Routine preoperative testing: a systematic review of the evidence.

OBJECTIVES. To review the available evidence on the value of routine preoperative testing in healthy or asymptomatic adults. To assess the completeness of existing reviews of preoperative testing and how applicable their conclusions are to the UK. To identify areas for further research. HOW THE RESEARCH WAS CONDUCTED. The databases Medline, Embase, Biological Abstracts, Science Citation Index and HealthSTAR were thoroughly searched for relevant articles which were then classified and appraised. The databases of the Centre for Reviews and Dissemination (DARE and NHS Economic Evaluations Database) and the Cochrane Collaboration (the Cochrane Library) were also used to verify the completeness of the search. In this review, 'routine' tests are defined as those ordered for an asymptomatic, apparently healthy individual in the absence of any specific clinical indication, to identify conditions undetected by clinical history and examination. RESEARCH FINDINGS. No controlled trials of the value of the following routine preoperative tests have been published. All available evidence reports the results of case-series. CHEST X-RAY. Few studies allow the outcome of routine chest X-rays to be distinguished from those of indicated chest X-rays, and fewer have gone beyond abnormality yields to examine the impact on clinical management. Findings from routine preoperative chest X-ray are reported as abnormal in 2.5-37.0% of cases, and lead to a change in clinical management in 0-2.1% of patients. The effect on patient outcomes is unknown. Both abnormality yield and impact on patient management rise with age and poorer American Society of Anesthesiologists (ASA) status. The limited evidence on the value of a chest X-ray as a baseline measure suggests that it will be of value in less than 9% of patients. ELECTROCARDIOGRAPHY. The findings from routine preoperative electrocardiograms (ECGs) are abnormal in 4.6-31.7% of cases, and lead to a change of management in 0-2.2% of patients. The effect on patient outcomes is unknown. The proportion of abnormal tests rises with age and worsening ASA status. The predictive power of preoperative ECGs for postoperative cardiac complications in non-cardiopulmonary surgery is weak. There is no evidence to support the value of recording a preoperative ECG as a 'baseline.' HAEMOGLOBIN MEASUREMENT AND BLOOD COUNTS. Routine preoperative measurement shows that the haemoglobin level may be lower than 10-10.5 g/dl in up to 5% of patients, but that it is rarely lower than 9 g/dl. The routine test leads to a change of management in 0.1% to 2.7% of patients. Routine preoperative measurement shows that the platelet count is abnormally low in less than 1.1% of patients, and that platelet count results rarely if ever lead to change in management of patients. Routine preoperative white blood cell count is abnormal in less than 1% of patients, and rarely if ever leads to change in management of patients. TESTS OF HAEMOSTASIS. Abnormalities of bleeding time, prothrombin time and partial thromboplastin time are found in up to 3.8%, 4.8% and 15.6% of routine preoperative tests, respectively. The results of these tests very rarely lead to change in the clinical management of patients. BIOCHEMISTRY. In routine preoperative tests of serum biochemistry, abnormal levels of sodium or potassium are found in up to 1.4% of patients, and abnormal levels of urea or creatinine are found in up to 2.5% of patients. Abnormal levels of glucose are found in up to 5.2% of patients. These abnormalities rarely lead to change in clinical management of patients. URINE TESTING. Routine preoperative urinalysis finds abnormal results in 1-34.1% of patients, and leads to a change of management in 0.1-2.8% of patients. The only abnormality that leads to a change in management of patients is the finding of white blood cells in the urine. There is no good evidence that preoperative abnormal urinalysis is associated with any postoperative complication in non-urinary tract surgery. (ABSTRACT TRUNCATED)