Studies

Placenta accreta

[Data collection for this study is complete. Analysis in progress]

Background

The incidence of placenta accreta is increasing 1,2 and it carries a high level of morbidity; most notably peripartum hysterectomy. There is a strong association between prior caesarean section and abnormal placental location and attachment.2 The increased incidence of placenta accreta is a cause of concern with the increasing caesarean section rate in Australia. Whilst many women with placenta accreta undergo hysterectomy at the time of caesarean delivery, some women will have their placenta left in-situ, which has been shown to be a safe alternative in some cases.3,4 The epidemiology and management of placenta accreta in Australia is not known.

Research questions

  1. What is the current incidence of placenta accreta in Australia and New Zealand?
  2. What are the risk factors for placenta accreta in Australia and New Zealand?
  3. How is placenta accreta managed in Australia and New Zealand?
  4. What are the outcomes for both the mother and the infant of placenta accreta in Australia and New Zealand?

Method

Prospective case-control study using monthly negative surveillance system of all birthing services in Australia (>50 births) – AMOSS. Nominated clinicians and midwives within each maternity unit will be e-mailed a simple tick-box to indicate whether a case occurred or whether there is ‘nothing to report’. If a case arose, the reporting clinician will complete a case form using the secure web-based data system. The clinician/midwife will also complete two control forms using the secure web-based data system. Only non-identifiable data will be collected.

Study period

January 2010 – December 2011 (Aust) 2012 (NZ)

Case definition

The cases will be all women in Australia identified as having placenta accreta (or increta or percreta):
EITHER diagnosed by antenatal imaging
OR diagnosed at operation
OR diagnosed by pathology specimen

Control selection

The two women giving birth immediately prior to the woman with the condition, in the same hospital.

Study size

The study was initially run for eighteen months. The estimated sample size for this time duration was between 112 and 506 based on the published incidence rates of 1 in 2510,5 and 1 in 553.6

Investigators

AMOSS CHIEF INVESTIGATORS

Professor Elizabeth Sullivan, Principal Investigator AMOSS, Professor of Public Health, Assistant Deputy Vice Chancellor, University of Technology Sydney and Conjoint Professor, UNSW Medicine, New South Wales

Professor David Ellwood, CI AMOSS, Director of Maternal-Fetal Medicine, Professor of Obstetrics & Gynaecology, Deputy Head of School Research, Gold Coast Health District, Queensland and Deputy Dean, College of Medicine, Australian National University, Australian Capital Territory

Professor Michael Peek, CI AMOSS, Associate Dean, Department of Obstetrics and Gynaecology, Medical School, College of Medicine, Biology and Environment, The Australian National University and Centenary Hospital for Women and Children, Australian Capital Territory

Professor Caroline Homer, CI AMOSS, Professor of Midwifery, Associate Dean: International and Development, Associate Head, WHO Collaborating Centre for Nursing, Midwifery and Health Development, Faculty of Health, University of Technology Sydney, New South Wales

Professor Lisa Jackson Pulver, CI AMOSS, ProVice Chancellor Engagement and Aboriginal and Torres Strait Islander Leadership, Western Sydney University, New South Wales 

Professor Marian Knight, NIHR Professor of Maternal and Child Population Health, National Perinatal Epidemiology Unit (NPEU), University of Oxford, UK.

Dr. Claire McLintock, CI AMOSS, Obstetric physician and haematologist, National Women's Health, Auckland City Hospital, New Zealand

AMOSS ASSOCIATE INVESTIGATORS

Professor Elizabeth Elliott, Professor of Paediatrics & Child Health, The University of Sydney and Australian Perinatal Statistics Unit, The Children's Hospital Westmead New South Wales

Clinical Assoc Professor Nolan McDonnell, Staff Specialist Department of Anaesthesia and Pain Medicine, King Edward Memorial Hospital for Women, Perth Western Australia

Dr Tessa Ho, Trustee, Mary Aitkenhead Ministries

Dr Wendy Pollock, Honorary Research Fellow, La Trobe University/Mercy Hospital for Women, Melbourne Victoria

Associate Professor Yvonne Zurynski, The University of Sydney and Australian Perinatal Statistics Unit, The Children's Hospital Westmead New South Wales

Funding and other support

We gratefully acknowledge our funding partners and participating AMOSS sites.

Initial funding was through a five year project grant (Australian National Health and Medical Research Council NHMRC #510298 2008-2012), which provided support for the first set of 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. Oyelese, Y. and J.C. Smulian, Placenta Previa, Placenta Accreta, and Vasa Previa. Obstet Gynecol, 2006. 107(4): p. 927-941.
  2. Armstrong, C.A., et al., Is placenta accreta catching up with us? Australian & New Zealand Journal of Obstetrics & Gynaecology, 2004. 44(3): p. 210-213.
  3. Kayem, G., et al., Conservative versus extirpative management in cases of placenta accreta. Obstetrics and Gynecology, 2004. 104(3): p. 531-536.
  4. Bretelle, F., et al., Management of placenta accreta: Morbidity and outcome. European Journal of Obstetrics & Gynecology and Reproductive Biology, 2007. 133(1): p. 34-39.
  5. Miller, D., Chollet, J. & Goodwin, T. Clinical risk factors for placenta previa-placenta accreta. AJOG, 1997;177:210-214.
  6. Whiteman, M., Kuklina, E., Hillis, S., Jamieson, D., Meikle, S., Posner, S. & Marchbanks, P. Incidence and determinants of peripartum hysterectomy. Obstet Gynecol 2006;108:1486-1492.

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