Quantification of Blood Loss (QBL) Calculator

How to use

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 irrigant volume if a cesarean was done.
Step 2. Enter the dry weight (preset or customized), the number used, and the post-weight of each blood-soaked item. Choose units (g/kg/pound). If items were weighed together, select “Weigh blood soaked items together” and enter the total post-weight.

Tip: On phones, the items table scrolls horizontally.

Calculator

1) Measured volumes — Vaginal delivery

Under-buttocks drape pre-placenta volume (mL)

Suction canister pre-placenta volume (mL)

Under-buttocks drape post-placenta volume (mL)

Suction canister post-placenta volume (mL)

Weight clots (g)

Net volume (mL)

Net volume = post − pre + clots (as entered)

1) Measured volumes — Cesarean delivery

Drape pre-placenta volume (mL)

Suction canister pre-placenta (amniotic fluid) volume (mL)

Drape post-placenta volume (mL)

Suction canister post-placenta volume (mL)

Irrigant volume (mL)

Weight clots (g)

Net volume (mL)

Net volume = post − pre − irrigant + clots (as entered)

2) Blood-soaked items (gravimetric)

Weigh blood soaked items separately Weigh blood soaked items together

Units for post-weight:

g kg pound

Item (editable)	Dry weight (g)	Number used	Post-weight (enter)












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

Formulas & references

Formula: (Postplacenta volumes − Preplacenta volumes) + 1.05 × (Weight blood-soaked item(s) − Dry weight items) = estimated blood loss (mL)

Density of blood ≈ 1.05 g/mL.

References

Waite GN. “Blood Components.” In: Rhoades R, Bell DR. Medical Physiology: Principles for Clinical Medicine, 4th ed. Lippincott Williams & Wilkins; 2012:107.
Quantification of Blood Loss: AWHONN Practice Brief Number 1. (Legacy link as provided in the original page.)

Note: External links may change over time.

Important notice

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