Diagnosing Stridor in Children

Specialists at the Pediatric Aerodigestive Center, part of Hassenfeld Children’s Hospital at NYU Langone, conduct a physical exam and perform diagnostic tests to identify the cause of stridor, or noisy breathing. The noisy breathing often sounds like a high-pitched wheezing or whistling, and may be audible when a child inhales, exhales, or both.

Stridor is usually the result of a narrowed or partially blocked airway, the passage that connects the mouth to the lungs. The condition is most common in newborns, infants, and toddlers because their airways are narrower—so even a small blockage can interfere with easy breathing. This condition also affects adults.

A narrowed or blocked airway can be a medical emergency. If your child struggles to breathe or if noisy breathing is accompanied by a cough, our experts recommend seeking immediate care at the nearest emergency room.

Causes of Stridor

There are many possible causes of stridor. In newborns and infants, the most common cause is laryngomalacia, a condition in which tissues located in the throat above the vocal cords are too soft and flop into the airway. This causes inspiratory stridor, meaning the symptoms of noisy breathing occur when a child inhales. Laryngomalacia is present at birth in some babies and almost always resolves on its own by the time a child is two.

Less commonly, stridor in infants is caused by vocal cord paralysis, in which nerve function in one or both of the vocal cords is disrupted, causing vocal cord tissues to relax and block the airway. This causes expiratory stridor, which means the symptoms of noisy breathing occur when a child exhales.

Another, less common, cause of stridor is called subglottic stenosis, an unusual narrowing of the airway below the vocal cords that causes noisy breathing during inhalation and exhalation. Laryngomalacia and subglottic stenosis are usually present at birth.

In young children, stridor is most often caused by croup, which is a swelling in the tissues around the vocal cords that is associated with a cough that sounds like barking. Croup usually develops as a result of a viral upper respiratory infection but is sometimes due to allergies or a bacterial infection.

In children of any age, stridor may occur if a child inhales a piece of food or a small object that gets stuck in the airway. If you see your child put an object in his or her mouth and then cough but not spit out the object, or if he or she develops noisy breathing and a cough, bring the child to the emergency room.

Many other conditions can cause stridor, but most of them are rare. Our specialists can accurately diagnose any condition that causes stridor and determine the best treatment for your child.

Our otolaryngologists—also known as ear, nose, and throat doctors, or ENTs—often diagnose the cause of stridor during a physical exam. If further diagnostic testing is necessary, doctors use advanced imaging techniques to get a clear look at the airway.

Medical History

A doctor may ask you to describe when you first noticed noisy breathing in your child, whether the noise comes and goes or is consistent, and whether your child has a lack of appetite or is having trouble sleeping.

Tell your pediatrician if your child has had cardiac or vocal cord surgery or if doctors have used an intubating device to help your child breathe. Scar tissue that may develop as a result of these procedures can sometimes cause a narrowed airway.

Physical Exam

Whether the initial examination is in a doctor’s office or an emergency room, a doctor examines your child’s face, neck, and throat for signs of a partially blocked airway. The doctor also listens to your child’s breathing with a stethoscope, an instrument used to magnify sounds in the lungs and airway. The doctor also looks for signs of infection, such as swelling in the throat.

Flexible Laryngoscopy

Flexible laryngoscopy helps a doctor examine your child’s airway and vocal cords. This exam, which takes place in the doctor’s office, lasts for about five minutes. Pediatricians use the procedure to determine whether the airway is narrow and, if so, identify the cause.

To perform the procedure, your child’s doctor first applies a local anesthetic spray that numbs the nose and throat. Then he or she inserts an endoscope—a very thin, flexible instrument with a camera and light at the end—into a nostril and down the airway. The high-definition video camera helps identify any narrowing, obstruction, or other abnormalities.


If you saw your child ingest or inhale a small object, such as a piece of food or a small toy, a doctor may recommend a chest X-ray. X-ray imaging creates detailed pictures of the structures inside the body and may show an object lodged in the airway or lungs. Chest X-rays are painless and can be performed in about 15 minutes.


Bronchoscopy is an examination of the airway and lungs using a bronchoscope, a long, thin instrument with a camera on the tip. A doctor may recommend a bronchoscopy if X-rays suggest that your child ingested or inhaled an object. Specialists use general anesthesia for the test to lessen any discomfort.

To perform this exam, your child’s doctor inserts the bronchoscope through the nose or mouth and into the lungs. The scope sends a clear image of the airway and lungs to a monitor and helps doctors determine whether an object is blocking airflow.

If the bronchoscope reveals that an object is present, your child’s doctor may pass small surgical instruments through the bronchoscope to remove it.

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