Landefeld et al described a Bleeding Severity Index (BSI) to classify bleeding occurring as a complication to a medical therapy such as anticoagulation or thrombolytic therapy. Using a standardized definition can help compare different therapies or quality of care. The authors are from the University Hospitals of Cleveland, Case Western Reserve University, and Harvard Medical School.


amount of blood loss in units =

= (number of units transfused) + (((initial hematocrit in percent) – (final hematocrit in percent)) / 3) – ((estimated blood loss during surgery) / 400)



• This is implemented in the chapter on transfusion medicine.

• The equation has hematocrit divided by 0.03, with the hematocrit reported as a decimal fraction.

• Dividing hematocrit by 3 (actually 2.941) gives hemoglobin. A rough rule of thumb is that a change 1 g/dL of hemoglobin reflects a comparable change of 1 unit of blood.

• The 400 indicates the volume in mL of a unit of whole blood (actually 405 to 495).

Amount of Blood Loss


< 1 unit


1 to < 2 units


2 to < 3 units


>= 3 units



Rate of Bleeding


< 3 days


3 – 7 days


> 7 days



Consequences of bleeding:

(1) fatal: results in the death of the patient

(2) life-threatening:

(a) causes serious, permanent injury such as myocardial infarction or stroke

(b) requires re-operation to control

(3) potentially life-threatening: 2 or 3 of the following

(a) severe blood loss

(b) hypotension: >=20% fall in systolic pressure to <= 90 mm Hg

(c) critical anemia: >= 20% fall in hematocrit to <= 20%


Major blood loss:

(1) fatal

(2) life-threatening or potentially life-threatening

(3) acute or subacute bleeding requiring reoperation

(4) acute or subacute bleeding with moderate or severe blood loss


Minor blood loss:

(1) acute or subacute non-major internal bleeding

(2) chronic moderate blood loss with loss >= 1 unit per week and transfused >= 2 units of blood

(3) chronic moderate blood loss with change in hematocrit >= 20% and transfused >= 2 units of blood

(4) chronic moderate blood loss with blood loss >= 1 unit per week, a change in hematocrit >= 20%, not transfused >= 2 units, and discharged with hematocrit <= 30%


Everything else is classed as "none", but I would think "minimal" would be more appropriate.


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