In Nevelle's Retrospective Study, what was the failure rate for indirect bypass?

• A. 9.1%
• B. 38.1%
• C. 50%
• D. 20%

Answer: (B)

The main idea here is understanding what a “failure rate” means in a surgical outcomes study. It refers to the proportion of cases where the chosen procedure did not achieve its intended, durable result during the follow-up period—often requiring additional intervention or showing inadequate revascularization.

Indirect bypass relies on the growth of new collateral vessels to improve blood flow. That process doesn’t happen in every patient, so some cases don’t achieve sufficient revascularization and are considered failures. In Nevelle’s Retrospective Study, about 38% of patients did not reach adequate revascularization with indirect bypass, meaning roughly two-fifths needed further intervention or showed insufficient collateral development.

The other numbers would imply notably different outcomes (much fewer or much more failures), which isn’t what the study reported. So the 38.1% figure best reflects the observed rate of failure for indirect bypass in that study.