What transvaginal ultrasound findings are diagnostic of pregnancy failure in a 32-year-old woman (G3P0) at 7 weeks and 6 days gestation by Last Menstrual Period (LMP)?

Diagnostic Criteria for Pregnancy Failure on Transvaginal Ultrasound

Option D is the only finding diagnostic of pregnancy failure: absence of embryo with heartbeat >11 days after a scan that showed a gestational sac with a yolk sac. 1

Analysis of Each Option

Option A: Crown Rump Length of 5mm and No Heart Rate

• This is NOT diagnostic - it is only "concerning for" early pregnancy loss, not definitive 1
• A crown-rump length (CRL) must be ≥7 mm without cardiac activity to definitively diagnose embryonic demise 1, 2
• At 5mm CRL, this finding requires follow-up imaging in 7-10 days before making a definitive diagnosis 1
• The 2025 Society of Radiologists in Ultrasound consensus specifically categorizes CRL <7mm without cardiac activity as "concerning for EPL" rather than "diagnostic of EPL" 1

Option B: Mean Sac Diameter of 20mm and No Embryo

• This is NOT diagnostic - it falls in the intermediate "concerning" zone 1
• The diagnostic threshold is a mean sac diameter (MSD) of ≥25 mm without an embryo 1, 3
• An MSD of 16-24mm without an embryo is classified as "concerning for EPL" and requires follow-up ultrasound in 7-10 days 1
• Making a diagnosis at 20mm MSD would risk misdiagnosing a viable early pregnancy 1

Option C: Absence of Embryo with Heartbeat >10 Days After Scan Showing Gestational Sac Without Yolk Sac

• This is NOT diagnostic - the time interval is insufficient 1
• The required interval is ≥14 days (not 10 days) after visualization of a gestational sac without a yolk sac 1
• At 7-13 days, this finding is only "concerning for EPL" 1
• The 2025 consensus guidelines explicitly state that 14 or more days is required for definitive diagnosis 1

Option D: Absence of Embryo with Heartbeat >11 Days After Scan Showing Gestational Sac With Yolk Sac

• This IS diagnostic of pregnancy failure 1
• The presence of a yolk sac establishes that sufficient time has passed for embryonic development 1
• After ≥11 days following visualization of a gestational sac with a yolk sac, absence of an embryo with cardiac activity definitively confirms pregnancy failure 1
• This criterion is based on the 2013 Doubilet criteria referenced in the 2025 SRU consensus guidelines 1

Critical Clinical Pitfalls to Avoid

• Never diagnose pregnancy failure on a single scan - these criteria specifically require serial examinations at defined time intervals 1
• Do not use transabdominal ultrasound alone for these measurements - transvaginal ultrasound is required for accurate assessment in the first trimester 1
• Avoid premature diagnosis - using thresholds below the established criteria (such as 5mm CRL instead of 7mm, or 20mm MSD instead of 25mm) risks terminating viable pregnancies 1
• Document exact measurements - crown-rump length must be measured accurately along the longest axis of the embryo 1, 2
• Confirm dates - ensure gestational age by last menstrual period is reliable, as dating errors can lead to misdiagnosis 1, 4

Summary of Definitive Diagnostic Criteria

The 2025 Society of Radiologists in Ultrasound consensus establishes these definitive criteria for pregnancy failure on transvaginal ultrasound 1:

• CRL ≥7 mm without cardiac activity
• MSD ≥25 mm without an embryo
• Absence of embryo with cardiac activity ≥14 days after visualization of gestational sac without yolk sac
• Absence of embryo with cardiac activity ≥11 days after visualization of gestational sac with yolk sac (Option D)