Pre-op Labs — When They Change Management

Healthy ambulatory ASA I-II patient for low-risk surgery: usually NO routine labs needed.

Routine 'panel' batteries on every patient generate low-yield results, false-positive workups, cancellations, and cost — no improvement in outcomes.

Routine BMP in a young healthy patient: no value.

Routine coag panel in a patient without anticoagulant or known bleeding history: no value (incidental abnormality without clinical correlate).

Routine CXR or ECG by age alone (no symptoms, low-risk surgery): no value.

These four categories represent ~80% of unnecessary preop lab orders.

The financial + workflow + patient-anxiety cost of these is real; the clinical benefit is essentially zero.

Intermediate (inguinal hernia, laparoscopic cholecystectomy, hysteroscopy): CBC if anticipated bleeding or anemia history; BMP if diuretic or renal disease.

Type-and-crossmatch when transfusion likely (anticipated EBL >500 mL or hemoglobin near transfusion threshold).

Cardiac/CT surgery, transplant, major trauma: comprehensive workup including ECG, echo, cath, baseline labs.

Age alone is NOT an indication; functional status + comorbidity is.

CKD (eGFR <60): BMP within 7 days; consider potassium day-of for dialysis patients.

DM: HbA1c if last value >3 months (target <7.5-8% for most surgery); finger-stick day-of for insulin users.

Anticoagulated: INR (for warfarin) or anti-Xa (for LMWH) + CBC + platelets.

Cardiac disease: ECG; BNP/NT-proBNP if dyspnea or volume status unclear.

Liver disease: LFTs + coags + albumin (albumin <3.0 portends worse outcome).

Thyroid disease: TSH if poorly controlled or recent dose change.

Hematologic disease: CBC, peripheral smear if indicated.

Yes → proceed.

Optimize before elective.

Proceed without testing.

Proceed.

Consider stress testing only if it will CHANGE management (i.e., would lead to revascularization that improves the patient regardless of surgery).

Don't 'stress them because they're old.'

If screen negative, electronic crossmatch can release units in 5-10 min.

Hold typically valid 3 days.

T&C: reserves specific units in the blood bank for the patient — ~45 min lead time including immediate-spin crossmatch.

Order T&C when transfusion is highly likely.

MSBOS (Maximum Surgical Blood Ordering Schedule) is each institution's procedure-specific recommendation.

Trauma + emergency: O-negative (female childbearing-age) or O-positive (everyone else) immediately available; switch to type-specific once T&S done.

Massive transfusion protocol bypasses individual cross-matching.

History alone misses early pregnancies.

Consequences of unknown early pregnancy include teratogenic anesthetic exposure (most agents low-risk but data sparse), miscarriage risk, and informed-consent gap.

Patient autonomy + privacy paramount.

Some institutions limit to surgical types with significant fetal risk — verify your local policy.

The chart audit question is: 'why did you order this?' Answer should not be 'because it's protocol' or 'just in case' — it should be 'patient has CKD' or 'on warfarin' or 'anticipated significant blood loss in elderly patient with cardiac disease.' Lab cost, OR delays from unexpected abnormal values, and patient anxiety from false-positive workups all flow back to the preop note's indication line.

Risk-targeted ordering is a quality metric, not a budgetary one.