Specimen Collection PDF

In order to carry out biochemical analysis , it is necessary that the laboratory be provided with both the 1- correct specimen for the requested test  2- Information which will ensure that the right test is carried out 3- The result returned to the requesting clinician with the minimu...

In order to carry out biochemical analysis , it is necessary that the laboratory be provided with both the 1- correct specimen for the requested test  2- Information which will ensure that the right test is carried out 3- The result returned to the requesting clinician with the minimum of delay As much detail as possible should be included on the request form to help both laboratory staff and the clinician in the interpretation of result. This information can be very valuable when assessing a patients progress over a period. Patient identification must be correct and the request form should include some indication of the suspected pathology. The requested analysis should be clearly Request forms differ in design indicated.  The request forms in general must contain the following : 1- Name of the pateint ( First, Mid and surename) 3- Patients identification ( Address, age, sex, simple history ) 4- pathological diagnosis. 5- the name of the clinician that ask for the request. A variety of specimens are used in biochemical analysis as in following : 1- Venous blood , serum , or plasma 2- Arterial blood 3- Capillary blood 4- Urine 5- Faeces 6-Cerebrospinal fluid ( CSF) 7-Sputume and Saliva 8-Tissue and cells 9-Fluids 10- Calculi ( Stones ) Blood Specimens Factors affecting the blood specimens are as follow : 1- Dietary constituents : CHO influence GTT 2- Drugs : phenobarb effects GGT 3- Diurnal variation: diff. time of the day ex. Iron and cortisol. 4-other factor as the patient in bed, or ambulant, or taking exercise. Time of collection the specimen  Factors include:  1- Posture of the patient  2- Choice of skin-cleaning agent  3- Selection of suitable vein  4- Amount of venous stasis  5- Ovoid haemolysis Several changes after blood collection   1- Glucose converted to lactate due to glycolysis found in the erythrocytes.  2- K, LDH, and AST, ALT pass through RBCs membrane to plasma on delay of separation.  3- Loss of CO2 since PCO2 of blood is much higher than in air.  4- Plasma phosphate increase due to hydrolysis  5- Acid phosphatase (Prostate type) loss activity  Hemolytic affect  Haemolysis affects all the biochemical parameters analysis due to one step methods so any changing in the color of serum or plasma will affect the results.  URINE   Most quantitative analysis of urine require a timed sample (usually 24 hour) which can be difficult to collect by the patient  Urine specimen container needs a preservative to inhibit bacteria growth or acid to stabilize certain metabolite. CSF Cerebral spinal fluid Cerebral spinal fluid biochemical analysis are as follow : 1- Glucose 2- Protein 3- other labs as in : Cytology Bacteriology Cell count and differtial Fluids  1- Pleural fluid  2- Pericardial fluid  3- Peritoneal fluid  4- Amniotic fluid  Storage &transport to lab -container must be correctly & sufficiently labeled -full details about the patient Full details about the test Specimen should be delivered to lab. As soon as possible storage of serum or plasma and not blood in refrigerator overnight  Most quantitative analytical procedures involve several operations or steps, and each operation  Is subject to some degree of inaccrracy or to the possibility of a mistake.  Clinical laboratories perform  -Qualitative – blood group ( Positive or negative)  - Semi quantative - dipstick for glucose in urine  Quatitative  The amount of particular subs. Measured by some instrument & the results expressed numerically.  Most quantitative analytical procedures involve several operations or steps, and each operation  Is subject to some degree of inaccrracy or to the possibility of a mistake.  Quality Control ( QC) has been defined as the study of those mistake.  The QC system is the laboratory system for minimizing and recognizing analytical errors.  A batch of control serum is to be prepared as much as 2000 L of plasma is thawed , poled , defibrinated, supplemented with various analytes to achieve the desired concentrations in the definrd products, mix thorughlly filtered , and dispensed into vials. The vials are then lypholized and capped under nitrogen. Quality Control  Internal QC ( Intralaboratory Q.C)  External QC ( Interlaboratory QC)  Survey programs ( Proficiency testing )  Regional QC program  The purpose of the QC system into :  Monitor analytical process.  Detect analytical errors during analysis  Prevent the reporting of incorrect patient value Case 1  Ablood sample from a 4 year-old boy with abdominal pain was sent to the laboratory from an accidental and emergency department some of the results were as follow:  Plasma bilirubin 14 U mol/L ( < 20 )  ALT 14 U/L  Alk. Phosphatase 326 U/L ( < 250)  Alb. 40 gm /L ( 35-45 )  GGT 14 U/L (