Associated localizing symptoms
Almost any virus can be accompanied by rash in the pediatric patient, and it is not always necessary to ascertain which virus is causing the illness. If the illness is prolonged or particularly bothersome, antibody titers can be ordered to determine the exact etiology of the illness.
LP-CSF analysis, esp if <3mo
Acute otitis media
Gastroenteritis (viral, bacterial, parasitic)
Other viral exanthem
Fifth disease (Parvovirus B19 infection)
Pneumatic otoscopy--key to look for the decreased TM mobility seen in otitis media
Tympanometry--useful in infants >6 months of age; confirmed abnormal TM mobility in otitis media
CBC with differential, blood culture--notably, a WBC >15k/uL is suggestive of occult bacteremia
Platelets, PT/PTT, D-dimer, fibrin split products, fibrinogen--evidence of DIC is often seen in meningococcemia
UA and urine culture--UTI may be occult and must be investigated
LP--CSF analysis--should be performed if there is any concern for meningitis.
CSF analysis includes cell count and differential, glucose, protein, Gram stain, culture, latex agglutination for common bacterial antigens, and occasionally PCR for specific viruses
CT-head--used mainly to rule out brain abscess or hemorrhage
CXR--to dx pneumonia
Throat culture--to isolate Streptococcus pyogenes (which causes Scarlet fever)
Parvovirus B19 IgM antibody--the best marker of acute or recent infection in suspected fifth disease
Skin lesion scrapings--varicella antigens are identifiable by PCR or direct immunofluorescence (DFA) of skin lesions. Also a Tzanck smear may show multinucleated giant cells in varicella infection.
Varicella antibody titer--may be useful in uncertain cases (look for a fourfold rise in antibody titer following acute infection)
Bronchoscopy--a diagnostic aid in severe or refractory pneumonia cases
Serum antibody titers--to identify causative viruses in pediatric infections (not commonly used)
U/S--renal--to look for anatomic anomalies that predispose to UTI
Voiding cystourethrogram--to look for vesicourethral reflex in UTI