The diagnosis of CVS has been difficult because vomiting may be caused by a large number of other disorders that are more common. CVS is usually a diagnosis by exclusion of all other causes. At present there are no diagnostic methods (e.g. no blood or urine tests) that can be used to diagnose the disorder. A diagnosis, or, more correctly, a classification of CVS may take several years to achieve. Many sufferers will undergo numerous tests and sometimes misdiagnoses before their condition is recognised.
Formal criteria for diagnosis are shown below, but these probably omit some very common signs. In some people the intense nausea is the predominant symptom. As will be seen there is no single agreed set of criteria, which serves to highlight the problems in obtaining a diagnosis.
In CVS, the pattern of vomiting is such that at the peak this can be 5-6 times per hour. This is different from vomiting induced by most other causes. Onset of vomiting is most often between 2 am and 8 am. Again, this is unusual in other forms of vomiting.
In 1994, the CVSA UK and USA (with support from Glaxo Wellcome) sponsored a symposium on CVS held in London, UK. During the meeting, a series of criteria were agreed for the formal diagnosis of CVS. In many ways this was a huge step forward in the recognition of CVS and its wider acceptance as a serious health issue. Essential criteria are a requirement for diagnosis. Supportive criteria may strengthen the diagnosis, but not all of the criteria may be apparent in any one individual. Associated signs are features that are more difficult to quantitate but may be associated with CVS. The proceedings of this symposium were published (see References).
Recurrent, severe, discrete episodes of vomiting
Various intervals of normal health between episodes
Duration of vomiting episodes from hours to days
No apparent cause of vomiting
Stereotypical: each episode similar within individuals as to time of onset, intensity, duration, frequency, and associated symptoms and signs.
ROME III Criteria
The Rome criteria is a system developed to classify the functional gastrointestinal disorders (FGIDs), disorders of the digestive system in which symptoms cannot be explained by the presence of structural or tissue abnormality, based on clinical symptoms. Some examples of FGIDs include irritable bowel syndrome, functional dyspepsia, functional constipation, and functional heartburn as well as CVS. About Rome.
Cyclic Vomiting Syndrome
At least 3 months, with onset at least 6 months previously of:
Stereotypical episodes of vomiting regarding onset (acute) and duration (less than 1 week)
3 or more discrete episodes in the prior year
Absence of nausea and vomiting between episodes
Supportive criteria: History of migraine headaches or a family history of migraine headaches
North American Society for Pediatric Gastroenterology, Hepatology,
and Nutrition (NAPGH)
At least 5 attacks in any interval, or a minimum of 3 attacks during a six month period
Episodic attacks of intense nausea and vomiting lasting 1h–10 days and occurring at least one week apart
Stereotypical pattern and symptoms in the individual patient
Vomiting during attacks occurs at least 4 times/h for at least 1 hr
Return to baseline health between episodes
Not attributed to another disorder
Li et al, J Ped Gastroenterol Nutr 47 379-393 2008
The International Headache Society
International Classification of Headache Disorders (ICHD) beta III 2013
Taken from here.