8
Fetal anemia due to non-Rhesus-D red-cell alloimmunization Kenneth J. Moise a,b, * a Department of Obstetrics and Gynecology, Division of MaternaleFetal Medicine, Baylor College of Medicine, Houston, TX, USA b Texas Children’s Fetal Center, Houston, TX, USA KEYWORDS Hemolytic disease of the fetus/newborn (HDFN); Irregular antibodies; Red-cell alloimmunization Summary Although anti-RhD was once the major etiology of hemolytic disease of the fetus/ newborn (HDFN), the widespread adoption of antenatal and postpartum Rhesus immune globulin has resulted in a marked decrease in the prevalence of alloimmunization to the RhD antigen in pregnancy. Maternal alloimmunization to other red cell antigens continues to play a role as the cause of fetal disease since no prophylactic immune globulins are available to prevent the formation of these antibodies. An increasing incidence of the Kell (anti-K1) antibody has been noted in the United States. Guidelines for intervention in cases of irregular red cell antibodies are limited by the bias of anecdotal reports in the literature in favor of severe cases of HFDN. Although most diagnostic protocols used in the management of the RhD-alloimmunized pregnancy can be applied in cases of non-RhD sensitization, Kell (K1 and K2) alloimmunization should be managed more conservatively. ª 2008 Elsevier Ltd. All rights reserved. Introduction More than 50 different red-cell antigens have been reported to be associated with hemolytic disease of the fetus and newborn (HDFN; Table 1). However, only three antibodies seem to be associated with severe fetal disease: anti-Rhesus (Rh) D, anti-Rhc, and anti-Kell (K1). In a 26-year series of 1022 cases of non-RhD alloimmunization in Manitoba, Canada, only anti-Rhc was associated with se- vere HDFN that ended in a hydropic stillbirth or necessitated intrauterine transfusion (IUT). 1 Anti-Rhc and anti-K1 antibodies were equivalent in their need for neona- tal exchange transfusion or phototherapy; anti-RhE was half as likely to require neonatal treatment. A select popu- lation of 22 patients was referred from outside Manitoba over the same time period. 1 The following antibodies were associated with the need for IUTs: anti-K1 (n Z 9), anti-k (n Z 1), anti-Rhc (n Z 7), anti-RhcE (n Z 1), anti- Fya (n Z 1), anti-Jka (n Z 1), anti-CCw (n Z 1), and anti- RhE (n Z 1). In a series of 258 pregnancies managed with IUTs at a single national referral center in the Netherlands from 1988 to 2001, 85% of cases involved RhD alloimmuniza- tion, 2 10% involved anti-K1, and 3.5% involved anti-Rhc. A single case each of anti-RhE, anti-Rhe, and anti-Fya was associated with the need for IUT. * Corresponding address. 6620 Main Street, Suite 1450, Houston, TX 77030, USA. Tel.: þ1 713 798 8621; fax: þ1 713 798 2810. E-mail address: [email protected] 1744-165X/$ - see front matter ª 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.siny.2008.02.007 available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/siny Seminars in Fetal & Neonatal Medicine (2008) 13, 207e214

Fetal anemia due to non-Rhesus-D red-cell alloimmunization

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Seminars in Fetal & Neonatal Medicine (2008) 13, 207e214

ava i lab le at www.sc ienced i rec t . com

journa l homepage : www.e lsev ie r . com/ loca te /s iny

Fetal anemia due to non-Rhesus-Dred-cell alloimmunization

Kenneth J. Moisea,b,*

a Department of Obstetrics and Gynecology, Division of MaternaleFetal Medicine,Baylor College of Medicine, Houston, TX, USAb Texas Children’s Fetal Center, Houston, TX, USA

KEYWORDSHemolytic disease ofthe fetus/newborn(HDFN);Irregular antibodies;Red-cellalloimmunization

* Corresponding address. 6620 MainTX 77030, USA. Tel.: þ1 713 798 8621

E-mail address: [email protected]

1744-165X/$ - see front matter ª 200doi:10.1016/j.siny.2008.02.007

Summary Although anti-RhD was once the major etiology of hemolytic disease of the fetus/newborn (HDFN), the widespread adoption of antenatal and postpartum Rhesus immuneglobulin has resulted in a marked decrease in the prevalence of alloimmunization to theRhD antigen in pregnancy. Maternal alloimmunization to other red cell antigens continues toplay a role as the cause of fetal disease since no prophylactic immune globulins are availableto prevent the formation of these antibodies. An increasing incidence of the Kell (anti-K1)antibody has been noted in the United States. Guidelines for intervention in cases of irregularred cell antibodies are limited by the bias of anecdotal reports in the literature in favor ofsevere cases of HFDN. Although most diagnostic protocols used in the management of theRhD-alloimmunized pregnancy can be applied in cases of non-RhD sensitization, Kell (K1 andK2) alloimmunization should be managed more conservatively.ª 2008 Elsevier Ltd. All rights reserved.

