Laboratory Medicine Updates - September 27, 2002

University of Virginia Health System

Medical Laboratories

“Quality You Expect, Service You Deserve”

LABORATORY MEDICINE UPDATE

September 27, 2002

 

Fluids in Blood Culture Bottles

 

The laboratory strongly discourages the practice on the clinical floors of inoculating normally sterile body fluids (except blood) into blood culture bottles.  When fluids are received in blood bottles, the laboratory cannot perform a gram stain or evaluate the quantity of any organisms that grow.  Please submit fluids in a sterile leak proof container such as a black top tube with a screw cap or SPS tube.

 

 

Blood Culture Collection Guidelines

 

Where possible, blood specimens for culture should be collected before treatment is initiated.  Collect two sets: one from each of two prepared sites, preferably peripheral.  The second should be drawn after a brief interval (30 min).  Follow up cultures should be limited to one per day.

 

Skin should be cleansed with 70% alcohol, swabbing in a concentric fashion with an alcohol pad a total of three times using three different alcohol pads.  Wait a minute to ensure that site is completely dry before performing venipuncture.  Decontaminate diaphragm of blood culture bottle with 70% alcohol before inoculation.  Inoculate blood culture bottles with approximately 10 cc. of blood per bottle.

 

 

Enterics testing now being performed in Clinical Microbiology

 

Fecal Lactoferrin, Clostridium difficile EIA and culture for Helicobacter pylori are now being performed in the clinical microbiology laboratory.   Results are usually available within 24 hours (except H. pylori culture).  H. pylori antibody testing is performed in the Davis Laboratory.

 

 

Guidelines for Cryptococcal antigen repeat testing:

 

When monitoring cryptococcal antigen titers after a positive result, it is recommended to repeat the test no more frequently than every two weeks.  This is due to the fact that the cyptococcal antigen is a complex heteropolysaccharide and is not cleared rapidly.  Titers in CSF (the specimen of choice) can be helpful in monitoring therapy only when the test is repeated over appropriate intervals (at least two weeks) 1.

                                1Manual of Clinical Microbiology 7th edition, Murray et.al 1999, pg 1180.        

 

 

Urine Microscopy Update

 

The 2002 Laboratory Handbook omitted the corrections made to the Urinalysis testing information. The Hematology Laboratory has updated the procedure for performing urine microscopic exams.  A microscopic analysis will be performed on samples from all patients 14 years old and under, regardless of the biochemical findings. A microscopic exam on specimens from patients over 14 years of age will be performed only when indicated:

If the urine is anything other than yellow and clear

or

If the biochemical results for RBC’s, Leukocyte Esterase, or Nitrite are positive

or

If there is a 1+ or greater protein

Please remember that the accuracy of any urinalysis test decreases with time.

 

 

Below is a snapshot of the Urinalysis testing information from the Laboratory Handbook. The changes to the Urinalysis testing information are highlighted in red.

 

 

TEST NAME:  URINALYSIS

TEST CODE:  UACHG/UASCR

CPT CODE:  81001, 81003 

SYNONYMS:

TEST INCLUDES:  Appearance, color, clarity, specific gravity, and chemistries. Microscopic exam on adults (>14 years old) will be performed only when indicated (color other than yellow, clarity other than clear, positive nitrite, blood, leukocyte esterase, > 1+  protein). A Clinitest is performed on children age 2 or under for other reducing substances.

LABORATORY:  Hematology, Ambulatory Care Services

SPECIMEN:  Fresh random urine, first morning void recommended

MINIMUM VOLUME:  5 mL urine

AVAILABILITY:  Daily, 24 hours   

TURNAROUND TIME:  Routine 4 hours, STAT 1 hour

SPRCIAL INSTRUCTIONS:  Cellular elements deteriorate rapidly if specimen not refrigerated or chemically preserved.       

REFERENCE INTERVAL:  See Appendix VI, Table 2. Dipstick Analysis Interferences, See Appendix VI, Table 3.

 


New Directors of the Molecular Pathology Laboratory

 

Two new directors of the Molecular Pathology Laboratory have recently joined the faculty of the Department of Pathology. 

