LAB INVESTIGATIONS IN ORAL AND MAXILLOFACIAL SURGERY

 Hematological
 Urine Analysis
 Blood gas analysis.
• Biochemistry :
 Renal function tests Tests
 Liver function tests Lipid Analysis
 Thyroid function tests
 Immunological investigations
 Microbiology
• References

 Diagnosis & identification - disease by careful
investigation of patients signs, symptoms and
history
• Times when more information is required
through the use of diagnostic tests.
• Clinical and/or lab data must be used to
distinguish between different diagnoses.

 laboratory tests - important in assisting &
management of the patient during treatment of
disease besides diagnosis.
1. screen - disease in asymptomatic individual
2. to establish or exclude presence of diseases in
symptomatic patients
3. assist the practitioner in the management of the
patient.

Hb, HCT
-anemia
-polycythemia
WBC
-leukocytosis
-leukopenia
-abnormal cells
Platelet
-thrombocytosis
-thrombocytopenia

 Hemoglobin :
 M: 13.8 to 17.2 gm/dL
 F: 12.1 to 15.1 gm/dL
 Hematocrit : (packed cell volume)
 It is ratio of the volume of red cell to the volume of
whole blood.
 M: 40.7 to 50.3 %
 F: 36.1 to 44.3 %

RED BLOOD CELL INDICES
MEAN CORPUSCULAR
VOLUME [MCV]
HCT X 10
MCV= --------------
RBC
Normal range- 82 to 98 ug
Below – microcytic anemia
Above- macrocytic anemi
MEAN CORPUSCULAR
HEMOGLOBIN [ MCH]
HB X 10
MCH= --------------
RBC
Normal range= 27 to 32pg
Below -microcytic anemia
Above- macrocytic anemi
MEAN
CORPUSCULAR HB
CONCENTRATION
HB X 100
MCH= --------------
HCT
Normal range= 32 to
38gm /100ml
Beloe – microcytic
anemias
Above – heredietary
spherocytosis.

 Normal range-
male = 0 to 20mm/hr
female = 0 to 10mm/hr
 Non specific test
 Eleveted in infections ,infarctions, trauma , or
tumours.

• This important value is needed in the evaluation
of any anemia.
• Normal range 1-2%
• Retic count goes up with
– Hemolytic anemia
• Retic goes down with
– Nutritional deficiencies
 _ Diseases of the bone marrow itself

 Hematocrit is valuable in evaluating
polycythemia, anemia and blood loss.
 RBC count provides a gross estimate of the
bodys oxygen carrying capacity and used in
red blood cell indices.

• WBCs are involved in the immune response.
• The normal range: 4 – 11x10^9 /L
• Two types of WBC:
1) Granulocytes consist of:
– Neutrophils: 50 - 70%
– Eosinophils: 1 - 5%
– Basophils: up to 1%
2) Agranulocytes consist of:
- Lymphocytes: 20 - 40%
– Monocytes: 1 - 6%
WHITE BLOOD CELLS

• polymorphneuclear leukocytes (PMN,s)
• Nucleus 3-5 lobes.
• Diameter 10-14 µm
• 50-70% WBC
• Function: Phagocytosis of bacteria and cell
debris
• Numbers rise with all manner of stress,
especially bacterial infections

• Neutrophil disorders
– Neutrophilia – an increase in neutrophils
– Conditions associated with neutrophilia are:
 1-Bacterial infections (most common cause)
 2-Tissue destruction
 e.g. tissue infarctions, burns.
 3- leukemoid reaction
 4-Leukemia

 Decrease in neutrophill count
 Conditions associated ;
1. Certain infections- typhoid, malaria
2. Drugs , chemical and physical agent
3. Certain hematological diseases; aplastic
anemia.

• Bilobed nucleus
• 1-5% of WBC
• Diameter about 10-14 µm
• Function: Involved in allergy, parasitic
infections
• Contains: Eosinophilic granules

– Eosinophilia may be found in
• Parasitic infections
• Allergic conditions and hypersensitivity
reaction

• No specific granules
• 20-40% of WBC
• Diameter 8-10 µm
• T cells: cellular
• (for viral infections)
• B cells: humoral (antibody)
• Natural Killer Cells

• Lymphocytosis – may indicate
 _ Viral infection
 e.g. Infectious mononucleosis, CMV or
pertussis.
 _ Bacterial infection
 e.g. TB
• Lymphopenia – caused by
 _Stress.
 _Steroid therapy
 _ Irradiation

• (Leukocytosis) may indicate:
 _ Infectious diseases
 _Inflammatory disease (such as
rheumatoid arthritis or allergy)
 _Leukemia
 _Severe emotional or physical stress
 _Tissue damage (e.g. necrosis,or burns)

• (Leukopenia) may result from:
 _ Decreased WBC production from BM.
 _ Irradiation.
 _ Exposure to chemical or drugs.

