Editing Coombs test (section)

==Mechanism==
[[File:Coombs test schematic.png|thumb|350px|Schematic showing the direct and indirect Coombs tests]]
The two Coombs tests are based on anti-human [[antibody|antibodies]] binding to human antibodies, commonly [[Immunoglobulin G|IgG]] or [[Immunoglobulin M|IgM]]. These anti-human antibodies are produced by [[plasma cell]]s of non-human animals after immunizing them with [[human plasma]]. Additionally, these anti-human antibodies will also bind to human antibodies that may be fixed onto [[antigen]]s on the surface of [[red blood cell]]s (RBCs). In the appropriate test tube conditions, this can lead to [[agglutination (biology)|agglutination]] of RBCs and allowing for visualisation of the resulting clumps of RBCs. If clumping is seen, the Coombs test is positive; if not, the Coombs test is negative.<ref name="Zantek et al. 2012">{{cite journal |last1=Zantek |first1=Nicole D. |last2=Koepsell |first2=Scott A. |date=2012-04-12 |title=The direct antiglobulin test: A critical step in the evaluation of hemolysis |journal=American Journal of Hematology |volume=87 |issue=7 |pages=707–709 |doi=10.1002/ajh.23218 |pmid=22566278 |doi-access=free }}</ref>

Common clinical uses of the Coombs test include the preparation of blood for [[Blood transfusion|transfusion]] in [[cross-matching]], atypical antibodies in the [[blood plasma]] of [[pregnant]] women as part of [[obstetrics|antenatal care]], and detection of antibodies for the diagnosis of immune-mediated [[hemolytic anemia]]s.<ref name="Theis and Hasmhmi 2020">{{cite book |last=Theiss |first=Samuel R. |author-link= |title=Coombs Test |year=2023 |url=https://www.ncbi.nlm.nih.gov/books/NBK547707/ |location= |publisher=StatPearls Publishing LLC |page= |pmid=31613487 |isbn=}}</ref>

Coombs tests are performed using RBCs or serum (direct or indirect, respectively) from venous whole blood samples which are taken from patients by [[venipuncture]]. The venous blood is taken to a laboratory (or blood bank), where trained scientific technical staff do the Coombs tests.  The clinical significance of the result is assessed by the [[physician]] who requested the Coombs test, perhaps with assistance from a laboratory-based [[hematologist]].{{cn|date=November 2021}}