Utility of routine laboratory preoperative tests based on previous results: Time to give up

The usefulness and cost-effectiveness of routine laboratory preoperative tests (POTs) have been challenged recently. In fact, the American Society of Anesthesiologists (ASA) Task Force has stated that test results obtained from the medical record within 6 months of surgery generally are mostly acceptable. The aim of our study was to evaluate the degree of utility of POTs and their clinical benefit based on this recommendation.

We studied retrospectively every routine POT request from 8 randomly selected weeks in 2016. Every POT contained glucose, creatinine, haemoglobin and coagulation tests (PT-INR). Each pathological result for these tests was registered and classified as "expected" (if previous pathological result within 6 months existed for that test) or "unexpected" (if previous pathological result within 6 months did not exist for that test). Results of ASA physical status classification (a system for assessing the fitness of patients before surgery) and changes in patient management after POTs were retrieved from medical history as well.

A total of 4516 tests (from 1129 patients) were analysed and 498 results were found pathological (11%). Of these, 403 were expected (8.9%) and 95 unexpected (2.1%). There was not any change in anaesthetic management for any patient due to these findings.

Routine POTs are an inefficient and low-value service. POTs have to be always ordered selectively after a previous consideration of specific information obtained from several sources (medical records, interviews, examinations, type of surgery) and only if the information obtained will result in changes in the management of the patient.