Diagnosis of Bronchiolitis

To diagnose bronchiolitis, physicians perform a physical examination and diagnostic tests. During the physical exam, the physician evaluates the child's breathing using a stethoscope and takes note of breaths per minute, retractions, flaring nostrils, and grunting or whistling sounds. He or she also takes the child's temperature.

In many cases, a mucus sample taken from the child's nose is examined under a microscope to help identify which virus is present. A pulse oximeter is used to measure blood oxygen levels. This instrument detects oxygen levels through a light sensor placed on the baby's finger or toe.

Urine tests may be performed to help determine the degree of dehydration. In severe cases, blood tests are also performed.

Bronchiolitis Differential Diagnosis

Bronchiolitis diagnosis involves ruling out other possible causes for symptoms. Sometimes a chest x-ray is used to detect other types of lung problems (e.g., pneumonia). If the child has a fever, blood tests can indicate an infection elsewhere in the body.

Other conditions that must be ruled out include the following:

  • Apnea (temporary pause in breathing; e.g., obstructive sleep apnea [OSA])
  • Aspiration (foreign substance, fluid, or food particles that are inhaled)
  • Asthma
  • Bronchitis
  • Congenital heart disease
  • Congestive heart failure (CHF)
  • Cystic fibrosis (CF)
  • Lobar emphysema (condition in which the child can breathe air in, but the air cannot get out of the lungs; causes the lungs to over-expand)
  • Pneumonia (e.g., lobar pneumonia [infection that affects only one section of the lung], viral pneumonia [lung infection caused by a virus], or bacterial pneumonia [lung infection caused by bacteria)
  • Pulmonary edema (abnormal fluid in the lungs)
  • Reflux disease
  • Vascular ring (congenital condition in which the aorta and surrounding blood vessels are arranged abnormally)

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 27 Aug 2008

Last Modified: 03 Sep 2015