Introduction

More than 50 different red-cell antigens have beenreported to be associated with hemolytic disease of thefetus and newborn (HDFN; Table 1). However, only threeantibodies seem to be associated with severe fetal disease:anti-Rhesus (Rh) D, anti-Rhc, and anti-Kell (K1). In a 26-yearseries of 1022 cases of non-RhD alloimmunization inManitoba, Canada, only anti-Rhc was associated with se-vere HDFN that ended in a hydropic stillbirth or

Street, Suite 1450, Houston,; fax: þ1 713 798 2810.

8 Elsevier Ltd. All rights reserved

necessitated intrauterine transfusion (IUT).1 Anti-Rhc andanti-K1 antibodies were equivalent in their need for neona-tal exchange transfusion or phototherapy; anti-RhE washalf as likely to require neonatal treatment. A select popu-lation of 22 patients was referred from outside Manitobaover the same time period.1 The following antibodieswere associated with the need for IUTs: anti-K1 (n Z 9),anti-k (n Z 1), anti-Rhc (n Z 7), anti-RhcE (n Z 1), anti-Fya (n Z 1), anti-Jka (n Z 1), anti-CCw (n Z 1), and anti-RhE (n Z 1). In a series of 258 pregnancies managed withIUTs at a single national referral center in the Netherlandsfrom 1988 to 2001, 85% of cases involved RhD alloimmuniza-tion,2 10% involved anti-K1, and 3.5% involved anti-Rhc.A single case each of anti-RhE, anti-Rhe, and anti-Fya wasassociated with the need for IUT.

.

208 K.J. Moise

Incidence

The widespread use of RhD immune globulin has resulted ina major reduction in the incidence of RhD alloimmunizationin pregnancy. However, prophylactic immune globulins toprevent maternal antibody formation to other red-cellantigens are not currently available. For this reason,maternal alloimmunization to non-RhD antigens continuesto contribute to perinatal morbidity and mortality.

In 1969, Queenan et al.3 reported the results of 18,000prenatal sera screened for red-cell antibodies associatedwith HDFN in the United States. A second series, reportedmore than 25 years later by Geifman-Holtzman and co-workers, involved 37,000 sera from women of reproductiveage.4 As expected, secondary to the widespread adoption

Table 1 Non-Rhesus-D antibodies associated with hemo-lytic disease of the fetus and newborn

Antigensystem

Specificantigen

Antigensystem

Specificantigen

Antigensystem

Specificantigen

Frequently associated with severe diseaseKell -K (K1)Rhesus -c

Infrequently associated with severe diseaseColton -Coa MNS -Mta Rhesus -HOFM

-Co3 -MUT -LOCRDiego -ELO -Mur -Riv

-Dia -Mv -Rh29-Dib -s -Rh32-Wra -sD -Rh42-Wrb -S -Rh46

Duffy -Fya -U -STEMKell -Jsa -Vw -Tar

-Jsb Rhesus -Bea Otherantigens

-HJK

-k (K2) -C -JFV-Kpa -Ce -JONES-Kpb -Cw -Kg-K11 -Cx -MAM-K22 -ce -REIT-Ku -Dw -Rd-Ula -E

Kidd -Jka -EwMNS -Ena -Evans

-Far -e-Hil -G-Hut -Goa7-M -Hr-Mia -Hro-Mit -JAL

Associated with mild diseaseDombrock -Doa Gerbich -Ge2 Scianna -Sc2

-Gya -Ge3 Other -Vel-Hy -Ge4 -Lan-Joa -Lsa -Ata

Duffy -Fyb Kidd -Jkb -Jra-Fy3 -Jk3

of RhD immune globulin, the incidence of RhD alloimmuni-zation decreased from 16.5 cases per 1000 samples in 1969to 2.7 per 1000 in 1996 (Fig. 1). Kell alloimmunization washigher in the 1996 series (3.2/1000) as compared to 1969(1.6/1000). However, in the later series, Kell had surpassedanti-RhD as the leading antibody associated with HDFN. Thereason for this increase is unknown, although currenttransfusion practices in the US do not include the use ofKell-negative blood in female children and women of repro-ductive ageda practice routinely employed in Australiaand the Netherlands. Thus two-thirds of women with Kellantibodies in the US have a history of a previous bloodtransfusion as the etiology of their sensitization.5

Specific antibodies

Rhc

Anti-Rhc antibody is a member of the Rhesus family, whichhas been associated with severe HDFN. In one series, morethan half of pregnant patients had a history of a previousblood transfusion.6 The hemolytic effect of anti-Rhc is verysimilar to that of anti-RhD. In one series of 177 pregnancies,there was one neonatal death secondary to hydrops and 11other infants requiring exchange transfusions. Wenk et al.7

reported 70 cases of maternal alloimmunization to Rhc witha known Rhc-antigen-positive infant. Eight cases resulted inhydropic stillborns or perinatal deaths, 26% of cases hadmild HDFN and did not require transfusions after birth,and an additional 29% had moderate HDFN requiringtransfusion therapy. In another series of 100 Rhc-antigen-positive neonates born to alloimmunized parturients, onepregnancy required IUTs whereas 14% required neonatal ex-change transfusions.8 Finally, in the most recent series,Hackney et al.9 found that 25% of antigen-positive fetusesexhibited severe HDFN, 7% of the total group were hydropicand 17% required IUTs.

