Bleeding Time

The bleeding time measures the time for bleeding to stop after a controlled skin incision. It reflects platelet number and function, von Willebrand factor activity and the integrity of small vessels. The Ivy method makes an incision on the volar forearm with a blood pressure cuff at 40 mmHg. A template method uses a spring loaded blade device to give a uniform cut.

It is no longer advised for screening, for predicting surgical bleeding or for monitoring antiplatelet drugs, since it is insensitive, poorly reproducible, operator dependent and leaves a scar. It has been replaced by platelet function tests, aggregometry and von Willebrand assays. It remains in use only where these are unavailable.

For many years it was a routine pre-operative screen, but studies showed that it does not predict operative bleeding, and its use has largely ceased.

Indications. Few remain. In services without other tests, it can serve as a crude screen when platelet function disorder, von Willebrand disease or uraemic platelet dysfunction is suspected and the platelet count is adequate.

Preparation.

• Platelet count over 100 x10⁹/L, since the test is inevitably prolonged under about 50 x10⁹/L and gives no further information.
• No aspirin or non-steroidal anti-inflammatory drugs for 7 to 10 days, and no other antiplatelet drug for the period set by its half life.
• Not suitable with skin disease or keloid tendency at the site, active anticoagulation, or in uncooperative patients.

Technique. Place a cuff on the upper arm at 40 mmHg. Use the volar forearm, avoiding veins, scars and hair. Make a controlled incision about 1 mm deep. Blot the blood with filter paper every 30 seconds, without touching the wound. Record the time to the end of bleeding. Stop the test and apply pressure if bleeding persists for 20 to 30 minutes.

Reference values. Ivy method about 2 to 7 minutes. Template method about 2.5 to 9.5 minutes. Values are operator- and device specific, and local ranges apply.

Complications. Pain, scarring, keloid formation, local infection and persistent bleeding.

Prolonged.

• Thrombocytopenia (under 50 to 100 x10⁹/L).
• Platelet function disorders: Glanzmann thrombasthenia, Bernard-Soulier syndrome, storage pool disorders, aspirin and other antiplatelet drugs, non-steroidal anti-inflammatory drugs, uraemia, liver disease, myeloproliferative neoplasms, paraproteinaemia, cardiopulmonary bypass.
• Von Willebrand disease, though the test is unreliable for diagnosis.
• Severe afibrinogenaemia.
• Vascular disorders: Ehlers-Danlos syndrome, scurvy, hereditary haemorrhagic telangiectasia, corticosteroid skin thinning.
• Technical errors.

Normal. Does not exclude mild von Willebrand disease, mild platelet function defects, factor XIII deficiency, or haemophilia (in which it is normal).

Uraemia. Desmopressin shortens the bleeding time in uraemic platelet dysfunction, which was historically used to monitor response.

Critical findings needing immediate action. Bleeding that does not stop within 20 to 30 minutes needs pressure, termination of the test and review. A prolonged result before urgent surgery does not alone justify cancellation, and the decision rests on the bleeding history and other tests.

Pitfalls.

• Poor reproducibility between operators and devices.
• Dependence on skin temperature, cuff pressure, incision depth and orientation.
• Poor correlation with surgical bleeding.
• Not suitable in infants or uncooperative patients.

Alternatives.

• Closure time on a platelet function analyser, with collagen and adrenaline, and collagen and adenosine diphosphate cartridges. It is sensitive to platelet dysfunction and von Willebrand disease, and is affected by haematocrit under 0.30 and platelet count under 100 x10⁹/L.
• Light transmission aggregometry for platelet function disorders.
• Flow cytometry for platelet glycoproteins (GPIIb/IIIa, GPIb).
• Von Willebrand antigen, activity and factor VIII.
• Point-of-care platelet inhibition assays for antiplatelet monitoring.

Special groups. Children and infants: not advised, since cooperation is poor and templates are not validated. Pregnancy: not advised. Older adults: fragile skin increases scarring and persistent bleeding.

Follow up tests. Full blood count and film, platelet function tests, von Willebrand screen, clotting screen, light transmission aggregometry, flow cytometry for platelet glycoproteins, urea and creatinine, liver function tests.