Which of the following noted on a peripheral smear is consistent with Disseminated Intravascular Coagulation (DIC): Reticulocytes, Schistocytes, Spherocytes, or Target cells?

From the Guidelines

Schistocytes are consistent with Disseminated Intravascular Coagulation (DIC). These fragmented red blood cells are characteristic findings on peripheral blood smears of patients with DIC. Schistocytes form when red blood cells are damaged as they pass through fibrin strands in small blood vessels, which occurs during the widespread microvascular thrombosis seen in DIC. This mechanical damage to red blood cells results in irregularly shaped cell fragments with sharp angles and points. The presence of schistocytes reflects the ongoing microangiopathic hemolytic anemia that commonly accompanies DIC. While other abnormal red cell morphologies may be present in various hematologic conditions (reticulocytes in hemolytic anemias, spherocytes in hereditary spherocytosis or autoimmune hemolytic anemia, and target cells in liver disease or hemoglobinopathies), schistocytes specifically indicate the microvascular damage and consumption of platelets and clotting factors that define DIC, as noted in studies such as 1 and 1.

Key Points

• Schistocytes are a hallmark of DIC due to the mechanical damage caused by fibrin strands in small blood vessels.
• The presence of schistocytes is indicative of microangiopathic hemolytic anemia, a common complication of DIC.
• Other abnormal red cell morphologies, such as reticulocytes, spherocytes, and target cells, are associated with different hematologic conditions and do not specifically indicate DIC.
• The diagnosis of DIC should be based on a combination of clinical and laboratory findings, including the presence of schistocytes, as well as other markers of coagulation and fibrinolysis activation, as discussed in 1.

Clinical Implications

The identification of schistocytes on a peripheral smear is crucial for the diagnosis and management of DIC. It is essential to recognize the presence of schistocytes and other laboratory markers of DIC, such as prolonged PT and APTT, thrombocytopenia, and low fibrinogen levels, to initiate prompt and appropriate treatment, as recommended in 1. This may include the transfusion of platelets, fresh frozen plasma, and cryoprecipitate, as well as the use of anticoagulant therapy in certain cases.

From the Research

Disseminated Intravascular Coagulation (DIC) and Peripheral Smear Findings

The following are notable findings on a peripheral smear that can be consistent with DIC:

• Schistocytes: These are fragmented red blood cells that can be seen in conditions involving mechanical damage to red blood cells, such as microangiopathic hemolytic anemia, which can occur in DIC 2, 3.
• The presence of schistocytes on a peripheral blood film is frequently observed in DIC patients, usually with a low percentage, within or close to the reference range (<0.5%) 2.
• Reticulocytes, spherocytes, and target cells can also be seen on a peripheral smear, but they are not as specifically associated with DIC as schistocytes are.
• Schistocytes are more commonly associated with thrombotic microangiopathies, which can include DIC, thrombotic thrombocytopenic purpura (TTP), and hemolytic uremic syndrome (HUS) 4.

Key Findings

• Schistocytes are the most relevant finding on a peripheral smear that is consistent with DIC 2, 3.
• The presence of schistocytes, particularly at a percentage of ≥ 1%, may suggest an associated or underlying thrombotic microangiopathy 2.
• DIC is characterized by systemic coagulation activation, anticoagulation pathway impairment, and persistent fibrinolysis suppression, resulting in widespread microvascular thrombosis and hemorrhagic consumption coagulopathy 5.
• Effective management of DIC requires treating the underlying condition, along with substitution therapies and, in some cases, antifibrinolytics 5, 6.