RhC, RhE, and Rhe

Anti-RhC, anti-RhE, and anti-Rhe antibodies are of theRhesus family. They usually occur in a low titer in conjunc-tion with anti-RhD antibody (e.g. anti-RhD, 128; anti-RhC, 2).

Figure 1 Frequency of non-Rhesus-D antibodies in two USseries from 1969 and 1996.

Fetal anemia due to non-Rhesus-D red-cell alloimmunization 209

Their presence can be additive to the hemolytic effect ofthe anti-RhD on the fetus.10 IUTs are reported only rarelywhen these antibodies occur as the sole finding.2,11 Joyand coworkers12 reported 32 pregnancies alloimmunizedonly to RhE. One fetus presented with hydrops fetalis and15% of offspring were noted to have evidence of mild fetalor neonatal anemia.

RhG

The presence of an anti-RhG antibody should be suspectedwhen the anti-RhD and anti-RhC titers in an alloimmunizedpatient are equal. In some cases, the anti-RhC value mightactually exceed that of the anti-RhD (e.g. anti-RhD, 128;anti-RhC, 256). Consultation with a blood bank pathologistshould be undertaken to clarify whether anti-RhG ispresent. Anti-RhG is usually associated with mild tomoderate HDFN; however, a high titer can be associatedwith significant fetal disease necessitating IUT.13e15 Impor-tantly, RhD immune globulin should be administered to pre-vent the formation of anti-RhD if an invasive procedure isundertaken in these patients.

Kell

The Kell red-cell antigen system has 24 members. Individualantigens in the system are designated by name, letterabbreviation, or number. At least eight of the antigens havebeen associated with HDFN. The most common of these areKell (K, K1) and cellano (k, K2); additional antigens thathave been reported to be causative for HDFN include Penny(Kpa, K3), Rautenberg (Kpb, K4), Peltz (Ku, K5), Sutter(Jsa,K6), Matthews (Jsb, K7), and Karhula (Ula, K10).

Anti-K (K1)The K1 antigen is found on the red cells of 9% of Caucasiansand 2% of people of African descent, with virtually all anti-gen-positive individuals being heterozygous (Table 2). Thesegene frequencies calculate to yield approximately a 5% riskof an affected fetus in the Kell alloimmunized pregnancy ifthe paternal antigen status and zygosity are unknown.

Table 2 Antigen frequencies and zygosity for red-cellantigens associated with hemolytic disease of the fetusand newborn

Caucasian African ancestry

Antigenþ (%)

Heterozygous(%)

Antigenþ (%)

Heterozygous(%)

K (K1) 9.0 97.8 2 100k (K2) 99.8 8.8 100 2M 78.0 64.0 70 63N 77.0 65.0 74 60S 55.0 80.0 31 90s 89.0 50.0 97 29U 100.0 e 99 e

Fya 66.0 26.0 10 90Fyb 83.0 41.0 23 96Jka 77.0 36.0 91 63Jkb 72.0 32.0 43 21

Bowman et al.16 reported a 46-year experience of 459Kell alloimmunized pregnancies in 311 women. In total,14% of these pregnancies ended in spontaneous or inducedabortions, 82% resulted in K1-negative infants or infantswith no recorded clinical disease, and the remaining 4%were affected. In these 20 infants, there was one neonataldeath and three fetuses with hydrops that died in utero.McKenna et al.5 described their 40-year experience of 156pregnancies in 134 women with anti-K1 antibodies. Eightinfants (5%) were severely affected. Six of the eightreceived IUTs; there were three fetal deaths. An additional13 infants (8%) were affected with mild HDFN.

Earlier efforts to manage the Kell alloimmunizedpregnancy typically utilized diagnostic tools that hadbeen employed in the care of the RhD alloimmunizedpatient. Berkowitz et al.17 were the first to describe anapparent discrepancy between fetal disease and the provenuse of serial amniocentesis to measure amniotic fluid levelsof bilirubin (DOD450). In this patient with a maternal anti-K1titer of 2048, amniocenteses at 20 and 21 weeks revealeda declining trend in the DOD450. A subsequent ultrasoundat 24 weeks gestation revealed fetal hydrops, whereasamniocentesis revealed a lower DOD450 value as comparedto the previous value. The authors concluded that thepresence of fetal hydrops on ultrasound might be superiorto amniotic fluid bilirubin in detecting severe HDFN. Subse-quently, Caine and Mueller-Heubach18 reported two casesof fetal hydrops and one case of neonatal demise in K1alloimmunized pregnancies after the DOD450 values1 week earlier were noted to be in the upper zone 2 ofthe Liley curve. Cordocentesis later gained widespreadacceptance in the management of the red-cell alloimmu-nized pregnancy. Vaughan et al.19 matched 11 anemicfetuses from pregnancies with Kell alloimmunization forgestational age and hematocrit to 11 anemic fetuses frompregnancies complicated by RhD alloimmunization. Fetalblood obtained by cordocentesis revealed lower levels ofboth reticulocytes and erythroblasts in the Kell pregnan-cies. A study of the relationship between fetal hemoglobinand the fetal bone marrow response to this anemia wasundertaken by comparing cordocentesis results from 11fetuses from Kell-sensitized pregnancies to 54 fetuses inRhD-sensitized pregnancies.20 An inverse correlationbetween the fetal hemoglobin concentration and the retic-ulocyte count was found in the RhD fetuses; such a correla-tion could not be demonstrated in the Kell fetuses.

