Another paper on the subject of unnecessary preoperative laboratory testing appeared not long ago.

A group from the University of Texas Medical Branch looked at more than 73,000 elective hernia repairs in the National Surgical Quality Improvement Project (NSQIP) database. Almost 2/3 of the patients had preoperative laboratory tests. Of that group, 58.6% had a CBC, 53.5% had electrolytes, 23.7% had liver function studies, 18.7% had coagulation studies, and 9.9% had all of the above. Even 54% of patients with no comorbidities had at least one test.

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An abnormal test was found in more than 60% of those tested; of the 7,200 patients who had lab tests done on the day of surgery, 61.6% had at least one abnormal test, including 23% with a coagulation abnormality, 41% with a chemical abnormality, and 33% with a liver function test abnormality. Despite these results, the scheduled surgery was done.

Tests did not predict complications in patients without comorbidities. Obtaining a test (not necessarily an abnormal result) was associated with a higher risk of major complications (0.4% versus 0.2% p < 0.0001) but not wound complications. However, abnormal results did not predict complications.

The authors of the paper recommended that surgical societies establish guidelines for preop testing.

Hernia patients, particularly those without comorbidities, are similar to normal people. Obtaining lab studies on these patients is analogous to obtaining labs on the next 100 people who walk past the hospital. Few abnormal results will be found, and most of them will be false positives.

This fact has been known for at least 30 years, yet surgeons — who as shown by previous studies order 80% of preop tests — still continue to order them. Some question whether anesthesiologists insist on having the tests done. Is it defensive medicine? Force of habit?

When I was a department chairman and this subject came up for discussion, at least one person always said, “But if you miss one patient with (fill in the blank), you will get sued.” That type of comment is very difficult to refute because there is a grain of truth to it.

As far as I can tell, “I was following evidence-based guidelines” is not a foolproof defense against a malpractice suit. While there have been some attempts to legislate that following evidence-based guidelines should “immunize” doctors against malpractice suits, to my knowledge no such laws exist. In 2004, an article in the AMA’s Virtual Mentor journal explores this point in depth as does a paper from the Journal of Law, Medicine & Ethics.

What, then, is a practicing physician to do? That unnecessary pre-op testing occurs has been understood for many years. The paper on the University of Texas study points out that the estimated cost of preoperative testing is anywhere from $3 billion to $18 billion. Several esteemed associations and societies have established guidelines that are not followed.

Meanwhile, extensive preoperative testing of ambulatory patients continues at the discretion of the surgeon, anesthesiologist, and probably the patient’s primary care doctor too. And the tab mounts.

Skeptical Scalpel is a recently retired surgeon and was a surgical department chairman and residency program director for many years. He is board-certified in general surgery and a surgical sub-specialty and has re-certified in both several times. For the last two years, he has been blogging at and tweeting as @SkepticScalpel. His blog averages over 800 page views per day, and he has over 5,000 followers on Twitter.