Early date for detection of fetal heart:: (A) 6.0-6.5 week, (B) 6.5-7 week, (C) 7.1-7.5 week, (D) 8 week
Answer is A. “Embryonic investigations suggest that cardiac contractions begin in fetus at 36 days gestational age.”
“For practical purposes, many sonologists consider the identification of cardiac activity in an embryo with a CRL of less than 5 mm as 6 weeks GA. Cardiac activity should be detected routinely when the embryo attains a length of 4 to 5 mm. This corresponds to a GA of 6.0 to 6.5 weeks, at which time the MSD is 13 to 18 mm. Using a transabdominal approach, cardiac activity should be evident by 8 weeks GA, when the MSD is 25 mm.”
Callen 4/e, p 120
Transvaginal USG At 5-6 weeks of gestational age corresponding to 13-18 mm of MSD.
Transabdominal USG At 8 weeks of gestational age corresponding to 25 mm of MSD.
MSD: Mean sac diameter.
To obtain uniformity gestational sac size is determined by calculating mean sac diameter (MSD).