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Assessment of blood loss
Prof. Aboubakr elnashar
Benha university hospital, Egypt
•Visual inspection is inaccurate. In some reports, the
amount of blood estimated to have been lost by
inspection was half the measured loss.
•Clinicians typically underestimate postpartum blood loss
•Importantly, in obstetrics, part or all of the hemorrhage
may be concealed.
•Clinicians commonly record blood loss using
inaccurately low numbers. "How can we teach people to
accurately and honestly record blood loss?“
•On average, women lose about
500 cc in a vaginal delivery,
1,000 cc in CS, and
1,500 cc in a cesarean hysterectomy.
•The critical area where you want to estimate blood loss
is over 2,000 cc, and we almost always underestimate
that. By that point, the patient has hypotension, has
significant tachycardia, and is in shock.
A. Clinical methods
1. BP, HR:
•By the time you detect changes in BP or HR suggesting
PPH, the woman already has lost 1/3 of her blood
•Orthostatic hypotension would tell you that the patient
has lost 20%-25% of her blood, but if she is sitting or
lying down on the delivery table, you're unlikely to detect
•Hypotension reflects a loss of 30%-35% of blood
volume. "Do not wait for hypotension" to treat for PPH
"Do not wait to start seeing S and S.
•It needs 4 h for significant changes and 48 h for
•In acute hemorrhage, the immediate hct may not reflect
actual blood loss.
•After the loss of 1000 mL, the hct typically falls only 3
volume % in the first hour.
•When resuscitation is given with rapid infusion of IV
crystalloids, there is rapid equilibration.
•During an episode of acute significant hemorrhage, the
initial hct is always the highest. This is true whether it is
measured in the delivery room, operating room, or
3. Urine output
•One of the most important "vital signs" to follow in the
bleeding patient with obstetrical hemorrhage.
•In the absence of diuretics, the rate of urine formation
reflects the adequacy of renal perfusion and, in turn,
perfusion of other vital organs, because renal blood flow
is especially sensitive to changes in blood volume.
•Urine flow of at least 30 mL and preferably 60 mL/h
should be maintained.
•With potentially serious hemorrhage, an indwelling
catheter should be inserted to measure urine flow.
4. Weighing packs and correlate with blood loss:
Hospital keeps scales in delivery rooms to weigh lap
sponges & other materials to estimate blood loss.
1kg soaked swabs: 1000ml
5. Perhaps the easiest method of estimating is to picture
a soda can, which would hold about 350 cc of blood.
When you look at blood clots or blood in a canister,
estimate how many cans of soda are represented, and
you'll be close to blood volume lost. "The principle is to
6. Maximum capacity of Swab
Small (10x10cm): 60ml
Medium (30x30 cm): 140ml
Large (45x45 cm): 350ml
7. Floor spill
50 cm diameter: 500ml
75 cm diameter: 1000ml
100 cm diameter: 1500ml
8. Vaginal PPH
limited to bed only Unlikely to exceed 1000ml
spilling from bed to floor likely to Exceed 1000ml
B. Actual blood loss
•In the perioperative period clinical estimation of blood
loss is inaccurate and alone should not be used to
determine the need for red blood cell transfusions.
•Poor agreement between the Actual Blood Loss and the
estimated blood loss. The 95% confidence intervals (-
719.939 ml to+1265.619 ml) suggest that clinical
estimation alone may result in unacceptable under or
•In 64% of the cases the blood loss was underestimated.
•Clinical estimations of blood loss suffer from large
interobserver variability and poor repeatability.
•The extent of blood loss and response to transfusion is
reflected in the changes in the hct.
•This change may be used to calculate the Actual Blood
Loss using suitable formulae.
The Actual Blood Loss is a modification of the Gross
ABL = BV [Hct (i) - Hct (f)]/ Hct (m)
Blood Volume=Body Wt in Kgs x 70 mlkg-1
Hct (i), Hct (f) and Hct (m): the initial, final and mean (of
the initial and final) Hematocrits respectively.
Neonates: 85-90ml/ kg body weight
Children: 80ml/ kg body weight
Adults: 70ml/ kg body weight
Calculating blood loss in theatre:
1. Weigh a dry swab.
2. Weigh blood soaked swabs as soon as they are
discarded and subtract their dry weight (1ml of blood
weighs approximately 1gm).
3. Subtract the weight of empty suction bottles from the
4. Estimate blood loss into surgical drapes, together with
the pooled blood beneath the patient and onto the
5. Note the volume of irrigation fluids, subtract this
volume from the measured blood loss to estimate the
final blood loss.
The decision to transfuse blood:
1. Percentage method.
Calculate the patient’s blood volume.
Decide on the percentage of blood volume that could be
lost but safely tolerated, depending on the clinical
condition of the patient, provided that normovolaemia
is maintained (table)
Patient condition Health Average Poor
Acceptable loss of
30% 20% <10%
Haemodilution Hb 7-8g/dl
2. Haemodilution method.
Decide on the lowest acceptable Hb or Haematocrit (Hct) that may
be safely tolerated by the patient (table ).
Calculate the allowable volume of blood loss that can
occur before a blood transfusion becomes necessary.
Replace blood loss up to the allowable volume with
crystalloid or colloid fluids to maintain
If the allowable blood loss volume is exceeded, further
replacement should be with blood.
•Whichever method is used, the decision to transfuse
will depend on the clinical condition of the patient and
their ability to compensate for a reduction in oxygen
supply. This is particularly limited in patients with
evidence of severe cardiac or respiratory disease or pre-
•The methods described are simple guidelines which
must be altered according to the clinical situation.
•Further blood loss should be anticipated, particularly
•Whenever possible, transfuse blood when surgical
bleeding is controlled. This will maximise the benefits of
•The American College of Physicians recommended that
RBC transfusions should be done unit by unit and the
patient should be evaluated between each transfusion.
•Excessive intraoperative transfusion and the practice of
administering blood without reevaluating the hct in
between resulted in 90% of the unnecessary
•Determination of the hct immediately before
administration of each unit would reduce blood
consumption by 25%.
A program to train doctors &
nurses to estimate blood loss.