Anticoagulants and Blood Samples in
Laboratory Medicine
A Complete Study Guide
Abstract
This study guide provides a clear, structured explanation of anticoagulants and their
role in blood sample analysis. It covers the differences between whole blood, plasma,
and serum, with detailed tables, stopper color codes, and specific uses of EDTA,
sodium citrate, heparin, and sodium fluoride. Practical notes on preanalytical errors,
order of draw, and common pitfalls make it ideal for students of clinical chemistry,
hematology, and laboratory medicine.
Page 1 of 5
, Contents
1. Introduction and Core Fundamentals
2. Key Definitions in Blood Analysis
3. Common Anticoagulants and Their Uses
4. Serum vs. Plasma: Advantages
5. Critical Pitfalls and Preanalytical Errors
Introduction and Core Fundamentals
The fundamental rule in medical laboratory testing is to keep a blood sample as close
as possible to its condition inside the body. To achieve this, specific blood collection
tubes require anticoagulants, which are essential additives that prevent the blood from
clotting.
Anticoagulants ensure that laboratory professional can analyze blood components in
their natural state (as whole blood or plasma). Understanding anticoagulants and their
correct application is essential for reliable results in laboratory medicine, clinical
chemistry, hematology, and coagulation testing.
Key Definitions in Blood Analysis
In laboratory medicine, blood samples are analyzed as whole blood, plasma, or serum.
The key difference between plasma and serum is the presence or absence of the
clotting agent fibrinogen.
Term Definition Anticoagul Fibrinogen
ant Used? Status
Whole Blood Freshly drawn blood containing all cells and Required to Present
plasma. stop clotting.
Plasma The noncellular liquid portion derived from Required. Present
whole blood. Obtained after centrifugation of (Contains
an anticoagulated tube. clotting
factors).
Serum The liquid portion derived after whole blood Not required Consumed
has been allowed to naturally clot and the (or contains during clotting
clot/cells are removed. a clot (Plasma
activator). without
fibrinogen).
Anticoagulant Chemicals added to stop clotting and keep the N/A N/A
sample close to its original state. Works by
binding calcium (e.g., EDTA, citrate) or
blocking clotting enzymes (e.g., heparin).
Page 2 of 5
Laboratory Medicine
A Complete Study Guide
Abstract
This study guide provides a clear, structured explanation of anticoagulants and their
role in blood sample analysis. It covers the differences between whole blood, plasma,
and serum, with detailed tables, stopper color codes, and specific uses of EDTA,
sodium citrate, heparin, and sodium fluoride. Practical notes on preanalytical errors,
order of draw, and common pitfalls make it ideal for students of clinical chemistry,
hematology, and laboratory medicine.
Page 1 of 5
, Contents
1. Introduction and Core Fundamentals
2. Key Definitions in Blood Analysis
3. Common Anticoagulants and Their Uses
4. Serum vs. Plasma: Advantages
5. Critical Pitfalls and Preanalytical Errors
Introduction and Core Fundamentals
The fundamental rule in medical laboratory testing is to keep a blood sample as close
as possible to its condition inside the body. To achieve this, specific blood collection
tubes require anticoagulants, which are essential additives that prevent the blood from
clotting.
Anticoagulants ensure that laboratory professional can analyze blood components in
their natural state (as whole blood or plasma). Understanding anticoagulants and their
correct application is essential for reliable results in laboratory medicine, clinical
chemistry, hematology, and coagulation testing.
Key Definitions in Blood Analysis
In laboratory medicine, blood samples are analyzed as whole blood, plasma, or serum.
The key difference between plasma and serum is the presence or absence of the
clotting agent fibrinogen.
Term Definition Anticoagul Fibrinogen
ant Used? Status
Whole Blood Freshly drawn blood containing all cells and Required to Present
plasma. stop clotting.
Plasma The noncellular liquid portion derived from Required. Present
whole blood. Obtained after centrifugation of (Contains
an anticoagulated tube. clotting
factors).
Serum The liquid portion derived after whole blood Not required Consumed
has been allowed to naturally clot and the (or contains during clotting
clot/cells are removed. a clot (Plasma
activator). without
fibrinogen).
Anticoagulant Chemicals added to stop clotting and keep the N/A N/A
sample close to its original state. Works by
binding calcium (e.g., EDTA, citrate) or
blocking clotting enzymes (e.g., heparin).
Page 2 of 5
