Preoperative anemia in major elective surgery

Clarissa P. Skorupski; Matthew C. Cheung; Yulia Lin

doi:10.1503/cmaj.221635

The prevalence of preoperative anemia is high

An estimated 23%–45% of patients undergoing major surgery have anemia, with the most common causes being iron deficiency anemia and anemia of inflammation or chronic disease.1^,2

Preoperative anemia leads to adverse outcomes

Regardless of its severity, preoperative anemia is an independent risk factor for postoperative death, major morbidity, increased length of hospital stay and transfusion.1^,3 In patients undergoing cardiac surgery, a 10 g/L decrease in preoperative hemoglobin levels increased mortality odds by 16% (95% confidence interval 10%–22%).2

A preoperative hemoglobin of 130 g/L or higher should be targeted for both sexes

Females have lower circulating blood volumes and greater proportional operative blood loss than males.4 Females with a hemoglobin of 120 g/L were shown to be twice as likely as males with a hemoglobin of 130 g/L to receive postoperative blood transfusions.4 When treating preoperative anemia, targeting the same hemoglobin level in both sexes minimizes the risk of unfavourable outcomes and transfusions.4

Patients undergoing major elective surgery, with expected blood loss of more than 500 mL, should be screened for anemia 6–8 weeks before their operation

Clinicians should order a complete blood count and ferritin levels, as iron deficiency anemia (ferritin < 30 ng/mL) is the most common cause.1^,4 When underlying inflammation is present, ferritin is less sensitive, and iron deficiency anemia can be diagnosed with a ferritin of 30–100 ng/mL and a transferrin saturation of less than 20%.1^,4 Patients with iron deficiency anemia should be investigated for an underlying cause (e.g., gastrointestinal blood loss, menorrhagia, malabsorption).

Preoperative iron deficiency anemia should be treated with iron supplementation

Patients with iron deficiency anemia at least 8 weeks from surgery should be treated with oral supplementation at equivalent doses of 40–60 mg elemental iron daily or 80–100 mg every other day.1^,4 If patients are within 8 weeks of surgery, or if they are unable to tolerate oral supplementation, they should receive intravenous iron.1 For patients with refractory or other forms of anemia, erythropoiesis-stimulating agents can be considered along with a specialist referral.1^,5

Footnotes

Competing interests: Yulia Lin has received research funding from Canadian Blood Services and Octapharma and is a consultant with Choosing Wisely Canada. No other competing interests were declared.
This article has been peer reviewed.

This is an Open Access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY-NC-ND 4.0) licence, which permits use, distribution and reproduction in any medium, provided that the original publication is properly cited, the use is non-commercial (i.e., research or educational use), and no modifications or adaptations are made. See: https://creativecommons.org/licenses/by-nc-nd/4.0/

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