 

Lawrence M. Silverman, Ph.D., Scientific Director, joins us from the University of North Carolina, Chapel Hill.  While at UNC from 1979-2002, he was director of the Division of Molecular Pathology, Professor of Pathology and Laboratory Medicine, Genetics, and Molecular Biology. His research interests are: (1) modifier genes (2) atypical cystic fibrosis, and (3) novel technologies in molecular diagnostics. Dr. Silverman can be reached at 434-243-2957 and lms7r@virginia.edu.

 

Mani S. Mahadevan, M.D., Medical Director, joins us from the University of Wisconsin-Madison.  While at UW-Madison from 1995-2002, he was associate medical director of the DNA Diagnostics Laboratory and Associate Professor of Medical Genetics.  His clinical interests are in the area of human genetics and the application of molecular techniques in the diagnosis of simple and complex genetic disorders. His research interests are focused in the general area of human genetics and triplet repeat mutations.  His research lab is funded to study the pathogenesis of Myotonic Muscular Dystrophy.  Dr. Mahadevan can be reached at 434-243-4816 and mahadevan@virginia.edu.

        

Department of Pathology Symposium

 

On October 14, 2002, the Department of Pathology will sponsor an all day symposium highlighting recent advances in molecular diagnostics and molecular medicine pertaining to inherited diseases.  The focus of the symposium will be spinal muscular atrophy, myotonic dystrophy, cystic fibrosis, and inherited breast/ovarian cancer (BRCA1/2).  For each of this disorders emphasis will be on recent developments that improve both the molecular testing and the understanding of the underlying molecular pathology. Speakers include:

John Day, MD - Univ. of Minnesota

Debra Leonard, MD, PhD, Univ. of Pennsylvania

Michael Knowles, MD, Univ. of North Carolina

Mark Graham, MD, Univ. of North Carolina

Mani Mahadevan, MD, University of Virginia

Lawrence Silverman, Ph.D., University of Virginia 

 

The complete agenda and registration form are available for download at:

www.med.virginia.edu/ed-programs/cme/PATHOLOGY2002/Pathology.htm

 

 


Retesting of Individuals for Neisseria gonorrhoeae

 

The Centers for Disease Control and Prevention have recommended that due to quality control concerns for Abbott reagents used for N. gonorrhoeae testing, clinicians should offer retesting to patients whose test results were negative, who were not presumptively treated, and for whom a clinical suspicion of N. gonorrhoeae carriage remains.  For the Medical Laboratories, suspect reagents were in use from January 1, 2002 through July 15, 2002.  Letters are being sent to any physician who requested testing during this time and for which negative results were released.

 

New Tests For Chlamydia trachomatis and Neisseria gonorrhoeae

 

 The Molecular Pathology Lab has changed from the Abbott LCx ligase chain reaction (LCR) based system to the Roche Cobas Amplicor polymerase chain reaction (PCR) based platform for the analysis of swab and urine specimens for Chlamydia trachomatis and Neisseria gonorrhoeae. This change was made primarily due to recurrence of manufacturing problems and recalls of the Abbott reagents, resulting in disruption of clinical service. The sensitivities of the two methodologies are comparable.

 

Swab specimens can continue to be collected with the Abbott collection devices now in circulation. When that supply has been exhausted, the laboratory will distribute a Roche collection device including M4 Culture Transport Media (MicroTest, Inc.). Endocervical and urethral swab specimens and "first catch" urine specimens are the only specimens acceptable for these tests. These tests are not intended for use with throat, rectal, or other types of specimens.  Throat specimens are especially unsuitable, as the test for Neisseria gonorrhoeae may detect non-pathogenic isolates of N. subflava and N. cinerea, common components of normal throat flora.

 

Test charge, availability and turnaround times will remain the same.  Reporting of results will be as follows:

None Detected

Positive

Inconclusive (Equivocal)

No Amplification/Suspect Inhibitor Present.

 

Repeat specimen collection is suggested for samples that are equivocal or fail to amplify if there is strong clinical suspicion of infection.  Please direct questions concerning these tests to the Molecular Pathology Lab (434-982-3310).

