Presentation
Pregnant. Dates unkown.
Patient Data
There is rounded, anechoic structure located eccentric to the endometrial cavity (intradecidual sign) - in keeping with an intrauterine gestational sac. The clip images (second stack) show more clearly the presence of a double decidual sign. Appearance is therefore compatible with an intrauterine gestational sac with a high level of certainty, even though no yolk sac or embryo are visible at this stage.
Mean sac diameter - 6mm.
Note the incidental presence of bilateral corpora lutea.
Case Discussion
An intrauterine gestational sac without a visible embryo with a heartbeat constitutes a pregnancy of uncertain viability. A repeat ultrasound should be performed, in a timeframe whereby the diagnosis of either a viable pregnancy or a miscarriage can be made definitively, as ongoing uncertainty and numerous scans could exacerbate the patient's anxiety.
Based on the landmark paper by Preisler et al 1, re-scan is recommended as follows:
MSD <12 mm with no embryo - rescan in 14 days
- if MSD has not doubled and there is still no embryo - diagnosis of failed pregnancy can be made
MSD 12-25 mm with no embryo - rescan in 7 days
- if no embryo with cardiac activity present - diagnosis of failed pregnancy can be made.
Please refer to the relevant article on pregnancy of uncertain viability (PUV) for further diagnosis and follow-up guidelines.
Note that quantitative bHCG has no role in the diagnosis of pregnancy failure - criteria are based on ultrasound only. Therefore, the radiology report does need to recommend serial bHCG in the follow-up of PUV.
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