Earliest detected fetal anomaly by USG:
**Core Concept**
Fetal anomalies can be detected early in pregnancy using ultrasound (USG), allowing for timely prenatal diagnosis and management. The earliest detectable anomalies are typically those involving the fetal heart and major organs.
**Why the Correct Answer is Right**
The earliest detectable fetal anomalies are usually related to the embryonic development of the heart, particularly the formation of the cardiac outflow tract and the separation of the atrial and ventricular chambers. The detection of these anomalies is often possible between 5-10 weeks of gestation. This is because the fetal heart is one of the first organs to develop and be visible on ultrasound. The presence of a single umbilical artery, conjoined twins, and other major anomalies can also be detected early in pregnancy.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not specified, but typically, fetal anomalies detected later in pregnancy include those involving the fetal limbs, spine, and abdominal organs.
* **Option B:** Fetal anomalies detected later in pregnancy include those involving the fetal brain and skull, such as microcephaly, which may not be detectable until after 16 weeks of gestation.
* **Option C:** Fetal anomalies detected later in pregnancy include those involving the fetal gastrointestinal system, such as gastroschisis, which may not be detectable until after 16 weeks of gestation.
**Clinical Pearl / High-Yield Fact**
The earliest detectable fetal anomalies are often related to the embryonic development of the heart, emphasizing the importance of cardiac evaluation in early pregnancy.
**Correct Answer:** A. Cardiac anomalies are the earliest detectable fetal anomalies by USG.