 

 

 

 

 


Transfusion reactions

 

The following is a list of selected acute transfusion reactions.  For the sake of brevity, the list is not complete.  Transfusion reactions not discussed include volume overload, citrate toxicity, reactions associated with leukocyte reduction filters, and delayed reactions such as graft verses host disease.

Whenever an acute adverse transfusion reaction is suspected, immediately:

  • Stop the transfusion
  • Check patient bracelet, blood bank bracelet, blood product, and compatibility tag for clerical errors
  • Maintain IV access with normal saline
  • Notify the patient’s physician and the Blood Bank

 

1.  Febrile non-hemolytic transfusion reactions:  This type of reaction typically consists of an increase of 1o C in temperature occurring within 2 hours of starting a transfusion.  Symptoms include chills, rigors, headache, nausea and vomiting.  Interestingly, a fever may not always occur with this type of reaction.  The incidence is 0.5 – 1.0 % for RBC transfusions and 1 – 15% of platelet transfusions.  This type of reaction usually resolves spontaneously.  The clinical management includes stopping the transfusion and obtaining a new sample for serological evaluation by the Blood Bank to exclude an acute hemolytic reaction.  Antipyretics and merperidine may be considered.

2.  Allergic transfusion reactions can vary from benign to extremely severe.  Symptoms include   pruritus, erythema, nausea, vomiting, tachycardia, hypotension, cardiac arrest and airway obstruction.  Fever is typically absent.  These reactions are not dose dependent.  Mild cutaneous reactions are self-limited.  Transfusing at a slower rate may lessen symptoms and discomfort.  Systemic reactions may require epinephrine, prednisone and antihistamine.  In cases of known, significant cutaneous allergic response where premedication is ineffective, washed cellular products may be indicated.  Patients who have experienced an anaphylactic reaction from a blood transfusion must receive washed cellular products as well as premedication.

  Cutaneous allergic reaction.

3.  Acute intravascular hemolysis occurs in approximately 1 in 75,000 RBC transfusions.  Approximately 10% of reported ABO incompatible transfusions are fatal.  The signs and symptoms include fever (usually greater than 2o C, unless masked by antipyretics), hypotension (often hypotensive shock), pain (at the infusion site, back and chest), headache, shortness of breath, hemoglobinuria and hemoglobinemia, hemorrhage, nausea, vomiting, and diarrhea.  Jaundice can occur 4-6 hours post transfusion and renal failure may develop.  Treatment includes stopping the transfusion, peripheral blood and urine samples for testing, symptomatic treatment with fluids, pressors, steroids, and furosemide.  Only group O cells should be transfused until the etiology of the reaction is resolved.  Exchange transfusion may be necessary.

4.  Transfusion related acute lung injury (TRALI) is an acute respiratory distress syndrome associated with transfusion.  The signs and symptoms include bilateral pulmonary edema, hypoxia, tachycardia, fever (typically 1-2o C), hypotension and cyanosis.  The incidence may be increasing and is as high as 1 in 5,000 transfusions of plasma, cryoprecipitate, and platelets.  The pathophysiology often involves donor granulocyte or HLA antibodies reacting with antigens in a susceptible recipient. Reactive lipid products and cytokines from stored blood products have also been implicated.  The diagnosis must exclude cardiac causes, volume overload, and, if fever is present, an acute hemolytic reaction.  A chest x-ray will typically show diffuse pulmonary infiltrates producing a “white-out” appearance.  In TRALI, the central venous and pulmonary wedge pressures are normal.  The clinical course is usually self-limited with most resolving completely within 72 hours.  Management includes respiratory support, pressors and steroids.

 

5.  Bacterial contamination resulting in morbidity occurs in approximately 1 / 15,000 platelet transfusions and 1 / 500,000 RBC transfusions.  The signs and symptoms include hypotension, fever (usually greater than 2 degrees C), chills, nausea, vomiting, dyspnea, and diarrhea.  In severe cases patients can develop septic shock, and disseminated intravascular coagulation leading to death.  The symptoms most commonly occur during the transfusion, but may not occur until several hours after transfusion.  Investigation should include Gram’s stain and culture of the blood components as well as blood cultures from the patient.  Immediate empirical treatment with antibiotics may be indicated.

 

Blood smear from a bacterially contaminated RBC unit showing numerous extracellular bacteria.