According to a series of reports published in the international journal Ultrasound in Obstetrics and Gynecology, current guidelines aimed to help clinicians determine if a women has had a miscarriage are ineffective and not reliable, and following these guidelines may result in wanted pregnancies accidently being terminated.

Professor BaskyThilaganathan, Editor-in-Chief of the journal, explains:

“This research shows that the current guidance on how to use ultrasound scans to detect a miscarriage may lead to a wrong diagnosis in some cases. Health professionals need clearer evidence-based guidance to prevent this happening.”

Often ultrasound scans are used see if there is any sign of a pregnancy sac or embryo in the womb in order to confirm whether a women has suffered a miscarriage. Women believe that when a diagnosis of miscarriage is made that it is correct.

In four investigations conducted at Imperial College London, UK, University of London, UK, Queen Mary, and the Katholieke Universiteit Leuven, Belgium, investigators discovered that the definitions used at present to diagnose miscarriage may result in incorrect diagnosis’s.

One piece of research revealed that the data backing the current guidelines were created on old and untrustworthy evidence. Author Dr. Shakila Thangaratinam, who works in the Women’s Health Research Unit at Queen Mary, University of London, said: “The majority of ultrasound standards used for diagnosis of miscarriage are based on limited evidence.”

When a miscarriage is suspected, clinicians use ultrasound in order to measure the size of the embryo and the gestational sac. One investigation revealed that in a few cases cut-off values to define miscarriage in these situations cannot be trusted.

At present, guidelines recommend that if there is any doubt regarding the diagnosis of miscarriage, the sac should be measured again after 7-10 days later. It is believed that if the sac does not grow in this time then a miscarriage has occurred. However, according to an investigation led by Professor Tom Bourne from Imperial College London, over this time period healthy pregnancies may not show any measurable growth.

Bourne explains:

“By identifying this problem we hope that guidelines will be reviewed so that inadvertent termination of wanted pregnancies cannot happen. We also hope backing will be given to even larger studies to test new guidelines prospectively. Currently there is a risk that some women seeking reassurance with pain or bleeding in early pregnancy may be told they have had a miscarriage, and choose to undergo surgical or medical treatment when the pregnancy is in fact healthy.

According to the final investigation, the difference in gestational sac size can vary up to 20% when different clinicians measured the same pregnancies. If the initial measurement over-estimated the size of the sac and the second underestimated the measurement some days later, it would be easy to incorrectly assume that the sac did not grow. Dr. Anne Pexsters of the Katholieke Universiteit Leuven, a co-author of this investigation, said: “These errors could lead to a false diagnosis of miscarriage being made in some women.”

Professor Dirk Timmerman from Katholieke Universiteit Leuven and co-author of three of the reports, states:

“Many of us in clinical practice have been concerned for some time about possible errors relating to the diagnosis of miscarriage. We are pleased that our data have identified where these errors might occur so that we can prevent mistakes happening in the future.”

A landmark enquiry based in Cardiff, UK, nearly two decades ago brought addition to the fact that early pregnancies might be wrongly diagnosed as a miscarriage. The researchers of the freshly published reports consider that their data reveals how to define miscarriage more carefully, with the importance being that terminations should only be carried out when there is no doubt about the miscarriage diagnosis.

Professor Bourne, explained:

“For most women sadly there is nothing we can do to prevent a miscarriage, but we do need to make sure we don’t make things worse by intervening unnecessarily in on-going pregnancies. We hope our work means that the guidelines to define miscarriage are made as watertight as we would expect for defining death at any other stage of life.”

Written by Grace Rattue