Preanalysis refers to all the complex steps that must take place before a sample can be analyzed.

1. Preanalysis:Precollection
variables,specimen collection and
collection techniques
Dr.Sourabh Paranjape
Guide: Dr.C.R.Gore

2. Introduction
Preanalysis refers to all the complex steps that must take place before a sample can be
analyzed.
Most of the testing errors occur in the preanalytic phase.
Technologic advances and quality assurance procedures have significantly reduced the
number of analytic-based errors.
This has exposed the preanalysis stage as a major source of residual “error” and/or
variables that can affect test results.
Preanalytic factors include patient-related variables (diet, age, sex, etc.), specimen
collection and labeling techniques, specimen preservatives and anticoagulants,
specimen transport, and processing and storage

3. Potential sources of error or failure in this process include
improperly ordered tests, sample misidentification, improper
timing, improper fasting, improper anticoagulant/blood ratio,
improper mixing, incorrect order of draw, and hemolyzed or
lipemic specimens.
The most frequent preanalytic errors include improperly filling the
sample tube, placing specimens in the wrong containers or
preservatives, and selecting the incorrect test.

4. Ten Common Errors in Specimen
Collection
1. Misidentification of patient
2. Mislabeling of specimen
3. Short draws/wrong anticoagulant/blood ratio
4. Mixing problems/clots
5. Wrong tubes/wrong anticoagulant
6. Hemolysis
7. Hemoconcentration from prolonged tourniquet time
8. Exposure to light/extreme temperatures
9. Improperly timed specimens/delayed delivery to
laboratory
10. Processing errors: Incomplete centrifugation,
incorrect log-in, improper storage

5. PreCollection Variables
In preparing a patient for phlebotomy, care should be
taken to minimize physiologic factors related to activities
that might influence laboratory determinations.
These include
• diurnal variation
• Exercise
• Fasting
• diet,
• ethanol consumption
• tobacco smoking
• drug ingestion
• posture.

6. Diurnal variation
This may be encountered when testing for
hormones,iron, acid phosphatase, and urinary
excretion of most electrolytes such as sodium,
potassium, and phosphate

7. Exercise
Physical activity has transient and long-term effects on laboratory
determinations.
Transient changes may include an initial decrease followed by an increase in
free fatty acids, and lactate may increase by as much as 300%.
Exercise may elevate creatine phosphokinase (CK),
aspartate aminotransferase (AST), and lactate dehydrogenase (LD), and
may activate coagulation, fibrinolysis, and platelets .
Long term effects of exercise may increase CK, aldolase, AST, and LD values.
Chronic aerobic exercise is associated with lesser increases in plasma
concentration of muscle enzymes such as CK, AST, alanine aminotransferase
(ALT), and LD.
Decreased levels of serum gonadotropin and sex steroid concentrations are
seen in long-distance athletes while prolactin levels are elevated .

8. Diet
Glucose and triglycerides, absorbed from food, increase after eating.
After 48 hours of fasting, serum bilirubin concentrations may increase.
Fasting for 72 hours decreases plasma glucose levels in healthy women to 45
mg/dL(2.5 mmol/L)
Eating a meal, depending on fat content, may elevate plasma potassium, triglycerides,
alkaline phosphatase, and 5-hydroxyindoleacetic acid (5-HIAA)
Stool occult blood tests, which detect heme, are affected by the intake of meat, fish,
iron, and horseradish, a source of peroxidase, causing a false-positive occult blood
reaction.

9. Long-time vegetarian diets are reported to cause decreased
concentrations of low-density lipoproteins (LDLs), very-low-density
lipoproteins (VLDLs), total lipids, phospholipids, cholesterol, and
triglycerides.
A high meat or other protein-rich diet may increase serum urea,
ammonia, and urate levels.

10. Alcohol
Ethanol ingestion increases plasma lactate, urate, and
triglyceride concentrations. Elevated high density
lipoprotein (HDL) cholesterol, γ-glutamyl transferase
(GGT), urate, and mean corpuscular volume (MCV)
have been associated with chronic alcohol abuse.

