**Question:** Test which detects true negative is said to have

A. 100% sensitivity and 100% specificity
B. High sensitivity and low specificity
C. Low sensitivity and high specificity
D. High sensitivity and high specificity

**Core Concept:**

A true negative result in a diagnostic test indicates that the test correctly identifies an individual as not having a particular disease or condition when they are actually free of it. This means that the test has both high sensitivity (ability to correctly identify those with the condition) and high specificity (ability to correctly identify those without the condition).

**Why the Correct Answer is Right:**

The correct answer, **D. High sensitivity and high specificity**, is chosen because a test with high sensitivity ensures that a large proportion of the individuals with the disease or condition are correctly identified, preventing false negatives (missed diagnoses). High specificity ensures that a large proportion of individuals without the disease or condition are correctly identified, preventing false positives (incorrect diagnoses). Both these aspects are crucial for reliable and accurate diagnosis.

**Why Each Wrong Option is Incorrect:**

A. A test with 100% sensitivity and 100% specificity is an ideal diagnostic test but is rarely achieved due to the inherent limitations of testing modalities and variations in disease presentation.

B. High sensitivity but low specificity indicates that the test identifies most cases but also falsely labels many individuals as diseased, leading to a high number of false positives.

C. Low sensitivity but high specificity indicates that the test correctly identifies most individuals without the disease but misses many cases, potentially leading to delayed or missed diagnoses.

**Clinical Pearl:**

The importance of considering both sensitivity and specificity in interpreting diagnostic test results cannot be overstated. A test with high sensitivity is crucial to prevent missing cases, while a test with high specificity is vital to prevent incorrect diagnoses. Combining both in a test ensures accurate and reliable diagnosis, minimizing the risks of false positives and false negatives.

**Correct Answer:**

D. High sensitivity and high specificity

**Explanation:**

A test with high sensitivity and high specificity is considered an ideal diagnostic test, as it helps in detecting true positives (individuals with the disease) and true negatives (individuals without the disease), respectively. This ensures accurate diagnosis, minimizing the risks of false positives and false negatives. A false positive indicates incorrect diagnosis, while a false negative represents a missed diagnosis. By balancing sensitivity and specificity, the test provides reliable results and reduces the likelihood of these errors.