Specimen Collection
Quality results begin with proper specimen collection!

Collection Facilities

The UCSF Clinical Laboratories operates multiple specimen collection facilities throughout San Francisco.  The addresses and hours of operation of these facilites can be found here.

Collection Containers and Patient Instructions

Inpatient collection supplies are obtained through material services. Urine containers requiring special preservatives are not stocked on the floors, but can be obtained from the specimen processing desk at each hospital laboratory.

For at home specimen collections, appropriate specimen containers and patient instructions can be obtained from any of our outpatient specimen collection facilities

Blood Collection Tubes and General Guidelines

Volume to collect

Please consult the laboratory test menu entry for collection instructions. While the minimum volume necessary for testing is stated in the test menu, when clinically possible it is advisable to collect the preferred volume, as this will allow for repeat testing when necessary. We recognize that this is not always possible, and will make every effort to provide a result on the sample submitted

General Technique

1. Avoid hemolysis

  • Avoid prolonged venous stasis prior to sample collection 
  • DO NOT force blood from syringe through a needle into a vacutainer as the resultant jet may damage red cells, instead allow the sample to be pulled into the vacutainer by the vacuum in the vacutainer
  • Mix specimens in the collection tubes by gentle inversion, DO NOT shake. 

2. Avoid a running IV line

DO NOT withdraw specimens from an extremity proximal to a running IV, nor from the IV line itself as this may result in contamination of the sample with the IV fluid. If it is necessary to draw proximal to an IV it is important that the IV be stopped and the vein allowed to clear (minimum 1 minute) before the sample is drawn. Laboratory phlebotomists have been instructed not to collect samples proximal to an IV, and will ask nursing personnel to stop the IV prior to phlebotomy and restart it after the samples have been collected.

3. Complete filling of vacutainers (especially for coagulation testing):

  • Liquid-containing vacutainers (e.g. Citrate; Blue tops & ACD; Yellow tops) should always be filled to their full draw volume for chemical analysis; this is particularly critical for coagulation testing. Short filling a citrate tube (Blue top) will alter the required 9:1 plasma:citrate ratio and may result in erroneously prolonged coagulation test results.
  • Note that if a winged blood collection set ("butterfly") is used and the coagulation tube is the first tube drawn, a discard blue top tube should be used to clear the dead-space volume of the line or the line should be allowed to 'fill' prior to attaching the vacutainer adapter. This will ensure that an adequate blood volume is collected.
  • Specimens for coagulation testing may also be affected by an abnormal hematocrit. If a patient's hematocrit is above 55%, contact the Hematology laboratory and request a tube adjusted to contain the appropriately decreased amount of citrate anticoagulant. There is no standard at present for adjusting the amount of anticoagulant for specimens with low hematocrits.
  • Finally, specimen(s) for coagulation testing should NOT be drawn from heparinized lines.

4. Order in which multiple samples should be drawn:

Blood samples should be collected directly into vacutainer(s) in the following order to prevent cross contamination of one tube with the additive of another tube that could result in spurious lab results. Check the expiration date of all tubes prior to collecting samples and discard any expired tubes. DO NOT use expired tubes for sample collection.

  • Blood Culture* 
  • Citrate tubes for coagulation tests (BLUE or LIGHT BLUE TOP)
  • Gel (SST) tube with clot activator (GOLD TOP) 
  • Activated clot tube without gel (RED TOP) 
  • Sodium-heparin tube without gel (GREEN TOP) 
  • Lithium-heparin tube with gel (LIME GREEN TOP) 
  • Trace metal free tube w/EDTA (NAVY BLUE TOP W/ PURPLE LETTERING)
  • EDTA tube (PURPLE TOP) 
  • Oxalate/fluoride tube (GRAY TOP) 
  • Acid-Citrate Dextrose tube (YELLOW TOP) 

* In general, because of the risk of bacterial contamination, if blood cultures are needed they should always be drawn first.

5. When drawing ONLY a (light) blue top tube for coagulation studies:

If the venipuncture is promptly successful with a good flow of blood directly into the vacutainer, that single, filled tube may be submitted for coagulation studies. If, by contrast, the venipuncture is difficult with much searching for the vein, the blood flow is slow, or the collection is made into a large syringe, the coagulation cascade may become activated; in that case, an initial blue top tube should be filled, discarded and a second filled tube should be collected for testing.

When a second tube appears to be needed:

  • If the patient is 6 years old or more, 5 mL of blood should be drawn and discarded before the second blue top tube is filled. 
  • If the patient is <6 years old, one (1) mL of blood should be drawn and discarded before the second blue top tube is filled, whether a syringe or a vacutainer is used. 
  • If using a syringe, draw the amount of blood to be discarded into one syringe, then use a second syringe to draw the sample which will be transferred to a blue top tube. 

6. DO NOT Transfer samples between vacutainer types:

Never transfer blood from one tube type to another to make up for short volume. The anticoagulants and clotting activators in each tube are specific for the type of sample necessary for testing. Transferring sample between tubes results in adulteration of the sample and will produce spurious test results.

7. Drawing from Intravascular Catheters:

  • Blood is preferably obtained by venipuncture and not from catheters. If blood is to be obtained from a catheter, it must be collected by nursing staff.
  • If blood is obtained from an intravascular line, it is important to clear the line of the fluid which has been infused through it or is "keeping it open" (e.g. heparin or saline). If this is not done, spurious results are likely to be obtained, e.g., an elevated PTT from residual heparin or a spuriously elevated glucose or potassium from the remnants of an intravenous solution.
  • To obtain a representative specimen uncontaminated by the initial contents of the line, a volume of blood at least six times (6x) greater than the catheter dead space should be removed and discarded prior to collecting the sample to be sent to the laboratory.

Urine Collection

Please see the Urine Preservative Table for important requirements relevant to chemical analyses of urine specimens.

CSF Collection

CSF should be collected and transported to the laboratory in the special vials provided in the lumbar puncture kit. If unavailable, a plastic vial with a black screw top cap is acceptable. Each vial should be labeled with patient information (full name and medical record number are minimum requirements) and also list the name of the person who collected the specimen and the date it was collected. Note: CSF samples for Beta Amyloid 42/Tau Protein Analysis must be collected in a special polypropylene tube to prevent adherence of the protein to the sides of the tube. The tubes are stocked in the Memory & Aging clinic and are available from laboratory processing areas at each hospital.

Unless otherwise specified, requested tests will be done on selected tubes as follows:

  • Tube #1 Chemistry & Immunology tests
  • Tube #2 Microbiology cultures/tests
  • Tube #3 Cell counts and differentials
  • Tube #4 Cytologic examination (done by pathology)

Cell counts are preferably performed on Tube #3 to reduce the impact of blood contamination secondary to the procedure itself. Counts on multiple tubes are rarely required unless Tube #3 is visibly bloody at which point a cell count on Tube #1 may be requested. A decrease in counts between Tube #1 and Tube #3 suggests a traumatic tap. In this circumstance cell counts should be interpreted with caution. Note: cell counts will not be performed on tube #1 if that sample is grossly bloodier than tube #3.