My friend's wife suffered a back injury 5+ years ago.

[elleng]

1. Routine pre-operative blood tests may not reliably detect opioid use:.

Test type: Routine drug screening panels often only detect natural opioids like heroin, morphine, and codeine. Synthetic and semi-synthetic opioids like tramadol, methadone, and fentanyl may require a more targeted test.
Test accuracy: Opioid test results can be affected by how fast your body uses opioids, other medicines you take, and the different ways labs do the tests. Positive results may not be accurate (false positives).

AI Overview

Opioid misuse and dependence screening practices prior to surgery.

https://pmc.ncbi.nlm.nih.gov/articles/PMC8668076/