What is 0.48cm Crown-Rump Length (CRL) in millimeters?

Crown-Rump Length Conversion: 0.48 cm to Millimeters

A CRL of 0.48 cm equals 4.8 mm.

Standard Measurement Practice

• CRL measurements must be reported in millimeters, not centimeters, to ensure accuracy in clinical practice 1
• The American College of Radiology defines CRL as the greatest linear dimension of the embryo measured from crown to rump, excluding limbs and yolk sac, and this measurement serves as the most accurate method for determining gestational age in the first trimester 1

Clinical Significance of 4.8 mm CRL

• At a CRL of 4.8 mm, the embryo is approximately 6 weeks gestational age, which is at the threshold where cardiac activity becomes reliably detectable on transvaginal ultrasound 1
• Absence of cardiac activity in an embryo measuring 4.8 mm is NOT diagnostic of embryonic demise, as cardiac activity may not yet be visible at this early stage 2
• Endovaginal ultrasound may fail to demonstrate cardiac activity in normal embryos with CRL less than 4.0 mm, and even in some embryos between 2.0-3.9 mm, warranting follow-up examination rather than immediate diagnosis of pregnancy loss 2

Diagnostic Thresholds to Remember

• The diagnostic threshold for embryonic demise is CRL ≥7 mm without cardiac activity, not 4.8 mm 3, 1
• An embryo measuring 4.8 mm without visible cardiac activity requires follow-up ultrasound examination in 5-7 days rather than immediate diagnosis of pregnancy failure 2
• The presence of cardiac activity at any CRL is associated with approximately 24% risk of spontaneous abortion, while absence of cardiac activity in embryos between 2.0-4.9 mm carries a 91% risk of abortion 2

Common Pitfall to Avoid

• Never diagnose embryonic demise based solely on absent cardiac activity when CRL is less than 7 mm, as this can lead to inappropriate intervention in viable pregnancies 3, 1