A new mechanism of depressed fetal bone marrowresponse was proposed as a possible contributing factor tofetal anemia in the case of the Kell alloimmunization. Thismechanism was confirmed by an in vitro investigation.Vaughan et al.21 established K1-negative and K1-positiveerythroid cell lines from umbilical cord blood. Serum from22 women sensitized to Kell suppressed the growth ofK1-positive erythroid burst-forming and colony-formingunits; no suppression occurred in K1-negative cultures.Monoclonal anti-K1 antibody caused a dose-dependentsuppression of growth in the K1-positive cell lines but notthe K1-negative cell lines. Monoclonal anti-RhD antibodyexhibited no suppression in either cell line. The Kell bloodgroup system consists of two proteins: Kell and XK. TheKell protein is structurally similar to the protein family ofzinc neutral endopeptidases, indicating that it probably

210 K.J. Moise

plays an important role in red-cell growth and differentia-tion.21 Thus the available data would suggest that fetalanemia in cases of Kell sensitization is secondary to twomechanisms: sensitization of antigen-positive cells withsubsequent sequestration by the fetal reticuloendothelialsystem and erythropoietic suppression.

Several authors have therefore advocated that severeHDFN in Kell alloimmunization can occur at a lower mater-nal titers than Rhesus disease. Bowman et al.16 describedone case of fetal hydrops at 23 weeks gestation in whichthe maternal titer was only 8. Other authors have reporteda maternal anti-K1 titer of 2 at 16 weeks gestation followedby fetal hydrops at 17 weeks.22 Another series found thata titer of 32 identified all fetuses that were severely anemicsecondary to Kell antibodies.5 It would therefore appearthat a maternal indirect Coombs titer of 8 or greater isa reasonable threshold for suspicion of fetal anemia.

The role of the Kell antibody in the suppression of red-cell production has led several experts to express concernregarding the use of the Liley curve to assess the presenceof fetal anemia. This has led some to advocate thata DOD450 in the 65th percentile of zone 2 of the Liley curveshould be used as a threshold for cordocentesis to deter-mine if the fetus is anemic.16 More recently, serial peakvelocity determinations in the fetal middle cerebral artery(MCA) using Doppler ultrasound have been found to besuperior to serial amniocenteses in the detection of severefetal anemia in red cell alloimmunized pregnancies.23

Although most of the data published to date have involvedRhD-alloimmunized pregnancies, several small series havesubstantiated that MCA Doppler is useful in detectingsevere HDFN in K1-alloimmunized gestations.24,25

Anti-k (K2)Bowman et al.26 reviewed 20 years of antibody screeningof approximately 350,000 pregnancies in a Manitobapopulation and detected only one case of anti-k alloimmu-nization. Levine et al.27 reported the first case of HDFNsecondary to anti-k with a resulting mildly affectedinfant; this was followed by the report of a second mildcase by Bryant.28 Additional cases of HDFN include twocases treated with a single neonatal exchange transfu-sion,29,30 a single simple neonatal transfusion,26 a simpleneonatal transfusion followed by a top-up transfusion fordelayed neonatal anemia,31 and neonatal phototherapyalone.32 One case of two consecutive hydropic fetal losseshas been described in a woman with a titer of 4096.32 Atenth case was treated by Bowman’s group with threeIUTs beginning at 30 weeks gestation and a subsequentsuccessful neonatal outcome;26 the maternal titer wasnoted to be 16. In the second case reported from theirinstitution, the maternal antiglobulin titer was only 8.These findings led the investigators to surmise that anti-kantibody might produce fetal erythropoietic suppressionat lower maternal titersdan analogous situation to theanti-K1 antibody.

MNS

Anti-MThe MNS system consists of 40 red-cell antigens; the M, N, S,s, and U antigens represent the members of this group that

have been associated with HDFN. In the great majority ofcases, the paternal phenotype will be positive for antigenwith the majority of individuals being heterozygous (seeTable 2).

Anti-M is a naturally occurring IgM that typically presentsas a cold agglutinin. Conversion to an IgG response occursrarely and has been associated with HDFN. In total, sixpatients with severe HDFN have been reported in theEnglish literature. The first case involved a maternal anti-M albumin titer of 1000 in association with a hydropic fetaldeath in one twin and the need for exchange transfusions inthe sibling.33 A second patient with a titer of 2048 wasnoted to have a history of four fetal deaths.34 Matsumotoet al.35 reported a patient that had experienced three fetallosses in conjunction with a maternal anti-M titer of 1024.Furukawa and coworkers36 reported a patient with a historyof three perinatal losses. A successful outcome wasachieved in a fourth pregnancy after intensive plasmaphe-resis to treat a titer of 4096; the infant required onlyphototherapy. Duguid et al.37 described a patient witha titer of 16 who gave birth to a child requiring photother-apy and exchange transfusion. Kanra et al.38 investigateda patient who had experienced seven pregnancies withlosses occurring between 10 and 33 weeks gestation sec-ondary to in utero or neonatal deaths; five of theses preg-nancies were associated with hydrops fetalis. A maternalanti-M titer of 512 was detected although little informationis available regarding the evaluation of the neonates.

