Risk factors for alloimmunization by patients with sickle cell disease

Blood transfusion in patients with sickle cell disease (SCD) is limited by the development of alloantibodies to erythrocytes. In the present study, the frequency and risk factors for alloimmunization were determined. Transfusion records and medical charts of 828 SCD patients who had been transfused and followed at the Belo Horizonte Blood Center, Belo Horizonte, MG, Brazil, were retrospectively reviewed. Alloimmunization frequency was 9.9 percent (95 percent CI: 7.9 to 11.9 percent) and 125 alloantibodies were detected, 79 percent of which belonged to the Rhesus and Kell systems. Female patients developed alloimmunization more frequently (P = 0.03). The median age of the alloimmunized group was 23.3 years, compared to 14.6 years for the non-alloimmunized group (P < 0.0001). Multivariate analyses were applied to the data for 608 hemoglobin (Hb) SS or SC patients whose number of transfusions was recorded accurately. Number of transfusions (P = 0.00006), older age (P = 0.056) and Hb SC (P = 0.02) showed independent statistical associations with alloimmunization. Hb SC patients older than 14 years faced a 2.8-fold higher (95 percent CI: 1.3 to 6.0) risk of alloimmunization than Hb SS patients. Female Hb SC patients had the highest risk of developing alloantibodies. In patients younger than 14 years, only the number of transfusions was significant. We conclude that an increased risk of alloimmunization was associated with older patients with Hb SC, specially females, even after adjustments were made for the number of transfusions received, the most significant variable.

Estudo das causas da isoimunização materna por antígenos eritrocitáros entre gestantes acompanhadas no Serviço de Medicina Fetal do HC-UFMG / Study of the causes of maternal erithrocytic antigen isoimmunization among pregnant women followed at the Fetal Medicine Service - HC-UFMG

Objetivo: Analisar as causas da isoimunização materna por antígenos entrocitários entre as gestantes acompanhadas no Serviço de Medicina Fetal do HC-UFMG, no período de junho de 1996 a junho /2003. Pacientes e Método: Trata-se de estudo prospectivo, qual 256 gestantes sensibilizadas por antígenos eritrocitários foram acompanhadas no Centro de Medicina Fetal do HC-UFMG. As pacientes foram avaliadas quanto ao passado obstétrico, visando identificar as causas de isoimunização. Resultados: Entre os 256 casos acompanhados, em 185(72,3%) a causa de isoimunização foi a ausência de profilaxia pós-parto; a transfusão sangüínea incompatível foi a responsável por 34 casos (13,3%) e a falta de profilaxia pós-aborto, por 29 casos (11,3%). Os oito casos restantes (3,1%) ocorreram durante o período gestacional. Conclusão: As principais causas de isoimunização materno-fetal continuam se relacionando à etiologia obstétrica, principalmente à falta de imunoprofilaxia no pás-parto e no pós-aborto. Portanto, a isoimunização, em nosso meio, pode ser facilmente prevenível com o uso da imunoglobulina anti-Rh (D), conforme rotina já estabelecida há décadas.

Objective: To analyze the causes of maternal erithrocytic antigen isoimmunization among pregnant women followed at the Fetal Medicine Service Hospital das Clínicas - Universidade Federal de Minas Gerais (FMSHC), from June/1996 to June/2003. Methods and Material: A prospective study, consisting of 256 pregnant women with sensitization by erithrocytic antigen were followed at the FMSHC. These patients were evaluated regarding the obstetric history, in order to identify the causes of isoimmunization. Results: In 185 cases (72.3%), isoimmunization was caused by lack of postpartum prophilaxy. Incompatibility in blood transfusion and absence of post-abortion prophilaxy were responsible for 34 (13.3%) and 29 cases (11.3%), respectively. The remaining eight cases (3.1%) occurred during gestational period. Conclusion: The main cause of fetal-maternal isoimmunization is still related to obstetric etiology, mainly to absence of postpartum or post-abortion immunoprophilaxy. Therefore, isoimmunization, in our population, can be easily prevented by the use of anti-Rh (D) immune globulin according to established routines.

Anemia fetal detectada por dopplervelocimetria da artéria cerebral média / Fetal anemia detected by doppler velocimetry of middle cerebral artery

A Anemia é condição clínica que pode acometer o feto gravemente, por diversas razões, sendo a isoimunização do sistema Rh a mais freqüente. O padrão-ouro para o diagnóstico intra-útero é a cordocentese e análise da hemoglobina fetal. As consequências para o feto podem ser hidropisia fetal, insuficiência cardíaca, óbito intra-útero ou neonatal, parto prematuro, dentre outras. Quando há redução na concentração da hemoglobina fetal, a viscosidade sanguínea é diminuída e a velocidade aumentada. Alguns vasos fetais foram estudados, como artéria umbilical, aorta e carótida interna. Para avaliação da velocidade do pico sistólico é necessário ângulo inferior a 20graus, por isso, determinou-se como ideal a artéria cerebral média. O desempenho do pico sistólico por dopplervelocimetria da artéia cerebral média na predição da anemia fetal está sendo exaustivamente estudado. Os autores fazem revisão sobre como a dopplervelocimetria de artéria cerebral média pode auxiliar no manejo da anemia fetal

Isoinmunización RH: manejo actual / Isoinmunización RH: present handling

La incompatibilidad rh materno fetal es un factor que complica aproximadamente 1 de cada 1000 embarazos en los EE.UU, constituye la principal causa de muerte fetal o neonatal por enfermedad hemolítica. Nuevas técnicas como la cordocentesis, transfusión intrautterina han mejorado el pronóstico en estas pacientes. En la presente revisión comentaremos los avances acerca del manejo de la isoinmunización Rh.

Jaundice in the newborn

Jaundice in the newborn is a relatively common symptom. It may be physiologic or due to a pathologic cause. Determination of the serum bilirubin is followed by serial determinations to document the rate of increase. Unconjugated hyperbilirubinemia, if left untreated, may reach toxic levels and cause bilirubin encephalopathy. Acceptable methods of treatment include phototherapy and exchange transfusion

Studies on the prenatal chromosomal analysis and the changes of maternal serum alpha-fetoprotein following chorionic villus sampling

Transcervical chorionic villus sampling (CVS) was performed in 174 patients between 7 & 12 menstrual weeks of pregnancy opting for prenatal diagnosis. Advanced maternal age was the most common indication for CVS (39.7%). The sampling success rate was 95.4% (166/174), representing 88.9% at 7 to 8 weeks, 98.9% at 9 to 10 weeks & 92.7% at 11 to 12 weeks gestation. In 139 of 174 patients (80%), successful sampling was accomplished in one or two catheter passages only. Four spontaneous fetal losses (2.3%) occurred. The cytogenetic analysis routinely used was the direct overnight & long-term culture methods which revealed 4 abnormalities (2.4%). To date, 90 of the women have been delivered & all infants are doing well and the remaining 65 pregnancies are continuing uneventually. Maternal serum alphafetoprotein (MSAFP) concentration was determined in 72 patients immediately before & after CVS. A significant increase of 20% or more, comparable to pre CVS levels, was noted immediately after sampling in 56 of 72 patients (77.8%). The increase in MSAFP concentration correlated with the amount of villi sampled (r = 0.498, p less than 0.001) & with the number of sampling attempts (p less than 0.05). Estimated CVS related fetomaternal hemorrhage (FMH) ranged from 0.005 to 0.1552 ml and in 5 of 72 patients (6.90%) 0.06 ml or more of FMH was noted. Two of the 5 patients had FMH of 0.1 ml or more.