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Four new papers investigated the diagnosis of miscarriage.
Prof Lesley Regan MD FRCOG, Imperial College at St Mary’s Campus London, said:
“The publication of these studies is to be welcomed. It is great news that people are undertaking this work since the current ultrasound reference values were developed many years ago.
“These studies are multicentred and have sufficient numbers to provide us with valuable and robust data on which to improve the current guidelines on miscarriage.”
Dr Tony Falconer, President of the Royal College of Obstetricians & Gynaecologists (RCOG), said:
“We welcome these papers on the accurate detection of early miscarriage.
“The RCOG peer reviews its guidelines routinely and works with other organisations such as NICE to develop best practice advice for doctors. The findings from these papers add to our knowledge of clinical practice and will be considered when we update our guidelines.
“Miscarriage is an upsetting experience for anyone and all women who have had a miscarriage should have access to support from the NHS. Healthcare professionals must receive the best training possible to ensure that they are competent in antenatal screening and diagnoses so that mistakes are avoided.”
Further information from RCOG: Miscarriage occurs in 20% of pregnancies. A miscarriage is often confirmed by using an ultrasound scan to see whether there is any sign of a pregnancy sac or embryo in the womb.
Professor Jane Norman, Director of the Tommy’s Centre for Maternal and Fetal Health, University of Edinburgh, said:
“These papers by Bourne and colleagues provide very helpful information on the ultrasound measurements that should be used to diagnose miscarriage. The information has been obtained from scans of over 1000 women presenting to early pregnancy units. In women in early pregnancy, it can often be difficult to confidently distinguish a very early ongoing pregnancy from a miscarriage. Most UK units will adhere to guidelines from the Royal College of Obstetricians (RCOG) on the management of early pregnancy loss in order to make this diagnosis (www.rcog.org.uk). These new data show that following the current RCOG guidelines will give the correct diagnosis in the vast majority of women. They also provide some robust new evidence on which to further improve guidelines for diagnosis in this very important clinical condition.”
Dr Mark Hamilton, Consultant Gynaecologist at Aberdeen Maternity Hospital and Honorary Senior Lecturer at the University of Aberdeen, said:
“Ultrasound is an excellent investigative tool in the assessment of women suspected of miscarriage. Gynaecologists have long been aware that in this distressing clinical situation the interpretation of ultrasonic measurements needs to take account of the particular clinical circumstances, the potential for change in scan findings over time, the nature and precision of the scan performed (vaginal or abdominal) and the skill of the sonographer. These papers reinforce the need for clinical staff to continue to exercise great care in the diagnosis of non-viable pregnancy to minimise the risk of misdiagnosis. Those working in early pregnancy assessment units should examine current protocols used in the diagnosis of miscarriage, including the time interval between scans. Where clinical circumstances permit, women should continue to be managed expectantly without the need for medical treatment or surgery until the diagnosis of non-viability is established with certainty.”
Dr Colin Duncan, Senior Lecturer in Reproductive Medicine, University of Edinburgh, said:
“Miscarriage is common and distressing for the couple involved. Staff in Early Pregnancy Units strive to make an accurate diagnosis that both avoids missing an ongoing pregnancy and unnecessarily prolonged periods of uncertainty.
“Assessment and diagnosis of women in early pregnancy takes into account multiple factors including date of the last menstrual period and positive pregnancy test, previous investigations, clinical symptoms and an ultrasound scan. Guidelines from the Royal College of Obstetricians and Gynaecologists have helped standardise the ultrasound criteria that can be used to diagnose an inevitable miscarriage.
“It is important that these guidelines are audited and scrutinised in an ongoing basis locally and nationally to ensure the highest quality of care.
“The papers by Bourne and colleagues are to be welcomed as they provide information that will be very helpful during the ongoing cycle of guideline review and revision.
The RCOG guidelines highlight two features that can be used on a single scan to diagnose miscarriage. A fetal size of 6mm or more with no heartbeat and pregnancy sac with a mean diameter of 20mm or more with no contents.
“No ongoing pregnancies were seen when the fetal size was ≥5.3mm or where an empty pregnancy sac had a mean diameter of >20mm. One patient with an empty sac diameter of 20mm had an ongoing pregnancy.
“As there is a variation between scanners the authors suggest that increasing the criteria for the diagnosis of miscarriage to a fetal size of more than 7mm or an empty sac diameter of more than 25mm would minimise any potential for the misdiagnosis of miscarriage due to intra-observer variation in scanning.
“The papers highlight the need to be cautious at the limits for diagnosis of miscarriage. The Association of Early Pregnancy Units recommends that a scan diagnosis of miscarriage is confirmed by a second ultrasonographer. While the British Medical Ultrasound Society states that it should not be necessary for a second opinion but that it should be available and considered if there is any doubt. These data highlight that one indication for a second opinion is at the limits for diagnosis of miscarriage.
“It is important that all units continue to audit their scanning service and local protocols. In Edinburgh we recently audited 776 pregnancies with a fetal size between 1mm and 6mm and no fetal heart. No pregnancy in the 462 patients with no FH and a fetal size >3mm had a subsequent ongoing pregnancy.
“The successful introduction of specialised Early Pregnancy Units in the UK has made this research possible and will continue to drive improvements in the difficult diagnosis and management of couples with early pregnancy problems.”
This series of 4 papers was published in Ultrasound in Obstetrics and Gynecology on Friday 14th October. The details are as follows: ‘Accuracy of first-trimester ultrasound in the diagnosis of early embryonic demise: a systematic review’ by Jeve et al., DOI: 10.1002/uog.10108. ‘Limitations of current definitions of miscarriage using mean gestational sac diameter and crown–rump length measurements: a multicenter observational study’ by Abdallah et al., DOI: 10.1002/uog.10109. ‘Gestational sac and embryonic growth are not useful as criteria to define miscarriage: a multicenter observational study’ by Abdallah et al., DOI:10.1002/uog.10075. ‘Clinical implications of intra- and interobserver reproducibility of transvaginal sonographic measurements of gestational sac and crown–rump length at 6–9 weeks’ gestation’ by Pexsters et al. DOI: 10.1002/uog.8884.