• Clinical science

Acquired diaphragmatic hernias

Summary

A diaphragmatic hernia is the protrusion of intra-abdominal contents through an abnormal opening in the diaphragm. Acquired diaphragmatic hernias are rare (overall incidence of < 5%). They occur mainly due to a direct penetrating injury to the diaphragm or, less commonly, secondary to blunt abdominal trauma. Most acquired hernias are left-sided due to the protective effect of the liver on the right side. Patients usually present early, with marked respiratory distress, abdominal pain, absent breath sounds on the ipsilateral side, and auscultation of bowel sounds in the chest. Smaller defects may present late. Diagnosis is confirmed on chest x-ray/CT scan but diagnostic laparoscopy/thoracoscopy is often required in patients in whom the diagnosis is uncertain. Surgery (open/minimally invasive) is indicated in all cases and can be done either through the abdomen or the thorax. Mortality rates are high (∼ 25%)and depend on coexistent trauma to other organs

Epidemiology

  • < 5% of all traumatic injuries
  • Most patients are males in their thirties

References:[1]

Epidemiological data refers to the US, unless otherwise specified.

Etiology

  • Penetrating injury
    • Accounts for ∼ 65% of acquired hernias
    • Etiology: gunshot/stab injuries
    • Diaphragmatic defects tend to be small and are, hence, likely to be missed.
  • Blunt abdominal trauma
    • Accounts for ∼35% of cases of acquired hernia
    • Etiology: motor vehicle accidents, falls, or crush injuries of the abdomen
    • Defect is usually large
    • Common on the left side

References:[2]

Clinical features

  • Acute presentation
    • Respiratory distress
    • Evidence of bowel in the chest
      • Absent breath sounds on the ipsilateral side (often the left side)
      • Auscultation of bowel sounds in the chest
      • Mediastinal shift → circulatory collapse
    • Diffuse abdominal pain
    • Evidence of causative injury
  • Delayed presentation
    • Non-specific abdominal pain
    • Retrosternal pain and pressure
    • Cardiopulmonary complaints: dyspnea, tachycardia, arrhythmias
    • Some patients may directly present with complications

References:[1][2]

Diagnostics

  • Chest x-ray
    • Detects ∼ 50% of diaphragmatic ruptures
    • Findings
      • Air- or fluid-filled stomach or bowel in the thorax
      • Nasogastric tube seen in the thorax
      • Elevated hemidiaphragm (left hemidiaphragm higher than the right by >4 cm)
      • Distortion of the diaphragmatic margin
  • Ultrasonography (FAST scanning)
    • Decreased diaphragmatic movement
    • Discontinuity of the diaphragm
    • Bowel loops in the thorax
  • Computed tomography of chest and abdomen
    • Indicated only in hemodynamically stable patients with abdominal/chest trauma
    • Findings
      • Discontinuity of the diaphragm
      • Abdominal contents into the chest
      • Collar sign: band-like constriction of bowel
      • Abnormal positioning of a nasogastric tube
  • Diagnostic laparoscopy/thoracoscopy
    • Indicated in hemodynamically stable patients if an isolated diaphragmatic hernia (i.e. involving no other organ) is suspected despite negative scans/chest x-ray
    • Diagnosis and repair can be done laparoscopically, especially since the abnormal opening in the diaphragm tends to be small.

Imaging techniques (X-ray/CT) are limited in diagnosing acquired hernias in patients who are intubated and mechanically ventilated, since the positive pressure of ventilation may push the herniated contents back into the abdominal cavity. Hence, many cases are missed on initial scanning.

A diaphragmatic hernia can be mistaken for a pneumothorax and a chest tube may be inserted. The release of air, together with bile or fecal matter on insertion of the chest tube strongly suggests bowel perforation. Hence, pleurocentesis or chest tube insertion in a suspected diaphragmatic hernia must be avoided.


References:[1][2]

Differential diagnoses

The differential diagnoses listed here are not exhaustive.

Treatment

  • All diaphragmatic hernias require surgical repair
  • In hemodynamically unstable patients
    • Initial resuscitation of the patient (airway, breathing, and circulation) as per ATLS protocol
    • Emergency exploratory laparotomy + repair of the defect, if present
  • In hemodynamically stable patients
    • CT scanning of the abdomen and pelvis
    • If there are no other organ injuries and
      • Diaphragmatic hernia has been confirmed → surgical repair (Open/laparoscopic, depending on the size of the hernia)
      • Imaging studies are negative but suspicion for diaphragmatic hernia is high → diagnostic laparoscopy/thoracoscopy; → confirms hernia surgical repair
    • If other organs are injured → exploratory laparotomy
  • Delayed presentation
    • These patients often have isolated diaphragmatic injuries and, therefore, present late (See “Symptoms/clinical findings” above)
    • Uncomplicated herniaselectively repaired, often laparoscopically/thoracoscopically
    • Complicated hernias (obstruction/strangulation) → emergency laparotomy/thoracotomy + repair of the hernia + resection of strangulated bowel, if necessary

References:[1][2]

Complications

  • Bowel complications: obstruction; , strangulation, incarceration, volvulus; , ileus, ulceration, perforation

References:[2]

We list the most important complications. The selection is not exhaustive.