How to diagnose allergic bronchitis or asthma in a pregnant woman?

Diagnosing Allergic Bronchitis or Asthma in Pregnant Women

The diagnosis of allergic bronchitis or asthma in pregnant women should follow standard diagnostic protocols with spirometry as the essential objective measure, while considering the physiological changes of pregnancy and prioritizing maternal and fetal safety. 1, 2

Key Diagnostic Approach

Initial Assessment

• Medical History: Focus on:
  • Recurrent episodes of cough, wheezing, chest tightness, or shortness of breath
  • Pattern and triggers of symptoms
  • Family history of asthma or allergic conditions
  • Pre-existing asthma diagnosis and its course during pregnancy
  • History of atopy (allergic rhinitis, eczema)
  • Response to previous treatments 1

Objective Testing

• Spirometry: The gold standard diagnostic test

  • Demonstrates obstruction and assesses reversibility
  • Essential objective measure as patient perception of airflow obstruction is highly variable
  • Look for FEV1/FVC ratio below normal and improvement after bronchodilator 1, 3
  • Interpret results considering pregnancy-related changes (FVC% decreases with advancing gestation) 3

• Peak Flow Monitoring:

  • Less reliable than spirometry for diagnosis but useful for monitoring
  • Establish baseline values and monitor for variability 2

Additional Diagnostic Tests

• Bronchoprovocation Testing:

  • Consider when asthma is suspected but spirometry is normal
  • Exercise challenge test showing ≥15% decrease in PEF or FEV1 can establish diagnosis
  • Should only be performed by trained individuals due to safety concerns 1

• Allergy Testing:

  • In vitro testing (specific IgE blood tests) preferred during pregnancy
  • Helps identify specific triggers 4

Special Considerations During Pregnancy

Physiological Changes Affecting Diagnosis

• Pregnancy can alter lung function parameters:
  • FVC% decreases with advancing gestation (-0.07%/week)
  • FEV1% decreases in women without asthma but may remain stable in women with asthma
  • FEV1/FVC% tends to increase slightly in women with asthma during pregnancy 3

Monitoring Frequency

• Monthly evaluation of asthma control and lung function during prenatal visits
  • Asthma course changes during pregnancy (improves in 1/3, worsens in 1/3, unchanged in 1/3)
  • Second and third trimesters often have increased symptoms 1, 2

Validated Questionnaires

• Consider using validated questionnaires like the Control of Allergic Rhinitis and Asthma Test (CARAT)
  • Helps assess control of both upper and lower airway symptoms
  • Correlates with need for step-up in controller medications 5

Differential Diagnosis

• Common conditions to consider:
  • Physiologic dyspnea of pregnancy
  • Vocal cord dysfunction
  • Gastroesophageal reflux disease (common in pregnancy)
  • Obstructive sleep apnea (may worsen during pregnancy)
  • Pulmonary embolism (increased risk during pregnancy)
  • Heart failure 1

Management Implications of Diagnosis

• Uncontrolled asthma increases risks of perinatal mortality, pre-eclampsia, preterm birth, and low birth weight
• It is safer for pregnant women to be treated with appropriate asthma medications than to have uncontrolled symptoms 2, 6
• Active management during pregnancy lessens risks of preterm birth and neonatal hospitalization 1

Common Pitfalls to Avoid

1. Underdiagnosing asthma due to concerns about medication use in pregnancy
2. Confusing physiologic dyspnea of pregnancy with asthma symptoms
3. Discontinuing asthma medications during pregnancy, which increases risks to both mother and fetus
4. Failing to monitor regularly throughout pregnancy as asthma severity can change
5. Not considering comorbidities like rhinitis, GERD, or sleep-disordered breathing that can worsen asthma control 1, 2

Following this diagnostic approach ensures proper identification of allergic bronchitis or asthma in pregnant women, allowing for appropriate management to optimize maternal and fetal outcomes.