Editing Blood type (section)

==Clinical significance==

===Blood transfusion===
{{Main|Blood transfusion}}
Transfusion medicine is a specialized branch of [[hematology]] that is concerned with the study of blood groups, along with the work of a [[blood bank]] that provides a [[Blood transfusion|transfusion]] service with blood and other blood products. Across the world, blood products must be prescribed by a medical doctor (licensed [[physician]] or [[surgeon]]) in a similar way as medicines.{{citation needed|date=November 2021}}

[[File:Main symptoms of acute hemolytic reaction.png|thumb|right|220px|Main symptoms of [[acute hemolytic reaction]] due to blood type mismatch.<ref>[https://www.cancer.org/docroot/ETO/content/ETO_1_4x_Possible_Risks_of_Blood_Product_Transfusions.asp Possible Risks of Blood Product Transfusions] {{Webarchive|url=https://web.archive.org/web/20091105182210/http://www.cancer.org/docroot/ETO/content/ETO_1_4x_Possible_Risks_of_Blood_Product_Transfusions.asp |date=2009-11-05 }} from American Cancer Society. Last Medical Review: 03/08/2008. Last Revised: 01/13/2009</ref><ref>[https://www.pathology.med.umich.edu/bloodbank/manual/bbch_7/index.html 7 adverse reactions to transfusion] {{Webarchive|url=https://web.archive.org/web/20151107032014/https://www.pathology.med.umich.edu/bloodbank/manual/bbch_7/index.html |date=2015-11-07 }} Pathology Department at University of Michigan. Version July 2004, Revised 11/5/08</ref>]]

Much of the routine work of a [[blood bank]] involves testing blood from both donors and recipients to ensure that every individual recipient is given blood that is compatible and as safe as possible. If a unit of incompatible blood is [[Blood transfusion|transfused]] between a [[Blood donation|donor]] and recipient, a severe [[acute hemolytic reaction]] with [[hemolysis]] (RBC destruction), [[kidney failure]] and [[shock (circulatory)|shock]] is likely to occur, and death is a possibility.<ref>{{cite book |last1=Rout |first1=Preeti |last2=Harewood |first2=Janine |last3=Ramsey |first3=Adam |last4=Master |first4=Samip R. |title=StatPearls |date=2024 |publisher=StatPearls Publishing |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK448158/ |chapter=Hemolytic Transfusion Reaction |pmid=28846280 }}</ref> Antibodies can be highly active and can attack RBCs and bind components of the [[complement system]] to cause massive hemolysis of the transfused blood.<ref>{{cite journal |vauthors= Fujii Y |title=Prevention of ABO-incompatible transfusion |journal=Masui |volume=60 |issue=1 |pages=47–54 |year=2011 |pmid=21348250 }}</ref>

Patients should ideally receive their own blood or type-specific blood products to minimize the chance of a [[transfusion reaction]]. It is also possible to use the patient's own blood for transfusion. This is called [[autotransfusion|autologous blood transfusion]], which is always compatible with the patient. The procedure of washing a patient's own red blood cells goes as follows: The patient's lost blood is collected and washed with a saline solution. The washing procedure yields concentrated washed red blood cells. The last step is reinfusing the packed red blood cells into the patient. There are multiple ways to wash red blood cells. The two main ways are centrifugation and filtration methods. This procedure can be performed with microfiltration devices. Risks can be further reduced by [[cross-matching]] blood, but this may be skipped when blood is required for an emergency. The oldest form of cross-matching involves mixing a sample of the recipient's serum with a sample of the donor's red blood cells and checking if the mixture ''agglutinates'' or forms clumps. If agglutination is not obvious by direct vision, blood bank technologist may check for [[Agglutination (biology)|agglutination]] with a [[microscope]]. If agglutination occurs, that donor's blood cannot be transfused to that particular recipient.  In a bank transfusion service, it is vital that all blood specimens are correctly identified, so labelling has been standardized using a [[barcode]] system known as [[ISBT 128]].

The blood group may be included on [[Dog tag (identifier)|identification tags]] or historically on [[tattoo]]s worn by military personnel, in case they should need an emergency blood transfusion. Frontline German [[SS blood group tattoo|Waffen-SS had blood group tattoos]] during [[World War II]].

