Bleeding classification On the Web
American Roentgen Ray Society Images of Bleeding classification
There are a variety of classification schemes that are designed to characterize the severity of bleeding. Some are used in clinical practice, others are used to quantitate bleeding in clinical trials.
Quantitating the incidence of bleeding is critical to characterize the side effects of new drugs, surgical procedures and devices. The incidence of bleeding complications varies from 1% to 10% during treatment of acute coronary syndromes (ACS) and PCI (Percutaneous coronary intervention). This is in part due to use of combination of multiple drugs like aspirin, heparin, warfarin, platelet P2Y12 inhibitors, glycoprotein IIb/IIIa inhibitors, direct thrombin inhibitor and also the invasive procedures (percutaneous coronary intervention, Coronary artery bypass graft) during this period. Also, the bleeding complications have been found to be associated with increase in incidence of short and long term adverse outcomes like death, non-fatal MI (myocardial infarction), stroke and stent thrombosis. The exact mechanism underlying this is not clearly defined but may be due to the cessation of evidence based therapies (like antiplatelet, Beta blockers, statin), effect ofblood transfusion, co morbidities and anemia that are seen more in patients with bleeding complications. Therefore, bleeding presents as an important safety endpoint in many of the cardiovascular trials. However, there is a lack of uniformity in the definitions of bleeding that could be used in the cardiovascular trials that in turn make it difficult to conduct and compare the results of different trials. Several bleeding definitions have been used in different clinical trials such as the TIMI, GUSTO, ACUITY, HORIZONS,and PLATO bleeding scales. To reduce the heterogeneity and to adopt standardized bleeding end-point definitions for patients receiving antithrombotic therapy, the Bleeding Academic Research Consortium (BARC) was convened comprising representatives from different fields of medicine. These standardized definitions will help researchers determine the relative safety of different antithrombotic therapies. These definitions are recommended for both clinical trials and registries 
American College of Surgeons' Advanced Trauma Life Support (ATLS) Scheme
- Class I Hemorrhage involves up to 15% of blood volume. There is typically no change in vital signs and fluid resuscitation is not usually necessary.
- Class II Hemorrhage involves 15-30% of total blood volume. A patient is often tachycardic (rapid heart beat) with a narrowing of the difference between the systolic and diastolic blood pressures. The body attempts to compensate with peripheral vasoconstriction. Skin may start to look pale and be cool to the touch. The patient might start acting differently. Volume resuscitation with crystaloids (Saline solution or Lactated Ringer's solution) is all that is typically required. Blood transfusion is not typically required.
- Class III Hemorrhage involves loss of 30-40% of circulating blood volume. The patient's blood pressure drops, the heart rate increases, peripheral perfusion, such as capillary refill worsens, and the mental status worsens. Fluid resuscitation with crystaloid and blood transfusion are usually necessary.
- Class IV Hemorrhage involves loss of >40% of circulating blood volume. The limit of the body's compensation is reached and aggressive resuscitation is required to prevent death.
Individuals in excellent physical and cardiovascular shape may have more effective compensatory mechanisms before experiencing cardiovascular collapse. These patients may look deceptively stable, with minimal derangements in vital sounds, while having poor peripheral perfusion (shock). Elderly patients or those with chronic medical conditions may have less tolerance to blood loss, less ability to compensate and take medications, such as betablockers, which may blunt the cardiovascular response. Care must be taken in the assessment of these patients.
World Health Organization
The World Health Organization (WHO) standardized grading scale to measure the severity of bleeding is as follows:
- Grade 0: no bleeding
- Grade 1: petechial bleeding;
- Grade 2: mild blood loss (clinically significant);
- Grade 3: gross blood loss, requires transfusion(severe;
- Grade 4: debilitating blood loss, retinal or cerebral associated with fatality
- Mehran R, Rao SV, Bhatt DL, Gibson CM, Caixeta A, Eikelboom J; et al. (2011). "Standardized bleeding definitions for cardiovascular clinical trials: a consensus report from the bleeding academic research consortium". Circulation. 123 (23): 2736–47. doi:10.1161/CIRCULATIONAHA.110.009449. PMID 21670242.
- Manning, JE "Fluid and Blood Resuscitation" in Emergency Medicine: A Comprehensive Study Guide. JE Tintinalli Ed. McGraw-Hill: New York 2004. p227