”The road to hell is paved with good intentions” – a first case report of anaphylaxis to tranexamic acid in an obstetric patient
Introduction
•Tranexamic acid (TXA) is a widely used antifibrinolytic that reduces bleeding by binding to plasminogen and inhibiting breakdown of fibrinogen and fibrin
•The World Maternal Antifibrinolytic trial (WOMAN, 2017) found that TXA reduces death due to bleeding in women with post-partum haemorrhage, and TXA has been increasingly used in obstetrics since
•The first case report of anaphylaxis to TXA was described in 2004, by 2021 this had risen to seven1
•Here we report the first case report to anaphylaxis in an obstetrics patient
Background
35 year-old female, P3 G4, presented for elective caesarean section
Past medical history: Gestational diabetes,
alpha-thalassaemia trait, BMI 27
Drug history: Metformin, insulatard, ferrous sulphate
No known drug allergies, no history of atopy
Previous surgical history: Three previous caesarean sections
Pre-operative concerns:
•Fourth caesarean section
•High risk of bleeding:
➢Discussed in team brief
➢Starting Hb 125
➢2 units of red blood cells crossmatched
➢Consented for cell saver and blood transfusion
Intra-operative events
08:50 Patient in theatre
•IV access
•09:02 Routine antibiotic prophylaxis given
•09:10 Combined spinal and epidural with 1.8mls 0.5% hyperbaric bupivicaine and 25mcg fentanyl: uneventful
09:31 Knife to skin
•Significant adhesions
•Second obstetric consultant to help
•Team informed that the patient is oozing
•Asked to administer prophylactic TXA 1g prior to delivery of baby
09:45 Tranexamic acid 1g IV administered
•09:50 Patient complains of itchy eyes
•09:55 Patient develops hoarse voice, significant facial angioedema and widespread rash
•BP 67/40 HR 95 O2Sats 88%
09:55 Anaphylaxis
•Obstetric team asked to deliver baby urgently
•Partner reluctant to leave
•Resuscitation of mother
•Adrenaline 0.5mg 1:1000 IM, hydrocortisone 200mg IV, chlorphenamine 10mg IV
09:57 Baby delivered in good condition
•Repeat IM adrenaline for significant angioedema
•4L of IV crystalloids given
•BP stabilised
•10:05 IV Carbetocin 100 mcg administered
•Estimated blood loss: 700mls
Postoperative management
•Epidural left in situ for pain relief until able to swallow oral medications
•Patient in monitored area for close observation 24 hours following reaction
•
•Symptoms continued to improve and had completely resolved by 5pm the same day
•Patient and partner informed of suspected reaction to TXA, letter written to GP and patient referred to drug allergy clinic
•
Follow-up
Mast cell tryptase levels
1st level at 10:30am: 16.7 ng/ml
2nd level at 12:30pm: 28.6 ng/ml
3rd level at 11:00am (>24hrs later): 4 ng/ml
Drug allergy clinic results
•POSITIVE intradermal test to TXA
•Negative skin prick test to TXA
•Negative skin prick and intradermal tests to:
Lidocaine 1%
Bupivicaine 0.25%
Fentanyl
Metronidazole
Cefuroxime
Povidone iodine
Chlorhexidine 0.05%
Latex
Diagnosis: Anaphylaxis to TXA
Discussion
•Anaphylaxis to TXA confirmed in our patient
•Significance of human factors when managing anaphylaxis during elective caesarean section
•A rare reaction to a commonly used drug in obstetrics – as TXA is increasingly used the number of anaphylaxis reactions is likely to rise
•Side effects of TXA: gastrointestinal disturbance, allergic dermatitis, venous thromboembolism, seizures, visual disturbance
•TXA is neurotoxic – safety alert following accidental intrathecal administration
•Possible rare long-term renal complications following TXA administration together with other drugs in women with severe post-partum haemorrhage2
•Recent systematic review and meta-analysis found no particular safety concern of TXA use for prevention of obstetric haemorrhage3, but many studies underpowered to detect adverse drug reactions and high risk groups excluded
Conclusion
•TXA forms part of guidelines for major obstetric haemorrhage worldwide
•Always consider risk/benefit before administrating TXA
•Particular caution prior to delivery of baby in view of anaphylaxis risk
