More on the Unreliability of First Trimester Ultrasounds

Doctors are so quick to tell us how accurate the first trimester ultrasound is.  On the Misdiagnosed Miscarriage site, we've been hearing it for years but we've also known it's not true.

If your doctor is telling you how accurate the first trimester ultrasound is, take a moment to look at an abstract of this study published in 2012:

Fertil Steril. 2012 Nov;98(5):1091-6. doi: 10.1016/j.fertnstert.2012.09.017. 

When is a pregnancy nonviable and what criteria should be used to define miscarriage?

Bourne T¹, Bottomley C.

Abstract

In 2011, the first systematic review of the evidence behind the diagnostic criteria for miscarriage was published. It states, "findings were limited by the small number and poor quality of the studies," and concluded that further studies were, "urgently required before setting future standards for the accurate diagnosis of early embryonic demise." This implies that data used to define criteria to diagnose miscarriage are unreliable. The 2011 Irish Health Service executive review into miscarriage misdiagnosis highlighted this issue. In parallel to these publications a multicenter prospective study was published examining cut-off values for mean sac diameter (MSD) and embryo size to define miscarriage. The authors also published evidence on expected findings when ultrasonography is repeated at an interval. This led to guidance on diagnostic criteria for miscarriage in the UK changing. These new criteria state miscarriage be considered only when: an empty gestation sac has an MSD of ≥ 25 mm (with no obvious yolk sac), or embryonic crown rump length ≥ 7 mm (the latter without evidence of fetal heart activity). If in doubt, repeating scans at an interval is emphasized. It is axiomatic that decisions about embryonic viability must not be open to doubt. So it is surprising how little evidence exists to support previous guidance. Any clinician working in this area knows of women being wrongly informed that their pregnancy has failed. This cannot be acceptable and guidance in this area must be "failsafe."
Copyright © 2012 American Society for Reproductive Medicine.

So, what does this mean?  These researchers bemoan the lack of studies for diagnosing a miscarriage.   This is something we've recognized on the site and if we could get doctors to listen to these researchers, it would cut the number of misdiagnosed miscarriages greatly. 

I put together a page some time ago What You May Not Know About a Blighted Ovum which discusses the inaccuracy of the current ultrasound guidelines.  By the ultrasound guidelines, my baby should have been a blighted ovum because the gestational sac was still empty looking at 21.5mm.  One week later, we saw our little baby be-bopping away in there and the sac was measuring 28.5mm. 

I like the new criteria used in the UK of 25mm for the gestational sac.  I know this would greatly cut down on misdiagnosed miscarriages. 

If your gestational sac is less than 25mm, looking empty and the doctor is mentioning miscarriage. click on the link in the article and print out that abstract.  Give him a copy.  You may just change his mind and you just may save future babies. 

As always, (((Hugs))) if you are going through a miscarriage scare right now.