What is the role of solid phase test systems in Rhesus (Rh) typing?

Updated: Aug 01, 2018
  • Author: Victoria K Gonsorcik, DO; Chief Editor: Jun Teruya, MD, DSc, FCAP  more...
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Answer

Answer

Commercial anti-D reagent is embedded in the bottom of micoplate wells. An individual's red cells (in a 2%-5% saline suspension) are mixed together with an enhancing reagent and centrifuged. The plates are then assessed. If there is just one tightly packed red cell pellet at the bottom of the well, there is no reaction. If there is a covering of red cells throughout the bottom of the well, this would indicate a positive reaction. The reaction is graded on a scale of 0 to 4+.

See table 3 below and the images above for further description of conventional agglutination grading.

Table 3. Standard Agglutination Grading (Open Table in a new window)

Marsh Score

Conventional Grading

Description of Grading

12-11

4+

Complete agglutination

10-9

3+

Strong reaction: 2-3 clumps

8-6

2+

Strong reaction: several clumps

5-4

1+

Many clumps

3-2

+

Scattered agglutination

1

W

Weak granularity

0

0

Even cell suspension


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