11. Stress
Mental and physical stresses induce the production of
adrenocorticotropic hormone (ACTH), cortisol, and
catecholamines.
Total cholesterol has been reported to increase with
mild stress, and HDL cholesterol to decrease by as
much as 15%
Hyperventilation affects acid-base balance and
elevates leukocyte counts, serum lactate, or free fatty
acids.

12. Posture
An upright position increases hydrostatic pressure, causing a
reduction of plasma volume and increased concentration of
proteins.
Albumin and calcium levels may become elevated as one
changes position from supine to upright.
Elements that are affected by postural changes are albumin,
total protein, enzymes,calcium, bilirubin, cholesterol,
triglycerides, and drugs bound to proteins.

13. Using a tourniquet to collect blood to determine lactate concentration
may result in falsely increased values. Prolonged tourniquet application
may also increase serum enzymes, proteins, and protein-bound
substances, including cholesterol, calcium, and triglycerides, as the
result of hemoconcentration when plasma water leaves the vein
because of back pressure.
After bed rest in the hospital, a patient’s hemoglobin (Hb) can decrease
from the original admitting value enough to falsely lead a physician to
suspect internal hemorrhage or hemolysis.

15. PATHOLOGISTS’/LAB
TECHNICIANS’/PHYSICIANS’ ROLE
Is to advice patients to avoid changes in
their diet, consumption of alcohol, and
strenuous exercise 24 hours before having their
blood drawn for laboratory testing.

16. Age
There are four age groups: newborn, childhood to puberty, adult, and
elderly adult
In the newborn, much of the Hb is Hb F, not Hb A, as seen in the adult.
Bilirubin concentration rises after birth and peaks at about 5 days. In
cases of hemolytic disease of the fetus and newborn (HDFN), bilirubin
levels continue to rise.
This often causes difficulty in distinguishing between physiologic
jaundice and HDFN.
Infants have alower glucose level than adults because of their low
glycogen reserve.

17. With skeletal growth and muscle development, serum alkaline
phosphatase and creatinine levels, respectively, also increase.
The high uric acid level seen in a newborn decreases for the first 10
years of life, then increases, especially in boys, until the age of 16 .
Most serum constituents remain constant during adult life until the
onset of menopause in women and middle age in men. Increases of
about 2 mg/dL (0.05 mmol/L) per year in total cholesterol and 2 mg/dL
(0.02 mmol/L) per year in triglycerides until midlife have been reported

18. The increase in cholesterol seen in postmenopausal women
has been attributed to a decrease in estrogen levels.
Uric acid levels peak in men in their 20s but do not peak in women
until middle age.
The elderly secrete less triiodothyronine, parathyroid hormone,
aldosterone, and cortisol.
After age 50, men experience a decrease in secretion rate and
concentration of testosterone and women have an increase in pituitary
gonadotropins, especially follicle-stimulating hormone (FSH)

19. Gender
After puberty, men generally have higher alkaline phosphatase,
aminotransferase, creatine kinase, and aldolase levels than women; this
is due to the larger muscle mass of men.
Women have lower levels of magnesium, calcium, albumin, Hb,
serum iron, and ferritin.
Menstrual blood loss contributes to the lower iron values.

20. COMMON INTERFERENCES
In Vivo
Tobacco smokers have high blood carboxyhemoglobin
levels, plasma catecholamines,and serum cortisol.
Changes in these hormones often result in decreased
numbers of eosinophils, while neutrophils, monocytes,
and plasma fatty free acids increase.
Chronic effects of smoking lead to increased Hb concentration,
erythrocyte (RBC) count, MCV, and leukocyte (WBC) count.
Increased plasma levels of lactate, insulin, epinephrine, and
growth hormone and urinary secretion of 5-HIAA are also seen.

21. Vitamin B12 levels may be substantially decreased
and have been reported to be inversely proportional
to serum thiocyanate levels.
Immunoglobulin (Ig)A, IgG, and IgM are lower in smokers, and
IgE levels are higher.
Decreased sperm counts and motility and increased abnormal
morphology have been reported in male smokers when
compared with nonsmokers.

