**Question:** Most peripheral laboratory under RNTCP

A. Blood smear examination
B. Bone marrow examination
C. Chest X-ray
D. Sputum examination

**Correct Answer:** D. Sputum examination

**Core Concept:**
The RNTCP (Revised National Tuberculosis Control Programme) is a public health program implemented in India to control and treat Tuberculosis (TB). In this context, the most peripheral laboratory test is the one performed at the patient's home or the initial point of contact with the healthcare system.

**Why the Correct Answer is Right:**
Sputum examination is considered a peripheral laboratory test under RNTCP because it involves collecting and testing samples directly from the patient's respiratory tract, typically performed at the household or community level. This test is crucial for diagnosing TB, particularly in the pulmonary form of the disease.

**Why Each Wrong Option is Incorrect:**

A. Blood smear examination: Although essential for diagnosing TB, blood smear examination is not considered peripheral as it requires venipuncture and is typically performed in a laboratory setting.

B. Bone marrow examination: This test is invasive, requiring a surgical procedure, and is not considered peripheral since it is performed in a specialized laboratory setting.

C. Chest X-ray: Although a valuable diagnostic tool for TB, chest X-ray is not considered a peripheral laboratory test as it is a radiological imaging procedure performed in a radiology department.

**Clinical Pearl:**
In RNTCP, sputum examination plays a pivotal role in diagnosing TB, particularly Mycobacterium tuberculosis. The program emphasizes the use of smear microscopy, culture, and molecular diagnostics, including GeneXpert MTB/RIF, for diagnosing TB and identifying drug resistance. By utilizing these diagnostic tools at the peripheral level, RNTCP aims to improve TB case detection, reduce overburdened central laboratories, and ensure early initiation of appropriate treatment.