• Clinical science

Acquired diaphragmatic hernias

Abstract

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.
    • Statistically, most hernias due to stab-injuries are left-sided
  • 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 Roemheld syndrome (gastric-cardia): characterized by cardiac symptoms triggered by an abdominal disorder. Cardiac symptoms such as tachycardia, extra-systole, angina pectoris are due to displacement of the mediastinum and the heart by the stomach, especially after meals.
    • 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
  • CT Tractography
    • Can be done in hemodynamically stable patients with stab wounds between T4 and T12
    • Sterile sponges soaked with either Betadine® or a contrast medium is inserted into the stab wound to obtain a CT scan IV contrast
    • Almost all patients with negative CT scans can be successfully observed. However, this depends on the depth of the wound and the packing technique used. If the wound has not been correctly packed with the sponges, some cases of acquired hernia may be missed.
    • This technique helps determine the wound trajectory
  • 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 these rents tend 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 the presence of fecal contamination, a prosthetic mesh is contraindicated due to high chance of infection. In these instances, a biological repair with either omentum/muscle flap is done
  • 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
    • Most patients have concomitant injuries to other abdominal organs.
      • An active search for a diaphragmatic injury must be made, depending on the mode of injury (See "Etiology” above)
      • If the patient has been hemodynamically stabilized during surgery → repair the hernia
      • If the patient continues to be unstable → Sterile mops are used to pack the defect → a second look laparotomy + repair of hernia can be done once patient is stabilized.
  • 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
      • Small right-sided hernias, if confirmed, can also be observed since the tamponading effect of the liver prevents herniation of bowel through the defect
    • 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
    • A thoracic approach is often necessary in repair of these hernias, as the herniated abdominal contents may have formed adhesions in the thoracic cavity.

References:[1][2]

Complications

  • Bowel complications: obstruction; , strangulation, incarceration, volvulus; , ileus, ulceration, perforation
  • Post-operative
    • Relapse
    • Gastric inlet stenosis
    • Gas-bloat syndrome

References:[2]

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