Definition and grading of anemia in pregnancy
WHO recommends hemoglobin Hb <110 g/L during pregnancy to be diagnosed as combined anemia of pregnancy. Anemia can be classified as mild anemia 100-109 g/L, moderate anemia 70-99 g/L, severe anemia 40-69 g/L, and very severe anemia <40 g/L. In the diagnosis of Asia-Pacific region, a pregnant woman with hemoglobin Hb <90 g/L is considered as severe anemia, but nowadays, China still follows WHO's diagnostic criteria. The significance of setting the grading is to pay attention to anemia in pregnancy because of the presence of hemorrhage in obstetrics.
Iron deficiency in pregnancy should also be taken seriously
There is no unified diagnostic criteria for iron deficiency in pregnancy, and the guidelines recommend that the diagnosis is made when serum ferritin is <20ug/L. Clinically, many doctors pay attention to this period of iron deficiency anemia, but not to the iron-decreasing phase and the iron-deficient erythropoietic phase that precede the onset of iron deficiency anemia.
The iron-depleted phase refers to a decline in body iron stores, serum ferritin <20ug/L, and normal transferrin saturation and Hb. The iron deficiency erythropoietic phase refers to a decline in body iron stores, serum ferritin <20ug/L, transferrin saturation <15%, and normal Hb. Iron deficiency anemia refers to a significant decrease in iron in the red blood cells, serum ferritin <20ug/L, transferrin saturation <15%, and Hb <110g/L.
Iron deficiency anemia during pregnancy is defined as anemia due to iron deficiency during pregnancy with Hb<110g/L.
Interpretation of guidelines for iron deficiency and iron deficiency anemia in pregnancy
Clinical presentation
Severe anemia is relatively rare in clinical practice, and most of them are mild anemia. In mild anemia, there are no obvious clinical manifestations, fatigue is more common, while in severe anemia, pallor, weakness, palpitations, dizziness, dyspnea and irritability can occur. iron stores can be depleted before Hb drops, so symptoms of iron deficiency such as fatigue, irritability, decreased concentration and hair loss can occur even before anemia occurs.
Diagnosis
1.Laboratory tests
a. Blood routine: Hb, MCV, MCH, MCHC are all decreased. Blood smear shows hypochromic small cell anemia.
b.Serum ferritin: It is the best laboratory diagnostic criteria for iron deficiency in pregnancy. IDA should be considered for anemia with serum ferritin <20ug/L. Serum ferritin <30ug/L indicates early stage of iron depletion and requires prompt treatment. However, serum ferritin may also be elevated during infection, and C-reactive protein can be tested for differential diagnosis.
2.Iron therapy test
In patients with small cell hypochromic anemia, iron therapy test has both diagnostic and therapeutic significance. An elevated Hb after 2 weeks of treatment is suggestive of IDA.
Differential diagnosis.
If iron therapy is not effective, further examination should be done for the presence of absorption disorders, poor compliance, blood loss and folic acid deficiency, and referral to a higher level of care. Areas with high prevalence of thalassemia, such as Guangdong, Guangxi, Hainan, Hunan, Hubei, Sichuan and Chongqing, should be routinely screened for thalassemia at the first prenatal visit.
The guidelines recommend.
1.Iron therapy trial is preferred for patients with small cell hypochromic anemia, and elevated Hb after 2 weeks of treatment is suggestive of IDA. differential diagnosis should be made for those who are ineffective with iron therapy.
2, those who are ineffective with iron therapy should be further examined for impaired absorption, poor compliance, blood loss and folic acid deficiency, and referred to a higher level of care.
3.Regions with a high prevalence of thalassemia, such as the two provinces, the two lakes, Sichuan and Chongqing, should be routinely screened for thalassemia during the first prenatal checkup.
4.Medical institutions with conditions should test serum ferritin for all pregnant women.
5.Pregnant women with hemoglobinopathies should be tested for serum ferritin.
6.The detection of C-reactive protein is helpful for differential diagnosis of increased serum ferritin due to infection.
Treatment recommendations.
1.General principles
Iron deficiency and mild to moderate anemia: take oral iron mainly, improve diet, and eat iron-rich food. Severe anemia: oral or injectable iron, and in some cases close to delivery or affecting the fetus, small and multiple transfusions of concentrated red blood cells. Very severe anemia: transfusion of concentrated red blood cells is preferred, until Hb>70g/L. After the symptoms are relieved, it can be changed to oral or injectable iron. after Hb is restored to normal, oral iron should be continued for 3-6 months, or until 3 months after delivery.
