Addendum to GTG No 25 (Oct 2006): The Management of Early Pregnancy Loss

Recent research suggests that given inter-observer variability in ultrasound measurements and the greater variation in early embryonic growth than has hitherto been assumed, a more conservative approach to the diagnosis of early pregnancy loss is warranted. 

The studies from Imperial College London, Queen Mary, University of London and the Katholieke Universiteit Leuven, Belgium published in the November 2011 issue of Ultrasound in Obstetrics and Gynaecology concluded that current definitions used to diagnose miscarriage could lead to an incorrect diagnosis and they call for clearer evidence-based guidance on detecting miscarriage through ultrasound scans. 

Having carefully considered these papers, we recommend adoption of the following interim guidance with immediate effect:

1. Ultrasound diagnosis of miscarriage should only be considered with a mean gestation sac diameter >/= 25mm (with no obvious yolk sac), or with a fetal pole with crown rump length >/=7mm (the latter without evidence of fetal heart activity)
2. Transvaginal ultrasound scan should be performed in all cases where there is uncertainty.
3. Where there is any doubt about the diagnosis and/or a woman requests a repeat scan, this should be performed at an interval of at least one week from the initial scan before medical or surgical measures are undertaken for uterine evacuation. No growth in gestation sac size or CRL is strongly suggestive of a non-viable pregnancy in the absence of embryonic structures.

These revised values for 'mean gestation sac diameter' and 'crown rump length' do not imply that previously used values were wrong, nor that diagnosis of miscarriage in the past has been unsafe, This interim guidance suggests a more cautious approach is warranted, pending more definitive data becoming available. It extends the criteria included in the RCOG Green Top Guideline No 25, which recommended a conservative approach with mean gestation sac diameter <20mm or fetal CRL <6mm. 

Authors:

• Christoph Lees MRCOG on behalf of the RCOG Ultrasound Advisory Group
• Kim Hinshaw FRCOG Lead author, Green Top Guideline No. 25  Philip Owen FRCOG Chair, RCOG Guidelines Committee
• David Richmond FRCOG RCOG Vice President (Standards)

19th October 2011

RCOG clinical guideline The Management of Early Pregnancy Loss

Ultrasound diagnosis of miscarriage should only be considered when:

• Mean Gestation Sac Diameter >/= 25mm (with no obvious yolk sac) on Transvaginal scan
• A fetal pole with Crown Rump Length (CRL) >/= 7mm on Transvaginal scan (without evidence of fetal heart activity)
• A fetal pole with Crown Rump Length (CRL) >/= 32mm on Transabdominal scan (without evidence of fetal heart activity)

A second Sonographer (with at least one years post competency experience) MUST physically rescan the woman to confirm the diagnosis. If this is not possible the same day then another scan should be performed by a DIFFERENT Sonographer at a time that suits patient/department or at an interval of at least one week from the initial scan if the scan is performed by the SAME Sonographer.

Sonographers MUST ensure the name and authorisation boxes are completed on Badger net.

In all cases, where there is any doubt about the diagnosis and/or a woman requests a repeat scan, this should be performed at an interval of at least one week from the initial scan before medical or surgical measures are undertaken for uterine evacuation.