Specimen Handling | The Children's Hospital of Philadelphia

Clinical Chemistry Laboratory

Specimen Handling

Blood Gas Specimens

Blood gas specimens require a full name of the specimen collector, sealed gas tight heparinized syringe. No bubbles! Proper mixing at the time of collection is essential to prevent clot formation.

Specimens transported via the pneumatic tube system should be double bagged. Blood gas specimens delivered by courier should be on ice and bagged. The requisition form accompanying a blood gas specimen must have the date and time of collection and the collector's signature. A peel off label on each requisition provides space for this information on both specimen and requisition.

For ionized Calcium test, a full 0.7 mL of whole blood in a 1 mL heparinized syringe or 2 mL in a 3 mL syringe is required.

Blood Specimen Collection

Serum Separator Tubes: For most tests requiring serum, the CHOP Clinical Laboratory recommends the use of plasma separator collection tubes. However, refer to the individual test for specific requirements since certain tests preclude their use. When using a serum separator tube, follow these instructions (Reference to the Phlebotomy “order to draw” section)

  1. Perform venipuncture as with any other blood collection vehicle.
  2. Invert the tube gently no more than five times (further inversion may cause alterations in sample integrity).Do not remove the stopper at any time. Allow the blood to clot for at least 30 minutes but not longer than I hour. Do not centrifuge immediately after drawing blood.
  3. Centrifuge at approximately 3400 RPM for at least 10 minutes.
  4. Transfer the clear serum to a labeled plastic vial for transport to the laboratory.

Red Top Tubes: Certain tests require the use of red top tubes rather than plasma separators or serum separators. If serum is to be sent for the test it must be removed from the cells to prevent hemolysis.

  1. Perform venipuncture as with any other blood collection vehicle.
  2. Do not remove the stopper at any time. Allow the blood to clot for at least 30 minutes but not longer than 1 hour. Do not centrifuge immediately after drawing blood.
  3. Centrifuge at 3400 RPM for at least 10 minutes.
  4. Transfer the clear serum to a labeled plastic vial, using a pipette. Do not transfer red blood cells to the vial. (Not in SOP)

Plasma: Plasma contains fibrinogen and other clotting factors when separated from the red cells. Evacuated tubes used to collect plasma specimens contain anticoagulant and frequently a preservative. An additive in the tube is specified and correlates to the color of the tube stopper. Consult the individual test specimen requirement to determine the correct additive/tube to use. Indicate that the specimen is plasma on the specimen container and test request form. Follow the instructions below for specimen preparation.

  1. Perform venipuncture as with any other blood collection vehicle.
  2. Invert the tube gently no more than five times to mix blood and additive.
  3. Centrifuge within I hour of collection at 3400 RPM for at least 10 minutes.
  4. Pipet the plasma into a clean labeled vial. Do not transfer red blood cells to the vial.

Whole Blood: Collect whole blood according to the instructions provided for the individual test. Thoroughly mix the blood with the additives by gently inverting the tube. Maintain the specimen at room temperature before shipping to the laboratory unless instructed otherwise. Never freeze whole blood unless specifically instructed by the specimen requirements. When frozen whole blood is required, transfer the specimen to a labeled plastic vial.

 

Urine Specimen Collection

Random: The normal composition of urine varies considerably during a 24-hour period. Most reference values are based on analysis of the first urine voided in the morning. This specimen is preferred because it has a more uniform volume and concentration, and its lower pH helps preserve the formed elements. Submit a first morning specimen whenever possible. Urine for pregnancy testing should be a first morning voiding, or a random specimen with a specific gravity of at least 1.010. Note the time of collection of the specimen on the test request form and on the label of the container. Submit urine for pregnancy testing in a plastic vial with no preservative. Refer to the Test Directory for specific analyte requirements.

To reduce contamination, the specimen submitted for urinalysis should be a clean catch "midstream sample." Urinalysis specimens must be submitted in a yellow capped urine transport tube containing preservative. (There should be no preservative in tubes for urinalysis. Only random urine specimens collected in preservative is they top for urine culture). The tubes are available through Client Services. (Central labs only supply containers for timed collections. Random collection tubes are supplied by SPD).

24-Hour Urine Collection: Proper collection and preservation of 24-hour urine specimens is essential for accurate test results. Patients must be carefully instructed in the correct procedure. Refer to the Test Directory for specific analyte information. If a frozen specimen is required, freeze the urine aliquot immediately after collection. Pack in dry ice for shipment to the laboratory.

Give a collection container and detailed instructions to the patient. If a urine preservative is required, it is important that the designated preservative be in the urine collection container at the start of the collection. Caution the patient that the preservative may be toxic and caustic and that it should not be spilled or discarded. Record any medication that the patient is receiving on the test request form. (Under CLS policy CLS 002, we no longer issue urine collection containers with preservative except for the following tests: 1) Porphyrins – Sodium Carbonate and 2) Kidney Stone Risk Analysis – special collection container provided Mission Pharmacal. All other preservatives are added when specimen is processed in CLS. As long as collection is refrigerated during the entire time of collection specimen is not compromised). Mix the urine well, measure the volume of the 24- hour collection and record volume on both the test request form and the transport vial. Transfer the required volume into a plain urine transport vial. Add any additional required preservative and mix well. Do not send the entire urine collection. (Send the entire urine collection not just an aliquot. The only exception is specimens coming from Heme/Onc clinic).

Note: For those analyses requiring the addition of 6N HCI or other preservatives, add the preservative at the start of collection. Have the patient collect each specimen in a smaller container and carefully pour the urine into the 24-hour container to avoid any possible acid burns to the patient. Be sure to mix urine thoroughly before removing the aliquot. (See comment above. CLS will add preservative at end of collection and we want full collection not aliquot).

Instructions to the Patient:

  1. Avoid alcoholic beverages and vitamins for at least 24 hours before starting to collect urine, and during the collection period. Do not discontinue medications unless instructed to do so by your physician. Inform the laboratory which medications you are taking.
  2. Do not exceed your normal intake of liquids or change your dietary habits during the day before and the day of your collection unless your physician gives you specific instructions to do so.
  3. Empty bladder (void) into the toilet on the morning of the collection day. Do not include the first urine specimen of the day. (Record date and time of start).
  4. Collect all subsequent urine voided for the next 24 hours and add to the container provided by the laboratory. The last sample collected should be the first specimen of the following morning at the same time as the previous morning's first voiding.
  5. Keep the urine in a cool place. KEEP REFRIGERATED AT ALL TIMES DURING COLLECTION.
  6. Deliver to the referring healthcare provider promptly.
  7. With the exception of the 2 tests mentioned previously no preservative should be added.
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