2.Diet
The dietary iron absorption rate of pregnant women is 15%, the physiological requirement of iron for pregnant women is 3 times higher than the amount during menstruation, and increases with the progress of pregnancy. 30mg/d of iron intake is required in the middle and late pregnancy. iron intake and iron absorption can be increased through dietary guidance. Ninety-five percent of dietary iron is non-heme iron.
Foods that contain heme iron are red meat and poultry. Foods that promote iron absorption are fruits, potatoes, green leafy vegetables, cauliflower, carrots and cabbage that contain vitamin C. Some foods inhibit iron absorption, such as milk and dairy products, cereal bran, grains, high gluten flour, beans, nuts, tea, coffee and cocoa.
3.Iron supplements
When the pregnant woman’s iron stores are depleted, it is difficult to replenish enough iron through food alone, so iron supplements are needed. Oral iron supplementation is effective, inexpensive and safe. IDA pregnant women with clear diagnosis should be supplemented with elemental iron 100-200mg/d. Pregnant women with hemoglobinopathy can be given oral iron supplements if their serum ferritin is <30ug/L.
a. Usage of oral iron: For the treatment of diagnosed IDA, pregnant women should supplement with elemental iron 100-200mg/d and recheck Hb after 2 weeks to assess the efficacy. Usually the Hb increases by 10g/L after 2 weeks and 20g/L after 3-4 weeks. non-anemic pregnant women with serum ferritin <30ug/L should consume elemental iron 60mg/d and assess the efficacy after 8 weeks.
b. Side effects of oral iron: About 1/3 of patients taking oral iron have dose-related adverse reactions. Gastrointestinal symptoms such as nausea and upper abdominal discomfort are likely to occur with elemental iron supplementation ≥200 mg/d.
There are many commonly used oral iron supplements, and the most commonly used now is polysaccharide iron complex. It is recommended to take iron orally 1h before eating, together with vitamin C to increase the absorption rate. Avoid taking it at the same time with other drugs.
c. Iron injection: those who cannot tolerate oral iron, whose compliance is uncertain or whose oral iron is ineffective may choose to inject iron. Injectable iron can cause a rapid and sustained increase in Hb levels, and its efficacy is better than that of oral ferrous sulfate. There are many commonly used iron supplements; iron sucrose is currently considered the safest, and iron dextran may have serious adverse effects.
d. Guideline recommendation: all pregnant women are given dietary guidance to maximize iron intake and absorption. Once stored iron is depleted, it is difficult to replace sufficient iron through food alone and iron supplementation is usually required. Treatment of pregnant women with a clear diagnosis of IDA should be supplemented with elemental iron 100-200 mg/d, and the efficacy should be assessed by rechecking Hb after 2 weeks of treatment. Treatment until Hb returns to normal should be continued with oral iron for 3-6 months or until 3 months after delivery. Non-anemic pregnant women with serum ferritin <30ug/L should receive elemental iron 60mg/d and the efficacy should be assessed after 8 weeks of treatment. Pregnant women with hemoglobinopathies who have serum ferritin <30ug/L may be given oral iron. It is recommended to take iron orally 1h before eating, together with vitamin C to increase the absorption rate. Avoid concomitant administration with other medications. Lower iron content preparations may reduce gastrointestinal symptoms. Anyone with obvious anemia symptoms, or Hb<70g/L, or 34 weeks of gestation, or if oral iron is ineffective, should be referred to a higher level medical institution.
4.Blood transfusion
Blood transfusion is recommended when maternal Hb<60g/L, and when Hb60-70g/L is decided according to factors such as whether the patient is operated or not and heart function. Because anemic pregnant women have a low tolerance for blood loss, blood transfusion should be given as early as possible if significant blood loss occurs during labor. Those with high risk factors for bleeding should have blood prepared prenatally or transfused preoperatively. Written informed consent should be obtained for all blood transfusions.
Prevention and Screening.
Blood tests should be performed on all pregnant women at the first maternity visit (preferably within 12 weeks of gestation) and repeated every 8-12 weeks thereafter. Routine blood measurements are the initial screening test to determine anemia, and serum ferritin can be tested if available.