Most commonly involved organ in congenital tuberculosis is
**Core Concept**
Congenital tuberculosis (TB) refers to the transmission of Mycobacterium tuberculosis from an infected mother to her fetus, either in utero or during delivery. This rare but serious condition can occur when the mother has active TB disease, particularly in the lungs or pleura.
**Why the Correct Answer is Right**
The most commonly involved organ in congenital TB is the liver. This is because the liver is one of the first organs to filter the blood from the placenta, and the bacteria can easily infect it. The liver's high blood flow and filtering function make it an ideal site for the bacteria to lodge and multiply. Additionally, the liver's immune response to the infection can lead to granuloma formation, which is a characteristic feature of TB.
**Why Each Wrong Option is Incorrect**
* **Option A:** While the lungs are a common site for TB infection in general, they are not the most commonly involved organ in congenital TB.
* **Option B:** The spleen can be involved in congenital TB, but it is less common than liver involvement.
* **Option C:** The brain can be involved in congenital TB, particularly in the form of TB meningitis, but it is not the most commonly affected organ.
**Clinical Pearl / High-Yield Fact**
The risk of congenital TB is highest when the mother has active TB disease, particularly in the lungs or pleura, and is not receiving appropriate treatment.
**Correct Answer:** A. Liver