22. COMMON INTERFERENCES
In Vitro
• Collection-Associated Variables
On occasion, when there is a problem finding a vein for phlebotomy, the
specimen may be hemolyzed as the result of sheer forces on the red blood
cells.
Hemolysis can also be caused by using a needle that is too small,
pulling a syringe plunger back too fast, expelling the blood vigorously into
a tube, shaking or mixing the tubes vigorously, or performing blood collection
before the alcohol has dried at the collection site.
Hemolysis is present when the serum or plasma layer is pink.
Hemolysis can falsely increase blood constituents such as potassium,
magnesium, iron, LD, phosphorus, ammonium, and total protein.

23. A special case where pseudohyperkalemia can occur is in patients
with extremely high blast counts in acute or accelerated phase leukemias.
Those blasts can be fragile and may lyse during standard phlebotomy,
releasing potassium.
In contrast, specimens with very high WBC counts that are collected gently can
show pseudohypokalemia when potassium is
taken up by highly metabolically active leukemic cells along with glucose;
such specimens can be transported on ice to slow this enzymatically
mediated uptake.
Normally platelets release potassium during clotting, so serum has a
slightly higher value of potassium than plasma from the same individual;
this difference is accentuated when the platelet count is extremely
elevated.

24. How to avoid problems during
phlebotomy
To avoid problems with hemoconcentration and hemodilution, the
patient should be seated in a supine position for 15 to 20 minutes before
the blood is drawn .
Extended application of the tourniquet can cause hemoconcentration, which
increases the concentrations cellular components. So we have to avoid the
extended use of tourniquets.
Mix an anticoagulated tube of blood after it has been filled.
Failure to mix a tube containing an anticoagulant will result in failure to
anticoagulate the entire blood specimen, and small clots may be formed.
Before running the sample on analyzer check for the clot,if a clot is present, it
may also occlude or otherwise interfere with an automated analyzer.

25. Specimen Collection
One of the most frequent preanalytic errors involves selecting the wrong
laboratory test or panel of tests, leading to inappropriate interpretation of
results.
Laboratory tests are usually ordered electronically (e.g., computer) or in
writing (e.g., paper requisition).
Verbal requests are made in emergency situations and should be documented
on a standard form; after the blood is drawn, an official laboratory request or
computerized order should be placed .
Patient demographics include the patient’s name, sex, age, date of birth (DOB),
date of admission, date on which measurement or examination was ordered,
hospital number, room number, physician, and physician’s pharmacy code
number.

26. All specimens must be clearly labeled. Preprinted bar code labels
applied after proper patient identification, and after the specimen is
collected, avoid preanalytic transcription errors.
Frequently, the laboratory receives requests for “add-ons.”
These are additional tests requested to be performed on a specimen
that has previously been collected.
Problems are encountered when the specimen is not the proper type for the
add-on requested test, the residual volume is not sufficient to perform the
test, or storage conditions result in deterioration of the analyte .
This is usually due to the presence or absence of a particular anticoagulant or
additive.
All add-on requests must be documented.

27. Medicolegal concerns
These include proper identification of the patient, proper labeling of the
specimen, patient consent issues, patient privacy issues, and chain of custody.
Laboratories should have clearly written policies for these issues.
Policies should describe what to do when a patient refuses to have blood
drawn, what to do if the patient was unable to be drawn, what to do if a
patient is unavailable, and how to deal with a combative patient, as well as
emergency measures for patients who become ill or faint during phlebotomy.
The Health Insurance Portability and Accountability Act (HIPAA) ensures the
security and privacy of health data and protects the confidentiality of all
patient record information, including all laboratory data.
Employees must be trained to comply with HIPAA.

28. TIME OF COLLECTION
Sometimes, samples have to be collected at a specific time.
The most common tests in this category are the ASAP and stat
collections. ASAP means “as soon as possible” and stat is an American
medical term meaning “immediately” (from the Latin “statim”).
Stat specimens are collected and analyzed immediately. They are given
the highest priority and are usually ordered from the emergency
department and critical care units .
Timed specimens are ordered for a variety of reasons, usually to
monitor changes in a patient’s condition, to determine the level of a
medication, or to measure how well a substance is metabolized.

