see also:

• gastro-oesophageal reflux
• SAGES US guidelines for Mx of hiatus hernia

• hiatus hernia is when a portion of the stomach passes up through the diaphragmatic oesophageal hiatus
• there are 4 types:
  • type I: sliding (95%) - where the lower oesophageal sphincter slides above the diaphragmatic oesophageal hiatus
  • type II: para-oesophageal - where the lower oesophageal sphincter remains below the diaphragmatic oesophageal hiatus and part of the stomach fundus passes through the hiatus next to the oesophagus
  • type III: mixed type I and II and accounts for 90% of para-oesophageal
  • type IV: para-oesophageal but stomach not in the hernial sac but instead it contains omentum, bowel, etc
• most are asymptomatic or only have mild symptoms, but sliding herniae may cause gastro-oesophageal reflux as they may reduce LES pressures, reduce oesophageal acid clearance, reduce the angle of His, and prolong the nocturnal transient LES relaxation episodes, while para-oesophageal herniae have a small risk of potentially fatal complications

• reflux of gastric contents into the oesophagus is prevented by:
  • the diaphragmatic crura
  • baseline pressures of the lower oesophageal sphincter
  • intra-abdominal segment of the oesophagus
  • the angle of His - the angle the oesophagus makes with the cardia of the stomach which can function as a flap valve
• the diaphragmatic oesophageal hiatus is approx 2cm long and consists of bilateral musculotendinous slips arising from either side of the spine and passing around the oesophagus to insert into the central tendon of the diaphragm
• the hiatus narrows if intra-abdominal pressure increases such as when coughing or lifting weights
• the upper part of the lower oesophageal sphincter (LES is 2.5-4.5cm in length) lies within the hiatus and the upper part sometimes forms an indentation of the oesophagus on barium studies called the A-ring

• age:
  • 10% prevalence in those aged < 40yrs, increasing to 70% of those aged > 70 yrs in Western cultures
  • presumably due to muscle weakening and loss of elasticity with age
• raised intra-abdominal pressures:
  • women > men - presumably due to intra-abdominal pressures of pregnancy
  • obesity
  • chronic constipation with straining at stool
  • heavy weight lifting
  • vomiting / coughing
• spinal anatomy factors:
  • kyphosis
  • degenerative disc disease in the spine
• genetic factors:
  • large diaphragmatic hiatus
  • familial clustering has been reported
  • right isomerism
  • Marfan syndrome
  • collagen type III alpha I
  • infantile hiatus hernia - 50% are still present in adult life
  • congenital diaphragmatic herniae (rare) - eg. posterolateral Bochdalek hernias and retrosternal Morgagni hernias
• iatrogenic (rare)

• may cause chronic gastro-oesophageal reflux which may lead to Barrett's mucosa and later oesophageal cancer if untreated
  • many recommend life-long proton pump inhibitors (PPIs) to prevent the above
• may cause recurrent aspiration pneumonia

• most are asymptomatic but do tend to enlarge over time, potentially with the whole stomach becoming intrathoracic
• these become symptomatic at a rate of ~14% per annum although risk of needing emergency surgery with it's moderately high mortality rate of around 17% is around 2% per annum
• respiratory symptoms may predominate secondary to pulmonary compression and reduction in forced vital capacity
• 50% develop iron deficiency anaemia from chronic gastric mucosal ischaemia, gastritis and ulceration
• obstructive symptoms range from mild nausea, bloating, or postprandial fullness to acute distress with dysphagia and retching
  • pain, often described as a full or heavy feeling in the upper abdomen or as severe postprandial pain is often relieved by vomiting
• 5% risk of potentially fatal incarceration leading to gastric volvulus, strangulation or perforation and thus elective surgical repair should be considered, particularly if symptomatic, although such surgery is not without its risks