Gastric volvulus or volvulus of stomach is a twisting of all or part of the stomach by more than 180 degrees with obstruction of the flow of material through the stomach, variable loss of blood supply and possible tissue death. The twisting can occur around the long axis of the stomach: this is called organoaxial or around the axis perpendicular to this, called mesenteroaxial. Obstruction is more likely in organoaxial twisting than with mesenteroaxial while the latter is more associated with ischemia. About one third of the cases are associated with a hiatus hernia. Treatment is surgical. The classic triad (Borchardts Triad) of gastric volvulus, described by Borchardt in 1904, consists of severe epigastric pain, retching (due to sour taste in mouth) without vomiting, inability to pass a nasogastric tube and reportedly occurs in 70% of cases. Sometimes severe pain at the top of left shoulder, this may be due to internal bleeding irritating the diaphragm upon respiration. Classification
Organoaxial type
In an organoaxial gastric volvulus, the stomach rotates around an axis that connects the gastroesophageal junction and the pylorus. The antrum rotates in opposite direction to the fundus of the stomach. This is the most common type of gastric volvulus, occurring in approximately 59% of cases, and it is usually associated with diaphragmatic defects. Strangulation and necrosis commonly occur with organoaxial gastric volvulus and have been reported in 5–28% of cases. The key imaging feature of organoaxial volvulus is that the greater curvature is located above the lesser curvature of the stomach.
Dicephalic parapagus () is a rare form of partial twinning with two heads side by side on one torso. Infants conjoined this way are sometimes called "two-headed babies" in popular media. The condition is also called parapagus dicephalus.If carried to term, most dicephalic twins are stillborn, or die soon after birth. A small number are known to have survived to adulthood.The extent to which limbs and organs are duplicated varies from case to case. One head may be only partially developed (anencephalic), or both may be complete. In some cases, two complete hearts are present as well, which improves their chances of survival. The total number of arms may be two, three or four.Their prospects are best if no attempt is made to separate them, except in cases in which one twin is clearly dying. Terminology
Dicephalus means two-headed. Parapagus means joined side by side.Dicephalic twins are called:

dibrachius if they have two arms altogether (one for each twin),
tribrachius, if they have three arms altogether,
tetrabrachius, if they have four arms altogether,
dipus, if they have two legs altogether (one for each twin). Incidence
Conjoined twins appear in one in 50,000 to one in 100,000 births. Dicephalic twins represent about 11 percent of all conjoined twins. Medical and social response
As late as the 1960s, some medical publications argued that newborn dicephalic twins should not be actively treated or resuscitated. An attempt at surgical separation was reported in a paper published in 1982, but did not result in long-term survival of either twin.