29. In therapeutic drug monitoring, trough and peak levels of a
drug may be ordered.
Trough specimens reflect the lowest level in the
blood and are generally drawn 30 minutes before the drug is
administered.
The peak specimen is drawn shortly after the medication is
given; the actual collection time varies by medication.
Drug manufacturers specify the length of time that must pass
between trough and peak collection times.

30. SPECIMEN REJECTION
Reasons for Specimen Rejection
Hemolysis
Clots present in an anticoagulated specimen
Non fasting specimen when test requires fasting
Improper blood collection tube
Short draws, wrong volume
Improper transport conditions (ice for blood gases)
Discrepancies between requisition and specimen
label
Unlabeled or mislabeled specimen
Contaminated specimen/leaking container
All specimens must be
collected, labeled,
transported, and processed
according to established
procedures that include
sample volume, special
handling needs, and
container type.
Failure to follow specific
procedures can result in
specimen rejection

31. Blood Collection Overview
Venipuncture is accomplished using a needle/adapter
assembly attached to an evacuated glass/plastic test tube
with a rubber/plastic stopper. Blood may also be collected in
a syringe and transferred to the appropriate specimen
container (evacuated tube system). A syringe may be helpful
when procuring a specimen from the hand or ankle, or from
small children.
In addition, patients with small or poor veins may experience
collapse of veins with use of an evacuated tube system.

32. AccuVein
AccuVein (AccuVein LLC, Huntington, N.Y.) is a newly marketed hand-
held medical device that helps medical staff visualize veins before
phlebotomy.
The device emits infrared light and is held about 7 inches over the
potential phlebotomy site. Hb in the blood absorbs infrared light and
projects an image map of the veins onto the patient’s overlying skin.
The device is able to distinguish between Hb in the veins and
surrounding tissue.
This device assists the phlebotomist in determining the best site for
needle placement, especially for challenging patients such as the
elderly, the obese, burn victims, oncology patients, and patients with
other chronic diseases requiring many diagnostic or therapeutic
procedures .

34. Blood collection tubes
They have color-coded stoppers that distinguish the presence of a
specific anticoagulant or additive, how the tube is chemically cleaned
(e.g., for lead or iron determinations), or if the tube does not contain
any additives.
Draw volume is determined by the internal vacuum within the sealed
tubes (e.g., 3.5, 4.0, 4.5, or 8.5 mL)
Many laboratories have converted from glass to plastic collection tubes
to minimize exposure to biohazardous material (e.g., blood) and broken
glass; to lower biohazard waste disposal costs; and to comply with
Occupational Safety and Health Administration (OSHA) guidelines .

35. Order of Draw: Evacuated Tube and Syringe
1. Blood-culture tubes (yellow)
2. Coagulation sodium citrate tube (blue stopper)
3. Serum tubes with or without clot activator or gel separator
4. Heparin tubes with or without gel (green stopper)
5. Ethylenediaminetetraacetic acid tubes (lavender stopper)
6. Glycolytic inhibitor tubes (gray stopper)

38. ANTICOAGULANTS AND ADDITIVES
Ethylenediaminetetraacetic acid (EDTA) is the anticoagulant of choice for hematology
cell counts and cell morphology. It is available in lavender-top tubes as a liquid or is
spray-dried in the dipotassium or tripotassium salt form (K2EDTA in plastic, spray-
dried, and K3EDTA in liquid form in glass tubes)
Pink top tubes also contain EDTA. The EDTA is spray-dried K2EDTA. Pink
tubes are used in immunohematology for ABO grouping, Rh typing, and
antibody screening
White-top tubes also contain EDTA and gel. They are used most often for molecular
diagnostic testing of plasma.
Sodium citrate is commonly used because it preserves the labile coagulation factors
Black-top tubes also contain buffered sodium citrate and are generally used for Westergren
sedimentation rates, as are lavender-top tubes.
They differ from light blue–top tubes in that the ratio of blood to anticoagulant is 4:1 in the
black-top tubes and 9:1 in the light blue–top tubes.

