Page 711 - Clinical Hematology_ Theory _ Procedures ( PDFDrive )

CHAPTER 32 ■ Laboratory Manual: Manual Procedures in Hematology 695

COAGULATION PROCEDURES (continued)

Tis proce ure, in CLSI ormat, is provi e on this book’s Quality Control

companion Web site at http://thepoint.lww.com/ urgeon6e. A normal patient plasma shoul be teste at the same time as

that o the unknown patient.
BLEEDING TIME: STANDARDIZED IVY METHOD

Principle Procedure

Te blee ing time test is an in vivo measurement o plate- 1. Using resh plasma, prepare the ollowing ilutions:

let a hesion an aggregation on locally injure vascular 2. Incubate the control an patient specimens an mix-

suben othelium. T is test provi es an estimate o the integ- tures at 37°C an per orm an AP or P assay on each

rity o the platelet plug an thereby measures the interac- plasma, control, an plasma-control mixture a er 10, 30,

tion between the capillaries an platelets. T e blee ing time an 60 minutes.

re ects this aspect o platelet unction by measuring the

length o time two stan ar ize punctures o the ventral Reporting Results

orearm take to stop blee ing. Clinically, the blee ing time I the abnormality is that o a ef ciency, a normal plasma

is prolonge in thrombocytopenia, qualitative platelet isor- sample will correct the assay results to a re erence value. I the

ers such as von Willebran ’s isease, aspirin ingestion, or abnormality is cause by a circulating anticoagulant (inhibi-

the presence o vascular problems. tor), a greater correction is emonstrate as the ratio o nor-

T is proce ure, in CLSI ormat, is provi e on this book’s mal plasma increases in the mixture.

companion Web site at http://thepoint.lww.com/ urgeon6e.

Patient Normal De ciency Inhibitor

CIRCULATING ANTICOAGULANTS

Principle 9 parts 1 part Signi cant No signi cant

Some coagulation ef ciencies are cause by inhibitors to correction correction

specif c actors rather than the lack o a actor. T ese inhibi- 5 parts 5 parts Signi cant Some
tors are sometimes re erre to as circulating anticoagulants. correction correction

o etect a circulating anticoagulant, the AP an the P 1 part 9 parts Signi cant More
that were originally abnormal are repeate using various correction correction

ilutions o patient plasma an normal plasma. T e ilu- Note: It is important to incubate the test specimens for 60 minutes because
tions are incubate at 37°C an teste a er 10, 30, 60, an some inhibitors act progressively, and it may take time for the APTT and/

120 minutes o incubation. I the abnormality is a ef ciency, or PT results of the patient plasma and patient plasma-normal control mix-
10% normal plasma will correct the test result to be close to tures to show the effects of the inhibitor (a prolonged clotting time). To inter-

the normal range, as will the a ition o 50% normal plasma. pret the results, the end point of the normal control has to be compared to
I the abnormality is cause by a circulating anticoagulant, the patient-normal plasma mixtures. As the specimens incubate, a slight
increase in the end points will be observed because of the loss of labile clot-
more correction will usually be shown as the ratio o nor- ting factors. The degree of prolongation in the patient and patient-control
mal plasma increases in the mixture. T e etection o an mixtures must be greater than the normal control plasma.

inhibitor may show up imme iately or may require incuba-
tion o the normal plasma in the presence o the inhibitor.

Di erentiation between a coagulation actor ef ciency an Factor Disorder
a circulating anticoagulant is important in the correct treat-

ment o a patient. II Myeloma, systemic lupus erythematosus (SLE)
V Streptomycin administration, idiopathic

Patient Plasma Normal Plasma VIII SLE, rheumatoid arthritis, drug reaction,
asthma, in ammatory bowel disease,

9 parts 1 part postpartum

5 parts 5 parts VIII, IX Following replacement therapy for hereditary

1 part 9 parts de ciency

IX SLE—rare
Specimen

Re er to the AP proce ure or treatment o the original X Amyloidosis
specimen. X, V SLE—common

Reagents, Supplies, and Equipment XI SLE—very rare

Re er to the AP proce ure. XIII Isoniazid administration, idiopathic

(continued)