Rare blood types can cause supply problems for [[blood bank]]s and hospitals. For example, [[Duffy antigen|Duffy]]-negative blood occurs much more frequently in people of African origin,<ref>{{cite journal |author=Nickel RG |title=Determination of Duffy genotypes in three populations of African descent using PCR and sequence-specific oligonucleotides |journal=Human Immunology |volume=60 |issue=8 |pages=738–42 |date=August 1999 |pmid=10439320 |doi=10.1016/S0198-8859(99)00039-7 |author2=Willadsen SA |author3=Freidhoff LR |display-authors=3 |last4=Huang |first4=Shau-Ku |last5=Caraballo |first5=Luis |last6=Naidu |first6=Raana P |last7=Levett |first7=Paul |last8=Blumenthal |first8=Malcolm |last9=Banks-Schlegel |first9=Susan|doi-access=free }}</ref> and the rarity of this blood type in the rest of the population can result in a shortage of Duffy-negative blood for these patients.  Similarly, for RhD negative people there is a risk associated with travelling to parts of the world where supplies of RhD-negative blood are rare, particularly [[East Asia]], where blood services may endeavour to encourage Westerners to donate blood.<ref>{{cite web|url=https://www.bloodcare.org.uk/html/resources_chairman_2001.htm |title=BCF&nbsp;– Members&nbsp;– Chairman's Annual Report |access-date=2008-07-15 |last=Bruce |first=MG |date=May 2002 |publisher=The Blood Care Foundation |quote=As Rhesus Negative blood is rare amongst local nationals, this Agreement will be of particular value to Rhesus Negative expatriates and travellers |url-status=dead |archive-url=https://web.archive.org/web/20080410111425/https://www.bloodcare.org.uk/html/resources_chairman_2001.htm |archive-date=April 10, 2008 }}</ref>

===Hemolytic disease of the newborn (HDN)===
{{Main|Hemolytic disease of the newborn}}
A [[Pregnancy|pregnant]] woman may carry a [[fetus]] with a blood type which is different from her own. Typically, this is an issue if a RhD negative mother has a child with a RhD positive father, and the fetus ends up being Rh positive.<ref>{{cite web |last1=Freeborn |first1=Donna |title=Hemolytic Disease of the Newborn (HDN) |url=https://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=90&ContentID=P02368 |website=University of Rochester Medical Center |access-date=30 November 2020 |archive-date=19 September 2016 |archive-url=https://web.archive.org/web/20160919082228/https://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=90&ContentID=P02368 |url-status=live }}</ref> In those cases, the mother can make [[Immunoglobulin G|IgG]] blood group antibodies. This can happen if some of the fetus' blood cells pass into the mother's blood circulation (e.g. a small fetomaternal [[bleeding|hemorrhage]] at the time of childbirth or obstetric intervention), or sometimes after a therapeutic [[blood transfusion]].  This can cause [[hemolytic disease of the newborn]] (HDN) in the current pregnancy and/or subsequent pregnancies.  Sometimes this is lethal for the fetus; in these cases it is called [[hydrops fetalis]].<ref name =Letsky2000>{{cite book |title =Antenatal & neonatal screening |edition = 2nd |chapter = Chapter 12: Rhesus and other haemolytic diseases |author = E.A. Letsky |author2=I. Leck|author3=J.M. Bowman |year = 2000 |publisher = Oxford University Press|isbn=978-0-19-262826-8}}</ref> If a pregnant woman is known to have anti-D antibodies, the RhD blood type of a [[fetus]] can be tested by analysis of fetal DNA in maternal plasma to assess the risk to the fetus of Rh disease.<ref>{{cite journal |vauthors=Daniels G, Finning K, Martin P, Summers J |title=Fetal blood group genotyping: present and future |journal=Annals of the New York Academy of Sciences |volume=1075 |pages=88–95 |date=September 2006 |issue=1 |pmid=17108196 |doi=10.1196/annals.1368.011 |bibcode=2006NYASA1075...88D }}</ref> Cell-free DNA testing can determine the fetal ''RHD'' genotype in a sample of material plasma after 10 weeks of gestation. One of the major advances of twentieth-century medicine was to prevent this disease by stopping the formation of anti-D antibodies by D negative mothers with an injectable medication called [[Rho(D) immune globulin]].<ref>{{cite web|url=https://www.rcog.org.uk/index.asp?PageID=1972 |title=Use of Anti-D Immunoglobulin for Rh Prophylaxis |publisher=[[Royal College of Obstetricians and Gynaecologists]] |date=May 2002 |url-status=dead |archive-url=https://web.archive.org/web/20081230200349/https://www.rcog.org.uk/index.asp?PageID=1972 |archive-date=December 30, 2008 }}</ref><ref>{{cite web |url = https://www.nice.org.uk/guidance/TA41/?c=91520 |title = Pregnancy&nbsp;– routine anti-D prophylaxis for D-negative women |publisher = [[National Institute for Health and Clinical Excellence|NICE]] |date = May 2002 |access-date = 2022-02-11 |archive-date = 2022-02-05 |archive-url = https://web.archive.org/web/20220205182251/https://www.nice.org.uk/guidance/TA41/?c=91520 |url-status = live }}</ref> Antibodies associated with some blood groups can cause severe HDN, others can only cause mild HDN and others are not known to cause HDN.<ref name="Letsky2000"/>

