Approach to anemia in the newborn and infant (destruction and blood loss): Clinical sciences

Anemia is a condition characterized by a decrease in healthy red blood cells, as indicated by low hemoglobin and hematocrit, or a low red blood cell count. Based on the underlying cause, anemia can be classified as anemia due to red blood cell underproduction, or due to red blood cell destruction or loss.

Now, if a pediatric patient presents with a chief concern suggesting anemia, you should first perform an ABCDE assessment to determine if the patient is unstable or stable. If unstable, stabilize their airway, breathing, and circulation. Next, obtain IV access, give IV fluids, and if necessary, consider blood products, such as packed red blood cells. Don’t forget to put your patient on continuous vital sign monitoring, including blood pressure, heart rate, and pulse oximetry, and provide supplemental oxygen if needed.

Here’s a clinical pearl! When a patient with anemia is unstable, be sure to look for active bleeding due to trauma, as well as signs of internal bleeding such as hematochezia, melena, or hematuria.

Now, let’s go back to the ABCDE and look at stable patients. First, obtain a focused history and physical examination and order labs, including CBC with indices, and a reticulocyte count. History might reveal symptoms like fatigue, malaise, or dyspnea; while the physical exam might demonstrate tachycardia, pallor, jaundice, or scleral icterus. Hepatosplenomegaly may also be present.

Next, check the CBC, and if results reveal a low hemoglobin and hematocrit for gestational and postnatal age, you can diagnose anemia.

Now, once you diagnose anemia, your next step is to assess the reticulocyte count. Reticulocytes are immature red blood cells produced by the bone marrow. If the reticulocyte count is below the reference range, then the bone marrow isn’t producing enough red blood cells to meet the body’s demand. In such cases, you can diagnose anemia due to red blood cell underproduction.

On the other hand, a reticulocyte count above the reference range suggests that the body is actively producing enough new red blood cells to compensate for the body’s demand. In this case, the anemia is due to either blood loss, like bleeding or hemorrhage; or red cell destruction, such as hemolysis.

So, to determine the underlying cause, order additional labs, including a Coombs test, also called direct antiglobulin test or DAT for short; as well as an unconjugated bilirubin, LDH, and haptoglobin. Also, be sure to order urinalysis and peripheral blood smear.

Alright, first let’s focus on anemia due to blood loss! In this case, the Coombs test will be negative and all other lab values will be normal! With these lab findings you can be sure that anemia is due to blood loss.

Let’s start by discussing peripartum blood loss. Typical patients are newborns who have experienced blood loss in the peripartum period, like in the case of a placental abruption. Physical exam will reveal pallor, tachycardia, and in some cases, hypotension. With these findings, you can diagnose anemia due to peripartum blood loss.

Here’s a clinical pearl to keep in mind! Subgaleal hematoma is an uncommon and life-threatening cause of blood loss that’s typically seen after vacuum or forceps extraction when there's damage to emissary veins. A tear in emissary veins creates a large blood collection between the periosteum and the galeal aponeurosis, which is typically seen as a large, fluctuant hematoma that crosses the suture lines of the scalp.

Next up is twin anemia polycythemia sequence, or TAPS for short. This subset of twin-to-twin transfusion syndrome is common in newborns that share one placenta or, in other words, in monochorionic twin gestation.

In TAPS, the placenta contains small arteriovenous anastomoses that favor one twin more than the other; for example twin B is favored more than twin A. As a result, twin A doesn’t get enough red blood cells, eventually developing anemia, while twin B receives too many red blood cells, subsequently developing polycythemia.

So, if the physical exam reveals pallor in a twin with anemia and ruddy or dusky color in a twin with polycythemia, consider TAPS as the cause. In this case, your next step is to evaluate the placenta. The presence of arteriovenous anastomoses within the placenta are suggestive of TAPS.

Now, let’s take a look at chronic fetomaternal bleeding. In this case, the fetomaternal circulation barrier breaks down, allowing fetal blood to slowly flow into the maternal circulation over the course of the pregnancy.

Typically, the history reveals a newborn without a history of peripartum blood loss or multiple gestation, while the physical exam reveals pallor and possibly tachycardia and hypotension.

With these findings, you should consider a chronic fetomaternal bleed, so your next step is to order a Kleihauer-Betke test, which identifies fetal blood cells within the maternal circulation. If the test is positive, diagnose chronic fetomaternal bleeding.

Finally, let’s take a look at newborns with iatrogenic anemia. A common example is an infant who has had numerous or excessive blood draws. Because newborns have a small total blood volume, their hemoglobin level is affected more significantly by blood draws, when compared with adult patients. So, a history of excessive blood draws in combination with pallor, and possibly tachycardia or even hypotension, are highly suggestive of iatrogenic anemia.