Reassessing critical maternal antibody threshold in RhD alloimmunization: a 16-year retrospective cohort study.
Ultrasound Obstet Gynecol
; 44(6): 669-73, 2014 Dec.
Article
em En
| MEDLINE
| ID: mdl-24706487
ABSTRACT
OBJECTIVE:
To determine the critical maternal antibody threshold for specialist referral in cases of RhD alloimmunization.METHODS:
This was a retrospective cohort study, covering a 16-year period at the national tertiary fetal medicine center for management of alloimmunization. Data concerning RhD alloimmunized pregnant women were extracted from an institutional database and maternal anti-D antibody levels were cross-checked with the national reference laboratory. Fetal hemoglobin (Hb) levels were determined only at the first intrauterine transfusion (IUT) and were compared with the pretransfusion maternal anti-D antibody level (IU/mL). Sensitivity, specificity and positive and negative predictive values of maternal antibody thresholds for detecting moderate to severe (Hb ≤ 0.64MoM) fetal anemia were calculated.RESULTS:
Between 1996 and 2011, 66 women underwent a first IUT for RhD alloimmunization at our institution. The highest serum anti-D antibody level was extracted for 208 RhD alloimmunized women who did not require IUT during the last 10 years of the study period. The traditional maternal antibody threshold of > 15 IU/mL failed to detect 20% of cases of moderate to severe fetal anemia. The ≥ 4 IU/mL threshold had 100% sensitivity but a 45% false-positive rate. The optimal anti-D antibody threshold for specialist referral in our population was ≥ 6 IU/mL; at this level, no case of moderate to severe anemia was missed and specificity was 61%. Use of this threshold would have eliminated 10% of referrals to our fetal medicine unit without compromising fetal outcomes.CONCLUSIONS:
Setting the critical maternal RhD antibody level at >15 IU/mL does not provide sufficient sensitivity. The lower threshold of ≥ 4 IU/mL, though sensitive, is associated with a 45% false-positive rate. In our population, a threshold of ≥ 6 IU/mL minimizes false-positive referrals while maintaining 100% sensitivity for moderate to severe fetal anemia.Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Isoimunização Rh
/
Doenças Fetais
/
Anemia
/
Isoanticorpos
Tipo de estudo:
Diagnostic_studies
/
Etiology_studies
/
Evaluation_studies
/
Incidence_studies
/
Observational_studies
/
Prognostic_studies
/
Risk_factors_studies
Limite:
Adult
/
Female
/
Humans
/
Pregnancy
Idioma:
En
Revista:
Ultrasound Obstet Gynecol
Assunto da revista:
DIAGNOSTICO POR IMAGEM
/
GINECOLOGIA
/
OBSTETRICIA
Ano de publicação:
2014
Tipo de documento:
Article
País de afiliação:
Irlanda