What is the recommended pre‑operative anemia screening and correction protocol for patients scheduled for elective surgery?

Preoperative Anemia Screening and Correction Protocol

All patients scheduled for elective surgery should have hemoglobin measured at least 28 days before the procedure, with any detected anemia fully investigated and corrected to WHO normal ranges (≥13 g/dL for men, ≥12 g/dL for women) prior to surgery. 1

Screening Timeline and Targets

• Measure hemoglobin 28 days (minimum) before scheduled surgery to allow adequate time for diagnostic workup and treatment 1, 2, 3
• Target hemoglobin within WHO normal range: ≥13 g/dL for men and ≥12 g/dL for women before proceeding with elective surgery 1, 2
• For patients with cardiovascular disease, maintain hemoglobin ≥10 g/dL as values of 6-9 g/dL are associated with a 12-fold increase in mortality 2
• Screen earlier than 28 days for high-risk patients including those with advanced age, diabetes, heart failure, or chronic inflammatory conditions 2

Diagnostic Evaluation When Anemia Detected

When hemoglobin falls below target thresholds, immediately order comprehensive laboratory testing 4, 3:

• Iron studies: serum ferritin, transferrin saturation (TSAT), serum iron, and total iron-binding capacity 4, 2, 3
• Nutritional assessment: vitamin B12 and folate levels 1, 4, 2
• Renal function: serum creatinine and estimated GFR to identify chronic kidney disease 1, 4, 2
• Inflammatory markers: C-reactive protein (CRP) and ESR to evaluate for chronic inflammatory disease 1, 2

Treatment Algorithm Based on Etiology

Iron Deficiency Anemia (Most Common Cause)

Iron deficiency accounts for approximately 33% of anemic surgical patients and is the most reversible cause 2, 5:

• If surgery is >6-8 weeks away: Oral iron therapy with 40-60 mg elemental iron daily in divided doses 4, 3
• If surgery is within 2-3 weeks: Intravenous iron is preferred due to faster response and superior absorption 4, 3
• For inflammatory bowel disease patients: IV iron is specifically indicated due to hepcidin-mediated inhibition of oral iron absorption 4
• If ferritin <30 ng/mL with gastrointestinal source: Refer to gastroenterology to rule out gastrointestinal malignancy as source of chronic blood loss 4, 3

Nutritional Deficiencies

• Treat vitamin B12 or folate deficiency with appropriate vitamin supplementation when identified 1, 4, 3
• Vitamin B12 deficiency occurs in approximately 12% and folate deficiency in 3% of surgical patients 2

Anemia of Chronic Disease/Inflammation

• Consider erythropoiesis-stimulating agents (ESAs) for anemic patients in whom nutritional deficiencies have been ruled out or corrected (Grade 2A recommendation) 1, 2
• For chronic kidney disease patients: Refer to nephrology for management and consider ESAs with concurrent IV iron 4

Anemia of Chronic Kidney Disease

• Evaluate renal function with creatinine and GFR to identify chronic kidney disease as underlying cause 1, 4
• Coordinate with nephrology for ESA therapy when appropriate 4

Surgery Timing Decisions

• Delay elective surgery if newly diagnosed anemia is detected close to the surgical date to allow time for proper evaluation and treatment 4
• For surgery >4 weeks away: Complete full diagnostic workup and initiate treatment to optimize hemoglobin to normal range 3
• For urgent or semi-urgent surgery: Proceed with surgery but optimize perioperatively if hemoglobin is adequate for the procedure 4
• Consider delaying elective surgery when hemoglobin is <10 g/dL in patients with cardiovascular disease or <9 g/dL in otherwise healthy patients 2

Re-assessment Protocol

• Re-measure hemoglobin after treatment to confirm adequate response before proceeding with surgery 2, 3
• Verify that hemoglobin has reached target values (≥13 g/dL men, ≥12 g/dL women) prior to surgical clearance 1, 2

Clinical Benefits of Correction

Treating preoperative anemia appropriately reduces perioperative morbidity and mortality, red blood cell transfusion requirements, hospital length of stay, and postoperative complications 4:

• Preoperative anemia independently increases perioperative morbidity and mortality, regardless of whether transfusion is required 2, 6
• Treatment improves postoperative physical rehabilitation and quality of life 4
• Anemia prevalence in elective surgical patients ranges from 30-40%, with up to 35% of orthopedic surgery patients having hemoglobin <13 g/dL 1, 6, 7

Critical Pitfalls to Avoid

• Do not proceed to surgery without investigating the cause of anemia, as this represents a missed opportunity to reduce perioperative morbidity and mortality 3
• Do not assume mild anemia is "acceptable"; the target should be within normal WHO range to optimize outcomes 3
• Do not delay necessary surgery for prolonged workup if hemoglobin is adequate and the patient is otherwise stable for the planned procedure 4
• Anemia should be viewed as a serious and treatable medical condition, rather than simply an abnormal laboratory value 1