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CPT®
85170

CPT® Code 85170

Official Description

Clot retraction

© Copyright 2025 American Medical Association. All rights reserved.

Common Language Description

The CPT® Code 85170 refers to a laboratory test known as clot retraction. This test is essential for evaluating the functionality of platelets in the blood, specifically assessing their ability to adhere, aggregate, and retract during the clotting process. Clot retraction is a critical component of hemostasis, the process that prevents and stops bleeding. When a blood vessel is injured, collagen fibers in the vessel's endothelium are exposed, initiating a cascade of events that lead to the conversion of fibrinogen, a soluble plasma protein, into fibrin, which forms a mesh-like structure that stabilizes the platelet plug. The platelets, which become trapped within this fibrin network, play a vital role in forming a thrombus, or blood clot. The retraction of the clot is facilitated by the interaction of integrin IIb 3, a receptor on the platelet surface that binds to fibrin. This interaction triggers the contraction of the platelet's actin-myosin cytoskeleton, effectively pulling the clot inward and expelling excess fluid, which helps to restore blood flow through the previously obstructed vessel. The normal time frame for clot retraction is between 0 to 120 minutes. Deviations from this range can indicate various underlying conditions; an increased clot retraction time may suggest abnormalities related to platelet function, such as those seen in hereditary or acquired platelet disorders, the influence of anti-platelet medications, or variations in platelet or fibrinogen levels. Conversely, a decreased clot retraction time may indicate a heightened risk for thrombosis, or excessive clot formation. The test requires a blood sample, which is obtained through a separate venipuncture procedure, and can be conducted using two distinct methods to ensure accuracy and reliability in results.

© Copyright 2025 Coding Ahead. All rights reserved.

1. Indications

The clot retraction test (CPT® Code 85170) is indicated for the evaluation of various conditions related to platelet function and hemostasis. The following are specific indications for performing this test:

  • Platelet Disorders The test is utilized to assess potential abnormalities in platelet function, including both hereditary conditions such as Glanzmann thrombasthenia and acquired disorders that may affect platelet aggregation and retraction.
  • Monitoring Anti-Platelet Therapy It is indicated for patients undergoing treatment with anti-platelet medications, as these drugs can influence platelet function and clot retraction times.
  • Assessment of Thrombosis Risk The test may be performed in patients with a history of thrombotic events to evaluate their tendency toward thrombosis formation, particularly when decreased clot retraction times are observed.
  • Evaluation of Bleeding Disorders It is also indicated in the workup of unexplained bleeding episodes, helping to determine if platelet dysfunction is contributing to the patient's symptoms.

2. Procedure

The procedure for conducting the clot retraction test involves several key steps to ensure accurate measurement of clot retraction time. The following outlines the procedural steps:

  • Step 1: Sample Collection A blood sample is obtained from the patient through a venipuncture, which is a separate reportable procedure. This sample is essential for conducting the clot retraction test.
  • Step 2: Test Setup The laboratory technician prepares the test by either setting up a test tube next to a camera or using a metal rod coated with platelet-rich plasma. The choice of method will depend on the laboratory's protocol.
  • Step 3: Clot Formation In the first method, photographs are taken of the clot at the start and then every 30 minutes until a human observer notes that the clot has completely retracted. In the second method, after the clot forms on the coated rod, the rod and clot are removed from the vial containing the whole blood sample.
  • Step 4: Measurement of Serum For the second method, the amount of serum expelled from the clot is measured to determine the extent of clot retraction. This measurement is crucial for evaluating platelet function.
  • Step 5: Control Sample Testing It is important to note that the patient sample is always tested alongside a control sample to ensure the reliability and accuracy of the results.

3. Post-Procedure

After the clot retraction test is completed, the laboratory will analyze the results and compare the patient's clot retraction time to the normal range of 0 to 120 minutes. Any deviations from this range will be documented, and the results will be communicated to the healthcare provider for further evaluation. Depending on the findings, additional tests or interventions may be recommended to address any identified platelet dysfunction or related conditions. Patients may not require specific post-procedure care, but it is essential to monitor for any signs of bleeding at the venipuncture site and provide appropriate aftercare instructions as needed.
Short Descr BLOOD CLOT RETRACTION
Medium Descr BLOOD CLOT RETRACTION
Long Descr Clot retraction
Status Code Statutory Exclusion (from MPFS, may be paid under other methodologies)
Global Days XXX - Global Concept Does Not Apply
PC/TC Indicator (26, TC) 9 - Not Applicable
Multiple Procedures (51) 9 - Concept does not apply.
Bilateral Surgery (50) 9 - Concept does not apply.
Physician Supervisions 09 - Concept does not apply.
Assistant Surgeon (80, 82) 9 - Concept does not apply.
Co-Surgeons (62) 9 - Concept does not apply.
Team Surgery (66) 9 - Concept does not apply.
Diagnostic Imaging Family 99 - Concept Does Not Apply
CLIA Waived (QW) No
APC Status Indicator Conditionally packaged laboratory tests
Type of Service (TOS) 5 - Diagnostic Laboratory
Berenson-Eggers TOS (BETOS) T1H - Lab tests - other (non-Medicare fee schedule)
MUE 1
CCS Clinical Classification 233 - Laboratory - Chemistry and Hematology
Date
Action
Notes
2013-01-01 Changed Medium Descriptor changed.
Pre-1990 Added Code added.
Code
Description
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