3-D power Doppler for diagnosis of abnormally invasive placentation
Research type
Research Study
Full title
Three dimensional power Doppler imaging for the diagnosis and clinical risk stratification of abnormally invasive placentation
IRAS ID
148255
Contact name
Sally Collins
Contact email
Sponsor organisation
Oxford University Hosptials NHS Foundation Trust
Research summary
Research Summary
Abnormally invasive placentation (AIP) had the potential to cause catastrophic bleeding at delivery and the incidence was increasing. This was probably due to the rising rate of caesarean section, an independent risk factor for AIP. There was evidence that maternal mortality could be significantly reduced if the diagnosis was made antenatally and delivery was undertaken in a tertiary referral centre with an experienced multi-disciplinary team.
However, diagnosis of AIP could be difficult as it relied on the subjective assessment of either ultrasound or MRI images. Consequently the accuracy was highly dependent on operator experience. The study team had developed novel ultrasound image analysis tools which could examine the utero-placental interface (UPI) in three dimensions. These tools could also be used to allow quantification of the size, site and depth of the power Doppler signal occurring within the placental bed, myometrium and adjacent structures such as the bladder wall.
The study team were proposing to undertake an image analysis study to develop and test whether these tools could diagnose AIP. The data was already collected as part of the standard diagnostic procedure for AIP but was currently only used in a qualitative manner. By generating numerical markers from the images, the study team planned to develop a quantitative test for AIP. This ultrasound based, objective image analysis tool should not only diagnose AIP but also stratify the risk it poses to the mother. This had the potential to decrease both maternal mortality and morbidity.
Summary of Results
This was a simple study which recruited pregnant women who had a diagnosis of abnormally invasive placenta (now called placenta accreta spectrum, PAS). This is a very rare but potentially life-threatening pregnancy condition. The study used the ultrasound scans routinely collected in Oxford as part of their NHS care, to see if we could find any more reliable or novel ways to diagnose the condition. We are very grateful to all of the women who allowed us to use their ultrasound scans, they have made a real difference to the care of women with PAS in the future.
The results have been excellent, and we have published six papers in the scientific literature already. We used the collected scans to develop two new ultrasound markers. One of these markers, the separation sign, is able to very effectively rule out PAS in high-risk patients. This is exceptionally important to women as it potentially avoids unnecessary surgical interventions which can have unpleasant side effects. We also used the data to demonstrate that the diagnosis was more accurate when the woman had a full bladder at the ultrasound scan. This will ensure that sonographers worldwide know to take this simple step to improve their diagnostic accuracy. Another paper used the ultrasound scan findings along with other known risk factors to develop an algorithm to help diagnose PAS. This is promising but the full clinical usefulness has yet to be demonstrated for different sonographers outside of our hospital. The final two papers used complex biomedical engineering techniques to try to develop fully-automated ultrasound markers for PAS. The results show promise, but techniques will need more work before they will be able to be employed to help patients directly.
REC name
North of Scotland Research Ethics Committee 2
REC reference
14/NS/0069
Date of REC Opinion
22 May 2014
REC opinion
Further Information Favourable Opinion