What is the treatment approach for mast cell activation syndrome (MCAS) in pregnancy?

Management of Mast Cell Activation Syndrome in Pregnancy

The treatment of mast cell activation syndrome (MCAS) during pregnancy should focus on trigger avoidance and prophylactic anti-mediator drug therapy using H1 and H2 antihistamines, corticosteroids, and epinephrine as standard approaches, with multidisciplinary management involving high-risk obstetrics, anesthesia, and allergy specialists. 1

First-Line Management Approach

Multidisciplinary Care

• Pregnant women with MCAS should be managed by a team including:
  • High-risk obstetrician
  • Anesthesiologist
  • Allergy specialist
  • During preconception, pregnancy, and peripartum period 2, 1

Core Treatment Strategy

1. Trigger Avoidance

   • Identification and strict avoidance of individual MCAS triggers 1
   • Common triggers include:
     • Specific foods
     • Certain medications
     • Temperature extremes
     • Emotional stress
     • Pain (critical to manage as it can trigger mast cell activation) 2

2. Pharmacological Management

   • H1 Antihistamines (first-line):

     • Cetirizine
     • Fexofenadine 1

   • H2 Antihistamines (first-line):

     • Famotidine
     • Ranitidine 1

   • Corticosteroids:

     • For acute symptom flares
     • Short courses to minimize potential fetal exposure 2, 1

   • Epinephrine:

     • Auto-injector must be available at all times for anaphylaxis 1

   • Cromolyn Sodium:

     • Mast cell stabilizer that can help with gastrointestinal symptoms
     • Has shown clinical improvement within 2-6 weeks of treatment initiation 3

Special Considerations During Pregnancy

Potential Complications

• Spontaneous miscarriages reported in 20-30% of pregnant women with mastocytosis 2
• Symptoms related to mast cell mediator release observed in 11% of patients 2
• Excessive release of mast cell mediators in later stages of pregnancy associated with preterm delivery 2

Peripartum Management

• Anesthetic Considerations:

  • Safer anesthetic agents include propofol, sevoflurane, and isoflurane 1
  • Safer analgesics include fentanyl and remifentanil 1
  • Avoid muscle relaxants atracurium and mivacurium
  • If muscle relaxants needed, use rocuronium or vecuronium 1
  • Exercise caution with opioids like codeine or morphine 2

• Labor and Delivery:

  • Prophylactic anti-mediator therapy before procedures
  • Pain management is crucial as pain can trigger mast cell activation 2
  • Higher risk of anaphylaxis during perioperative period 2

Severe or Refractory Cases

• For pregnant women with severe symptoms refractory to conventional therapy:
  • Cytoreductive therapy with interferon-alfa can be considered 2
  • NOT recommended: cladribine, imatinib, and midostaurin 2

Postpartum Considerations

Breastfeeding

• Should be done in consultation with:
  • Pediatrician
  • International board certified lactation consultant 2
• Medication safety during lactation must be evaluated individually 1

Monitoring

• Regular assessment of MCAS symptoms throughout pregnancy and postpartum
• In case of anaphylaxis or mast cell activation event:
  • Full allergic workup
  • Measurement of serum tryptase level within 30-120 minutes of symptom onset 2

Treatment Algorithm

1. Pre-pregnancy:

   • Identify and optimize MCAS control before conception when possible 4
   • Establish baseline medication regimen that is pregnancy-compatible

2. First Trimester:

   • Continue H1 and H2 antihistamines
   • Minimize corticosteroid use if possible
   • Ensure epinephrine auto-injector availability

3. Second and Third Trimesters:

   • Monitor for increased symptoms as pregnancy progresses
   • Adjust medications as needed
   • Develop delivery plan with anesthesia consultation

4. Labor and Delivery:

   • Premedication with antihistamines and corticosteroids
   • Careful selection of anesthetic agents
   • Immediate availability of resuscitation equipment

5. Postpartum:

   • Continue vigilance for mast cell activation
   • Evaluate medication safety if breastfeeding

By following this structured approach to managing MCAS during pregnancy, the risks to both mother and fetus can be minimized while effectively controlling symptoms of mast cell activation.