Surveillance of amniotic fluid embolism

Summary

Amniotic fluid embolism has been identified by the UK Confidential Enquiry into Maternal Deaths as a leading cause of maternal mortality. A wide range of treatments have been described in case reports, but there has been no comprehensive study of the epidemiology and management of this condition in the UK. This descriptive study incorporates the previous voluntary register of cases and aims to document the incidence of the condition, its management and outcomes.

Key findings

• Analysis of data reported over four years to UKOSS shows an estimated incidence of amniotic fluid embolism (AFE) of 2.0 cases per 100,000 maternities (95% CI 1.5-2.5/100,000).
• AFE occurrence was significantly associated with induction of labour (adjusted odds ratio (aOR) 3.86, 95% confidence interval (CI) 2.04-7.31) and multiple pregnancy (aOR 10.9, 95%CI 2.81-42.7). An increased risk was also noted in older ethnic minority women (aOR 9.85, 95%CI 3.57-27.2).
• Caesarean delivery was associated with postnatal amniotic fluid embolism (aOR 8.84, 95%CI 3.70-21.1).
• Twelve women died (case fatality 20%, 95%CI 11-32%); women who died were significantly more likely to be from ethnic minority groups (aOR 11.8, 95%CI 1.40-99.5).
• In view of the extreme rarity of this condition and the significant associated mortality, surveillance through UKOSS is ongoing in order to further investigate risk factors and describe outcomes following the use of different management techniques.

Analysis of nine years' data showed:

• There was no significant change in the incidence or fatal incidence of AFE over the time period of the study.
• In common with previous analyses, women aged 35 years and over had significantly raised odds of having AFE. The odds of having AFE were also significantly increased in women who had a multiple pregnancy, placenta praevia and induction of labour using any method.
• Women who died or who had permanent neurological injury were more likely to present with cardiac arrest (83% versus 33%, P < 0.001), be from ethnic-minority groups (aOR 2.85, 95% CI 1.02–8.00), to have had a hysterectomy (OR 2.49, 95% CI 1.02–6.06), and were less likely to receive cryoprecipitate (OR 0.30, 95% CI 0.11–0.80).
• These findings may reflect that the women who die or have permanent neurological injury are sickest at presentation; however, further investigation is warranted to establish whether better and more rapid correction of coagulopathy, through the use of cryoprecipitate, fresh frozen plasma, platelets and fibrinogen is associated with improved outcomes.

Publications

Journal Articles

• Knight M, Tuffnell D, Brocklehurst P, Spark P, Kurinczuk JJ. Incidence and Risk Factors for Amniotic-Fluid Embolism. Obstet Gynecol. 2010;115(5):910-17.
• Knight M, Berg C, Brocklehurst P, Kramer M, Lewis G, Oats J, Roberts C, Spong C, Sullivan E, van Roosmalen J, Zwart J. Amniotic fluid embolism incidence, risk factors and outcomes: a review and recommendations. BMC Pregnancy Childbirth. 2012;12:7.
• Knight M, Fitzpatrick K, Kurinczuk JJ, Tuffnell D. Use of recombinant factor VIIa in patients with amniotic fluid embolism (author reply). Anesthesiology. 2012;117(2):423-4.
• Kristufkova A, Borovsky M, Korbel M, Knight M. Amniotic fluid embolism--investigation of fatal cases in Slovakia in the years 2005-2010 compared with fatal cases in the United Kingdom. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub. 2014;158(3):397-403.