Studies

Amniotic fluid embolism (AFE)

Background

Amniotic fluid embolism (AFE) is the leading cause of direct maternal death in Australia.1 We currently have a poor understanding of the incidence of this condition with estimates ranging from 1 in 8 000 to 1 in 80 000 maternities.2 The UKOSS found active surveillance identified twice as many cases as passive registration.3 Previous studies have identified a number of risk factors for AFE which may affect the incidence4 whilst the early diagnosis and treatment may affect the outcomes for this condition.3 There has been no comprehensive study of this major cause of maternal mortality in Australia, with the epidemiology and management of this condition unknown.

Research questions

  1. What is the current incidence of amniotic fluid embolism in Australia?
  2. How is amniotic fluid embolism managed in Australia?
  3. What are the outcomes for both mother and infant of amniotic fluid embolism in Australia?
  4. Are there any risk factors that may alter the outcomes for mothers and infants in Australia?

Method

Prospective prevalence study using monthly negative surveillance system of all birthing services in Australia (>50 births) – AMOSS. Nominated clinicians and midwives within each maternity unit are e-mailed a simple tick-box to indicate whether a case has occurred or whether there is ‘nothing to report’. If a case arises, the reporting clinician completes a case form using the secure web-based data system. Only non-identifiable data are collected.

Study period

January 2010 – ongoing (surveilance and observational study ANZ)

Case definition

All women in Australia identified as having AFE using the following definition:
EITHER a clinical diagnosis of AFE (acute hypotension or cardiac arrest, acute hypoxia and coagulopathy in the absence of any other potential explanation for the symptoms and signs observed)
OR a pathological/post mortem diagnosis (presence of fetal squames/debris in the pulmonary circulation).

Study size

The study was run initially for three years, with an estimated sample size during this period of between 11 and 20 cases based on the incidence found in the UK of 1.8 (95%CI 1.3 to 2.4) cases per 100 000 maternities.3 However, AMOSS has found a higher incidence in Australia which is consistent with the maternal deaths reported in the 2003-2005 triennium as well as separation data from the NHMD.

Funding

We gratefully acknowledge our funding partners.

Initial funding was through a five year project grant (Australian National Health and Medical Research Council NHMRC #510298 2008-2012), which provided support for AFE and other AMOSS studies as well as the AMOSS infrastructure.

The University of New South Wales provided support to redevelop the AMOSS site with a Major Research Equipment and Infrastructure Initiative (MREII) Grant in 2013.

Other funding support has been provided through the University of Technology Sydney.

Data collection is supported by AMOSS participating sites.

References

  1. Sullivan, E., B. Hall, and J. King, Maternal deaths in Australia 2003-2005, in Maternal Deaths Series no. 3. Cat. no. PER 42. 2008, AIHW National Perinatal Statistics Unit: Sydney.
  2. Moore, J. and M. Baldisseri, Amniotic fluid embolism. Crit Care Med, 2005. 33 (Supplement): p. S279-S285.
  3. Knight M, Kurinczuk JJ, Spark P and Brocklehurst P on behalf of UKOSS. United Kingdom Obstetric Surveillance System (UKOSS) Annual Report 2008. National Perinatal Epidemiology Unit, Oxford 2008.
  4. Wagner, M., From caution to certainty: hazards in the formation of evidence-based practice – a case study on evidence for an association between the use of uterine stimulant drugs and amniotic fluid embolism. Paediatric & Perinatal Epidemiology, 2005. 19(2): p. 173-176.
  5. National Hospital Morbidity Database – AIHW.