39. Heparin, a mucoitin polysulfuric acid, is an effective anticoagulant in
small quantities without significant effect on many determinations.
Heparin is available as lithium heparin (LiHep) and sodium heparin (NaHep) in
green-top tubes.
Heparin has an advantage over EDTA as an anticoagulant, as it does not affect
levels of ions such as calcium.
Heparin should not be used for coagulation or hematology testing. Heparinized
plasma is preferred for potassium measurements to avoid an elevation
due to the release of potassium from platelets as the blood clots.
Lithium heparin may be used for most chemistry tests except for lithium and folate
levels.Sodium heparin cannot be used for assays measuring sodium levels, but it is
recommended for trace elements, leads, and toxicology.

40. Gray-top tubes are generally used for glucose
measurements because they contain a preservative
or antiglycolytic agent, such as sodium fluoride,
which prevents glycolysis for 3 days .
Red-top tubes have no additive, so blood collected in
these tubes clots. Plain red-stoppered tubes with no
additives take about 60 minutes to clot completely

41. BLOOD COLLECTION DEVICES
The most common blood collection system uses a vacuum to
pull blood into a container; it consists of a color-coded
evacuated collection tube, a double- headed needle, and an
adapter/holder.
Small tubes are available for pediatric and geriatric collections. The
blood collection holder accommodates various sizes (gauge) of blood
collection needles.
Winged infusion sets (butterfly needles) can be used when blood has to be
collected from a very small vein.
Butterfly needles come in 21, 23, and 25 gauge. These needles have plastic
wings attached to the end of the needle that aid in insertion of the needle into
the small vein.

42. Needles:gauge and colour code

43. BLOOD STORAGE AND PRESERVATION
In general, to afford the greatest sample integrity, samples should be processed as
quickly as possible (ideally within 1 hour of collection) and testing performed within
4 hours of procurement (or else be processed by centrifugation and plasma frozen).
During this short-term storage, whole blood samples should be kept capped and
maintained at room temperature. If testing is not to be performed within about 4
hours for the APTT and 24 hours for the PT, the plasma should be separated from the
cellular fraction of the once or twice- centrifuged sample, without disturbing the cell
pellet.
Separated plasma can generally be maintained at room temperature or
refrigerated for a few hours without an adverse effect on coagulation.
Testing for samples maintained at around -20°C should be finalized within 2–4 weeks
of storage, whereas testing for samples maintained at around -80°C can occur several
months and sometimes years later.

44. IMPORTANCE OF POLICIES AND
PROCEDURES
• Policies to be decided by laboratories ,apex
institutions in order to prevent biohazards.
• To fulfill all medicolegal entities.
• To follow WHO guidelines

45. Blood Collection Techniques
• ARTERIAL PUNCTURE
Arterial punctures are technically more difficult to perform than venous punctures. Increased
pressure in the arteries makes it more difficult to stop bleeding, with the undesired
development of a hematoma. In order of preference, the radial, brachial, and femoral arteries
can be selected. Before blood is collected from the radial artery in the wrist, one should
do a modified Allen test to determine whether the ulnar artery can provide collateral circulation
to the hand after the radial artery puncture.
The femoral artery is relatively large and easy to puncture, but one must be especially careful in
older individuals because the femoral artery can bleed more than the radial or brachial. Because
the bleeding site is hidden by bedcovers, it may not be noticed until bleeding is massive.
The radial artery is more difficult to puncture, but complications occur less frequently.
The major complications of arterial puncture include thrombosis, hemorrhage, and
possible infection. When performed correctly, no significant complications are
reported except for possible hematomas.

46. Modified Allen Test
1. Have the patient make a fist and occlude both the ulnar (opposite the
thumb side) and the radial arteries (closest to the thumb) by compressing
with two fingers over each artery.
2. Have the patient open his or her fist, and observe if the patient’s palm
has become bleached of blood.
3. Release the pressure on the ulnar artery (farthest from the thumb) only,
and note if blood return is present. The palm should become perfused
with blood. Adequate perfusion is a positive test indicating that arterial
blood may be drawn from the radial artery. Blood should not be taken
if the test is negative. Serious consequences may occur if this procedure
is not followed, which may result in loss of the hand or its function.

