Croup Workup

  • Author: Germaine L Defendi, MD, MS, FAAP; Chief Editor: Russell W Steele, MD   more...
 
Updated: Oct 5, 2011
 

Approach Considerations

Croup is primarily a clinical diagnosis, with the diagnostic clues based on presenting history and physical examination findings.

Laboratory test results rarely contribute to confirming this diagnosis. The complete blood cell (CBC) count is usually nonspecific, although the white blood cell (WBC) count and differential may suggest a viral cause with lymphocytosis. Identifying the specific viral etiology (eg, respiratory syncytial virus [RSV[) via nasal washings is typically not necessary but may be useful to determine isolation needs in the hospital care setting or, in the case of influenza A, to decide whether antiviral therapy should be initiated.

Pulse oximetry readings are within the normal reference range for most patients; however, this monitoring is helpful to assess for the need for supplemental oxygen support and to monitor for worsening respiratory compromise as seen with tachypnea and poor maintenance of oxygen saturations. Standardly, arterial blood gas (ABG) measurements are unnecessary and do not reveal hypoxia or hypercarbia unless respiratory fatigue ensues.

Patients who present with fevers, tachypnea, and history of decreased oral fluid intake require evaluation of their hydration status. Depending on their oral ability or inability to maintain needed fluid volume, intravenous fluid support may be required to stabilize and support their ongoing fluid requirements.

Procedures

Laryngoscopy is required only in unusual circumstances (eg, the course of illness is not typical, the child has symptoms that suggest an underlying anatomic or congenital disorder). This procedure may also be required in patients with bacterial tracheitis to obtain the necessary cultures.

Other procedures that may be indicated and may require the guidance of a pediatric otolaryngologist include the following:

  • Direct laryngoscopy if the child in not in acute distress
  • Fiberoptic laryngoscopy
  • Bronchoscopy
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Radiography

Plain films can verify a presumptive diagnosis or exclude other disorders causing stridor and hence mimic croup, such as an aspirated foreign body, esophageal foreign body, congenital subglottic stenosis, epiglottitis, or retropharyngeal abscess. Croup is a clinical diagnosis. Radiographs can be used as a tool to help confirm this diagnosis, but they are not required in uncomplicated cases.

The anteroposterior radiograph of the soft tissues of the neck classically reveals a steeple sign (also known as a pencil-point sign), which signifies subglottic narrowing, whereas the lateral neck view may reveal a distended hypopharynx (ballooning) during inspiration (see the images below). However, these findings may not be seen in up to 50% of children with croup. A steeple sign may also be observed in patients without croup, which warrants other differential considerations for this radiographic finding, such as epiglottitis, thermal injury, angioneurotic edema, or bacterial tracheitis.[10] Monitor patients during imaging, because progression of airway obstruction may be rapid.

Child with croup. Note the steeple or pencil sign Child with croup. Note the steeple or pencil sign of the proximal trachea evident on this anteroposterior film. Courtesy of Dr. Kelly Marshall, CHOA at Scottish Rite. Steeple sign on radiograph. Steeple sign on radiograph.
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Contributor Information and Disclosures
Author

Germaine L Defendi, MD, MS, FAAP  Associate Clinical Professor, Department of Pediatrics, Olive View-UCLA Medical Center

Germaine L Defendi, MD, MS, FAAP is a member of the following medical societies: American Academy of Pediatrics

Disclosure: Nothing to disclose.

Coauthor(s)

Antonio Muñiz, MD  Professor of Emergency Medicine and Pediatrics, University of Texas Medical School at Houston; Medical Director of the Pediatric Emergency Department, Children's Memorial Hermann Hospital

Antonio Muñiz, MD is a member of the following medical societies: American Academy of Emergency Medicine, American Academy of Pediatrics, American College of Emergency Physicians, American Heart Association, American Medical Association, Society for Academic Emergency Medicine, and Southern Medical Association

Disclosure: Nothing to disclose.

Rona E Molodow, MD, JD  Clinical Professor, Department of Pediatrics, Olive View-UCLA Medical Center

Rona E Molodow, MD, JD is a member of the following medical societies: American Academy of Pediatrics and American Professional Society on the Abuse of Children

Disclosure: Nothing to disclose.

Chief Editor

Russell W Steele, MD  Head, Division of Pediatric Infectious Diseases, Ochsner Children's Health Center; Clinical Professor, Department of Pediatrics, Tulane University School of Medicine

Russell W Steele, MD is a member of the following medical societies: American Academy of Pediatrics, American Association of Immunologists, American Pediatric Society, American Society for Microbiology, Infectious Diseases Society of America, Louisiana State Medical Society, Pediatric Infectious Diseases Society, Society for Pediatric Research, and Southern Medical Association

Disclosure: Nothing to disclose.

Additional Contributors

Joseph Domachowske, MD Professor of Pediatrics, Microbiology and Immunology, Department of Pediatrics, Division of Infectious Diseases, State University of New York Upstate Medical University

Joseph Domachowske, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Pediatrics, American Society for Microbiology, Infectious Diseases Society of America, Pediatric Infectious Diseases Society, and Phi Beta Kappa

Disclosure: Nothing to disclose.

Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Nothing to disclose.

References

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Child with croup. Note the steeple or pencil sign of the proximal trachea evident on this anteroposterior film. Courtesy of Dr. Kelly Marshall, CHOA at Scottish Rite.
Steeple sign on radiograph.
 
 
 
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