=== Blood products ===
To provide maximum benefit from each blood donation and to extend shelf-life, [[blood bank]]s [[blood fractionation|fractionate]] some whole blood into several products. The most common of these products are RBCs, [[Blood plasma|plasma]], [[platelet]]s, [[cryoprecipitate]], and [[Blood plasma#Fresh frozen plasma|fresh frozen plasma]] (FFP).  FFP is quick-frozen to retain the labile [[clotting factor]]s [[Factor V|V]] and [[Factor VIII|VIII]], which are usually administered to patients who have a potentially fatal clotting problem caused by a condition such as advanced [[liver]] disease, overdose of [[anticoagulant]], or [[disseminated intravascular coagulation]] (DIC).{{citation needed|date=November 2021}}

Units of packed red cells are made by removing as much of the plasma as possible from whole blood units.

[[Clotting factors]] synthesized by modern [[Recombinant DNA|recombinant]] methods are now in routine clinical use for [[hemophilia]], as the risks of infection transmission that occur with pooled blood products are avoided.

===Red blood cell compatibility===
{{Further|Blood compatibility testing}}
* '''Blood group AB''' individuals have both A and B antigens on the surface of their RBCs, and their [[blood plasma]] does not contain any antibodies against either A or B antigen. Therefore, an individual with type AB blood can receive blood from any group (with AB being preferable), but cannot donate blood to any group other than AB.  They are known as universal recipients.
* '''Blood group A'''  individuals have the A antigen on the surface of their RBCs, and blood serum containing [[IgM]] antibodies against the B antigen. Therefore, a group A individual can receive blood only from individuals of groups A or O (with A being preferable), and can donate blood to individuals with type A or AB.
* '''Blood group B'''  individuals have the B antigen on the surface of their RBCs, and blood serum containing IgM antibodies against the A antigen. Therefore, a group B individual can receive blood only from individuals of groups B or O (with B being preferable), and can donate blood to individuals with type B or AB.
* '''Blood group O''' individuals have no A or B antigens on the surface of their RBCs, and their blood serum contains IgM anti-A and anti-B antibodies. Therefore, a group O individual can receive blood only from a group O individual, but can donate blood to individuals of any ABO blood group (i.e., A, B, O or AB). If a patient needs an urgent blood transfusion, and if the time taken to process the recipient's blood would cause a detrimental delay, O negative blood can be used. Because it is compatible with anyone, there are some concerns that O negative blood is often overused and consequently is always in short supply.<ref name="AABBfive">{{Citation |author1 = American Association of Blood Banks |author1-link = American Association of Blood Banks |date = 24 April 2014 |title = Five Things Physicians and Patients Should Question |publisher = American Association of Blood Banks |work = [[Choosing Wisely]]: an initiative of the [[ABIM Foundation]] |url = https://www.choosingwisely.org/doctor-patient-lists/american-association-of-blood-banks/ |access-date = 25 July 2014 |archive-url = https://web.archive.org/web/20140924075027/https://www.choosingwisely.org/doctor-patient-lists/american-association-of-blood-banks/ |archive-date = 24 September 2014 |url-status = dead }}, which cites
* {{cite web|author1=The Chief Medical Officer's National Blood Transfusion Committee|title=The appropriate use of group O RhD negative red cells|url=https://hospital.blood.co.uk/library/pdf/nbtc_bbt_o_neg_red_cells_recs_09_04.pdf|archive-url=https://web.archive.org/web/20140809134013/https://hospital.blood.co.uk/library/pdf/nbtc_bbt_o_neg_red_cells_recs_09_04.pdf|archive-date=9 August 2014|publisher=[[National Health Service]]|access-date=25 July 2014|year=c. 2008}}</ref> According to the Association for the Advancement of Blood and Biotherapies ([[AABB]]) and the British Chief Medical Officer's National Blood Transfusion Committee, the use of group O RhD negative red cells should be restricted to persons with O negative blood, women who might be pregnant, and emergency cases in which blood-group testing is genuinely impracticable.<ref name="AABBfive"/>

