Prognosis for 7 Weeks 5 Days Gestation with 5.5mm Yolk Sac
A yolk sac measuring 5.5mm at 7 weeks 5 days gestation is within normal limits and carries a favorable prognosis, provided cardiac activity is present and the yolk sac demonstrates normal morphology. 1
Critical Prognostic Determinants
The most important factor determining prognosis at this gestational age is the presence or absence of embryonic cardiac activity, not the yolk sac measurement alone 1, 2:
- Yolk sac size of 5.5mm is reassuring: Normal yolk sac measurements range from <6mm, with the upper limit of normal extending to approximately 8.1mm in documented viable pregnancies 1
- Your measurement falls comfortably within the normal range and does not indicate poor prognosis 1
Essential Next Steps for Prognostication
You must document the following parameters to provide accurate prognostic information 1, 2:
- Confirm presence of embryo with cardiac activity: This is the single most critical prognostic factor at 7 weeks 5 days gestation 1
- Measure crown-rump length (CRL) if embryo is visible 1
- Assess yolk sac morphology: Should be thin-rimmed, circular, and eccentrically positioned within the gestational sac 1
Poor Prognostic Indicators to Exclude
While your yolk sac measurement is normal, be vigilant for these concerning findings 1:
- Yolk sac ≥6mm or progressive enlargement on serial ultrasounds indicates impending pregnancy loss 1
- Calcified yolk sac appearance represents advanced degeneration and definitive poor prognosis 1
- Expanded amnion sign: enlarged amniotic cavity relative to embryonic CRL 1
- CRL ≥7mm without cardiac activity is diagnostic of pregnancy loss 1
Critical Pitfall to Avoid
Do not diagnose pregnancy loss based solely on yolk sac size 1. The 2025 Society of Radiologists in Ultrasound guidelines emphasize that yolk sac abnormalities alone are only "concerning for" but not "diagnostic of" early pregnancy loss 1. Additional definitive criteria must be documented before making a definitive diagnosis 1.
Recommended Management Algorithm
If cardiac activity is present 1, 2:
- Prognosis is excellent with yolk sac 5.5mm
- Routine prenatal care continues
- Serial measurements are more valuable than single measurements for predicting outcomes 1
If no embryo is yet visible 2:
- This is acceptable at 7 weeks 5 days gestation
- Follow-up ultrasound in 7-10 days to document embryonic cardiac activity 2
- Presence of yolk sac confirms intrauterine pregnancy and is reassuring 2
If embryo is visible without cardiac activity 1: