To estimate the frequency of perioperative morbidities in patients who underwent anesthesia
and a surgical procedure with no preoperative laboratory testing.
Material and Methods
We conducted an electronic database search of medical records of 56,119 patients who
underwent surgical or diagnostic procedures and anesthesia at Mayo Clinic Rochester
in 1994 and found 5,120 who had no laboratory tests done within 90 days before the
procedure. From this group, we randomly selected 1,044 patients (87 from each month)
to document the absence of preoperative tests, the presence of preexisting disease
(by organ system), the type of anesthetic agent, and the outcomes and tests intraoperatively
The 1,044 patients ranged in age from 0 to 95 years (median age, 21). No deaths or
major perioperative morbidities occurred (0.0%; exact 95% confidence interval, 0.00
to 0.35 %). Although 10 patients underwent blood typing and screening for antibodies
immediately preoperatively, no blood transfusions were necessary. Intraoperatively,
17 laboratory tests and 1 electrocardiogram were obtained, and 3 results were abnormal.
Postoperatively, 42 blood tests and 2 electrocardiographic procedures were per- formed.
Five of the 42 blood tests showed abnormal results (hemoglobin levels in 3, serum
sodium in 1, and arterial blood gases in 1). One electrocardiogram showed normal findings,
and the other revealed normal results except for premature ventricular contractions.
No laboratory test done intraoperatively or postoperatively was found to change surgical
or medical management substantially. One patient who had unanticipated blood loss
during an outpatient procedure was admitted to the hospital for observation.
All 1,044 patients, 97% of whom were relatively healthy, with no recent laboratory
testing safely underwent anesthesia and an operation. We conclude that patients who
have been assessed by history and physical examination and determined to have no preoperative
indication for laboratory tests can safely undergo anesthesia and operation with tests
obtained only as indicated intraoperatively and postoperatively. Current anesthetic
and medical practices rapidly identify perioperative indications for laboratory evaluation
as they arise.