The bleeding time was the first in vivo platelet function test. The test measures the time taken for bleeding to stop after a standardized incision is made into the skin, usually on the anterior forearm. Normal bleeding times are usually 30 mins may result in patients with severe platelet dysfunction. [back to top] This test historically has been ordered to assess the integrity of hemostasis. It has been assumed that bleeding time correlates well with platelet function and can predict the likelihood of bleeding with
surgery or invasive procedures. However, this assumption has been poorly documented and test has been discontinued in most institutions. [back to top] Not applicable.
[back to top] Bleeding time is an indicator of the status of in vivo primary hemostasis. An abnormal bleeding time suggests a platelet disorder and would require additional laboratory evaluation.
[back to top] Most laboratories have discontinued bleeding time due to its variability, poor reproducibility, lack of correlation with intraoperative bleeding, and invasiveness. Other assays have taken the place of the
bleeding time, including but not limited to von Willebrand evaluation and platelet aggregation studies. [back to top] Factors that can affect the bleeding time include a low platelet count, low hemoglobin, use of aspirin or other platelet inhibitors, von Willebrand disease or other
hereditary platelet disorders such as Glanzmann thrombasthenia and Bernard-Soulier disease. [back to top] Not applicable. Bleeding time has been replaced by other, modern laboratory tests. Specifically,
patients with a suspected low platelet count or platelet dysfunction should be evaluated:Bleeding Time: Optimal Testing Recommendations
Guidelines for Test Utilization
What does the test tell me?
When should I order this test?
When should I NOT order this test?
How should I interpret the result?
Is the test result diagnostic/confirmatory of the condition? If not, is there a diagnostic/confirmatory test?
Are there factors that can affect the lab result?
Are there considerations for special populations?
What other test[s] might be indicated?
- Family history of bleeding disorders
- CBC and specific tests for platelet dysfunction, including the laboratory evaluation of von Willebrand disease [factor VIII levels, ristocetin cofactor activity, and GP-Ib binding assay] and platelet aggregation studies [back to top]
References
Peterson P, Hayes T, et al. The preoperative bleeding time test lacks clinical benefit. College of American Pathologists and American Society of Clinical Pathologists position article. Arch Surg. 1998;132:134-139.
Lind SE. The bleeding time does not predict surgical bleeding. Blood. 1991, 77:2547-52.
Rodgers R, Levin J. A critical reappraisal of the bleeding time. Semin Thromb Hemost. 1990; 16:1-20.21990;16:1-20.
Last reviewed: June 2020. The content for Optimal Testing: AACC's Guide to Lab Test Utilization has been developed and approved by the AACC Academy and AACC's Science and Practice Core Committee.
As the fields of laboratory medicine and diagnostic testing continue to grow at an incredible rate, the knowledge and expertise of clinical laboratory professionals is essential to ensure that patients received the highest quality and most useful laboratory tests. AACC's Academy and Science and Practice Core Committee have developed a test utilization resource focusing on commonly misused tests in hospitals and clinics. Improper test utilization can result in poor patient outcomes and waste in the healthcare system. This important resource geared toward medical professionals recommends better tests and diagnostic practices. Always consult your laboratory director to make sure these recommendations are appropriate for your patient population.
Bleeding times are typically performed as pre-operative screens. The dog is positioned in sternal or lateral recumbency after anesthetic administration. The upper lip is everted and secured using a strip of gauze wrapped snugly around the muzzle. The template device is placed on the buccal mucosa and triggered as the timer or stopwatch is started. Simplate
incisions are made parallel and Surgicutt incision is made perpendicular to the lip margin. Blood flow from the incision[s] is blotted using filter paper held directly below, but not touching the wounds. The time from triggering the device until blood no longer appears on the paper is recorded as the bleeding time. The muzzle gauze is removed and pressure applied to the wounds until active bleeding ceases. If needed, topical tissue adhesive [cyanoacrylate] can be applied to prevent rebleeding.
Buccal Mucosal Bleeding Time
Supplies
Procedure
The buccal bleeding time is not inherently painful, but dogs must remain quiet and in position for up to 10 to 12 minutes after anesthetic induction.
Normal Range
Two to four minutes.
Interpretation
Lip bleeding time is expected to be prolonged in patients with severe acquired or inherited platelet dysfunction or severe von Willebrand disease. There is a variable response in dogs with DIC or mild forms of vWD. Dogs with even severe coagulation factor deficiencies usually have normal lip bleeding time.
The upper lip is everted and held in place with muzzle gauze that encircles the upper and lower jaw. The gauze must be tied snugly. The buccal bleeding time is not inherently painful, but dogs must remain quiet and in position for up to 10 to 12 minutes. Sedation may be required for adequate restraint.
The Simplate device is triggered parallel to the lip margin. Blood flowing from the wounds is then gently blotted below the incisions. Do not wipe or disturb the wounds. The time from incision to cessation of blood flow is recorded as the buccal mucosal bleeding time.
Cuticle Bleeding Time [Toenail Bleeding Time]
Supplies
- timer or stopwatch
- guillotine type toenail clippers
- silver nitrate cautery sticks
- anesthetic or tranquilizer: [dogs must be anesthetized or heavily sedated to prevent movement and discomfort during this procedure]
- do not use narcotic drugs, acceptable drugs include xylazine, propofol, barbiturates or inhalant gas
Technique
- The dog is positioned in lateral recumbency.
- Remove any hair that covers the nails.
- The guillotine clipper is used to sever the apex of the nail cuticle. A clean transection of the nail is made just into the quick, to produce a free flow of blood. An arterial pulse indicates that the cut was too high, and only two or three drops of blood means the cut was too low. Several nails can be cut at one time to ensure appropriate technique.
- A stopwatch is started simultaneously with the cut, and the nail is left to bleed freely. The time until bleeding stops is recorded as the bleeding time.
- The nail is cauterized with silver nitrate sticks to prevent rebleeding.
Normal Range
Two to eight minutes.
Interpretation
Toenail bleeding time is expected to be prolonged in patients with acquired or inherited platelet dysfunction, coagulation factor deficiency, severe von Willebrand disease, or the hemorrhagic phase of DIC.
The nail cuticle is exposed. Cuticle bleeding time can be performed simultaneously on several nails. The cuticle bleeding time wound is painful, dogs should be sedated or anesthetized for this procedure.
Transection at appropriate site for steady flow from the cuticle. Discrete drops of blood should fall from the wound for at least the first 30 to 60 seconds after transection. A steady stream or arterial pulse indicates that the wound is too far into the cuticle. That nail should be cauterized and the test repeated using a different nail.
Bleeding Time References
American Journal of Veterinary Research 1987;48:1337-42
Canadian Veterinary Journal 1989;30:344-5
Thrombosis and Haemostasis 1993; 70:777-80.