Which of the following congenital malformations can be diagnosed in the first trimester ?
**Core Concept**
The question tests the ability to identify congenital malformations diagnosable in the first trimester, typically through high-resolution ultrasound. **Congenital malformations** such as anencephaly, omphalocele, and cystic hygroma can be detected early due to advances in **prenatal ultrasound technology**.
**Why the Correct Answer is Right**
Although the specific correct answer is not provided, typically, malformations like **anencephaly** can be diagnosed in the first trimester. This is because anencephaly results from the failure of the **upper end of the neural tube** to close, leading to the absence of a major portion of the brain, skull, and scalp, which can be visible on ultrasound.
**Why Each Wrong Option is Incorrect**
**Option A:** Without the specific details of each option, it's challenging to provide a precise explanation for why each might be incorrect. However, generally, options that are not typically diagnosable in the first trimester due to their nature or the limitations of ultrasound resolution at this stage would be incorrect.
**Option B:** Similarly, this option would be incorrect if it represents a condition that either does not have noticeable ultrasound findings in the first trimester or is not commonly diagnosed until later in pregnancy.
**Option C:** and **Option D:** would follow the same logic, being incorrect if they are conditions not diagnosable in the first trimester.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that **anencephaly** is one of the most common congenital malformations detectable in the first trimester, often identified between 10-14 weeks of gestation. This highlights the importance of early prenatal screening.
**Correct Answer:** Correct Answer: D. Anencephaly