Fetal cardiac activity is detected with Transvaginal USG as early as?
**Core Concept**
Fetal cardiac activity detection with Transvaginal USG (Ultrasound) is a critical milestone in obstetric ultrasound, allowing for early assessment of fetal well-being and diagnosing fetal anomalies.
**Why the Correct Answer is Right**
Transvaginal USG is more sensitive than transabdominal USG due to its proximity to the cervix, enabling earlier detection of fetal cardiac activity. This is made possible by the higher frequency transducers used in transvaginal USG, which provide better resolution and can detect the tiny movements of the fetal heart as early as 5-6 weeks of gestation. The fetal heart starts to beat around 6 weeks, and the earliest detectable cardiac activity is often seen around 5-6 weeks.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is too early for the detection of fetal cardiac activity, as the earliest detectable cardiac activity is around 5-6 weeks.
**Option B:** While 5-6 weeks is the correct answer, this option might be considered a distractor by providing a plausible but incorrect answer.
**Option C:** This option is too late for the detection of fetal cardiac activity, as the fetal heart starts to beat around 6 weeks, and the earliest detectable cardiac activity is often seen around 5-6 weeks.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that transvaginal USG is the preferred method for detecting fetal cardiac activity early in pregnancy due to its higher sensitivity.
**Correct Answer:** C. 5-6 weeks.