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The Bleeding Time

(Download  The Bleeding Time.pdf)

The skin bleeding time reflects 'primary haemostasis', the interaction of platelets with arterioles and capillaries. The bleeding time may be abnormal in acquired and inherited disorders of platelet function, von Willebrand's disease, the rare afibrinogenaemias and inherited disorders of collagen, and in patients with 'senile purpura'. Although the bleeding time may detect these disorders, the limited sensitivity and lack of specificity of the technique renders it of little clinical value.

The bleeding time, even the "standardised" modified Ivy technique currently in use, is subject to many technical variables. The reference interval varies with the age and gender of the patient [1,2], with the position, direction and depth of the skin incision(s) [3], and with ambient temperature4. There is significant inter- and intra-operator variability and the test is not reproducible. Although traditionally used as a screening test for von Willebrand's disease, the bleeding time is an insensitive test for this disorder [5], is known to vary over time [6], and may not be shortened after infusion of cryoprecipitate [7]. Similarly, although the bleeding time is often prolonged in patients with myeloproliferative disorders, the prolongation correlates poorly with the bleeding tendency [8]. The bleeding time has only a limited place in the characterisation of patients with known bleeding disorders, and should not be used as a screening test for the presence of such disorders [9].

The bleeding time is prolonged by aspirin and other non-steroidal anti-inflammatory drugs; this prolongation is statistically significant and clinically insignificant [10]. The lack of correlation between the prolongation of the bleeding time and operative bleeding has been repeatedly demonstrated for both aspirin and ticlopidine [10]. In a review of the literature on both cardiac and general surgery, Lind concluded that there was no correlation between anti-platelet drug use, bleeding time and operative blood loss [10].

The bleeding time is often abnormal in uraemic patients and appears to correlate with spontaneous clinically significant bleeding [11]. There is currently no evidence that uraemic patients with a prolonged bleeding time are more likely to bleed at renal biopsy10.

A normal bleeding time does not exclude a clinically significant acquired or inherited disorder of haemostasis and does not automatically indicate that surgery can be undertaken safely. A prolonged bleeding time does not necessarily indicate the presence of a clinically significant bleeding disorder and does not indicate that surgery will be associated with significant blood loss. As the bleeding time is not a predictor of surgical bleeding, its use as a pre-operative "screening test" cannot be justified, whether or not the patient is taking anti-platelet drugs.

References

  1. Macpherson CR et al. Arch Pathol Lab Med 1987; 111: 328.
  2. Bain B et al. Thromb Haemostas 1980; 43: 131.
  3. Mielke CH. Blood 1982; 60: 1139.
  4. Harker L. N Engl J Med 1972; 287: 155.
  5. Coller BS. In Colman RW et al (eds): Hemostasis and Thrombosis: Basic Principles and Clinical Practice. Philadelphia PA, Lippincott. 1987.
  6. Abildgaard CF et al. Blood 1980; 56: 712.
  7. Larrieu MJ et al. Am J Med 1968; 43: 354.
  8. Berild D et al. Scand J Clin Lab Invest 1987; 47: 497.
  9. McPherson J. Common Sense Pathology, April 1993.
  10. Lind SE. Blood 1991; 77: 2547.
  11. Burns ER et al. Arch Pathol Lab Med 1989; 113: 1219.

Written by:     Dr Jean McPherson, Haematology HAPS
Written:           May 1998

Last Reviewed:     10.05.2001