abdominal wall endometriosis (at Pfannenstiel scar)

Evaluation

Workup

• Physical examination is the primary diagnostic tool for external hernias
  • Examine with patient standing and supine
  • Ask patient to perform Valsalva maneuver / cough while palpating the incision site
  • Assess reducibility — gently attempt reduction only if no signs of strangulation
  • Note size of the defect, tenderness, skin changes, and whether contents are reducible
• Labs (if incarceration or strangulation suspected):
  • CBC (leukocytosis suggests strangulation/ischemia)
  • BMP (electrolytes, renal function — dehydration from vomiting)
  • Lactate — elevated lactate raises concern for bowel ischemia, but a normal lactate does NOT exclude strangulation
  • VBG/ABG if metabolic acidosis suspected
  • Type and screen (anticipate possible surgery)
• Imaging:
  • CT abdomen/pelvis with IV contrast — study of choice for complicated incisional hernias
    • Identifies hernia contents (fat only vs. bowel), signs of obstruction, bowel wall thickening/enhancement (or lack thereof), free fluid, pneumoperitoneum
    • Determines defect size and relationship to surrounding structures
    • Can identify strangulation (non-enhancing bowel wall, mesenteric congestion, free fluid)
  • Abdominal XR (upright/supine): May show dilated loops and air-fluid levels consistent with SBO; insufficient alone to evaluate the hernia
  • Ultrasound: Can identify hernia defect and contents at bedside; useful as initial evaluation in hemodynamically unstable patients or pregnant patients; operator-dependent

Diagnosis

• Uncomplicated incisional hernia: Clinical diagnosis — reducible bulge at a surgical incision site with positive cough impulse; imaging usually not required
• Incarcerated/strangulated hernia: Clinical diagnosis confirmed by CT
  • CT findings concerning for strangulation: bowel wall thickening with decreased enhancement, mesenteric haziness/fat stranding, transition point at the hernia defect, free fluid, pneumoperitoneum (perforation)
• Key distinction: Incarcerated hernia containing only omentum/fat (no bowel) is painful but NOT a time-critical surgical emergency (no risk of bowel ischemia); still typically requires surgical repair but can be semi-elective

Management

Reducible hernia

• Manual reduction if uncomplicated and no signs of strangulation:
  • Position patient supine (Trendelenburg may assist)
  • Apply ice to the hernia to reduce edema
  • Provide analgesia; procedural sedation may be necessary to relax the abdominal wall
  • Apply steady, gentle pressure to the hernia, directing contents back through the defect
• After successful reduction: observe for signs of bowel compromise (pain, peritoneal signs, tachycardia)
• Arrange elective surgical referral for definitive repair

Incarcerated hernia (without signs of strangulation)

• Attempt reduction with analgesia and sedation as above
• If reduction is successful: Observe in ED for 4–6 hours for signs of delayed ischemia → arrange urgent surgical follow-up
• If reduction fails: Emergent surgical consultation for operative repair

Strangulated hernia

• Do NOT attempt reduction — risk of reducing necrotic bowel into the abdomen
• Emergent surgical consultation — this is a time-critical surgical emergency
• Resuscitation:
  • Two large-bore IVs; aggressive crystalloid resuscitation
  • NPO
  • Nasogastric tube for decompression if bowel obstruction
  • Broad-spectrum IV antibiotics (e.g. piperacillin-tazobactam or cefepime + metronidazole) — cover for gram-negative and anaerobic organisms in anticipation of ischemic/perforated bowel
  • Correct electrolyte abnormalities
• Surgery: Open or laparoscopic approach depending on surgeon preference and clinical stability; may require bowel resection if necrosis is found

General principles

• Pain control: IV opioid analgesia; do not withhold despite the need for serial abdominal exams — pain control facilitates reduction and improves cooperation
• Abdominal binder: May provide symptomatic comfort for chronic, reducible hernias while awaiting elective repair; does NOT prevent incarceration

Disposition

• Discharge home:
  • Asymptomatic or mildly symptomatic reducible hernia with no signs of incarceration or strangulation
  • Successful reduction with observation period showing no signs of bowel compromise
  • Arrange general surgery follow-up within 1–2 weeks for discussion of elective repair
  • Provide strict return precautions: irreducible bulge, increasing pain, vomiting, inability to pass stool/gas, skin changes overlying the hernia, fever
• Admit:
  • Failed reduction (incarcerated, requires operative repair)
  • Successful reduction but with persistent pain, concerning exam, or laboratory abnormalities suggesting bowel compromise
  • Bowel obstruction requiring decompression and observation
• Emergent surgery:
  • Strangulated hernia (skin changes, systemic toxicity, elevated lactate, peritoneal signs)
  • Incarcerated hernia with bowel obstruction that cannot be reduced
  • Evidence of perforation on imaging
• Post-reduction observation pearl:
  • Even after successful reduction of an incarcerated hernia, patients should be observed for delayed ischemia — bowel that appeared viable during reduction may declare itself as ischemic hours later; worsening pain, tachycardia, or peritoneal signs after reduction warrant urgent re-evaluation and possible surgical exploration

See also

• Small bowel obstruction
• Inguinal hernia
• Umbilical hernia
• Femoral hernia
• Internal hernia
• Strangulated hernia
• Bariatric surgery complications

External links

• Incisional Hernia - StatPearls
• Strangulated Hernia - StatPearls
• Risk of incarceration during nonoperative management of incisional hernias - Ann Surg 2022
• What's new in the management of incarcerated hernia - J Gastrointest Surg 2024