The Disappearing Antibody: A Case Study (Online CE Course)

(based on 565 customer ratings)

Author: Pat Letendre, M.Ed., MT(CSMLS)
Reviewer: Laurie Bjerklie, MA, MLS(ASCP)CM

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Mr. R.M., a 55-year old male, was admitted to a hospital emergency department with severe lower gastrointestinal bleeding. His physician orders an emergency transfusion of O Rh-negative Red Blood Cells, but problems arise when the laboratory discovers the presence of an antibody. This interactive case study will allow you to work through Mr. R.M.’s case that becomes even more curious when the antibody apparently disappears.

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Continuing Education Credits

P.A.C.E.® Contact Hours (acceptable for AMT, ASCP, and state recertification): 2 hour(s)
Approved through 7/31/2024
Florida Board of Clinical Laboratory Personnel Credit Hours - General (Blood Banking / Immunohematology): 2 hour(s)
Approved through 7/31/2024


  • Describe possible serological test results in a patient experiencing a hemolytic transfusion reaction.
  • Explain the characteristics of mixed-field agglutination and the significance of a positive DAT with mixed-field agglutination in a recently transfused patient.
  • Identify the problems involved in antigen phenotyping patients who have been recently transfused and those who have a positive DAT.
  • List the signs and symptoms of immediate and delayed hemolytic transfusion reactions and differentiate which ones are associated with severe acute hemolytic reactions.
  • Identify antibodies using an antigram and antibody exclusion protocol.
  • Apply standard good laboratory practices to confirm the logical consistency of antibody identification test results and related clinical data.
  • Evaluate serological and clinical inconsistencies when identifying antibodies to determine if further investigative tests are required.
  • Explain the risks of transfusing uncrossmatched red blood cells and when the risks may be acceptable.

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(based on 565 customer ratings)

Course Outline

Click on the links below to preview selected pages from this course.
  • Case Scenario
  • Test Results
    • Compatibility Testing
      • The ABO, Rh, and antibody screen results were obtained by the transfusion services laboratory using the blood specimen that was collected prior to sta...
      • The antibody screen is positive but the transfusion of the O Rh-negative RBCs is already in progress. What are the transfusion service (TS) laboratory...
      • Crossmatch Results
      • Pretransfusion Direct Antiglobulin Test Result
    • Post-Transfusion Tests
      • Post-Transfusion DAT Results
      • Which of the following statements about mixed-field agglutination (MFA) is inaccurate?
      • In this case, which red blood cells (RBCs) are agglutinating in the DAT and why?Antibody Screen CellsGel IAT*Screen Cell I 3+Screen Cell II 2+Screen C...
      • Antibody Investigation
      • Which of the following most likely accounts for the patient's post-transfusion plasma giving negative panel results?
      • Other Post-Transfusion Tests
      • Consulting the Patient's Physician
      • Follow-up With Clinical Staff
      • Immediate Hemolytic Transfusion Reaction Signs and Symptoms
      • Cause of Delayed Hemolytic Transfusion Reaction
      • Delayed Hemolytic Transfusion Reaction Signs and Symptoms
      • Signs and Symptoms Precaution
      • Which of the following signs and symptoms most likely indicate a severe immediate hemolytic transfusion reaction?
      • Investigating Weak Antibodies
      • Two Weeks Post-Transfusion Antibody Identification
      • Antibody Exclusion Protocol
      • Using the guidelines in the Antibody Exclusion Protocol, which antibodies are possible (have not been excluded) using this panel? Select all that appl...
      • Which of the following antibodies in this scenario could explain all reactions by itself?Antibody identification results:CellRh-HrKellDuffyKiddLewisLu...
      • Which of the following cells would be the most useful in excluding anti-E and anti-K in this patient?
      • Variations in Antibody Strength
      • When the patient's plasma was non-reactive with panel cells and very weak and unidentifiable in the post-transfusion RBC eluate, no attempt was made t...
      • DAT Change of Status
      • Antigen Phenotyping
      • Antigen Phenotyping Issues
      • Antigen Phenotyping Results
      • Which of the following statements about antigen phenotyping is inaccurate?
  • Post-Examination Check of Data
      • Evaluating Inconsistencies
      • Unexpected Anomaly
      • Reflecting on Probability of the Solution
      • When performing an antibody investigation, which of the following would indicate an inconsistency that needs to be further investigated?
      • The patient's red cell eluate initially was unidentifiable, reacting weakly with only two panel cells that did not fit a pattern. Once anti-Jka was id...
      • Using Probability Values
      • Antibody Identification Checklist
      • As discussed earlier, one of the post-examination tools for confirming that the serologic data fit the solution is to consider the big picture, as pre...
  • Case Outcome
      • Case Study Summary
      • Risks of Transfusing Unmatched Red Blood Cells
      • Balancing the Risks
      • Consider your responses to each of the following questions, then click on the questions.
  • References
      • References

Additional Information

Level of Instruction: Intermediate
Intended Audience: Medical laboratory scientists, medical laboratory technicians, laboratory supervisors, and laboratory managers. This course is also appropriate for MLS and MLT students and pathology residents.
Author Information: Pat Letendre, M.Ed., MT(CSMLS), is a medical laboratory scientist, educator, and consultant. Currently, she consults full-time in the areas of transfusion medicine, education, professional development, and the use of the Internet in education. Ms. Letendre is the Webmaster for the Canadian Society for Transfusion Medicine and the TraQ website coordinator. She holds a Master of Education degree in adult education from the University of Alberta and a Bachelor of Science degree from the University of Manitoba.  
Reviewer Information: Laurie Bjerklie, MA, MLS(ASCP)CM, is currently an Education Developer for MediaLab and LabCE. She earned a B.S. in Medical Laboratory Science from the University of North Dakota and an M.A. in Curriculum and Instruction from Saint Xavier University. She has over 15 years of experience in higher education and has held program director and faculty positions in both MLT and MLS programs
Course Description: This course presents a case in which a patient has an unexpected antibody that disappears after they are transfused with unmatched group O Rh negative red blood cells.

How to Subscribe
MLS & MLT Comprehensive CE Package
Includes 180 CE courses, most popular
$109Add to cart
Pick Your Courses
Up to 8 CE hours
$55Add to cart
Individual course$25Add to cart
Post-transfusion microscopic DAT

Antibody screen cells

DAT micro4