Rumination syndrome is diagnosed based on a complete history of the individual. Costly and invasive studies such as gastroduodenal manometry and esophageal PH testing are unnecessary and will often aid in misdiagnosis. Based on typical observed features, several criteria have been suggested for diagnosing rumination syndrome. The primary symptom, the regurgitation of recently ingested food, must be consistent, occurring for at least six weeks of the past twelve months. The regurgitation must begin within thirty minutes of the completion of a meal. Patients may either chew the regurgitated matter or expel it. The symptoms must stop within ninety minutes, or when the regurgitated matter becomes acidic. The symptoms must not be the result of a mechanical obstruction, and should not respond to the standard treatment for gastroesophageal reflux disease.
In adults, the diagnosis is supported by the absence of classical or structural diseases of the gastrointestinal system. Supportive criteria include regurgitant that is not sour or acidic tasting, is generally odourless, is effortless, or at most preceded by a belching sensation, that there is no retching preceding the regurgitation, and that the act is not associated with nausea or heartburn.
Patients visit an average of five physicians over 2.75 years before reaching being correctly diagnosed with rumination syndrome.
Differential diagnosis
Rumination syndrome in adults is a complicated disorder whose symptoms can mimic those of several other gastroesophogeal disorders and diseases. bulimia nervosa and gastroparesis are especially prevalent among the misdiagnoses of rumination.
Bulimia nervosa, among adults and especially adolescents, is by far the most common misdiagnosis patients will hear during their experiences with rumination syndrome. This is due to the similarities in symptoms to an outside observer - "vomiting" (purging) following food intake (binging) - which in long-term patients may include ingesting copious amounts to offset malnutrition (followed by a hasty retreat to the washroom), and a lack of willingness to expose their condition and its symptoms. While it has been suggested that there is a connection between rumination and bulimia, unlike bulimia, rumination is not self-inflicted. Adult and adolescents with rumination syndrome are generally well aware of their gradually increasing malnutrition, but are unable to control the reflex. In contrast, those with bulimia intentionally induce vomiting, and seldom re-swallow food.
Gastroparesis is another common misdiagnosis. Like rumination syndrome, patients with gastroparesis often bring up food following the ingestion of a meal. Unlike rumination, gastroparesis causes vomiting (in contrast to regurgitation) of food, which is not being digested further, from the stomach . This vomiting occurs several hours after a meal is ingested, is preceded by nausea and retching, and has the bitter or sour taste typical of vomit.