Background
Upside-down stomach (UDS) is the rarest type of hiatal hernia (< 5%). It is characterized by herniation of the entire stomach or most gastric portions into the posterior mediastinum. Both gastroesophageal junction and parts of the stomach migrate intrathoracically, thus UDS represents a large mixed type - sliding and paraesophageal (type 3) hernia. By many authors, UDS is also referred to as type 4 hiatal hernia. Other intra-abdominal organs can be involved in the herniation. The pathophysiology of hiatal hernias remains poorly understood. Three pathogenic components are widely found in the literature which can individually exist in different proportions (1) increased intra-abdominal pressure (transdiaphragmatic pressure gradient); (2) esophageal shortening (fibrosis, vagal nerve stimulation); (3) widening of the diaphragmatic hiatus due to congenital or acquired structural changes of periesophageal ligaments and muscular crura of the hiatus. The latter include abnormalities of elastin, collagens, and matrix metalloproteinases.
As hiatal and true paraesophageal hernia, UDS can manifest itself clinically in a wide variety of symptoms including substernal pain, heartburn, postprandial distress and fullness, dysphagia, postprandial nausea and vomiting. They occur due to reflux related to the sliding component and mechanically impaired gastric emptying, thereby, the latter symptoms usually preponderate. Chronic mucosal bleeding may cause anemia and is ascribed to venous obstruction of the migrated stomach. While UDS itself is a very rare condition it is associated with a risk of incarceration as well as volvulus development. These complications can cause acute gastric outlet obstruction and thereby present clinically as acute abdomen. Further complications are acute and severe gastric bleeding, ischemia and perforation. All of these complications represent true emergencies as life-threatening conditions. Prevalence of acute symptoms or incarceration in paraesophageal hernia was reported to be 30,4%.
Once diagnosed, UDS should be surgically addressed by reduction of the migrated stomach, excision of hernia sac, and hiatal defect closure combined with an anti-reflux procedure as 360° or partial fundoplication. Laparoscopic repair provides benefits as reduced postoperative morbidity and hospital stay. Even if asymptomatic a surgical intervention is indicated as a conservative approach bears the risk of a high mortality rate due to complications which is significantly reduced by elective surgery. In the light of only few series and cases reported, there is no clear evidence from review of the current literature for the management of acute paraesophageal hernia or UDS as very rare conditions. In addition, there is an ongoing controversial discussion about whether prothetic reinforcement of the hiatus by mesh insertion is reasonable and effective. In the face of high recurrence rates several surgeons recommend the use of prosthetic meshes. However, many severe complications can be associated with mesh implantation as perforation necessitating partial esophagogastrectomy or acute erosive bleeding of the abdominal aorta. In summary, there is still a considerable controversy regarding the routine mesh insertion and the quality of evidence is very low.