The incidence, characteristics, managements and outcomes of anaphylaxis in pregnancy:a population-based descriptive study

Objective The aim of this study was to estimate the incidence of anaphylaxis in pregnancy and describe the management and outcomes in the UK. Design A population-based descriptive study using the UK Obstetric Surveillance System (UKOSS). Setting All consultant-led maternity units in the UK. Population All pregnant women who had anaphylaxis between 1 October 2012 and 30 September 2015. Anaphylaxis was defined as a severe, life-threatening generalised or systemic hypersensitivity reaction. Methods Prospective case notification using UKOSS. Main outcome measures Maternal mortality, severe maternal morbidity, neonatal mortality and severe neonatal morbidity. Results There were 37 confirmed cases of anaphylaxis in pregnancy, giving an estimated incidence of 1.6 (95% CI: 1.1–2.2) per 100 000 maternities. Four cases of anaphylaxis were in women with known penicillin allergies: two received co-amoxiclav and two cephalosporins. Twelve women had anaphylaxis following prophylactic use of antibiotics at the time of a caesarean delivery. Prophylactic use of antibiotics for Group B streptococcal infection accounted for anaphylaxis in one woman. Two women died (5%), 14 (38%) women were admitted to intensive care and seven women (19%) had one or more additional severe maternal morbidities, which included three haemorrhagic events, two cardiac arrests, one thrombotic event and one pneumonia. No infants died; however, in those infants whose mother had anaphylaxis before delivery (n = 18) there were seven (41%) neonatal intensive care unit admissions, three preterm births and one baby was cooled for neonatal encephalopathy. Conclusions Anaphylaxis is a rare severe complication of pregnancy and frequently the result of a reaction to antibiotic administration. This study highlights the seriousness of the outcomes of this condition for the mother. The low incidence is reassuring given the large proportion of the pregnant population that receive prophylactic antibiotics during delivery

A randomised controlled trial and economic evaluation of intraoperative cell salvage during caesarean section in women at risk of haemorrhage: the SALVO (cell SALVage in Obstetrics) trial

Background Caesarean section is associated with blood loss and maternal morbidity. Excessive blood loss requires transfusion of donor (allogeneic) blood, which is a finite resource. Cell salvage returns blood lost during surgery to the mother. It may avoid the need for donor blood transfusion, but reliable evidence of its effects is lacking. Objectives To determine if routine use of cell salvage during caesarean section in mothers at risk of haemorrhage reduces the rates of blood transfusion and postpartum maternal morbidity, and is cost-effective, in comparison with standard practice without routine salvage use. Design Individually randomised controlled, multicentre trial with cost-effectiveness analysis. Treatment was not blinded. Setting A total of 26 UK obstetric units. Participants Out of 3054 women recruited between June 2013 and April 2016, we randomly assigned 3028 women at risk of haemorrhage to cell salvage or routine care. Randomisation was stratified using random permuted blocks of variable sizes. Of these, 1672 had emergency and 1356 had elective caesareans. We excluded women for whom cell salvage or donor blood transfusion was contraindicated. Interventions Cell salvage (intervention) versus routine care without salvage (control). In the intervention group, salvage was set up in 95.6% of the women and, of these, 50.8% had salvaged blood returned. In the control group, 3.9% had salvage deployed. Main outcome measures Primary – donor blood transfusion. Secondary – units of donor blood transfused, time to mobilisation, length of hospitalisation, mean fall in haemoglobin, fetomaternal haemorrhage (FMH) measured by Kleihauer–Betke test, and maternal fatigue. Analyses were adjusted for stratification factors and other factors that were believed to be prognostic a priori. Cost-effectiveness outcomes – costs of resources and service provision taking the UK NHS perspective. Results We analysed 1498 and 1492 participants in the intervention and control groups, respectively. Overall, the transfusion rate was 2.5% in the intervention group and 3.5% in the control group [adjusted odds ratio (OR) 0.65, 95% confidence interval (CI) 0.42 to 1.01; p = 0.056]. In a planned subgroup analysis, the transfusion rate was 3.0% in the intervention group and 4.6% in the control group among emergency caesareans (adjusted OR 0.58, 95% CI 0.34 to 0.99), whereas it was 1.8% in the intervention group and 2.2% in the control group among elective caesareans (adjusted OR 0.83, 95% CI 0.38 to 1.83) (interaction p = 0.46, suggesting that the difference in effect between subgroups was not statistically significant). Secondary outcomes did not differ between groups, except for FMH, which was higher under salvage in rhesus D (RhD)-negative women with RhD-positive babies (25.6% vs. 10.5%, adjusted OR 5.63, 95% CI 1.43 to 22.14; p = 0.013). No case of amniotic fluid embolism was observed. The additional cost of routine cell salvage during caesarean was estimated, on average, at £8110 per donor blood transfusion avoided. Conclusions The modest evidence for an effect of routine use of cell salvage during caesarean section on rates of donor blood transfusion was associated with increased FMH, which emphasises the need for adherence to guidance on anti-D prophylaxis. We are unable to comment on long-term antibody sensitisation effects. Based on the findings of this trial, cell salvage is unlikely to be considered cost-effective. Future work Research into risk of alloimmunisation among women exposed to cell salvage is needed. Trial registration Current Controlled Trials ISRCTN66118656. Funding This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 22, No. 2. See the NIHR Journals Library website for further project information