47. FINGER OR HEEL SKIN PUNCTURE
For routine assays requiring small amounts of blood,
skin puncture is a simple method by which to collect
blood samples in pediatric patients. In the neonate,
skin puncture of the heel is the preferred site to
collect a blood sample; in older children, the finger
is the preferred site.

48. CENTRAL VENOUS ACCESS DEVICES
Central venous access devices (CVADs) provide ready access to the
patient’s circulation, eliminating multiple phlebotomies, and are
especially useful in critical care and surgical situations.
Indwelling catheters are surgically inserted into the cephalic vein, or
into the internal jugular, subclavian, or femoral vein and can be used
to draw blood, administer drugs or blood products, and provide total
parenteral nutrition.
Continuous, real-time, intraarterial monitoring of blood gases and
acid-base status has been accomplished with fiberoptic channels
containing fluorescent and absorbent chemical analytes.

49. Urine and Other Body Fluids
Collection
URINE
Laboratory testing of urine generally falls into three categories: chemical,
bacteriologic, and microscopic examinations.
Random, clean-catch, timed, 24 hour, and catheterized.
Random specimens may be collected at any time.
A clean-catch midstream specimen is most desirable for bacteriologic
examinations. Proper collection of a clean-catch specimen requires that the
patient first clean the external genitalia with an antiseptic wipe; the patient
next begins urination, stops midstream, and discards this first portion of urine,
then collects the remaining urine in a sterile container.

50. Urine specimens for a 24-hour total volume collection are most
difficult to obtain and require patient cooperation. Incomplete
collection is the most frequent problem. In some instances, too
much sample is collected.
Pediatric collections require special attention to avoid stool
contamination.
Over collection occurs if the first morning specimen is included
in this routine.

51. Special Urine Collection Techniques
Catheterization of the urethra and bladder may cause infection
but is necessary in some patients (e.g., for urine collection when
patients are unable to void or control micturition).
Ureteral catheters can also be inserted via a cystoscope into the
ureter.. Ureteral urine specimens are useful in differentiating
bladder from kidney infection, or for differential ureteral
analysis, and may be obtained separately from each kidney
pelvis (labeled left and right).
First morning urine is optimal for cytologic examination.

52. Urine Storage and Preservation
Urine may be frozen.
Sodium fluoride can be added to 24-hour urine for glucose determinations to inhibit
bacterial growth and cell glycolysis, but not growth of yeast.
Tablets containing formaldehyde ,mercury, and benzoate (95 mg tablet/20 mL urine)
have also been used; however these preservatives elevate specific gravity (0.002/one
tablet/20 mL).
Boric acid in a concentration of 1 g/dL preserves urine elements such as estriol and
estrogen for up to 7 days. Boric acid is a bacteriostatic preservative, not a bactericidal,
and it does not inhibit the growth of yeasts.
For catecholamines, vanillylmandelic acid (VMA), or 5-hydroxyindoleacetic acid (5-
HIAA) collections, 10 mL of 6N HCl is added to a 3 to 4 L container.

53. Changes in Urine With Delayed Testing
Changes in color Breakdown or alteration of chromogen or
other urine constituent (e.g., hemoglobin,
melanin, homogentisic acid, porphyrins)
Changes in odor Bacterial growth, decomposition
Increased turbidity Increased bacteria, crystal formation,
precipitation of amorphous material
Falsely low pH Glucose converted to acids and alcohols by
bacteria producing ammonia. Carbon
dioxide (CO2) lost
Falsely elevated pH Breakdown of urea by bacteria, forming
ammonia
False-negative glucose Utilization by bacteria (glycolysis)
False-negative ketone Volatilization of acetone; breakdown of
acetoacetate by bacteria
False-negative bilirubin Destroyed by light; oxidation to biliverdin
False-negative
urobilinogen
Destroyed by light
False-positive nitrite Nitrite produced by bacteria after specimen

54. Synovial Fluid
Synovial fluid is collected by arthrocentesis, an aspiration of the joint using a
syringe, moistened with an anticoagulant, usually 25 units of sodium heparin
per mL of synovial fluid.
Oxalate, powdered EDTA, and lithium heparin should not be used, as they
can produce crystalline structures similar to monosodium urate (MSU)
crystals.
Once removed, the synovial fluid is usually transferred to three tubes—one
sterile, one containing EDTA or heparin, and one red-top tube; 5–10 mL of fluid
is added to each.
The sterile tube is sent to microbiology,
the anticoagulated tube is sent to hematology, and the red-top
tube, after centrifugation, is used for chemical analysis.

