Question

A 50-year-old woman is admitted to the hospital for cardiac surgery, and the order is for 4 Units packed RBCs. The woman types as an O Positive, genotype DcE/dce. During the preparation of the units of packed cells, one of the units was weakly incompatible. The unexpected antibody screening cells were very weakly positive microscopically. The DAT was positive. When the cells were tested with monoclonal IgG AHG and monoclonal C₃d AHG they reacted with the IgG, but not the C₃d AHG at AHG phase only.

1. What is the most probable cause of the positive DAT?

2. What procedure would you do after identifying a positive DAT?

3. What is the significance of the positive DAT reaction?

4. If a person would suspect an Rh antibody, considering the person’s genotype, what would be the most likely antibody?

Answer 1

1. Auto antibodies to intrinsic RBC antigen.

2.add one or two drops of patients cells to a tube labelled wit the patient s initial cells from EDTA tube again wash the tube three times with isotonic saline after the third wash prepare 3% suspension from the washed cell. Label four tubes poly, igG, C3, saline.add one drop of washed 3% suspension to each tube. Wash tubes again when decanting drain well blot dry immediate add of one drop of poly specific antihuman globulin to the tube,one drop of anti-igG to ig tube, one drop of anti-C3 to C3 tube, one drop of saline to saline tube

Centrifuge it immediately resuspend gently examine agglutination read grade record it

3. Positive DAT reaction means there are antibodies attached to the RBC

4.Rh D factor