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 3,4. Demise can be confirmed with repeated scanning and serial quantitative beta-HCG.
- 1. N Gupta and TL Angtuaco "Embryosonology in the First Trimester of Pregnancy" Ultrasound Clinics 2 (2007) 175-185
- 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. 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
- 4. Bickhaus J, Perry E, Schust DJ. Re-examining Sonographic Cut-off Values for Diagnosing Early Pregnancy Loss. (2013) Gynecology & obstetrics (Sunnyvale, Calif.). 3 (1): 141. doi:10.4172/2161-0932.1000141 - Pubmed