Vasa praevia

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Vasa praevia occurs when exposed fetal vessels traverse the amniotic membranes between the baby’s presenting part and the internal cervical os. Because VP is rare, it is extremely difficult to conduct prospective studies to record the incidence of the condition, and despite improvements in technology, VP is still under-reported or miscoded in maternal morbidity and mortality coding systems and epidemiological data collections2.

There is limited experience among individual practitioners in detecting VP during pregnancy and little information about what is the best management for the mother or the expected outcomes of the pregnancy for the mother and her baby.

This will be the first national population-based study of VP internationally.

Key points

  1. Vasa praevia (VP) is an uncommon obstetric condition that has a fetal mortality rate of over 60% if not prenatally detected and appropriately managed1
  2. This study will investigate the current incidence of Vasa Praevia. It will describe the current management and the association outcomes for women and their infants and contribute to evidence-based guidelines for their optimal management

Surveillance period

May 2013 - April 2014


  • To use the Australian Maternity Outcomes Surveillance System (AMOSS) to describe the incidence, management and outcomes of vasa praevia in Australia.
  • To use this information to inform guidelines for the optimal management of pregnancies complicated by vasa praevia.

Research questions

  • What is the current incidence of vasa praevia in the Australia?
  • What are the outcomes for women and their babies?
  • How are the women who have this condition managed in Australia?

Case definition

All pregnant women aged at least 18 in Australia, with the clinical diagnosis of vasa praevia at birth.

Inclusion criteria

Women were included if they met at least one of the criteria below:


  • Suspected VP on antenatal U/S ≥18 weeks gestation, and confirmed VP on antenatal U/S ≥31 weeks gestation (if not delivered prior to 31 weeks)
  • Palpation or visualisation of the fetal vessels in labour
  • Rupture of membranes with bleeding associated with fetal death/exsanguination or severe anaemia
  • Antenatal or intrapartum bleeding of fetal origin with pathologic CTG and/or positive APT test
  • VP documented in medical record as reason for admission and caesarean

And at least one of the below:

  • Clinical examination of the placenta confirming intact or ruptured velamentous vessels or fetal blood vessels in membranes. These may be a velamentous insertion of the umbilical cord or exposed fetal vessels between placental lobes
  • Placenta sent to pathology*
  • Torn umbilical cord or placenta (not able to provide placental confirmation)

* Cases will be reviewed and included if pathology report confirms fetal vessels in membranes


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

Associate Professor Yinka Oyelese, Perinatal Institute, Jersey Shore University Medical Center, United States

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

Associate Professor Robert Cincotta, Director of Queensland Ultrasound for Women and visiting Staff Specialist Dept of Maternal Fetal Medicine, Mater Mothers Hospital, Queensland

Dr. Greg Duncombe, Co-Director of Queensland Ultrasound for Women and Staff Specialist in Maternal Fetal Medicine, Royal Brisbane Women’s Hospital, Queensland

Funding and other support

We gratefully acknowledge our funding partners and participating AMOSS sites.

This study was funded by the International Vasa Praevia Foundation (# RG123304).

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.


  1. Oyelese, Y., V. Catanzarite, F. Prefumo, S. Lashley, M. Schachier, Y. Tovbin, V. Goldstein, and J. C. Smulian. 2004. Vasa previa: The impact of prenatal diagnosis on outcomes. Obstetrics and Gynecology 103 (5): 937-942. (accessed March 1, 2010).
  2. Daly-Jones, E., A. John, A. Leahy, C. McKenna, and W. Sepulveda. 2008. Vasa praevia; a preventable tragedy. Ultrasound 16 (1): 8-14. IngentaConnect. (accessed March 1, 2010).