Perhaps the greatest information for the management ofpregnancy complicated by anti-M can be gleaned from the26-year experience reported by De Young-Owens et al.39

The series included 115 pregnancies in 90 women. A signif-icant increase in the incidence of the antibody in prenatalsera was detected over time with anti-M comprising 10%of all positive antibody screens. Explanations offered forthe increasing frequency included a change in antibodyscreening technique from albumin to ethylene glycol andthe addition of indicator red cells homozygous for the Mantigen to their red-cell screening panel. In 90% of theirreported cases, the antiglobulin titer was less than 4. Infive cases there was more than a two-tube increase in titer;however, the fetuses were noted to be antigen negative orof unknown antigen status in these cases. When the antigenstatus of the fetus was noted to be positive, no increase inserial maternal titers was found. Clinical outcome for thefetuses revealed minimal disease. Of the 70 infants whotested positive for the M antigen, only 17% exhibited a pos-itive direct Coombs at birth; only one of these infantsrequired phototherapy. In this case, the maternal anti-Mantibody titer was one and the neonatal 3þ direct Coombswas felt to be related to an ABO incompatibility. Fouradditional infants required phototherapy; all had negativedirect Coombs testing in association with a maternal titerof less than 2.

This data led De Young-Owens and coworkers toconclude that if there is no previous history of an affectedpregnancy, an initial maternal titer of 4 or less requires nofurther evaluation. If the titer is greater than 4 or there isa history of a previously affected fetus or infant, serialtiters should be obtained. Bowman has recommendedamniocentesis for DOD450 assessment if the indirectCoombs titer is 64 or higher.1 Following serial maternal

Fetal anemia due to non-Rhesus-D red-cell alloimmunization 211

titers until a threshold value of 32 is reached seems to bea reasonable diagnostic approach. One should thenconsider undertaking a consultation with the transfusionservice to determine if the anti-M antibody is predomi-nantly IgM or a combination of IgM and IgG.29 This can beaccomplished by treating the serum with dithiothreitol(DTT) or 2-mercaptoethanol. These agents disrupt thedisulfide bonds between the components of the pentamerstructure of the IgM, molecule thereby abolishing theagglutinating and complement-binding properties. Serumtreated with DTT containing only an IgM antibody willexhibit a loss of reactivity and a subsequent negative titer.Serum containing a mixture of IgM and IgG antibody willexhibit a decrease from the original titer. Once the IgGcomponent of the titer reaches 32, serial MCA Dopplersshould be considered. In cases of a heterozygous paternalgenotype, fetal typing using polymerase chain reaction(PCR) techniques on amniotic fluid is available for the Mantigen (M.J. Hessner, the Blood Center of SoutheasternWisconsin, personal communication) using a techniquepreviously described by Corfield et al.40

Anti-SIn one series of 175,000 pregnancies during a 5-year periodin the Oxford region of the UK, anti-S antibody was detectedin 22 pregnancies in 19 women.41 Previous transfusions werefelt to be the likely source of sensitization in two-thirds ofthe patients. A positive neonatal direct Coombs was notedin only four cases; one infant required exchange transfu-sions. Most cases of HDFN described in the literature involvemild neonatal disease.42 Only three cases of severe diseasehave been described. The first case was reported in 1952,with the infant dying secondary to kernicterus at 60 h oflife.43 Griffith44 described a case of stillbirth at 41 weeksgestation complicated by the finding of a maternal anti-Santibody and autopsy findings consistent with erythroblasto-sis fetalis. Finally, Mayne and coworkers41 reported a case ofmaternal anti-S alloimmunization that resulted in the birthof a neonate requiring three exchange transfusions and5 days of phototherapy.

Anti-sThree cases of severe HDFN and one case of mild HDFN havebeen reported.45

Anti-NOne case of mild HDFN requiring only phototherapy hasbeen reported.46 PCR typing of the fetus on amniotic fluidhas proven problematic, particularly in individuals ofAfrican descent, in whom there is up to 15% discordancebetween paternal serology and genotype (M.J. Hessner,the Blood Center of Southeastern Wisconsin, personalcommunication).

Anti-UThe U antigen is a high frequency antigen found in themajority of individuals. Smith et al.47 reviewed six of theirown cases of HDFN secondary to anti-U alloimmunizationand an additional nine cases from peer-reviewed literature.The neonates in four of the cases managed at their institu-tion required only phototherapy for treatment despite

maternal antibody titers of as high as 4000 in conjunctionwith a strongly positive direct Coombs assay on cord blood.One patient delivered an infant who required six simpletransfusions after birth. A subsequent pregnancy in thissame patient was complicated by the need for four IUTs.At birth, two additional exchange transfusions and threesimple transfusions were necessary during the neonatalcourse. In the review of the nine cases reported in the lit-erature, they noted one stillbirth at 35 weeks,48 three neo-nates requiring exchange transfusions,49e51 one infant withlate-onset of anemia at 3 weeks of age52 and four additionalcases with minimal evidence of HDFN.53e55 Based on theclinical course noted in these 15 cases, the authors recom-mended a maternal critical titer of 128 if there was noHDFN in a previous pregnancy.

