Quantification of Blood Loss (QBL) Calculator

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This calculator may be used as a worksheet to calculate blood loss during delivery.

Step 1.  Enter the volumes of fluids collected from canisters, drapes etc, and the weight of blood clots. Include volume of irrigant if cesarean was done

Step 2  

Enter the individual item and weight for each item before it is blood soaked  if it is different from the preset value.

Check off the units you are using to weigh the blood soaked items. Enter the number of each item used and the weight of the item (s) after they have been blood soaked . If the items were all weighed together after they were blood  soaked, then check  "Weigh blood soaked items together" and  enter the value into the "Weight of all blood soaked items" field.

1. Enter the amounts of fluids measured during vaginal delivery or cesarean delivery
Vaginal delivery Cesarean delivery
Under-buttocks drape pre-placenta volume  (ml)= Drape pre-placenta volume  (ml) =
Suction canister pre-placenta volume (ml) = Suction canister pre-placenta (amniotic fluid) volume (ml)  =
Under-buttocks drape post-placenta volume (ml) = Drape post-placenta volume (ml)  =
Suction canister post-placenta volume (ml)  = Suction canister post-placenta volume (ml)=
    Irrigant volume (ml) =
Weight clots (g)= Weight clots (g)=

Net volume (ml) = Net volume (ml) =

2. Enter information for blood soaked items

Weigh blood soaked items separately      Weigh blood soaked items together

Item Weight (g) Number Weight of blood soaked Item
 gkg pound

Weight of all blood soaked items
(Enter this value directly if weighing all items together)


 ( Postplacenta volumes -Preplacenta volumes  )+ 1.05 X( Weight blood-soaked item(s) -Dry weight items)=  weight of blood loss in mL

Density of blood =1.05 g/ml  [1]


1. Waite GN "Blood Components " In: Rhoades R and , Bell D.R. 3rd ed. Medical Physiology: Principles for Clinical Medicine, 4th Edition. Lippincott Williams & Wilkins 2012; 107
2. Quantification of Blood Loss: AWHONN Practice Brief Number 1 ACCESSED 5/28/2015

All calculations must be confirmed before use. The suggested results are not a substitute for clinical judgment. Neither nor any other party involved in the preparation or publication of this site shall be liable for any special, consequential, or exemplary

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