Cyclic Vomiting Syndrome Workup

Updated: Oct 20, 2023
  • Author: Thangam Venkatesan, MD; Chief Editor: Carmen Cuffari, MD  more...
  • Print

Approach Considerations

Because no biochemical markers for cyclic vomiting syndrome (CVS) have been identified, the guidelines formulated by the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition (NASPGHAN) suggest that physicians must initially look for alarming symptoms and then tailor the workup accordingly. Suspicious symptoms include the following:

  • Bilious vomiting, abdominal tenderness, or severe abdominal pain

  • Attacks precipitated by intercurrent illness, fasting, or a high-protein meal

  • Abnormal neurologic examination findings, such as severe alteration of mental status, abnormal eye movements, papilledema, motor asymmetry, or gait abnormality (ataxia)

  • Progressively worsening episodes or conversion to a continuous or chronic pattern

Depending on the presenting symptoms and signs other than vomiting, different diagnostic approaches are recommended. In addition, certain subgroups of patients are thought to be at high risk for metabolic disorders. If the following conditions are met, early referral to a metabolic specialist or neurologist should be considered:

  • Presentation before the age of 2 years (with cyclic vomiting or comorbidities below)

  • Vomiting episodes associated with intercurrent illnesses, prior fasting, or increased protein intake

  • Any neurologic finding, such as ataxia, dystonia, or another gait disturbance; mental retardation; or seizure disorder or acute encephalopathy (including true lethargy, severe irritability, confusion, psychosis, or rapidly changing or unstable mental status)

  • Laboratory findings suggestive of a metabolic disorder, such as hypoglycemia, substantial anion gap metabolic acidosis (see the Anion Gap calculator), respiratory alkalosis, or hyperammonemia

A heterogeneous group of disorders can mimic CVS, and these disorders must be excluded with systematic laboratory and radiographic testing. An analysis by Li et al identified 3 main categories to be considered in the differential diagnosis [49] :

  • Gastrointestinal (GI) disorders

  • Extraintestinal disorders

  • Idiopathic CVS

A psychological evaluation may reveal ongoing panic, anxiety, and eating disorders, and stress management may attenuate the stress triggers. [50]


Laboratory Studies

In the evaluation of the patient for possible GI disease, screening blood work should include a complete blood count (CBC) with differential, assessment of the erythrocyte sedimentation rate (ESR), and measurement of levels of hepatic transaminases, pancreatic amylase, and lipase. Nonanatomic renal disease can be detected by means of serum blood urea nitrogen (BUN) and creatinine tests, urinalysis, and urine calcium-to-creatinine ratio. [50]

Screening for multiple metabolic and endocrine disorders can be accomplished by assessing pH and measuring levels of electrolytes, glucose, lactic acid, ammonia, amino acids, adrenocorticotropic hormone (ACTH), and antidiuretic hormone (ADH).

Urinary ketones, organic acids, ester-to-free carnitine ratio, porphobilinogen, and aminolevulinic acid may also guide diagnosis in the correct direction. [50] These metabolic and endocrine tests must be obtained during the vomiting episode to detect intermittent disorders (eg, disorder of fatty acid oxidation) or heterozygote disorders (eg, partial ornithine transcarbamylase deficiency).

All blood and urine tests must be performed before the administration of intravenous (IV) fluids containing glucose or other medical treatments.

In a postmenarchal girl, the physician must consider a beta human chorionic gonadotropin (beta-hCG) test for pregnancy. [50]


Radiography, Endoscopy, US, CT, and MRI

Imaging studies may be indicated as follows.

In evaluation for GI diseases, upper GI (UGI) radiography with small-bowel follow-through (SBFT), esophagogastroduodenoscopy (EGD), abdominal ultrasonography (US), or computed tomography (CT) and gastric-emptying scanning may provide definitive information. [50] In evaluation for neurologic or otolaryngologic diseases, sinus CT or brain MRI should be considered. CT scans may not adequately visualize the subtentorial region. Obstructive renal disease can be revealed with renal ultrasonography or CT imaging.

With a broad array of possible diagnoses and possible diagnostic approaches, an extensive evaluation may appear cumbersome. Olson and Li reported that UGI radiography followed by empiric antimigraine therapy for 2 months is the most cost-effective approach ($1600) for the initial treatment of recurrent episodic vomiting in children ($3020 for extensive diagnostic evaluation, and $1830 for empiric treatment alone). [51]

Until prospective trials are conducted, the authors’ current approach generally includes initial blood and urine screens, including metabolic screening and UGI radiography at initial presentation.

The presence of specific symptoms such as hematemesis, bilious vomiting, persistent headache, flank pain, acidosis, or uncharacteristically severe or atypical vomiting episodes should raise the clinician’s index of suspicion of an underlying disorder and should warrant a prompt and more extensive or repeat evaluation. [51] The 4 tests with the highest yield are endoscopy, sinus radiography or CT imaging, small-bowel radiography, and head CT or MRI. [50]