What you can do to optimize blood conservation in ObGyn practice
This institution’s protocol is worth considering for identifying and correcting iron-deficiency anemia before delivery and elective gyn surgery. The goals? To avert complications and avoid transfusion.
IN THIS ARTICLE
IV iron isn’t as risky as you think
Historically, clinicians have avoided using parenteral iron sucrose (Venofer) because they have been taught that it can cause an anaphylactic reaction. In fact, although anaphylaxis may have been associated with older intravenous (IV) iron preparations, clinical trials have demonstrated the safety of IV iron sucrose and low-molecular-weight iron dextran. In a study involving 800 patients, Breymann and colleagues demonstrated that parenteral iron preparations containing dextran or iron dextrin could be safely given to pregnant women.4 Only 1.5% of the patients in the study experienced side effects from the therapy, and no anaphylactic reactions were observed.
In another study, 25 pregnant patients were given IV iron sucrose, and the only adverse reaction reported was a “not-unpleasant taste” during the injection.8
In an additional study, Breymann and colleagues found no adverse outcomes in 20 postpartum patients who received IV iron sucrose in addition to erythropoietin therapy.9
- The daily iron requirement is 2 mg of elemental iron in pregnancy and lactation, 1 mg at all other times
- The typical US diet contains about 18 mg of iron a day, of which only about 1 mg is absorbed
- Iron absorption occurs primarily in the second portion of the duodenum
- Iron absorption increases with iron deficiency
- One unit of blood contains 250 mg of iron
- Total body iron store is between 1,000 and 3,000 mg, depending on body size
- Each pregnancy depletes maternal iron stores by about 750 mg
- Latent iron deficiency is common in women who have had many pregnancies and in women who have menorrhagia.
Our preference for parenteral therapy is iron sucrose, classified by the Food and Drug Administration (FDA) as Pregnancy Category B. Iron sucrose is contraindicated in patients who have iron overload, hypersensitivity to inactive components of iron sucrose, or anemia that is not caused by iron deficiency. Adverse reactions to iron sucrose include, but are not limited to, anaphylaxis, hypotension, cramping, nausea, headache, vomiting, diarrhea, and chest pain. Adverse reactions are very rare, occurring in fewer than 1% of patients.
To determine whether the patient has an allergy to iron sucrose, give a test dosage of 25 mg via slow IV push and wait 20 minutes. If a reaction occurs, hold the remainder of the dose and consider alternative therapies. If no allergic reaction occurs, administer the remaining 275 mg in 50 mL to 100 mL of saline.
You may need to add erythropoietin to the regimen
Erythropoietin is a hormone made by the kidneys to promote formation of red blood cells in the bone marrow. A deficiency in this hormone causes anemia in patients who have renal disease, and nephrologists use a synthetic form of epoetin alfa (Epogen) to increase the hemoglobin level in dialysis patients.10 Epoetin alfa falls into FDA Pregnancy Category C.
In rare instances, erythropoietin-stimulating agents (ESAs), such as epoetin alfa, in addition to both IV and oral iron supplementation, are needed to increase the patient’s hemoglobin level and hematocrit before delivery or surgery. Before beginning ESA therapy, the patient’s platelet count and activity level need to be considered. ESAs have been linked to thrombolytic events and, therefore, should not be used in patients who have an elevated platelet count. The risk of thrombolytic events is a particular danger for antepartum patients on bed rest, and ESAs may be contraindicated for that reason.
Obstetric and surgical patients whose anemia has proven refractory to iron therapy may be considered for an ESA, as long as the benefits of this choice outweigh the risks. At an approximate cost of $400 for every 40,000 U, ESA therapy is by far the most expensive alternative to blood transfusion for patients who have iron-deficiency anemia. The patient typically receives one to two doses of an ESA.
Cost comparisons for alternative treatment modalities in iron-deficiency anemia can be found in TABLE 2.
TABLE 2
Estimated cost of treatment of anemia*
| Therapy | Dosage | Cost per dose |
|---|---|---|
| ORAL THERAPY | ||
| Ferrous sulfate | 325 mg | $0.05–$0.09 |
| Vitamin C | 500 mg | $0.04 |
| Vitron C | 1 tablet | $0.20 |
| Folic acid | 800 μg | $0.02 |
| INTRAVENOUS THERAPY | ||
| Iron sucrose | 100 mg | $80.00 |
| OTHER INTERVENTIONS | ||
| Transfusion | 1 U | $500.00–$600.00 |
| Erythropoietin | 40,000 U | $400.00 |
| * Local averages in central Pennsylvania | ||
TABLE 3
How safe are iron compounds in pregnancy and lactation?
| Compound | FDA pregnancy category | World Health Organization lactation recommendation | Thompson lactation rating |
|---|---|---|---|
| Parenteral iron dextran | C | Compatible with breastfeeding | Risk to infant cannot be ruled out |
| Parenteral iron sucrose | B | ||
| Oral iron | A | Unavailable | |
| Oral sodium ferric gluconate | A | Compatible with breastfeeding |
Erythropoietin-stimulating agents carry serious risks
The FDA issued the first of a series of letters to health-care professionals warning of adverse events associated with the use of ESAs in March 2007, after several randomized, controlled trials found an increased risk of stroke, blood clots, myocardial infarction, and death with high dosages. In November 2008, the FDA approved a black-box warning for the labels of Procrit and Aranesp, the two ESAs in general use in the United States. The new labels advise clinicians to modify dosages for patients who are in renal failure to maintain a target hemoglobin level between 11 and 12 g/dL, rather than the higher targets that had been in use.11,12
