Routine preoperative testing of serum electrolytes, blood urea, serum creatinine in patients undergoing elective...

There is limited evidence to suggest that routine testing of serum electrolytes, blood urea, and serum creatinine in low-risk patients significantly improves surgical outcomes or reduces complications. This study aimed to evaluate the need of these investigations in patients of American Society of Anesthesiologists physical status (ASA-PS) I and II scheduled to undergo elective surgeries of minor and intermediate risk.

We conducted a prospective, observational study at a tertiary care hospital, involving 1166 patients aged 18-60 years with ASA-PS grades I and II, undergoing elective minor and intermediate-risk surgeries. Comprehensive preoperative evaluation included documentation of demographic data, medical history, medications, pre- and postoperative values of blood urea, serum creatinine, and serum electrolytes. The study design incorporated assessment of changes in anesthetic management, including ordering of repeat tests, specialist referrals, and surgery postponements or cancelations. Postoperative complications related to electrolyte disturbances were monitored. Statistical analysis included Chi-squared test for categorical variables and dependent t-test for comparing pre- and postoperative changes in biochemical parameters. Data was entered in Excel and analyzed using Statistical Package for the Social Sciences (IBM, Bangalore, India) version 23.

A total of 148 (12.69%) patients underwent repeat tests preoperatively; none of them experienced any postponements/cancelations or changes in anesthetic management. Statistically significant changes were observed in blood urea, serum creatinine, and serum electrolyte values across all anesthesia types and comorbidities (P < 0.05). However, these changes remained within clinically acceptable limits and did not necessitate alterations in patient management. Notably, only 0.26% of patients required postoperative repeat tests, and no patients needed referral to superspecialty care.

Our study provides substantial evidence indicating that routine preoperative assessment of blood urea, serum creatinine, and serum electrolytes may not be necessary for ASA-PS I and II patients undergoing elective minor and intermediate-risk surgeries.