- Clinical science
A hiatal (or hiatus) hernia is the abnormal protrusion of any abdominal structure/organ, most often a portion of the stomach, into the thoracic cavity through a lax diaphragmatic esophageal hiatus. It may be congenital or secondary to ageing, obesity, and/or smoking. There are four types of hiatal hernia: sliding, paraesophageal, mixed, and complex. Sliding hiatal hernias, where the gastroesophageal junction (GEJ) and the gastric cardia migrate into the thorax, account for 95% of hiatal hernias. In paraesophageal hernias (PEH), only the gastric fundus herniates into the thorax, whereas in mixed hiatal hernias, the GEJ as well as the gastric fundus herniate. Complex hiatal hernias are rare and characterized by protrusion of any abdominal organ other than the stomach. Nearly half of all patients with hiatal hernia are asymptomatic and require no medical or surgical intervention. Symptomatic patients with sliding hiatal hernia present with features of gastroesophageal reflux disease (GERD), which are usually managed with lifestyle modification and proton pump inhibitors. Patients with PEH or mixed hiatal hernias typically present with intermittent dysphagia, substernal discomfort, or abdominal pain, and in rare cases present acutely with gastric volvulus and strangulation. All symptomatic PEH, mixed, and complex hiatal hernias require operative intervention to avoid life-threatening complications.
- The etiology is multifactorial. 
- Lax diaphragmatic esophageal hiatus
- Prolonged periods of increased intra-abdominal pressure
Types of hiatal hernias
Type I: Sliding hiatal hernia
- Most common type (95% of cases)
- The GEJ and the gastric cardia slide up into the posterior mediastinum.
- The gastric fundus remains below the diaphragm.
Type II: Paraesophageal hiatal hernia
- Part of the gastric fundus herniates into the thorax.
- The GEJ remains in its anatomical position below the diaphragm.
- Upside-down stomach (extreme type): A rare type of paraesophageal hernia in which the entire stomach herniates into the thoracic cavity and rotates on its organoaxial axis. It is associated with a high mortality and morbidity rate due to strangulation of the stomach.
Type III: Mixed hiatal hernia
- Mix of types I and II
- The GEJ and a portion of the gastric fundus prolapse through the hiatus.
Type IV: Complex hiatal hernia
- Herniation of any abdominal structure other than the stomach (e.g., spleen, omentum, or colon)
- Rarest type
Esophageal hiatus: central opening of the diaphragm, which allows the esophagus to pass through into the peritoneal cavity; forms the upper part of the esophageal sphincter and the reflux barrier
- Formed by:
- Left and right paravertebral tendinous crura
- Median arcuate ligament
- Formed by:
- Gastroesophageal junction (GEJ): normally lies at the level of the esophageal hiatus
Changes in the presence of a hiatal hernia
- Predisposing factors lead to laxity of the esophageal hiatus, e.g.:
- Relative negative intrathoracic pressure + the lax hiatus → herniation of the abdominal contents into the thorax → loss of reflux barrier + compromised fluid emptying of distal esophagus → gastroesophageal reflux disease (GERD); ; ; 
most sensitive test :
- Assesses type and size of a hernia (including location of the stomach and the GEJ) (see “Classification” above)
Endoscopy: used to diagnose hiatal hernia and evaluate for possible complications (see “Complications” below)
- Z-line: squamocolumnar junction, which represents the transition from the squamous epithelium-lined esophageal mucosa to the columnar epithelium-lined gastric mucosa; corresponds to the GEJ
Other tests that can detect hiatal hernias include:
- Chest x-ray
- Usually incidental finding
- Types I, II, III: Retrocardiac soft tissue opacity with/without an air-fluid level
- Type IV: Retrocardiac visceral gas (small bowel/colon) or soft tissue shadows (spleen/omentum)
- CT Thorax: Recommended for urgent preoperative evaluation of complicated type II, III, and IV hernias
- Esophageal manometry: Helps calculate the size of a sliding hiatal hernia by accurately identifying the level of the diaphragmatic hiatus
- gastroesophageal reflux : Not a diagnostic test; useful for determining the extent of
- Chest x-ray
- Endoscopic ultrasound and Transesophageal ECHO can also detect Hiatal hernias but are not commonly used modalities for diagnosis
Management of patients with sliding hiatal hernia
- Conservative management
Surgery: laparoscopic/open fundoplication + hiatoplasty .
- Persistence of symptoms despite conservative management
- Patient's refusal to take long-term PPIs
- Severe symptoms/complications of : bleeding, strictures, ulcerations
Management of patients with types II, III, IV hiatal hernias
Complications of type I
- Arise from long-standing gastroesophageal reflux (see "Complications” in )
Complications of type II, III, IV
- Occur mainly due to vascular compromise of the herniated portion of the stomach, which leads to mucosal ischemia
- They include:
The complications of types II, III, and IV are often medical emergencies!
We list the most important complications. The selection is not exhaustive.