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Australian and New Zealand Journal of Obstetrics and Gynaecology

A prediction model for viability at the end of the first trimester after a single early pregnancy evaluation

Authors

  • Jennifer Oates,

    1. Early Pregnancy and Advanced Endosurgery Unit, Acute Gynaecology, Nepean Centre for Perinatal Care, Nepean Clinical School, Nepean Hospital, University of Sydney, Kingswood, Australia
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  • Ishwari Casikar,

    Corresponding author
    • Early Pregnancy and Advanced Endosurgery Unit, Acute Gynaecology, Nepean Centre for Perinatal Care, Nepean Clinical School, Nepean Hospital, University of Sydney, Kingswood, Australia
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  • Anna Campain,

    1. School of Mathematics and Statistics, University of Sydney, Sydney, Australia
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  • Samuel Müller,

    1. School of Mathematics and Statistics, University of Sydney, Sydney, Australia
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  • Jean Yang,

    1. School of Mathematics and Statistics, University of Sydney, Sydney, Australia
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  • Shannon Reid,

    1. Early Pregnancy and Advanced Endosurgery Unit, Acute Gynaecology, Nepean Centre for Perinatal Care, Nepean Clinical School, Nepean Hospital, University of Sydney, Kingswood, Australia
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  • George Condous

    1. Early Pregnancy and Advanced Endosurgery Unit, Acute Gynaecology, Nepean Centre for Perinatal Care, Nepean Clinical School, Nepean Hospital, University of Sydney, Kingswood, Australia
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Correspondence: Dr Ishwari Casikar, Early Pregnancy and Advanced Endosurgery Unit, Acute Gynaecology, Level 3, Women and Children's Outpatients Department, Nepean Hospital, Penrith, Sydney, Australia. Email: i_vidyasagar@hotmail.com

Abstract

Objective

The aim was to develop a new model to predict the outcome at the end of the 1st trimester after a single visit to the early pregnancy unit (EPU).

Methods

Prospective observational study in the EPU at Nepean Hospital, between November 2006 and February 2009. Data were collected from all women in the 1st trimester of their pregnancy who had a live intrauterine pregnancy (IUP) at the 1st transvaginal ultrasound scan (TVS). 29 historical, clinical and ultrasound end points were recorded. Women were followed until the final diagnosis was established at the end of the 1st trimester: viability or nonviability. A multinomial logistic regression model was developed. The performance of this model was evaluated using receiver operating characteristic (ROC) curves.

Results

Data from 416 pregnancies were included: 92.1% were live beyond the 1st trimester, and 7.9% had miscarried. The most useful prognostic variables for developing the logistic regression model were gestational age by dates, vaginal (PV) bleeding, PV clots, gestational age by TVS, consistency with menstrual dates, mean gestational sac (GS) size, mean yolk sac (YS) size and number of previous caesarean sections. Used retrospectively on 416 women based on 25 imputations, the model gave an AUC of 0.88. Based on cross-validation, the independent predictive power obtained an AUC of 0.78.

Conclusions

We have developed a new model to predict the outcome of the 1st trimester in women with live IUP at the 1st scan.

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