In cases of anti-U alloimunization requiring treatmentwith IUT, maternal blood should be strongly considered asthe primary source of red cells as fresh U-negative blood isoften not readily available due to the high frequency of thisantigen.56 Alternatively, maternal siblings or parents can betested to determine if they can serve as donors.

Duffy

The Duffy antigen system consists of two antigens: Fya andFyb. Inheritance is by codominant allelles that result in fourpossible phenotypes (see Table 2). Anti-Fyb antibodies havenot been associated with HDFN. A review of 19 cases ofHDFN secondary to anti-Fya antibody between 1956 and1975 revealed a neonatal mortality of 18%, with almostone-third of cases requiring neonatal exchange transfu-sion.57 Maternal titers of as low as 8 were associated withmoderate HDFN necessitating exchange transfusion. PCRtyping of the fetus through amniocentesis is available incases of a heterozygous paternal genotype.58

Kidd

The Kidd system antigen system consists of two antigens:Jka and Jkb. Inheritance is by codominant allelles thatproduce four possible phenotypes, although the Jka-/Jkb-genotype is extremely uncommon (see Table 2). Rare casesof mild hemolytic disease have been reported. A single caseof a neonatal death due to kernicterus and renal failure hasbeen reported recently.59 PCR typing of the fetus throughamniocentesis is available in cases of a heterozygous pater-nal genotype.60

Overall management

Fig. 2 summarizes the management of the non-RhD red-cellalloimmunized pregnancy. Once a maternal antibodyassociated with HDFN is detected, an indirect Coombs titershould be requested. Paternal testing should be undertakento see if the patient’s partner is heterozygous for theoffending antigen. If he is found to be negative for theantigen and there is no question of paternity, no furthertesting is warranted as the fetus will not be at risk forHDFN. If paternal testing returns positive, zygosity testingshould be requested from the blood bank as a heterozygousstate can be detected through serologic testing.

Figure 2 Algorithm for the clinical management of the non-Rhesus-D alloimmunized pregnancy.

212 K.J. Moise

Maternal titers should be repeated every month untilapproximately 28 weeks gestation, when the testing inter-val should be increased to every 2 weeks. If a value of 32or greater (value of 8 or greater in the case of anti-K oranti-k antibody) in conjunction with a heterozygouspaternal phenotype is found, amniocentesis should beundertaken to determine the fetal antigen status. Alterna-tively, free fetal DNA in a maternal plasma sample can nowbe routinely employed for Kell (K1), C, c, and E antigentyping of the fetus in the UK.61 The finding of an antigen-negative fetus indicates that no further testing is needed.An antigen-positive fetus (or a homozygous paternalphenotype) requires referral to a perinatal center for serialMCA Dopplers every 1e2 weeks. A value of more than1.5 multiples of the median (MoM) indicates the need forcordocentesis and probable intrauterine blood transfusion.

Early referral to a perinatal center is warranted fora red-cell alloimmunized woman with a previous history of

an affected fetus or infant. The maternal titer is not usefulin these pregnancies as fetal disease usually occurs earlierin gestation than the previous pregnancy. Serial MCADopplers can be initiated as early as 16e18 weeks gestationonce a positive fetal antigen status has been confirmed byamniocentesis or free fetal DNA in maternal plasma. IUTcan be usually be successfully accomplished in most experi-enced centers by 20 weeks.

Conclusion

Non-RhD red-cell antibodies associated with HDFN willcontinue to challenge practitioners because the develop-ment of these antibodies is often related to transfusiontherapy. In addition, prophylactic immune globulins areunlikely to be developed due to the rarity of thesesituations. Guidelines for intervention in cases are limitedby the bias of anecdotal reports in the literature in favor of

Fetal anemia due to non-Rhesus-D red-cell alloimmunization 213

severe cases of HDFN. Large published series of patientswith anti-K1 or anti-M in which most fetuses and neonatesare minimally affected or unaffected substantiate this bias.

Practice points

� In general, principles used in the management ofthe RhD-alloimmunized pregnant patient shouldbe followed in most cases of non-RhD red-cellantibodies.� A maternal titer of >32 indicates the need for fe-

tal surveillance for anemia.� A notable exception is Kell (anti-K1 or anti-K2) al-

loimmunization. A lower maternal critical titer of8 should be used.� In the case of heterozygous paternal phenotype,

DNA analysis of amniotic fluid or free fetal DNAin maternal plasma (limited to the K1, C, c, andE antigens) can be employed to test the fetal anti-gen status.� Serial peak systolic velocities in the fetal middle

cerebral artery can be used to detect fetal ane-mia; a value >1.5 MoMs indicates the need for cor-docentesis and possible IUT.

References

1. Bowman JM. Treatment options for the fetus with alloimmunehemolytic disease. Transfus Med Rev 1990;4:191e207.

2. van Kamp IL, Klumper FJ, Bakkum RS, et al. The severity ofimmune fetal hydrops is predictive of fetal outcome after in-trauterine treatment. Am J Obstet Gynecol 2001;185:668e73.

