Bronchiolitis Obliterans

What is Bronchiolitis Obliterans?

Bronchiolitis obliterans (BO) is a very rare, life-threatening irreversible obstructive lung disorder in which the small airway branches known as bronchioles are narrowed and compressed fibrosis (scarred tissues) and/or inflammations. The term Bronchiolitis obliterans is occasionally used to refer to a particularly severe type of pediatric bronchiolitis that is caused by adenovirus. The word bronchiolitis signifies inflammations of the bronchioles; obliterans refers to partial or complete obliteration of the airways caused by fibrosis or inflammations.

The condition is also referred to by other names, such as:

  • Obliterative bronchiolitis or OB
  • Constrictive bronchiolitis or CB

Bronchiolitis Obliterans Causes

This disorder can be caused by several factors such as:

  • Drug reactions
  • Rheumatoid arthritis
  • Collagen vascular disease
  • Pneumocystis pneumonia
  • Stevens-Johnson Syndrome
  • Certain connective tissue diseases
  • Transplant rejection in the organ transplant patients
  • Chronic aspiration of the stomach contents caused by gastroesophageal reflux
  • Aspiration and the complications of prematurity such as bronchopulmonary dysplasia
  • Viral infections caused by agents such as adenovirus, cytomegalovirus, respiratory syncytial virus, and HIV
  • The condition can also arise as a result of exposure to various toxic fumes, such as:


  1. Ozone
  2. Diacetyl
  3. Chlorine
  4. Phosgene
  5. Ammonia
  6. Mustard gas
  7. Sulfur dioxide
  8. Thionyl chloride
  9. Nitrogen dioxide
  10. Hydrogen sulfide
  11. Hydrogen fluoride
  12. Methyl isocyanate
  13. Hydrogen chloride
  14. Hydrogen bromide
  15. Polyamide-amine dyes
  • Certain oral emergency medications, like activated charcoal can give rise to the disorder when aspirated
  • Fatigue and/or wheezing in absence of cold or asthma
  • It can also be caused by idiopathic factors

BO can also be caused by barotrauma, as observed in bronchopulmonary dysplasia.

Bronchiolitis Obliterans Symptoms

Initially, people having BO may exhibit the symptoms associated with bronchitis, common bronchiolitis or pneumonia that might be accompanied by dry cough, fever, shortness of breath along with periods of wheezing. However, these signs and symptoms trigger on and off for several weeks to months for a period longer than a regular infection. People having BO may experience recurrent episodes of dyspnea, wheezing, chronic and productive cough, pneumonia and atelectasis (a form of chronic bronchiolitis). When the disease reaches an acute phase, the symptoms can progress very quickly which might turn fatal in certain cases.

A form of chronic pulmonary disorder can be seen in some other cases that involve recurrent bronchiectasis and pneumonias. In some instances, they can even develop a form of unilateral hyperlucent lung syndrome, known as Swyer-James Syndrome. Symptoms associated with BO may develop gradually, or they may occur suddenly.

Bronchiolitis Obliterans Diagnosis

The diagnosis of BO is carried out by conducting the following procedures:

  • Chest X-ray tests
  • Diffusing capacity of the lung (DLCO) tests show normal results
  • Spirometry tests reveal obstructions and restrictions of fixed airways; hence FEV1/FVC is less than 75%
  • Hyperinflation (excessive air in the lungs due to air trapping) can be detected by lung volume tests
  • High-resolution chest CT scans at full inspiration and expiration reveals heterogeneous air trapping and haziness and thickening of the airway walls
  • Constrictive BO (severe narrowing and/or complete obstruction of small airways) is revealed by lung biopsies. Open lung biopsies, such as those conducted by thoracoscopy, are more likely to be conclusive than Transbronchial biopsy. Specialized processing, staining, and reviewing of numerous tissue sections might be necessary for diagnosis

Bronchiolitis Obliterans Differential Diagnosis

There are certain disorders whose symptoms overlap with those of BO. Hence, while determining the diagnosis of BO, it should be differentiated from these similar-appearing disorders. The differential diagnoses of BO include telling its symptoms apart from those of conditions such as:

  • Asthma
  • Bronchitis
  • Pneumonia
  • Emphysema

Bronchiolitis Obliterans Treatment

The disorder is irreversible and treatment is commonly required to manage underlying causes such as inflammation or aspiration in order to prevent additional damage to the lungs. However, the treatment is primarily supportive for many people.

Children with BO frequently have labored or difficult breathing, which utilizes more calories than normal. This leads to poor weight gain or failure to thrive. It is thus necessary to optimize the nutritional needs of a child to facilitate adequate growth and promote overall good health.

Individuals having BO may also need oxygen supplementation. The amounts of oxygen required may vary from one case to another. Flu and common colds are often more severe in individuals suffering from bronchiolitis obliterans, and so limiting the exposure to various respiratory infections is necessary as well. Seasonal flu shots should be given to the people having BO. Oral corticosteroids have been proven effective in the treatment of BO in several cases. Immunosuppressive medications such as Prednisone can also be used to treat this disorder. Severe cases of BO are usually treated with lung transplant surgeries.

Bronchiolitis Obliterans Complications

Treatment with medications such as oral corticosteroids can have side effects such as adrenal failure and osteoporosis.

Bronchiolitis Obliterans Prognosis

The prognosis for this disorder may vary from one person to another, depending on the severity of symptoms and acceptance of the transplanted organ. If left untreated, BO can be fatal. It is the primary death-causing factor after a lung or a heart-lung transplant surgery. An early detection of the condition followed by appropriate treatment is necessary to ensure a better outcome.

Bronchiolitis Obliterans Pictures

The following images will give you a clearer idea about the condition of the lungs affected by this disease.

Picture 1 – Bronchiolitis Obliterans

Picture 2 – Bronchiolitis Obliterans Image


  1. Faith Adams March 22, 2017
  2. Rochelle August 14, 2017
  3. Brooke October 16, 2017

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