principle and procedure of BT CT

1. DR.SAMIYAH SYEED

2. BLEEDING TIME
 The time in minutes which is taken for a standardized
skin wound to stop bleeding.
 Test of platelet function.
 Used as a screening test of haemostasis.
 It assesses Platelet integrity & Vessel Wall Integrity

3. METHODS
1) IVY METHOD
2) DUKE METHOD
3) TEMPLATE METHOD

4. IVY`S METHOD
 Principle- 3 standard punctures made by a lancet on
volar aspect of forearm.
- Average time required for bleeding to stop is
recorded.
 Equipments- Sphygmomanometer.
- Sterile disposable lancets
-Stop watch
- Filter Paper

5. IVY METHOD
1. Sphygmomanometer cuff is applied to the upper arm & inflated to
40 mmHg.
2. Volar aspect of forearm is cleansed with spirit & dried
3. 3 punctures are made with a lancet
4. Wounds should be 3mm in depth and 2-3 mm in length.
5. Stopwatch started as soon as puncture is made. One stopwatch for
each puncture
6. Blood oozing from each puncture is gently blotted with filter paper at
30 s interval.
7. Continue till blood no longer stains filter paper.
8. Time required for bleeding to stop noted & average time reported.
9. Sterile adhesive tape is applied over puncture.

8. DUKE METHOD
 Difficult to get a standardized wound
 Can be used in infants in whom it is very difficult to fit
a BP cuff.
 It can cause a large hematoma
SITE OF PUNCTURE:
- Ear lobe in adult or older child
- Heel of foot in infant

9.  Clean the area
 Make a wound 3mm deep as in Ivy method
 Time is begun soon after this
 Blot drop of blood with filter paper every 30 seconds
and report the time when blood no longer stains the
filter paper.

10. TEMPLATE METHOD
 Newer method
 Use a glass or plastic template with a transverse slit,
which allows a lancet to make a cut on the volar aspect
of forearm – Exactly 11 mm long and 1 mm deep
 Very sensitive and reproducible test

11. REFERENCE RANGES
 Normal Bleeding Time- 2-7 minutes
 Usually, BT <4 mins
 When bleeding continues beyond 20 minutes- report
at >20 minutes
- Test discontinued.

12. PROLONGED BT
 1. Disorders of Platelets
- Thrombocytopenia
- Increased Destruction of platelets
- ITP
- Infection- malaria, dengue, septicemia
- Drugs- Quinine, Heparin
- DIC
- Increased Pooling of platelets
- Hypersplenism
- Decreased production of platelets in bone marrow
- Aplastic anemia
- Bone marrow infiltration- leukemia, lymphomas
- Megaloblastic anemia
- Drugs, radiation, infections

13. PROLONGED BT
- Disorders of platelet function
- Acquired- Drugs- Aspirin, NSAID
- Myeloproliferative disorders
- Hereditary- Bernard Soulier Syndrome
- Glanzmanns Thrombasthenia
2. Disorders of coagulation
- Hereditary- Von Willebrands Disease
- Hemophilia A, B
- Acquired – DIC, Liver disease, Vit. K Deficiency,
Heparin therapy.

14. PROLONGED BT
3. Disorders of Blood Vessels
Acquired- Allergic Purpura
Infections- Viral Septicemia
Scurvy, Senile Purpura
Inherited- Hereditary hemorrhagic telangiectasia

15. CLOTTING TIME
 Time required for blood to form a clot
 It is a rough measure to assess clotting factors in blood
 It is a crude test, has been replaced by aPTT
 PROCEDURE- Clean finger with spirit
- Prick with lancet, note the time of prick
- Take a capillary tube & hold
horizontally over the blood
- Place in water bath after sealing tube.
 After 2 minutes of prick, take the capillary tube &
break it , separate the 2 ends slowly.

16.  Repeat the process at 30 seconds interval
 When a thin thread-like clot is formed, note the time.
 Time from finger prick to appearance of clot is
Clotting Time.
 Normal Referance Range- 5-15 mins
 Prolonged in deficiency of intrinsic coagulation
Pathway. Eg- Hemophila due to Factor VIII deficiency