55. Pleural Fluid, Pericardial Fluid,
Peritoneal Fluid ,Ascitic fluid,CSF
• These fluids are sent to the laboratory for
routine microscopy,biochemical analysis
(sugar protein,LDH ,etc.) and microbiological
analysis.

56. Semen Analysis
• Abstinence of 3-5 days
• Colour,volume,pH,liquifaction time to be noted
• Wet mount preparation to check for motility.(Active
motile,sluggish motile and non motile)
• If found,pus cells,to be mentioned.
• With semen diluting fluid diluting the semen sample in
1:19 ratio,loading to Neubaur’s chamber will give us
the sperm count in millions.
Number of sperms counted in all 64 small squares X
50000

57. Specimen Transport
Transport of blood, urine, body fluids, and tissue specimens from the collection site to
the laboratory is an important component of processing. Specimens should be
protected from direct exposure to light.
For analysis of unstable constituents such as ammonia, plasma renin activity, and acid
phosphatase, specimens must be kept at 4° C immediately after collection and
transported on ice.
All laboratory specimens must be transported in a safe and convenient manner to
prevent biohazard exposure or contamination of the specimen .
Polystyrene or other high-impact plastic-type containers are commonly used.
Stool specimens are transported in a cardboard container and placed in a polyethylene
bag.

58. Interferences
One of the main concerns in the preanalysis phase is
whether any substance or artifact is introduced as the
result of specimen handling or other patient related
factors that lead to alterations in the technical
measurement of clinical specimens in the analysis.
The patient’s medical condition might cause
abnormalities that can be evaluated by measurement of
various analytes, and some of those abnormally elevated
substances can markedly interfere with some basic
modes of analysis.

59. SPECIMEN COLLECTION
The appropriate tube should always be used for collection of blood
specimens.
Volume of drawn blood should be appropriate.
Excess citrate in plasma from insufficient blood volume leads to
falsely elevated clotting times. This interference is also important in
polycythemia, when the hematocrit is abnormally
high and plasma volume in which the citrate distributes is small.
Thus, even in an apparently correctly filled tube, polycythemia can
lead to falsely prolonged PT and PTT unless the amount of citrate
anticoagulant in the tube is reduced proportionally to the decrease in
plasma volume in that patient.

60. OPTICAL INTERFERENCES
The most common interfering conditions are hemolysis and icterus, which
strongly absorb particular wavelengths of light, and also lipemia, which
scatters light and so blocks its transmission.
Lipemia can potentially be cleared from a serum or plasma specimen by
ultracentrifugation.
Hemolysis that occurs at the time of blood collection can be eliminated by re-
collection of the specimen
Bilirubin in a specimen is not readily removed.
Result reporting should include a statement about the appearance of a
specimen if it is particularly abnormal which helps the physician to
interpret abnormal findings (e.g., elevated potassium in hemolyzed
specimens).

61. EFFECTS OF DRUGS
If a patient is on rifampicin the orange coloured urine may ring
a bell about the abnormality,but if the history is provided we
can avoid giving false positive result.(So it is of prime
importance to know the patients drug history)
In stool testing for occult blood, peroxidases from meats
(myoglobin) or vegetables (horseradish) in the diet can yield a
false-positive results.
Prolonged prothrombin time with Coumarin.
Lower potassium in blood with some diuretics-potassium
sparing diuretics such as spironolactone)

62. References
• Favaloro, Emmanuel J., Dorothy M. Adcock Funk, and Giuseppe Lippi.
"Pre-analytical variables in coagulation testing associated with
diagnostic errors in hemostasis." Laboratory Medicine 43.2 (2012): 1-
10.
• HENRY’S CLINICAL DIAGNOSIS AND MANAGEMENT, Twenty-Second
Edition

63. THANK YOU