Which diagnostic feature is primarily evaluated when considering a diagnosis of cyclic vomiting syndrome?

The diagnosis of cyclic vomiting syndrome (CVS) hinges on the frequency and pattern of vomiting episodes experienced by the patient. This condition is characterized by recurrent, intense episodes of vomiting that occur in a stereotypical pattern, often with symptom-free intervals in between episodes. The frequency of these vomiting episodes is a key diagnostic feature, as it helps clinicians to differentiate CVS from other gastrointestinal disorders.

In assessing a patient for CVS, clinicians look for a specific history of recurrent vomiting that typically arises suddenly and can last for hours to days, with symptom-free periods in between. This cyclic nature is crucial to distinguishing CVS from other causes of vomiting, such as gastroenteritis or structural abnormalities.

While factors such as family history of gastrointestinal disease and the impact on growth and development are valuable components of the overall clinical picture, they do not specifically inform the diagnosis of CVS. Similarly, while the presence of pain during vomiting may accompany some episodes, it is not a defining characteristic of cyclic vomiting syndrome itself. Therefore, the frequency of vomiting episodes stands out as the primary diagnostic feature for confirming a diagnosis of cyclic vomiting syndrome.