TOPIC 3

Preanalysis

All the complex steps that MUST take place BEFORE a sample can be analyzed.

Preanalysis

32-75% of testing errors happens here

32-75%

Percentage of preanalysis that testing errors usually happens in this stage.

Preanalysis

Careful attention is necessary in this phase to ensure meaningful results.

Preanalysis

This emphasizes, errors = extra work; diagnosis delayed; extra cost.

PRE-ANALYTIC FACTORS

POTENTIAL ERRORS (PRE-ANALYTICAL)

IN VIVO

IN VITRO

Online computer input

the most error-free in test order

Verbal requests

are made only in emergency situations and should be documented on a standard form

PATIENT DEMOGRAPHICS

LAB INFO SYSTEM (LIS)

MORTAL SIN: MISIDENTIFICATION

TEST REQUIRING COC

STAT

“immediately” and is highest priority

as soon as possible

ASAP

IPSG#1

IDENTIFY PATIENTS CORRECTLY

Blood (WB, SERUM/PLASMA)

Most common specimen.

Blood (WB, SERUM/PLASMA)

performed using a needle/adapter assembly attached to a syringe/evacuated glass

Blood (WB, SERUM/PLASMA)

transferred to the appropriate specimen container

PROBLEMATIC SITES

Sclerosed vein

vein is hardened or thickened

Thrombosed vein

vein contains a blood clot

Edema

Area has excess fluid swelling

Hematoma

Collection of blood under the skin

Mastectomy

Removal of breast tissue (often with lymph nodes)

Fistula

Surgical connection between an artery and vein (for dialysis)

Blood Collection Tubes

• color-coded

• pre-determined internal vacuum

• converted from glass to plastic collection tubes to minimize exposure to biohazards and broken glass

ANTICOAGULANTS

ANTIGLYCOLYTIC AGENTS

CLOT ACTIVATORS

THIXOTROPIC GEL

– Separates serum/plasma from cells

SPS

anticoagulant, anticomplement

ARD

antibiotic removal device

EDTA (Ethylenediaminetetraacetic acid)

Anticoagulant of choice for hematologic counts and morphology.

EDTA (Ethylenediaminetetraacetic acid)

Has two salts: K2 EDTA and K3 EDTA

CITRATES

Commonly used for coagulation studies and sedimentation rates

CITRATES

Very sensitive about anticoagulant:blood ratio

Black, Blue

CITRATE

1:4 (?), 1:9(?)

CITRATES

0.105 M or 0.129 M (3.2% or 3.8%)

HEPARIN

effective anticoagulant in small quantities without significant effect on many determinations

HEPARIN

Inhibits thrombin

LiHep & NaHep

HEPARIN has 2 forms which are

SODIUM FLUORIDE-OXALATE

generally used for glucose measurements because they contain a antiglycolytic agent which prevents glycolysis for 3 days

3 days

SODIUM FLUORIDE-OXALATE generally used for glucose measurements because they contain a antiglycolytic agent which prevents glycolysis for ___

SEPARATOR TUBES

Either contains clot activators and/or thixotropic gels

SEPARATOR TUBES

During centrifugation, the gel undergoes a change in viscosity lodges between the cells and the top layer.

URINE

Next most common specimen

URINE

Usually requires a timed specimen and/or complete collection

Creatinine

is often used to assess completeness of a collection (in urine)

Lumbar punctures

performed to collect CSF

3rd and 4th & 4th and 5th

most common site for an LP is between the ___ and ___ lumbar vertebrae or between the ___ and ___ lumbar

Chemistry or Immuserology

CSF: Tube #1

Microbiology

CSF: Tube #2

Hematology

CSF: Tube #3

SYNOVIAL FLUID

Ultrafiltrate of plasma found in the joints

arthrocentesis

an aspiration of the joint using a syringe, moistened with an anticoagulant

SYNOVIAL FLUID

collected by arthrocentesis, an aspiration of the joint using a syringe, moistened with an anticoagulant

Microbiology

SYNOVIAL FLUID: Sterile Tube:

Hematology

SYNOVIAL FLUID: EDTA Tube:

Chemistry

SYNOVIAL FLUID: Red Tube:

SPECIMEN TRANSPORT

accounts for approx. 1/3 of the total TAT

45 mins & 1 hr

Routine: delivered <___ after collection & centrifuged <___