[[Image:Blood Compatibility.svg|right|230px|thumb|'''Red blood cell compatibility chart'''<br />In addition to donating to the same blood group; type O blood donors can give to A, B and AB; blood donors of types A and B can give to AB.]]
{| class="wikitable" style="text-align:center;"
|+ Red blood cell compatibility table<!--
 --><ref name=rbccomp>{{cite web |url=https://chapters.redcross.org/br/northernohio/INFO/bloodtype.html |title=RBC compatibility table |access-date=2008-07-15 |date=December 2006 |publisher=American National Red Cross |url-status=dead |archive-url=https://web.archive.org/web/20080913165654/https://chapters.redcross.org/br/northernohio/info/bloodtype.html |archive-date=2008-09-13 }}</ref><ref name=bloodbook>[https://www.bloodbook.com/compat.html Blood types and compatibility] {{Webarchive|url=https://web.archive.org/web/20100419103919/https://www.bloodbook.com/compat.html |date=2010-04-19 }} bloodbook.com</ref><!--
 -->
|-
! rowspan="2" | Recipient<sup>[1]</sup>
! colspan="8" | Donor<sup>[1]</sup>
|-
! O−
! O+
! A−
! A+
! B−
! B+
! AB−
! AB+
|-
! O−
| style="width:3em" | {{Y}}
| style="width:3em" | {{N}}
| style="width:3em" | {{N}}
| style="width:3em" | {{N}}
| style="width:3em" | {{N}}
| style="width:3em" | {{N}}
| style="width:3em" | {{N}}
| style="width:3em" | {{N}}
|-
! O+
| {{Y}}
| {{Y}}
| {{N}}
| {{N}}
| {{N}}
| {{N}}
| {{N}}
| {{N}}
|-
! A−
| {{Y}}
| {{N}}
| {{Y}}
| {{N}}
| {{N}}
| {{N}}
| {{N}}
| {{N}}
|-
! A+
| {{Y}}
| {{Y}}
| {{Y}}
| {{Y}}
| {{N}}
| {{N}}
| {{N}}
| {{N}}
|-
! B−
| {{Y}}
| {{N}}
| {{N}}
| {{N}}
| {{Y}}
| {{N}}
| {{N}}
| {{N}}
|-
! B+
| {{Y}}
| {{Y}}
| {{N}}
| {{N}}
| {{Y}}
| {{Y}}
| {{N}}
| {{N}}
|-
! AB−
| {{Y}}
| {{N}}
| {{Y}}
| {{N}}
| {{Y}}
| {{N}}
| {{Y}}
| {{N}}
|-
! AB+
| {{Y}}
| {{Y}}
| {{Y}}
| {{Y}}
| {{Y}}
| {{Y}}
| {{Y}}
| {{Y}}
|}
<small>
Table note<br />
1. Assumes absence of atypical antibodies that would cause an incompatibility between donor and recipient blood, as is usual for blood selected by cross matching.
</small>

An Rh D-negative patient who does not have any anti-D antibodies (never been previously sensitized to D-positive RBCs) can receive a transfusion of D-positive blood, but this may cause sensitization to the D antigen, and a female patient could become at risk for [[hemolytic disease of the newborn]].  If a D-negative patient has developed anti-D antibodies, a subsequent exposure to D-positive blood could lead to a potentially dangerous transfusion reaction. Rh D-positive blood should never be given to D-negative women of child-bearing age or to patients with D antibodies, so blood banks must conserve Rh-negative blood for these patients. In extreme circumstances, such as for a major bleed when stocks of D-negative blood units are very low at the blood bank, D-positive blood might be given to D-negative females above child-bearing age or to Rh-negative males, providing that they did not have anti-D antibodies, to conserve D-negative inventory in the blood bank. The converse is not true; Rh D-positive patients do not react to D negative blood.

This same matching is done for other antigens of the Rh system as C, c, E and e and for other blood group systems with a known risk for alloimmunization such as the Kell system, particularly for chronically transfused patients.

