Importance of Routine Laboratory Investigations Before Elective Surgery

Certain routine pre-operative laboratory investigations are performed in all patients before elective surgeries. We conducted this study to assess the value of routine pre-operative tests in the ASA (American Society of Anesthesiologists) Grade I and II adults undergoing elective surgery and their influence in the conduct of anaesthesia together with the costs incurred on unwarranted tests.

A total of 1271 patients posted for elective surgery under anaesthesia were recruited. Each patient attended the Pre-Anaesthetic Checkup Clinic and underwent clinical evaluation and investigations according to institutional policy. Demographic data and other characteristics were recorded, along with the results of laboratory test, any peri-operative intervention done as a result of abnormality and the cost incurred on tests.

Majority of the patients belonged to ASA status I (74%) and underwent moderately invasive surgery (78%). The total number of routine investigations performed was 8015. Of these, 351 (4.37%) tests had abnormal results. Amongst these 333 (4.15%) abnormalities were suspected clinically and peri-operative intervention was only performed in 0.43% of patients. Anemia was the most common abnormal finding. Abnormal blood glucose was detected in 6 patients who were not clinically suspected. Abnormal electrocardiograph (ECG) was found in 54 patients. However, the intervention was required only in 13 patients. No intervention was required because of abnormal findings of the chest X-Ray. In total cost of investigations, only 6.9% was contributed by abnormal investigations and the rest was spent on the normal tests.

The incidence of tests with abnormal results was very low in our study, and less than 1% of the patients with abnormal tests required changes in their peri-anaesthetic management. No major complications were seen in any patient with normal or abnormal test results. Most of the expenses (93%) were related to the normal test, which did not contribute to the perioperative management, safety and outcome of the patient. Thus, pre-operative investigations should be judiciously advised to avoid inconvenience, surgical delays and escalation of the costs of surgical care.