*3. Queenan JT, Smith BD, Haber JM, et al. Irregular antibodies inthe obstetric patient. Obstet Gynecol 1969;34:767e71.

*4. Geifman-Holtzman O, Wojtowycz M, Kosmas E, et al. Femalealloimmunization with antibodies known to cause hemolyticdisease. Obstet Gynecol 1997;89:272e5.

5. McKenna DS, Nagaraja HN, O’Shaughnessy R. Management ofpregnancies complicated by anti-Kell isoimmunization. ObstetGynecol 1999;93:667e73.

6. Bowell PJ, Brown SE, Dike AE, et al. The significance of anti-calloimmunization in pregnancy. Br J Obstet Gynaecol 86;93:1044e1048.

7. Wenk RE, Goldstein P, Felix JK. Alloimmunization by hr0(c),hemolytic disease of newborns, and perinatal management.Obstet Gynecol 1986;67:623e6.

8. Kozlowski CL, Lee D, Shwe KH, et al. Quantification of anti-cin haemolytic disease of the newborn. Transfus Med 1995;5:37e42.

*9. Hackney DN, Knudtson EJ, Rossi KQ, et al. Management ofpregnancies complicated by anti-c isoimmunization. ObstetGynecol 2004;103:24e30.

10. Spong CY, Porter AE, Queenan JT. Management of isoimmuni-zation in the presence of multiple maternal antibodies. Am JObstet Gynecol 2001;185:481e4.

11. Bowman JM, Pollock JM, Manning FA, et al. Severe anti-Chemolytic disease of the newborn. Am J Obstet Gynecol1992;166:1239e43.

*12. Joy SD, Rossi KQ, Krugh D, et al. Management of pregnanciescomplicated by anti-E alloimmunization. Obstet Gynecol2005;105:24e8.

13. Huber AR, Leonard GT, Driggers RW, et al. Case report:moderate hemolytic disease of the newborn due to anti-G.Immunohematology 2006;22:166e70.

14. Hadley AG, Poole GD, Poole J, et al. Haemolytic disease of thenewborn due to anti-G. Vox Sang 1996;71:108e12.

15. Trevett Jr TN, Moise Jr KJ. Twin pregnancy complicated bysevere hemolytic disease of the fetus and newborn due toanti-g and anti-C. Obstet Gynecol 2005;106:1178e80.

*16. Bowman JM, Pollock JM, Manning FA, et al. Maternal Kellblood group alloimmunization. Obstet Gynecol 1992;79:239e44.

17. Berkowitz RL, Beyth Y, Sadovsky E. Death in utero due to Kellsensitization without excessive elevation of the delta OD450

value in amniotic fluid. Obstet Gynecol 1982;60:746e9.18. Caine ME, Mueller-Heubach E. Kell sensitization in pregnancy.

Am J Obstet Gynecol 1986;154:85e90.*19. Vaughan JI, Warwick R, Letsky E, et al. Erythropoietic

suppression in fetal anemia because of Kell alloimmunization.Am J Obstet Gynecol 1994;171:247e52.

20. Weiner CP, Widness JA. Decreased fetal erythropoiesis andhemolysis in Kell hemolytic anemia. Am J Obstet Gynecol1996;174:547e51.

21. Vaughan JI, Manning M, Warwick RM, et al. Inhibition oferythroid progenitor cells by anti-Kell antibodies in fetalalloimmune anemia. N Engl J Med 1998;338:798e803.

22. van Wamelen DJ, Klumper FJ, de Haas M, et al. Obstetrichistory and antibody titer in estimating severity of Kellalloimmunization in pregnancy. Obstet Gynecol 2007;109:1093e8.

*23. Oepkes D, Seaward PG, Vandenbussche FP, et al. Dopplerultrasonography versus amniocentesis to predict fetal anemia.N Engl J Med 2006;355:156e64.

24. van Dongen H, Klumper FJ, Sikkel E, et al. Non-invasive teststo predict fetal anemia in Kell-alloimmunized pregnancies.Ultrasound Obstet Gynecol 2005;25:341e5.

25. Rimon E, Peltz R, Gamzu R, et al. Management of Kell isoim-munizationeevaluation of a Doppler-guided approach. Ultra-sound Obstet Gynecol 2006;28:814e20.

26. Bowman JM, Harman FA, Manning CR, et al. Erythroblastosisfetalis produced by anti-k. Vox Sang 1989;56:187e9.

27. Levine P, Backer M, Wigod M. A human blood group property(Cellano) present in 99.8% of all bloods. Science 1949;109:464e6.

28. Bryant LB. A case of anti-cellano (k) with review of the pres-ent status of the Kell blood group system. Bull South CentralAssoc Blood Banks 1965;8:4e13.

29. Moncharmont P, Juron-Dupraz F, Doillon M, et al. A case ofhemolytic disease of the newborn infant due to anti-K(Cellano). Acta Haematol 1991;85:45e6.

30. Kulich V. Hemolytic disease of the newborn caused by anti-kantibody. Cesk Pediatr 1967;22:823e6.

31. Duguid JK, Bromilow IM. Haemolytic disease of the newborndue to anti-k. Vox Sang 1990;58:69.

32. Rigal D, Juron-Dupraz F, Biggio B, et al. [Fetal death andbenign hemolytic disease of the newborn from anti-Cellanoalloimmunization: 2 new case reports]. Rev Fr Transfus Immu-nohematol 1982;25:101e4.

