A tool to predict spontaneous preterm birth, incorporating fetal fibronectin and cervical length, in symptomatic women and high-risk asymptomatic women

About this app

Intended usage

This application has been designed for health, allied health and health research professionals who look after pregnant women to calculate individualized % risk scores of delivery within pre-specified clinically relevant timeframes.  Accurate diagnosis of preterm labour is desirable in order to prevent the maternal and fetal risks incurred to the majority of women who are over-managed, without missing true cases.   It is designed to be used with women as an educational tool and to arrive at shared decisions regarding the management of their pregnancy.

It is designed for use in two clinical settings:

  1. For management of asymptomatic women at high-risk for preterm birth (delivery before 37 weeks’ gestation) who are attending preterm surveillance clinics
  2.  For management of women with symptoms suggestive of abnormal or premature uterine activity (e.g. abdominal pain, contractions, tightenings).

It relies on a relevant clinical history having been taken regarding the woman’s risk factors for preterm birth and her current symptoms.   It relies on existing point-of-care testing: quantitative fetal fibronectin (fFN) sampling of the cervico-vaginal fluid and/or transvaginal ultrasound cervical length (CL) measurements.   Therefore the user is expected to have significant midwifery or obstetric experience in order to use QUiPP app or is working closely with a team-member who does.

Relevant clinical history and examination

The assessment of gestational age should be based on the last day of the menstrual period and confirmed by ultrasound before 20 weeks’ gestation.

The asymptomatic algorithm is suitable for women who are assessed between 18+0 and 36+6 weeks, with at least one of the following risk factors for preterm birth, so the clinician needs to ask the woman regarding all of the following:

The symptomatic algorithm is suitable for women between 23+0 and 34+6 weeks with abdominal pain, contractions or tightenings suggestive of threatened preterm labour. The following risk factors should be sought from the clinical history:

Neither algorithm is suitable for women with

Quantitative Fetal Fibronectin (fFN) Measurement

All clinicians should be trained in the use of quantitative fFN analysers.  A quantitative fFN sample should be obtained by an obstetrician or midwife during a sterile speculum examination in which a polyester swab is inserted into the posterior fornix of the vagina to collect cervicovaginal secretions. One aliquot (200 µL) of the sample should be analyzed with the quantitative Rapid fFN 10Q analyzer (Hologic) according to manufacturer’s instructions.

Results from women with blood-stained swabs or sexual intercourse within the last 48 hours should not be used in the QUiPP app due to know interference with qfFN measurements.

Cervical Length Measurement

Cervical length measurements (mm) should be performed after the fFN swab has been taken using trans-vaginal ultrasonography performed by trained staff only.   The shortest of three values should be used in the QUiPP app.

Calculation methods and functions

The current version of the QUiPP predictor (asymptomatic) is based on 1,803 asymptomatic women at high risk of premature delivery who provided CL & fFN measurements at 3878 visits; including 288 spontaneous and 165 iatrogenic preterm deliveries. Measurements of fFN & CL were made around 23+0 weeks, with all between 18+0 and 36+6 weeks.

The current version of the QUiPP predictor (symptomatic) is based on 1,032 women with symptoms suggestive of premature labour, providing fFN samples on 1,173 occasions, starting between 23+0 and 34+6 weeks, of whom 204 women had cervical length measured on 227 occasions, and 122 women had spontaneous premature deliveries before 37 weeks of gestation. Measurements of fFN & CL were made around 29+3 weeks, with all between 23+0 and 34+6 weeks.

The probabilities of delivery are estimated by survival analysis models using lognormal (for symptomatic women) and loglogistic distributions (for asymptomatic women), adjusting for measured values of CL and fFN, and reported risk factors, conditional on the pregnancy having continued to the day of testing.

Notes on Percentage Risks and Management

If a 0.0% risk is quoted - this means that no women in our cohort delivered within this timeframe with this set of parameters.  It cannot mean that the woman truly has no risk of delivery within the timeframe, just that it is negligible.

A very low-risk test still implies that there is a small risk of delivery and with-holding treatments in these women may be an accepted part of the clinical pathway, in order to balance harm of over-treatment.  In the unlikely event that a woman goes on to labour, despite a low-risk test, the clinical pathway should still allow for these women to re-present and receive timely interventions.

The QUiPP app is a decision-making aid and is not meant to replace clinical judgement.  Whilst the creators of the QUiPP app expect that these more precise estimations of risk will facilitate more targeted therapeutic interventions to those who need them and decrease unnecessary intervention to those who do not, the precise % risk which should warrant interventions such as admission or steroids is left to individual care providers.

Terms of use

By using this application you acknowledge that you are over 18 years of age and are a health, allied health or health research professional.  This application is not designed for use by patients, general public, or those under the age of 18 years. By using this application you acknowledge full responsibility and liability pertaining to your use and any courses of action you take as a direct or indirect result of using the application.    

Disclaimer

Every effort has been made to ensure that all calculations are entirely accurate, however calculation accuracy is not guaranteed and King’s College London accepts no liability for any calculation error. King’s College London holds no claims to the clinical validity or plausibility of generated results and it is your responsibility to interpret the generated results.  The application is not a substitute for medical advice or diagnosis.  Kings College London accepts no liability for your use of this application and advise that your use is at your own risk. It is your responsibility to ensure you are using the most up-to-date version to accommodate evolving changes in best practice and evidence base.

Acknowledgements

The app has been developed by Genetic Digital and its development and research has been funded by Guy’s and St Thomas’ Charity, National Institute of Health Research, Tommy’s Charity and the King’s College London Lionsden Health Innovation Prize.

We would like to thank all the women and families who have contributed to our preterm birth studies which have enabled the creation of QUiPP.  

The QUiPP app has undergone independent testing and has received regulatory approval by the competent authority and we declare that this product conforms to the relevant requirements of the Medical Devices Directive (MDD) 93/42/EEC.

Version history

QUiPP version 2.0, released Oct 2017
Concept by Women's Health academic Division, King's College London
© 2017 King's College London, All rights reserved