#### § 493.959 Immunohematology.

(a) *Types of services offered by laboratories.* In immunohematology, there are four types of laboratories for proficiency testing purposes—

(1) Those that perform ABO group and/or D (Rho) typing;

(2) Those that perform ABO group and/or D (Rho) typing, and unexpected antibody detection;

(3) Those that in addition to [paragraph (a)(2)](/on/2024-09-17/title-42/section-493.959#p-493.959(a)(2)) of this section perform compatibility testing; and

(4) Those that perform in addition to [paragraph (a)(3)](/on/2024-09-17/title-42/section-493.959#p-493.959(a)(3)) of this section antibody identification.

(b) *Program content and frequency of challenge.* To be approved for proficiency testing for immunohematology, a program must provide a minimum of five samples per testing event. There must be at least three testing events at approximately equal intervals per year. The annual program must provide samples that cover the full range of interpretation that would be expected in patient specimens. The samples may be provided through mailed shipments.

(c) *Challenges per testing event.* The minimum number of challenges per testing event a program must provide for each analyte or test procedure is five.

## Analyte or Test Procedure

ABO group (excluding subgroups)

D (Rho) typing

Unexpected antibody detection

Compatibility testing

Antibody identification

(d) *Evaluation of a laboratory's analyte or test performance.* HHS approves only those programs that assess the accuracy of a laboratory's response in accordance with [paragraphs (d)(1)](/on/2024-09-17/title-42/section-493.959#p-493.959(d)(1)) through [(5)](/on/2024-09-17/title-42/section-493.959#p-493.959(d)(5)) of this section.

(1) To determine the accuracy of a laboratory's response, a program must compare the laboratory's response for each analyte with the response that reflects agreement of either 100 percent of 10 or more referee laboratories or 95 percent or more of all participating laboratories except for antibody identification. To determine the accuracy of a laboratory's response for antibody identification, a program must compare the laboratory's response for each analyte with the response that reflects agreement of either 95 percent or more of 10 or more referee laboratories or 95 percent or more of all participating laboratories. Both methods must be attempted before the program can choose to not grade a PT sample.

(2) *Criteria for acceptable performance.* The criteria for acceptable performance are—

Table 2 to Paragraph (d)(2)—Criteria for Acceptable Performance

| Analyte or test | Criteria for acceptable performance |
| --- | --- |
| ABO group | 100% accuracy. |
| D (Rho) typing | 100% accuracy. |
| Unexpected antibody detection | 100% accuracy. |
| Compatibility testing | 100% accuracy. |
| Antibody identification | 80%+ accuracy. |

(3) The criterion for acceptable performance for qualitative immunohematology tests is positive or negative.

(4) To determine the analyte testing event score, the number of acceptable analyte responses must be averaged using the following formula:

[![](https://img.federalregister.gov/ER25SE06.023/ER25SE06.023_large.png)](https://img.federalregister.gov/ER25SE06.023/ER25SE06.023_original_size.png)

(5) To determine the overall testing event score, the number of correct responses for all analytes must be averaged using the following formula:

[![](https://img.federalregister.gov/ER25SE06.022/ER25SE06.022_large.png)](https://img.federalregister.gov/ER25SE06.022/ER25SE06.022_original_size.png)

[[57 FR 7151](https://www.federalregister.gov/citation/57-FR-7151), Feb. 28, 1992, as amended at [87 FR 41242](https://www.federalregister.gov/citation/87-FR-41242), July 11, 2022]