57. Diaphragmatic and internal hernias

1. Definition

• Diaphragmatic hernia → passage of abdominal organs into the chest through a defect in the diaphragm
  • Hiatus hernia → through the oesophageal hiatus
  • Congenital diaphragmatic hernia (CDH) → Bochdalek (posterolateral) or Morgagni (anterior, retrosternal)
  • Traumatic → rupture after blunt or penetrating injury
• Internal hernia → bowel passes through a normal or abnormal opening inside the peritoneal cavity (no external lump)

2. Epidemiology

• Hiatus hernia → very common; increases with age (over 50% over 60 years on barium studies); obese, women
  • Sliding (type I) → about 90–95%
  • Paraoesophageal (types II–IV) → about 5–10%
• CDH → about 1 in 2,500–4,000 births; Bochdalek 85–90%, left side 80–85%; Morgagni 2–5%, usually right
• Traumatic rupture → 1–5% of major blunt trauma; left side in about 75% (liver protects the right)
• Internal hernia → under 1% of all hernias, but 0.5–5% of small bowel obstructions; common after Roux-en-Y gastric bypass (Petersen's)

3. Aetiology and risk factors

Anatomy (revision)

• Diaphragm → central tendon, muscle from sternum, ribs and lumbar spine (crura)
• Openings → T8 inferior vena cava, T10 oesophagus (and vagi), T12 aorta (and thoracic duct, azygos)
• Phreno-oesophageal ligament holds the gastro-oesophageal junction in the hiatus
• Foetal development → pleuroperitoneal membranes close at weeks 8–10; left side closes last → Bochdalek defects left

Causes

• Hiatus → age, obesity, pregnancy, raised abdominal pressure, weak phreno-oesophageal ligament, short oesophagus
• CDH → failure of the pleuroperitoneal canal to close; associated anomalies 30–40% (heart, chromosomes)
• Morgagni → defect at the sternocostal triangle (foramen of Morgagni, superior epigastric vessels)
• Traumatic → high-energy blunt trauma (car crash), stab wounds of the lower chest
• Internal hernia:
  • Congenital pockets → paraduodenal (left and right), foramen of Winslow, pericaecal, intersigmoid, supravesical
  • Acquired defects → mesenteric gaps after surgery: Petersen's space (behind the Roux limb), mesocolon, jejunojejunostomy, stomas, adhesive bands

4. Pathogenesis

• Sliding hernia → gastro-oesophageal junction moves up into the chest → loss of the lower oesophageal sphincter barrier → reflux
• Paraoesophageal (rolling) → junction stays in place; fundus rolls up beside the oesophagus → volvulus, obstruction, strangulation, bleeding (Cameron ulcers)
• CDH → bowel in the chest during foetal life → pulmonary hypoplasia (both lungs, worse on the side of the defect) and pulmonary hypertension → main cause of death
• Traumatic → sudden rise in abdominal pressure tears the diaphragm; it never heals (negative chest pressure pulls organs up); may present years later with strangulation
• Internal hernia → bowel enters a pocket → closed-loop obstruction → strangulation; symptoms come and go

5. Classification

Hiatus hernia

• Type I → sliding
• Type II → pure paraoesophageal (junction in place, fundus up)
• Type III → mixed (junction and fundus up)
• Type IV → other organs too (colon, spleen, small bowel)

Diaphragmatic hernia

• Congenital → Bochdalek, Morgagni, eventration (thin, high diaphragm with no defect), central tendon
• Acquired → hiatus, traumatic, iatrogenic

Internal hernia

• Paraduodenal → left (fossa of Landzert, behind the inferior mesenteric vein) more common than right (fossa of Waldeyer, behind the superior mesenteric artery)
• Foramen of Winslow (lesser sac)
• Transmesenteric, transmesocolic, Petersen's
• Pericaecal, intersigmoid, supravesical, broad ligament

6. Clinical picture

Symptoms

• Sliding → heartburn, regurgitation, worse lying down and bending
• Paraoesophageal → postprandial chest fullness, dysphagia, vomiting, breathlessness, anaemia; acute volvulus → severe pain
• Borchardt's triad (gastric volvulus) → epigastric pain, retching without vomiting, cannot pass an NG tube
• CDH (Bochdalek) → respiratory distress at birth, cyanosis
• Morgagni → often adults; vague chest or epigastric pain, found by chance
• Traumatic → breathlessness, chest pain; or late bowel obstruction
• Internal hernia → intermittent colicky pain, obstruction; after gastric bypass → pain out of proportion, often little vomiting