===Plasma compatibility===
[[File:Plasma donation compatibility path.svg|right|190px|thumb|'''Plasma compatibility chart'''<br />In addition to donating to the same blood group; plasma from type AB can be given to A, B and O; plasma from types A, B and AB can be given to O.]]
[[Blood plasma]] compatibility is the inverse of red blood cell compatibility.<ref>{{cite web|title=Blood Component ABO Compatibility Chart Red Blood Cells and Plasma|url=https://www.pathology.med.umich.edu/blood-bank/blood-component-and-compatibility|archive-url=https://web.archive.org/web/20190616012246/https://www.pathology.med.umich.edu/blood-bank/blood-component-and-compatibility|archive-date=16 June 2019|website=Blood Bank Labsite|publisher=University of Michigan|access-date=16 December 2014}}</ref> Type AB plasma carries neither anti-A nor anti-B antibodies and can be transfused to individuals of any blood group; but type AB patients can only receive type AB plasma. Type O carries both antibodies, so individuals of blood group O can receive plasma from any blood group, but type O plasma can be used only by type O recipients.
<!--Please don't switch donor and recipient here without being absolutely sure they're wrong. Check the cited source; any change must match it. It seems a lot of people switch this without actually understanding it, because it's often edited from the correct (AB can donate plasma to all blood groups) to the wrong.-->

{| class="wikitable" style="text-align:center;"
|+ Plasma compatibility table<ref>{{cite web|title=Plasma Compatibility|url=https://mytransfusion.com.au/about-blood/matching-blood-groups|archive-url=https://web.archive.org/web/20200507180725/https://mytransfusion.com.au/about-blood/matching-blood-groups|archive-date=7 May 2020|website=Matching Blood Groups|publisher=Australian Red Cross|access-date=19 June 2020}}</ref>
! rowspan=2 | Recipient
! colspan="4" | Donor
|-
! style="width:3em" | O
! style="width:3em" | A
! style="width:3em" | B
! style="width:3em" | AB
|-
! O
| {{Y}}
| {{Y}}
| {{Y}}
| {{Y}}
|-
! A
| {{N}}
| {{Y}}
| {{N}}
| {{Y}}
|-
! B
| {{N}}
| {{N}}
| {{Y}}
| {{Y}}
|-
! AB
| {{N}}
| {{N}}
| {{N}}
| {{Y}}
|}

<small>
Table note<br />
1. Assuming absence of strong atypical antibodies in donor plasma
</small>

===Universal donors and universal recipients===
[[File:US Navy 060105-N-8154G-010 A hospital corpsman with the Blood Donor Team from Portsmouth Naval Hospital takes samples of blood from a donor for testing.jpg|thumb|right|220px|A hospital worker takes samples of blood from a donor for testing]]

In transfusions of red blood cells, individuals with type O Rh D-negative blood are often called universal donors. Those with type AB Rh D-positive blood are called universal recipients. However, these terms are only generally true with respect to possible reactions of the recipient's anti-A and anti-B antibodies to transfused red blood cells, and also possible sensitization to Rh D antigens. One exception is individuals with [[hh antigen system]] (also known as the Bombay phenotype) who can only receive blood safely from other hh donors, because they form antibodies against the H antigen present on all red blood cells.<ref>{{cite book |title=Harrison's Principals of Internal Medicine |last=Fauci |first=Anthony S. |author2=Eugene Braunwald |author3=Kurt J. Isselbacher |author4=Jean D. Wilson |author5=Joseph B. Martin |author6=Dennis L. Kasper |author7=Stephen L. Hauser |author8=Dan L. Longo |year=1998 |publisher=McGraw-Hill |isbn=0-07-020291-5 |page=[https://archive.org/details/harrisonsprincie14harr/page/719 719] |url-access=registration |url=https://archive.org/details/harrisonsprincie14harr }}</ref><ref>{{cite web |url=https://www.webmd.com/a-to-z-guides/blood-type-test |title=Universal acceptor and donor groups |publisher=Webmd.com |date=2008-06-12 |access-date=2010-08-01 |archive-date=2010-07-22 |archive-url=https://web.archive.org/web/20100722071429/http://www.webmd.com/a-to-z-guides/blood-type-test |url-status=live }}</ref>

Blood donors with exceptionally strong anti-A, anti-B or any atypical blood group antibody may be excluded from blood donation of high plasma volume blood products. In general, while the plasma fraction of a blood transfusion may carry donor antibodies not found in the recipient, a significant reaction is unlikely because of dilution.

Additionally, red blood cell surface antigens other than A, B and Rh D might cause adverse reactions and sensitization, if they can bind to the corresponding antibodies to generate an immune response.  Transfusions are further complicated because [[platelet]]s and [[white blood cell]]s (WBCs) have their own systems of surface antigens, and sensitization to platelet or WBC antigens can occur as a result of transfusion.

For transfusions of [[Plasma (blood)|plasma]], this situation is reversed.  Type O plasma, containing both anti-A and anti-B antibodies, can only be given to O recipients.  The antibodies will attack the antigens on any other blood type.  Conversely, AB plasma can be given to patients of any ABO blood group, because it does not contain any anti-A or anti-B antibodies.