Intro to Lab Medicine Specimen

What are the 4 basic techniques for collecting patient samples?

What are the 4 basic techniques for collecting patient samples?

Venous, arterial, capillary blood samples, and urine samples

Types of anatomic Laboratories

Histology, cytology, autopsy

Types of Clinical Laboratories

Microbiology, hematology, urinalysis, serology, chemistry, immunohematology

Laboratory tests are used for?

- to confirm a disease or condition based on the patient's clinical presentation.
-to "rule out' certain conditions
-to monitor effectiveness of therapy
- to provide prognostic information or assess disease severity
- to screen for disease

What is the cellular portion of blood composed of ?

RBCs, WBCs, and platelets

What is the liquid portion of blood and what does it consist of ?

Plasma consists of water, minerals, nutrients, wastes, hormones, antibodies, and various proteins

what three components does whole blood divide into after centrifugation?

Liquid portion (plasma or serum depending on coagulation), "buffy coat" ( WBC and platelets) and RBC at the bottom

what is the most common specimen submitted to the laboratory>

venous blood samples

what is a bore

inner wall diameter of the needle

Large needles size and use?

(14-18 gauge) used for blood donations or mass transfusions

smaller needles size and use?

20-22 gauge and used for routine blood collection

what is the smallest appropriate size of a needle?

22 ( if larger, RBS can be damaged)

drawing blood is what kind of collection system?

closed collection system

plain red or gold tubes

-no anticoagulant (RBC can clot)
-chemistry and serology testing

red/gray or gold or Tiger Top

SST (serum separator tube)
no anticoagulant
tests requiring serum- most chemistry tests
contains inert polymer gel

what does SST inert polymer barrier gel do

separates serum from cell with gel barrier and clotted blood cells sink to bottom

lavender/ purple top

anticoagulant : EDTA (ethylenediaminetetraacetic acid)
inversion required to prevent clotting
(purple cares about RBC)

EDTA what does it do? best for what test? unacceptable for what?

binds and neutralizes calcium required for blood coagulation, best for preserving blood cell integrity. unacceptable for calcium sodium or potassium analysis

light blue top

anticoagulant: sodium citrate
coagulation testing (plasma and platelet function)

how does sodium citrate stop blood coagulation

binds calcium

green top

anticoagulant: heparin
arterial blood gasses, chemistry analytes: troponin and ammonia

heparin

anti coagulant
in form of sodium, lithium or ammonium salt
enhances activity of antithrombin III that inhibits blood coagulation
does not preserve blood cell integrity

gray tubes

anticoagulant: potassium oxalate
additive: sodium fluoride (antiglycolytic agent)
glucose and blood alcohol testing

what is the blood specimens collection order of draw?

1. sterile specimens : blood cultures
2. coagulation studies: light blue top
3. no anticoagulant: red top, red/gray or gold (SST) tops
4 with anticoagulant: green, lavender, gray

when are syringes used?

on patients with fragile viens. could callapse by pressure from vacuum

when are butterfly infusion sets used?

small or fragile veins. pediatric and elderly patients

what is the most perforable site for venous blood collection

in the antecubital fossa- located anterior to elbow
- the median cubital vein

sites of venous blood collection?

median cubital vein, cephalic vein, basilic vein

what are arterial samples used for?

-analysis of blood gas values
-assess respiratory and metabolic status of the body
-blood form arteries is oxygenated

what angle do you insert the needle?

15 degrees with bevel up

common site for arterial sample collection>

radial artery in the wrist (first choice)
brachial artery near basilic bein in the antecubital area

what test is used to determine adequate circulation through the ulnar artery for arterial sample collection?

modified allen test

what is the modified allen test?

apply pressure to both radial and ulnar arteries and have pt open and close fist till hand is pale, release and see color returns within 5 seconds

what angle is the needle inserted in with an radial artery collection?

45 to 60 degrees 10-15 mm below the palpating

capillary blood samples are used when?

ventipunctures sites are unavailable or inadequate: infants/ neonates, elderly, chemotherapy, and burn patients

sites of collection on an infants ( less than 15 months)

DO NOT use fingers, use medial or lateral planter surface of the heal

how does strenuous exercise affect venous blood samples

increase blood lactate dehydrogenase and creatinine kinase levels
increased serum creatinine and potassium levels
increase WBC count
increase hematuria and proteinuria

hemolysis

destruction of red blood cells

random urine specimens

diagnose urinary tract diseases, evaluate renal function, detect metabolic or systemic diseases

first- morning urine specimens

best specimen for pregnancy testing and better specimen for routine urinalysis

(collects immediately upon arising and delivered to lab within 1 hour of collection)

clean- catch midstream urine specimens

used for microbiology ( urine culture and antibiotic sensitivity testing)

(Beginning of void is not kept and area is wiped before sample)

24 hour urine specimens

quantitated procedures for manyu analytes- commonly tested analytes are protein, creatinine, calcium, and cortisol

(sample must be refrigerated and first void is not kept)