LEUKOCYTOSIS LEUKOPENIA
• Fever
• Malaise
• Weakness
• Others depend on each
system which is involved
e.g. » chest: cough, chest
pain
» abdomen: diarrhea,
vomiting, dehydration.
»CNS: headache, visual
disturbance,
 Neck stiffness
• Infection of the mouth
and throat.
• Painful skin ulceration.
• Recurrent infection.
• Septicemia

Platelet: < 20,000
20,000-50,000
50,000-70,000
Spontaneous bleeding
Bleed after minor trauma
Bleed after major trauma
NORMAL RANGE = 1,50,000 TO 4,00000 cells/cu mm.

• Numbers of platelets
– Increased (Thrombocythemia)
• Pregnancy.
• Exercise.
• splenectomy

– Decreased (Thrombocytopenia)
• Menstruation.
• Haemorrhage.
• Bone marrow destruction or suppression e.g. leukemia

• Petechial hemorhage.
• Easy bruising.
• Mucosal bleeding
 e.g. _ epistaxes.
 _ gum bleeding

•Platelet function •Normal: 2-7 minute
Increased bleeding time
1.Thrombocytopenia
2. Von willebrands disease,
3. Disorders of platelet function.

 Initial coagulation profile
1.Prothrombin time
2.Partial thromboplastin time
3.Platelet count
4.Bleeding time
5. Fibrinogen

 It measures the extrinsic and common
pathways.
 Normal range = 11 to 15 seconds
 Prolonged
1. In deficiency of factor I, II, V, VII and X.
2. Oral anticoagulent therapy
3. Liver diseases
4. Vitamin k deficiency.

INR = Control PT
patient PT ISI
ISI = international sensitivity index

 It measures the extrinsic and common
pathways.
 Normal range= 25-42 sec
 Prolonged in
1. In factor VIII, IX, XI and XII deficiency
2. In pts undergoing heparin therapy.

 Normal level – 200 to 400mg%
 Below 100 % -bleeding occurs
 Decreased levels found in
liver diseases and circulating fibrinolysis.

 Direct measure of blood glucose
 Commonly used to evaluate diabetic pts
 Part of “routine” testing
 Normal: Fasting blood sugar - 70 - 100 mg/dL
Post prandial blood sugar- 120- 160 mg/dl
 ↑ (hyperglycemia): DM, acute stress response, Cushing
syndrome, pheochromocytoma, chronic renal failure,
acute pancreatitis, acromegaly, corticosteroid therapy
 ↓ (hypoglycemia): insulinoma, hypothyroidism,
hypopituitarism, Addison disease, extensive liver
disease, insulin overdose, starvation

 for
 adults with impaired FBG
 during pregnancy if at risk
 Procedure
 Following 8 hour fast
 Glucose dose = 1.75g/kg IBW
 Maximum 75 g dose (BW<43kg, 94lbs)
 Test at 2 hours

 DM if [glu] > 200 mg/dl at 2 hours
 IGT if [glu] >140 - 199 at 2 hours
 normal if [glu] < 140 mg/dl

 a. Considered elevated if values above 7%
 b. Blood test analyzes excess glucose attached to
hemoglobin. Since RBC lives about 120 days gives
an average of the blood glucose over previous 2 to
3 months
 Not a fasting test, can be drawn any time of the day
 % of glycated (glucose attached) hemoglobin measures
how much glucose has been in the bloodstream for the
past 3 months

Normal constituents
• Water – 95%
• Organic – Urea, uric Acid, Creatinine
• Inorganic – NaCl, sulphates & phosphates
• Pigments – derived bile pigments .

1.General physical
characteristics &
measurements
2.Chemical Examination 3. Microscopic
examination of
centrifuged sediment
• Appearance - clear :
white & cloudy
• Colour – straw ,
yellow,amber
• Odour – ammonia
• Quantity – 1500ml
• Specific gravity –
1.010 to 1.030
Reaction – ph acidic
4.5-8
• Protein – albumin
• Glucose – no
• Ketone – no :
• Bilirubin – no
• Blood – no
• Uribilinogen – small
amts
• Cells
• Casts
• Bacteria
• Parasites & yeasts
• Crystals
• Artifacts &
contaminants

 Helps in evaluation of acid-base balance and
The degree of oxygenation.
Contents:
1. Ph
2. Pco2
3. Po2
4. Bicarbonate
5. Base deficit
6. O2 saturation

 Ph
normal range- 7.35 to 7.45
>7.35- acidosis
<7.45- alkalosis
 Pco2
Normal range= 35 to 45 mmHG- arterial blood
41 to 51 mmHG- venous blood
Refers to the pressure of dissolved co2 in blood.

