False-Positive Reactions With Rh Typing Reagents
| Likely Cause | Corrective action, in compliance with direction circular |
|---|---|
| Fibrin interference | Use saline-washed cells; retest |
| Rouleaux | Use saline-washed cells; retest |
| Bacterial contamination of reagent vial | Open new vial of reagent; retest |
Can blood group test go wrong?
Several conditions can cause false or inconclusive results in blood compatibility testing. When these issues affect ABO typing, they are called ABO discrepancies. ABO discrepancies must be investigated and resolved before the person’s blood type is reported.
Are blood group tests accurate?
After analyzing 3,550 clinical blood samples, the test demonstrated more than a 99.9 percent accuracy rate, and the only inconsistencies occurred in trials with highly uncommon blood types.
When might you spot a false positive in the typing of blood?
False-positive results may also be seen when high-protein Rh reagents that contain 20% protein or other high molecular weight additives are used for typing. Therefore, a proper Rh control reagent should be tested simultaneously before the Rh typing results can be correctly interpreted.
What causes false positive in ABO grouping?
Antibodies to preservatives, medications, disease states, Wharton’s jelly, and/or cross- contamination of reaction microtubes may cause false positive reactions.
What happens if a mother is Rh negative and the baby is Rh positive?
If the mother is Rh-negative, her immune system treats Rh-positive fetal cells as if they were a foreign substance. The mother’s body makes antibodies against the fetal blood cells. These antibodies may cross back through the placenta into the developing baby. They destroy the baby’s circulating red blood cells.
Is A+ A common blood type?
Thirty-four of every 100 people have A+. These are rare blood types and less than 10 percent of the population have this blood type. This blood type is acknowledged to be the “universal recipient” because AB+ people can accept red blood cells from any other blood type.
What are limitations of ABO grouping?
As noted earlier, the amount of sample can limit ABO typing. For standard tube testing, column agglutination “gel card” methodology (see the image below) and solid phase test systems, at least 1 mL of blood is required.
How do you resolve ABO Rh discrepancies?
In this situation, the discrepancy can be resolved by washing and re-suspending patient RBCs in saline, followed by repeat forward typing with anti-A and anti-B.
What can cause false positive and false negative results in PCR?
In the case of dirty glassware. If there is an improper cell to serum ratio, it will give a false positive or false-negative result. If reagents are contaminated or expired, it will give a false-positive result. If you do over centrifugation, it will give a false-positive result.
Can 2 positive blood cultures with the same pathogen mean anything?
The clinician can be quite confident, then, that 2 out of 2 blood cultures positive with the same pathogen, even one that is commonly a contaminant, represents real disease, assuming that the 2 blood cultures were obtained from separate venipunctures or catheter draws.
What is ABO blood grouping based on?
ABO blood grouping is based on observation of agglutination in test tubes of they various types with the blood cells and sera. The results of those interactions with known types of cells and sera determine each patients’ type. The concepts of “false positive” and “false negative” don’t really make sense when applied to ABO grouping.
What are the possible causes of delayed diagnosis of positive blood culture?
Misinterpretation of the clinical significance of the positive blood culture result; Failure of the primary and covering physicians to communicate effectively, ultimately resulting in delayed diagnosis and increased patient morbidity.
