Case Report
A 26-year-old Caucasian primigravid woman presented at 38 weeks and 4 days after the onset of spontaneous labour. She did not have any medical conditions and was not on regular medications prior to pregnancy. She had an uneventful antenatal course, with well managed hypothyroidism and iron deficiency anaemia. Ultrasound at the 34th week of gestation was within reference ranges, with an estimated foetal weight of 2.8 kg (85th percentile). She had no known drug allergies or history of hay fever, asthma or eczema. However, had a strong family history of atopy on her maternal side. Drug doses were administered as per hospital guidelines.
After 2.5 hours of an uncomplicated first stage of labour, she required 10 units of intravenous (IV) Syntocinon (as per hospital protocol) augmentation during the second stage of labour. Cardiotocography showed a baseline foetal heart rate of 140 beats per minute, normal variability, and recurrent variable decelerations. Eight minutes later, she complained of facial oedema, the Syntocinon infusion was immediately ceased. Over the next ten minutes, the facial swelling subsided with stable vital signs. Due to prolonged foetal bradycardia down to 80 beats per minute, mediolateral episiotomy and vacuum extraction was performed. This was complicated by one minute of shoulder dystocia which was managed using the McRoberts manoeuvre. An infant weighing 4.1 kg was born in good condition, with Apgar scores of 8 and 9 at 1 and 5 minutes, respectively. To augment delivery of the placenta, 10 units of intramuscular (IM) Syntocinon was administered. However, postpartum haemorrhage (PPH) developed shortly afterwards due to uterine atony and a fourth-degree vaginal tear, with an estimated blood loss of 2 litres. This was controlled with IV fluid resuscitation, 1g of IV tranexamic acid, and 250mcg of IV and IM doses of ergometrine, with a plan to repair the fourth-degree tear urgently in the operating theatre. Sixteen minutes later, there was worsening throat discomfort and chest tightness. The midwife noted facial oedema, patchy erythema on her back, increased work of breathing, and dysphonia. No gastrointestinal symptoms or urticaria were noted. Anaphylaxis was suspected and a rapid response was initiated. Oxygen was administered through a non-rebreather mask at 15 litres/minute. Vital signs were stabilised with an oxygen saturation of 100%, blood pressure of 140/84 mmHg (systolic blood pressure/diastolic blood pressure), heart rate of 108 beats/min, and respiratory rate of 16 breaths/minute. Electrocardiography (ECG) demonstrated sinus tachycardia with no concerning features. Two 500mcg doses of IM 1:1000 adrenaline and 200mg of IV Hydrocortisone were administered, the airway was stabilised with endotracheal tube intubation in the operating theatre. Of note, no laryngeal swelling was visualised during intubation by the Anaesthesiologist.
The patient was transferred to the intensive care unit (ICU) after the operation. She was extubated six hours later with a patent airway and no increased work of breathing. The results of serial tryptase measurements, absolute basophils, serum immunoglobulin-E (IgE), and complement C3 and C4 levels post-surgery were all within normal limits (Table 1). Serum electrolytes were normal throughout her admission. Mobile chest x-ray immediately post-surgery demonstrated extensive subcutaneous emphysema, but no other significant abnormalities. She recovered well in ICU with 24 hours of 4mg IV dexamethasone three times per day, and 2 units of packed red blood cells due to haemorrhage. She was discharged from the hospital after a four-day admission.