 Increase pco2 – hypoventilation- resp. acidosis
 Decrease pco2 –hyperventilation- resp.alkalosis
 Po2
 Normal range- 80 to 100mm HG-arterial blood
35to 40mmHG-venous blood
Decreased levels of po2-hypoxia-resp. acidosis

 Represents the difference between therotical
and actual total co2 content of the blood.
 Normally – 0 with a ranga of +/-2mEq/L.
 Negative value- bicarbonate deficit-metabolic
acidosis
 Positive value - bicarbonate excess-metabolic
alkalosis.

 A. Estimation of electrolytes
 B. Renal function
 C. Liver function
 D. Thyroid Function

•Normal range: 10-47IU/L –increased in
chronic alcoholism
Serum γ-Glutamyl Transferase
•Normal range: 2-17IU/L – increased in
hepatobilary disease
Serum 5’-Nucleotidase

 Liver is the main source of synthesis of
 Plasma proteins
 - Albumin
 - Globulin
 Blood clotting factors
 - Prothrombin and
 factors V, VII and X.

 Normal range – 50 to 175 ug/100ml
 Available for Hb formation
 Increased
1.Hemolytic anemias
2.Pernicious anemia
 Decreased
1.IDA
2.Anemia secondary to chronic infection.

 Normal value – 250 to 410 ug/100ml.
 Increases
1. IDA
2. Anemias secondary to blood loss
 Deceased
1. Chronic infection
2. Liver diseases.

 Useful screening test to determine the presence
or absence of hepatitis virus.
 Typically oppears in the last few weaks of
incubation period.
 High risk carriers of HBsAg are,
pt on renal dialysis, receiving blood transfusion
and blood derivatives and chronic drug
abusers.

 Thyroid stimulating hormone
 Total thyroxine T4
 Triidothyronine T3

TSH - In most situations TSH analysed using a
high sensitivity assay is now accepted as the
first line test for assessment of thyroid
function.
A TSH between 0.4 and 4.0 mIU/L gives 99%
exclusion of hypo- or hyperthyroidism.
while the TSH is considered more sensitive than
FT4 to alterations of thyroid status in patients
with primary thyroid disease.

 FT4 –
 This test measures the metabolically active,
unbound portion of T4.
 Measurement of FT4 eliminates the majority
of protein binding errors associated with
measurement of the outdated total T4, in
particular the effects of oestrogen.

 FT3 –
 FT3 has little specificity or sensitivity for
diagnosing hypothyroidism and adds little
diagnostic information.
 The main value of FT3 is in the evaluation of
the 2 to 5% of patients who are clinically
hyperthyroid, but have normal FT4.
 In this situation, an elevated FT3 would be
suggestive of T3 toxicosis, in which the thyroid
secretes increased amount of T3 or there is
excessive conversion of T4 to T3.

 ) The cultures : can be used to detect the
 microorganisms Which cause an infection in any
 part of the body such as ; urinary tract , throat, GIT,
 ear, eye and the respiratory tract; etc .
 2) The sensitivity test : can be used to detect the
 most effective antibiotic against the microorganism
 that cause a certain infection.

• Pus from abscess is best collected at the time the
abscess is incised and drained.
• Using sterile technique, aspirate or collect from
drainage tube up to 5 ml of pus, transfer to sterile
container.
• If pus is not being discharged use sterile cotton wool
swab to sample from the infected site.
• Extend the swab deeply into the depth of the lesion.
• Immerse the swab in container of transport medium
• Label it and send to the laboratory as soon as
possible.

 Procedure :
 1) Take a loop of one colony which
previously grown
 on Mackonkey medium or on all media
( blood agar,
 chocolate agar or SS agar media) by
using a sterile
 swab

 Then by the swab, spread the loop on a nutrient agar
 medium in 3 direction to ensure confluence

 3) By using a dispenser, antibiotic-impregnated disks
 are placed onto agar surface ( See fig. 2).

 4) As the bacteria on the lawn grow, they are inhibited
 to varying degrees by the antibiotic diffusion from the
 disk.

 5) It has been determined that zones of inhibition of
 a certain diameter ( varies for antibiotic and to a lesser
extent, bacterial species) correlate with sensitivity or
 resistance to the antibiotic tested.

 Incubate the culture at 37C° for 24 hour
in an incubator.
 Observe the results.
 Note : the larger the inhibition zone, the
more the sensitivity the antibiotic .

 Practice of surgery-Baily’s and love.
 Laskin’s textbook of oral and maxillofacial
surgery
 Medical physiology – Sembulingam
 Harshmohan textbook of pathology

LAB INVESTIGATIONS IN ORAL AND MAXILLOFACIAL SURGERY

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