Signs

• CDH → scaphoid abdomen, barrel chest, bowel sounds in the chest, heart sounds shifted to the right
• Traumatic → reduced breath sounds, bowel sounds in the chest
• Internal hernia → few signs early; distension, tenderness later; peritonitis when strangulated

7. Diagnosis

• Hiatus hernia:
  • Barium swallow → type and size
  • Gastroscopy → oesophagitis, Barrett's, Cameron ulcers
  • Manometry and 24-hour pH monitoring → before antireflux surgery
  • CT → paraoesophageal and complicated hernias
• CDH:
  • Antenatal ultrasound (most diagnosed by 20–24 weeks); lung-to-head ratio and foetal MRI predict outcome
  • Chest X-ray at birth → bowel loops in the chest, NG tube in the chest
  • Echocardiography
• Traumatic → chest X-ray (raised hemidiaphragm, NG tube above it); CT; laparoscopy for left thoracoabdominal stab wounds (CT misses small tears)
• Internal hernia → CT: cluster of small bowel loops in an abnormal place, swirl sign of the mesentery, displaced vessels

8. Differential diagnosis

• Hiatus hernia → angina, peptic ulcer, achalasia, oesophageal cancer
• CDH → congenital lung cysts (CPAM), eventration, pneumothorax
• Traumatic → raised hemidiaphragm from phrenic nerve palsy, effusion, lung collapse
• Internal hernia → adhesive obstruction, volvulus, intussusception, mesenteric ischaemia

9. Treatment

Conservative

• Sliding hiatus hernia → treat the reflux: weight loss, raise the head of the bed, small meals, stop smoking and alcohol, proton pump inhibitors
• Small asymptomatic paraoesophageal hernia in an elderly patient → may be watched
• CDH → no emergency operation; stabilise first:
  • Intubate at birth; no bag-and-mask ventilation (fills the bowel in the chest)
  • NG tube to decompress
  • Gentle ventilation, permissive hypercapnia
  • Treat pulmonary hypertension (nitric oxide); ECMO if needed
  • Foetal tracheal occlusion (FETO) in severe cases

Surgical: hiatus hernia

• Indications → reflux not controlled by drugs, complications, symptomatic paraoesophageal hernia
• Laparoscopic repair:
  1. Reduce the hernia and excise the sac
  2. Mobilise the oesophagus (at least 2–3 cm in the abdomen)
  3. Crural repair (posterior sutures, mesh in selected cases)
  4. Fundoplication → Nissen (360°) or partial (Toupet 270° posterior, Dor anterior)
  5. Short oesophagus → Collis gastroplasty
• Acute volvulus → decompress (NG or endoscope), emergency reduction; resect necrotic stomach; gastropexy in unfit patients

Surgical: congenital and traumatic

• CDH → repair when stable (days): abdominal (subcostal) approach; reduce, close primarily or with a patch; thoracoscopic repair in selected cases
• Morgagni → laparoscopic reduction and repair (sutures or mesh)
• Traumatic rupture → repair always (strangulation risk):
  • Acute → laparotomy (other abdominal injuries common) or laparoscopy; non-absorbable sutures
  • Late (chronic) → thoracotomy or thoracoscopy (adhesions in the chest)

Surgical: internal hernia

• Urgent operation (laparoscopy or laparotomy) → reduce the bowel, resect if dead, close the defect
• Paraduodenal → open the sac along the avascular side (avoid the inferior mesenteric vein or superior mesenteric artery in its edge)
• After gastric bypass → close Petersen's and mesenteric defects at the first operation (prevention)

10. Complications

• Hiatus hernia → oesophagitis, stricture, Barrett's oesophagus, bleeding, iron deficiency, gastric volvulus, strangulation
• Antireflux surgery → dysphagia, gas bloat, recurrence (up to 30% for large paraoesophageal hernias), slipped wrap
• CDH → survival about 70–90%; chronic lung disease, reflux, recurrence (patch), developmental delay
• Traumatic → strangulation of the stomach or colon, tension gastrothorax
• Internal hernia → strangulation, short bowel after resection