How to manage Mast Cell Activation Syndrome (MCAS) in pregnancy?

Management of Mast Cell Activation Syndrome in Pregnancy

The management of Mast Cell Activation Syndrome (MCAS) during pregnancy requires a multidisciplinary team approach involving high-risk obstetrics, anesthesia, and allergy specialists, with trigger avoidance as the cornerstone of management and H1/H2 antihistamines as primary prophylactic therapy. 1, 2

Core Management Strategy

First-Line Medications

• Use H1 antihistamines (preferably non-sedating) such as cetirizine and fexofenadine to target dermatologic manifestations, flushing, pruritus, tachycardia, and abdominal discomfort 1, 2
• Combine with H2 antihistamines (famotidine, ranitidine) to enhance cardiovascular symptom control and address gastrointestinal symptoms 1, 2
• Oral cromolyn sodium is particularly effective for gastrointestinal symptoms (bloating, diarrhea, abdominal cramps) and may improve neuropsychiatric manifestations 2

Trigger Avoidance

• Identify and avoid individual MCAS triggers including:
  • Temperature extremes
  • Mechanical irritation
  • Alcohol
  • Certain medications (aspirin, radiocontrast agents, specific anesthetics) 2
• Pain management is critical as pain can trigger mast cell activation 1, 2

Emergency Medications

• Ensure epinephrine auto-injector is available at all times for anaphylaxis 1, 2
• Albuterol via nebulizer or metered-dose inhaler should be accessible for bronchospasm symptoms 2
• Corticosteroids may be used for acute symptom flares as needed 1

Special Considerations During Pregnancy

Medication Safety

• Use medications with established safety profiles during pregnancy:
  • Second-generation H1 antihistamines (cetirizine, fexofenadine) are preferred over first-generation options 1, 2
  • H2 antihistamines (famotidine) have reasonable safety profiles 1
  • Avoid medications known to worsen MCAS or with unclear safety profiles in pregnancy 1

Peripartum Management

• Develop a detailed delivery plan with the multidisciplinary team 1, 2
• For anesthesia, safer agents include:
  • Propofol, sevoflurane, and isoflurane
  • Fentanyl and remifentanil for analgesia 1, 2
• Avoid muscle relaxants atracurium and mivacurium; use rocuronium or vecuronium if needed 1
• Exercise caution with opioids like codeine or morphine 1

Monitoring During Pregnancy

• Regular assessment of MCAS symptoms throughout pregnancy 1
• Monitor for potential complications:
  • Spontaneous miscarriages
  • Symptoms related to mast cell mediator release
  • Increased risk of preterm delivery 1
• The risk of anaphylaxis is higher in the perioperative period 1, 3

Postpartum and Lactation Considerations

• Consult with a pediatrician and lactation specialist regarding medication safety during lactation 1
• Continue MCAS management postpartum as symptoms may fluctuate with hormonal changes 4
• Monitor for postpartum flares of symptoms 4

Common Pitfalls and Caveats

• First-generation H1 antihistamines (diphenhydramine, hydroxyzine) should be used with caution due to sedation and potential cognitive decline 1, 2
• Untreated pain can trigger mast cell activation and should be actively managed 2
• Aspirin may reduce flushing and hypotension in some patients with MCAS but is contraindicated in those with allergic reactions to NSAIDs 2
• Ideally, MCAS should be identified and controlled prior to pregnancy for optimal outcomes 4

Long-term Management Approach

• Adjust therapeutic interventions based on specific symptoms and mediator levels 1
• Regular follow-up with the multidisciplinary team throughout pregnancy and postpartum 1, 2
• Consider long-term management strategies that can be continued safely through pregnancy, delivery, and lactation 4, 5