33. Stone B, Marsh WL. Hemolytic disease of the newborn causedby anti-M. Br J Haemotol 1959;5:344e7.

34. Macpherson CR, Zartman ER. Anti-M antibody as a cause ofintrauterine death: a follow-up. Am J Clin Pathol 1965;43:544e7.

35. Matsumoto H, Tamaki Y, Sato S, et al. A case of hemolyticdisease of the newborn caused by anti-M: serological studyof maternal blood. Acta Obstet Gynaecol Jpn 1981;33:525e8.

36. Furukawa K, Nakajima T, Kogure T, et al. Example of a womanwith multiple intrauterine deaths due to anti-M who delivered

214 K.J. Moise

a live child after plasmapheresis. Exp Clin Immunogenet 1993;10:161e7.

37. Duguid JK, Bromilow IM, Entwistle GD, et al. Haemolyticdisease of the newborn due to anti-M. Vox Sang 1995;68:195e6.

38. Kanra T, Yuce K, Ozcebe IU. Hydrops fetalis and intrauterinedeathsduetoanti-M.ActaObstetGynecol Scand1996;75:415e7.

*39. De Young-Owens A, Kennedy M, Rose RL, et al. Anti-Misoimmunization: management and outcome at the OhioState University from 1969 to 1995. Obstet Gynecol 1997;90:962e6.

40. Corfield VA, Moolman JC, Martell R, et al. Polymerase chainreaction-based detection of MN blood group-specific se-quences in the human genome. Transfusion 1993;33:119e24.

41. Mayne KM, Bowell PJ, Green SJ, et al. The significance of anti-Ssensitization in pregnancy. Clin Lab Haematol 1990;12:105e7.

42. Feldman R, Luhby AL, Gromisch DS. Erythroblastosis fetalisdue to anti-S antibody. J Pediatr 1973;82:88e91.

43. Levine P, Ferraro LR, Koch E. Haemolytic disease of thenewborn due to anti-S. Blood 1952;7:1030e7.

44. Griffith TK. The irregular antibodies: a continuing problem.Am J Obstet Gynecol 1980;137:174e7.

45. Davie MJ, Smith DS, White UM, et al. An example of anti-scausing mild haemolytic disease of the newborn. J Clin Pathol1972;25:772e3.

46. Telischi M, Behzad O, Issitt PD, et al. Hemolytic disease of thenewborn due to anti-N. Vox Sang 1976;31:109e16.

47. Smith G, Knott P, Rissik J, et al. Anti-U and haemolytic diseaseof the fetus and newborn. Br J Obstet Gynaecol 1998;105:1318e21.

48. Burki U, Degan T, Rosenfield R. Stillbirth due to anti-U. VoxSang 1964;9:209e11.

49. Austin TK, Finklestein J, Okada DM, et al. Letter: Hemolyticdisease of newborn infant due to anti-U. J Pediatr 1976;89:330e1.

50. Dhandsa N, Williams M, Joss V, et al. Haemolytic disease ofthe newborn caused by anti-U. Lancet 1981;2:1232.

51. Gottschall JL. Hemolytic disease of the newborn with anti-U.Transfusion 1981;21:230e2.

52. Magaud JP, Jouvenceaux A, Bertrix F, et al. [Perinatalhemolytic disease due to incompatibility in the U system.Arch Fr Pediatr 1981;38:769e71.

53. Alfonso JF, de Alvarez RR. Maternal isoimmunization to thered cell antigen U. Am J Obstet Gynecol 1961;81:45e8.

54. Tuck SM, Studd JW, White JM. Sickle cell disease in pregnancycomplicated by anti-U antibody. Case report. Br J ObstetGynaecol 1982;89:91e2.

55. Dopp SL, Isham BE. Anti-U and hemolytic disease of thenewborn. Transfusion 1983;23:273e4.

*56. Gonsoulin WJ, Moise Jr KJ, Milam JD, et al. Serial maternalblood donations for intrauterine transfusion. Obstet Gynecol1990;75:158e62.

57. Weinstein L, Taylor ES. Hemolytic disease of the neonatesecondary to anti-Fya. Am J Obstet Gynecol 1975;121:643e5.

58. Hessner MJ, Pircon RA, Johnson ST, et al. Prenatal genotypingof the Duffy blood group system by allele-specific polymerasechain reaction. Prenat Diagn 1999;19:41e5.

59. Kim WD, Lee YH. A fatal case of severe hemolytic disease ofnewborn associated with anti-Jk(b). J Korean Med Sci 2006;21:151e4.

60. Hessner MJ, Pircon RA, Johnson ST, et al. Prenatal genotypingof Jk(a) and Jk(b) of the human Kidd blood group system byallele-specific polymerase chain reaction. Prenat Diagn1998;18:1225e31.

*61. Finning K, Martin P, Summers J, et al. Fetal genotyping for theK (Kell) and RhC, c, and E blood groups on cell-free fetal DNAin maternal plasma. Transfusion 2007;47:2126e33.

*The most important references are indicated with an asterisks.