HEMA2 LAB - CLOT RETRACTION TIME

CLOT RETRACTION

Regression in the size of blood clot over a number of days

CLOT RETRACTION

A process that is driven by the outside-in signaling of platelet integrin aIIbβ3 (gp IIb/IIIa)

GP IIb/IIIa

Transmembrane receptor of fibrinogen or vWF

CLOT RETRACTION

Results in the contraction of the fibrin mesh

CLOT RETRACTION

Obsolete method

Measures platelet function

Ability of your blood to clot and to retract/push away your RBC

Contraction of Fibrin Mesh

End result for CLOT RETRACTION

Factors affecting CLOT RETRACTION

Normal numbers of contractile platelets

Presence of Ca & ATP

Normal concentration of fibrinogen

Normal numbers of contractile platelets

Platelets are very important in the clotting or coagulation.

Failure to clot retraction decreases platelet count since platelets aggregates at the sight of injury.

Presence of Ca & ATP

Calcium binds to phospholipids and support granules that leads to secondary platelet activation

Calcium

support granules and activates coagulation factors

Presence of Ca & ATP

Calcium bind to phospholipids and leads to secondary platelet activation that will serve as a surface for coagulation factors

Normal concentration of fibrinogen

Interaction of platelets with fibrinogen and fibrin must also be normal for clot retraction to occur

Normal concentration of fibrinogen

Promotion of stability of clot

Blood vessel patency

blood vessel is not obstructed/blocked

GLANZMANN THROMBASTHENIA

Only disease associated with Clot Retraction

GLANZMANN THROMBASTHENIA

Inherited autosomal recessive disorder

deficiency or abnormality of the platelet membrane glycoprotein (GP) IIb/IIIa complex

GLANZMANN THROMBASTHENIA

Platelet Count

Normal

Platelet Morphology

Normal

Complete Blood Count

Usually Normal

Platelet Aggregation

Abnormal

GLANZMANN THROMBASTHENIA

Bleeding time

Prolonged

Clot retraction time

Diminished

GLANZMANN THROMBASTHENIA

•Rashes
•Bleeding in gums
•Mucocutaneous bleeding
•Epistaxis
•Menorrhagia
•Purpura

QUALITATIVE TEST for CLOT RETRACTION

Hirschboeck Method

Hirschboeck Method

• Known as Castor oil method

• Presence or absence of retraction

1

Hirschboeck Method: Add _ big drop of fresh blood to the test tube with castor oil and

start the timer (both capillary or venipuncture)

3/4 of the tube

Hirschboeck Method: Volume of castor oil

dimpling or Nipple like extrusion or protrusion

Hirschboeck Method: Observe for _______ or extrusion of droplet-like serum on the top portion of the drop of blood

dimpling

Hirschboeck Method: Stop timer as soon as the __________ of serum is observed.

Sally pipette

Hirschboeck Method: : used for Aspiration of blood and to submerge it to castor oil

15-45 minutes

Hirschboeck Method: Reference Value

Normal or Defective/Poor

Hirschboeck Method: REPORTING

Platelet count is
< 100,000 cells/mm3 or
100 x 109 /L

Hirschboeck Method: POOR CLOT RETRACTION

Hemorrhagic Tendency

Hirschboeck Method: > 45 minutes

Thrombotic Tendency

Hirschboeck Method: < 15 minutes

QUANTITATIVE TEST for CLOT RETRACTION

Stefanini Method (Test Tube Method)

MacFarlane Method

Stefanini Method (Test Tube Method)

Venipuncture is done instead of capillary puncture

Begins within 1 hour. Complete within 18-24
hours

Stefanini Method (Test Tube Method): REFERENCE VALUE

Stefanini Method (Test Tube Method)

Clean tube is needed - since it causes false result

ring the clot using a stiff straight wire to
separate it from the wall of the tube

Stefanini Method (Test Tube Method): the clot may adhere to the wall of the tube, what is the course of action

Short retraction time

Stefanini Method (Test Tube Method): NORMAL blood results in

3-5

Stefanini Method (Test Tube Method): Perform venipuncture and place _________ ml of fresh venous blood in a clean tube.

cotton plug
37C

Stefanini Method (Test Tube Method): Close the tube with a _________ and incubate it for 1 hour in a water bath set at _______.

room

Stefanini Method (Test Tube Method): After 1 hour, let the tube stand at _________ temperature and

observe for retraction to take place.

1
18-24

Stefanini Method (Test Tube Method): Clot retraction starts within __ hour after blood extraction and it usually complete

within ______ hours (1 hr /2 hrs /16 hrs /18 hrs /24 hrs)

oNormal / Complete Retraction
oPartial Retraction
oPoor Retraction
oVery Poor Retraction

Stefanini Method (Test Tube Method): REPORTING

MacFarlane Method

Determine degree of clot retraction

44% - 67%

MacFarlane Method: REFERENCE VALUE

5 mL

MacFarlane Method: Volume of Blood

MacFarlane Method

Clots which have retracted by the end of the 1st hour of incubation may be freed by carefully passing a fine stiff wire around the inside
of the tube. Tube should then be re-incubated for another hour.

MacFarlane Method

Clot retraction is actually a complicated process that involves the interaction of at least 4 effects

oPresence of platelets
oConcentration of fibrinogen
oNature of tube surface to be used
oRetraction promoting principle in serum

MacFarlane Method: Interaction of the 4 effects

MacFarlane Method: FORMULA

calibrated centrifuge

MacFarlane Method: Fill a ____________ tube with freshly drawn blood up to the 5ml mark

glass rod

MacFarlane Method: Place a __________ inside the tube with the expansion immersed

in the column of blood.

cork

MacFarlane Method: Fit a ________ into place over the projecting end of the glass rod.

coagulation
5 - 10

MacFarlane Method: Place the tube in a water bath set at 37C and examine the

blood for evidence of _________ at ________ minutes.

one hour

MacFarlane Method: Remove the tube from the water bath ______ after a firm clot

has formed.

shrink

MacFarlane Method: If retraction has taken place, the clot will ________ and attach to

the glass rod.

graduated scale

MacFarlane Method: •

Pull the glass rod and the clot will be removed together with

the rod.

Read the volume of the serum directly in the __________ of the tube.

Red top tube also known as

in MacFarlane Method: blood is collected in what tube?

Cork

used to stabilize the glass rod thus will avoid disturbance
that may be caused by the glass rod due to its movement from the boils in the water bath.

cause false results while the remaining serum may get mixed (serum may contain RBCs)

in MacFarlane Method: What is the effect if glass rod disturbed the clot formation while performing incubation at a water bath?

MacFarlane Method

Observe 5 to 10 minutes first for evidence of coagulation or any clot formation before starting the 1-hour timer

MacFarlane Method

After 1 hour, the remaining serum is measured firstly by removing the Para film and glass rod or applicator stick with solid clot. The
remaining serum is transferred to the graduated cylinder using Pasteur pipette.

soft clot
solid clot

In MacFarlane Method, Quality of clot formed must be noted as

soft clot

there are remaining RBCs at
the bottom

solid clot

serum remains at the bottom

solid clot

target quality of clot at the end of the activity to obtain the correct measurement of the serum.