Should healthcare providers strictly adhere to clinical guidelines, or is some discretion beneficial? Using bunching estimation and microdata from 619,907 patients in Chile, I examine discretion in the diagnosis of hypertension (blood pressure ≥ 140/90mmHg). I find bunching in blood pressure at 10% of clinics, where 6 to 62% of patients' test results expected just above the hypertension diagnostic threshold are instead recorded just below it, suggesting providers use their discretion to consider some tests false positives. Leveraging variation in bunching across clinics, I show that affected patients have lower cardiovascular risk, suggesting discretion improves patient classification, partially driven by heuristic thinking.