Fetal heart beat can be detected as early as 34 days (just under 6 weeks) gestation on good quality, high frequency transvaginal ultrasound, as a crown rump length (CRL) of as little as 1-2 mm.
If a fetal heartbeat cannot be identified with a CRL >7 mm using transvaginal scanning, then embryonal demise can be diagnosed 3. Demise can be confirmed with repeated scanning and serial quantitative beta-HCG.
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- 2. Merz E, Bahlmann F. Ultrasound in obstetrics and gynecology. Thieme Medical Publishers. (2005) ISBN:1588901475. Read it at Google Books - Find it at Amazon
- 3. 3. Jain KA, Hamper UM, Sanders RC. Comparison of transvaginal and transabdominal sonography in the detection of early pregnancy and its complications. AJR Am J Roentgenol. 1988;151 (6): 1139-43. AJR Am J Roentgenol (abstract) - Pubmed citation