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Serologic Information and Courses from MediaLab, Inc.

These are the MediaLab courses that cover Serologic and links to relevant pages within the course.

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Current Topics in Clinical Microbiology
Thus, in follow-up to the previous discussion, the reaction shown in the photograph establishes the identification of a group A, beta hemolytic streptococcus.View Page

Introduction to the ABO Blood Group System
The History of the ABO System (cont.)

Landsteiner, knowing that none of his subjects had been immunized, realized that “natural” antibodies must develop which are directed against antigens not present on the red cells. Individuals with “A” antigens on their red cells had sera containing “Anti-B” antibody. Individuals with “B” antigens had sera containing “Anti-A.” “AB” individuals had sera with no ABO antibodies present and “O” individuals’ sera contained “Anti-A” and “Anti-B.” Sera from group O individuals may contain a separate antibody, “Anti-A,B.” Anti-A,B possesses serologic activity not found in mixtures of Anti-A and Anti-B. Anti-A,B sera will agglutinate A, B, and AB cells. It is particularly useful in detecting weak A and B antigens. See the table on the next page.

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Strength of the A Antigen

The strength of the A antigen can vary considerably, and although most A cells react strongly with anti-A and anti-A1B, some cells have been found that are very weakly reactive. The blood group has been divided into subgroups and is classified not only by the strength of the A antigen but also by certain other serologic characteristics.

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Parasitology Review
Serologic methods have been developed to identify which of these parasites?View Page
Which of the following parasites may be identified by being cultured?View Page

The Disappearing Antibody: A Case Study
Antibody identification checklist

To improve the quality of conclusions when identifying antibodies, a checklist is a simple quality control tool to increase transfusion safety. If a specific antibody pattern cannot be identified with acceptable confidence, or if significant serologic or non-serologic data are inconsistent and cannot be rationalized, further testing will be required.Before concluding that the investigation is complete, unless not applicable, mentally reply to each question in the checklist. If any answer is no, has it been resolved? Antibody Identification Checklist Yes/No/NA 1. For a single antibody, does the reaction pattern fit only one antibody specificity? 2. Is antibody specificity consistent with the results of the initial antibody screen? 3. Are reaction phases consistent with antibody specificity? 4. If multiple antibodies are present, can all reactions be explained by the antibody combination? 5. If the autocontrol is negative, are patient red cells negative for the corresponding antigen(s)? 6. Have additional possible antibodies been excluded by selected red cells? 7. Can all variable reaction strengths be explained? 8. If tested, are antigen-negative donor cells compatible by antiglobulin crossmatch? 9. If there are data that do not fit antibody specificity or if there are results that are improbable, are they explainable? 10. Have all results and conclusions been systematically evaluated for consistency?

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As discussed earlier, one of the post-analytic tools for confirming that the serologic data fit the solution is to consider the big picture, as presented below. Think of how you would reply to each question in this case and then click each question to see sample responses.View Page
Literature and online resources

Literature Dutton RP, Shih D, Edelman BB, Hess J, Scalea TM. Safety of uncrossmatched type-O red cells for resuscitation from hemorrhagic shock. J Trauma. 2005 Dec;59(6):1445-9. Johnson ST, Rudmann SV,Wilson, SM. Serologic problem solving strategies:a systematic approach. Bethesda, MD: AABB, 1996.Online resourcesThe following are online examples of good practice. The information should not be used as a substitute for technical and clinical judgment. Medical and technical information becomes obsolete quickly and current sources relevant to the user's location should always be consulted. Urgent requirements for blood (Calgary Laboratory Services, Calgary,Alberta, Canada) Online resource for laboratory's clients Why is there never enough O Rh negative blood? (American Red Cross) Advice for physicians on how to help prevent shortages of O Rh negative blood Transfusion reactions: Transfusion complications (Canadian Blood Services) Education website for CBS's hospital customers REACT (Sunnybrook HSC, Toronto, ON, Canada) Pocket reference card for nurses on signs and symptoms of transfusion reactions Quick cals (online calculator of p values for Fisher's exact test) Use a one-tailed test (since we would expect an antibody to react with red cells that are positive for the corresponding antigen)

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