A 57-year-old man with a history of bleeding per rectum visits his physician to discuss the results of his recent CT colpography test. The test was positive for the presence of a colorectal polyp. The sensitivity and specificity of this test to detect a colorectal polyp is 75% and 90% respectively.

What is the probability that this patient indeed has a colorectal polyp?

A – 92%

B – 90%

C – 88%

D – 86%

E – 84%

**Answer**

Positive predictive value of the test is the probability that a patient with a positive test indeed has a disease. This patient has a positive test. To estimate the PPV of the test we must draw a 2×2 table.

RPV = TP/all positive (TP+FP)

= 75/75+10

= 75/85

= 88%

The correct answer is C

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B

A

Answer is 84

84%

C-88%

C- 88%

84% The answer is E

C 75/85 = 88%

C -88%

ANSWER: B- 90%