Management of fetal alloimmune thrombocytopenia by weekly in utero platelet transfusions

The Sonographic Detection of Intracranial Hemorrhage Due to Alloimmune Thrombocytopenia

Alloimmune thrombocytopenia is a rare condition in which antibodies from the mother's circulation cross the placenta and destroy the platelets in the fetus. Approximately 14% of affected fetuses or neonates develop intracranial hemorrhage, leading to death or long-term central nervous system disabilities. After treating two such cases, 26 previously reported cases of alloimmune thrombocytopenia with intracranial hemorrhage were examined to discover if these hemorrhages exhibit a typical sonographic appearance, course, and time of hemorrhage. When intracranial hemorrhage occurs in cases of alloimmune thrombocytopenia, it has a typical appearance in 76% of cases: a large hematoma in the center of the cerebral hemisphere. There is no difference between genders in the occurrence of alloimmune thrombocytopenia unless hemorrhage occurs: 72% of neonates with alloimmune thrombocytopenia and intracranial hemorrhage are male. Intracranial hemorrhage occurs before labor and delivery in 76% of cases. Sonographers cannot depend on a history of the condition in previous pregnancies as an indication of alloimmune thrombocytopenia: only 35% of neonates with alloimmune thrombocytopenia and hemorrhage have previously affected siblings.

Advances in the management of alloimmune thrombocytopenia

There have been considerable advances in the clinical and laboratory diagnosis of alloimmune thrombocytopenia (AIT), and its postnatal and antenatal management. The antenatal management of AIT has been particularly problematic, because severe haemorrhage occurs as early as 16 weeks gestation and there is no non-invasive investigation that reliably predicts the severity of AIT in utero. The strategies for antenatal treatment have included the use of serial platelet transfusions that, while effective, are invasive and associated with significant morbidity and mortality. Maternal therapy involving the administration of intravenous immunoglobulin and/or steroids is also effective and associated with fewer risks to the fetus. Significant recent progress has involved refinement of maternal treatment, stratifying it according to the likely severity of AIT based on the history in previous pregnancies. However, the ideal antenatal treatment, which is effective without causing significant side-effects to the mother or fetus, has yet to be determined, and further clinical trials are needed.

Alloimmune thrombocytopenia: state of the art 2006

In alloimmune thrombocytopenia maternal immunoglobulin G anti-platelet alloantibodies cross the placenta and cause fetal thrombocytopenia. The diagnosis requires laboratory demonstration of incompatibility between a maternal and paternal platelet alloantigen, and detection of maternal antibody to the discordant paternal alloantigen. This disorder should be treated in utero because of its propensity to cause fetal intracranial bleeding. Administration of intravenous immunoglobulin 1 gm/kg/wk to the mother is successful in substantially raising the platelet count in many fetuses, but this is most successful if the count is >20,000/mL3 at the time that the therapy is initiated. The addition of prednisone administered daily to the mother and/or increasing the dose of intravenous immunoglobulin has a therapeutic benefit in cases that have failed to respond to initial therapy with intravenous immunoglobulin alone. The only reliable noninvasive indicator of the potential for severe fetal thrombocytopenia is a history of an antenatal intracranial hemorrhage in a prior affected sibling. Because fetal blood sampling to determine the fetal platelet count may be associated with significant fetal morbidity, attempts are being made to derive a rational, non-invasive, stratified approach to patient-specific therapy of this disorder in affected pregnancies.

Antenatal interventions for fetomaternal alloimmune thrombocytopenia

BACKGROUND

Fetomaternal alloimmune thrombocytopenia occurs when the mother produces antibodies against a platelet alloantigen that the fetus has inherited from the father. A consequence of this can be a reduced number of platelets (thrombocytopenia) in the fetus, which can result in bleeding whilst in the womb or shortly after birth. In severe cases this bleeding may lead to long-lasting disability or death. Antenatal management of fetomaternal alloimmune thrombocytopenia centres on preventing severe thrombocytopenia in the fetus. Available management options include administration of intravenous immunoglobulins or corticosteroids to the mother or intrauterine transfusion of antigen compatible platelets to the fetus. All options are costly and need to be assessed in terms of potential risk and benefit to both the mother and an individual fetus.

OBJECTIVES

To determine the optimal antenatal treatment of fetomaternal alloimmune thrombocytopenia to prevent fetal and neonatal haemorrhage and death.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group trials register (February 2004), EMBASE (1980 to February 2004) and bibliographies of relevant publications and review articles.

SELECTION CRITERIA

Randomised controlled studies comparing any intervention, including corticosteroids with no treatment, or comparing any two interventions.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed eligibility, trial quality and extracted data.

MAIN RESULTS

One study met the inclusion criteria (54 pregnant women). This trial compared intravenous immunoglobulins plus corticosteroid (dexamethasone) with intravenous immunoglobulins alone. No significant differences were reported between the treatment and control groups, in any outcome measured: mean platelet count at birth (weighted mean difference (WMD) 14.10 x 10 9/l, 95% confidence interval (CI) -30.26 to 58.46), mean gestational age at birth (WMD -0.50 weeks, 95% CI -2.69 to 1.69), mean rise in platelet count from first to second fetal blood screen (WMD -3.50 x 10 9/l, 95% CI -24.62 to 17.62) and mean rise in platelet count from birth to first fetal blood screen (WMD 24.40 x 10 9/l (95% CI -14.17 to 62.97)). This trial had adequate methodological quality; however the method used to calculate sample size was inappropriate: therefore the power calculation was not sufficient to determine any significance in differences between the treatment groups.

AUTHORS' CONCLUSIONS

There are insufficient data from randomised controlled trials to determine the optimal antenatal management of fetomaternal alloimmune thrombocytopenia. Future trials should consider the dose of intravenous immunoglobulins, the timing of initial treatment, monitoring of response to treatment by fetal blood sampling, laboratory measures to define pregnancies with a high risk of intercranial haemorrhage, management of non-responders and long-term follow up of children.

Prenatal treatment of severe fetomaternal alloimmune thrombocytopenia

Prenatal treatment of fetomaternal alloimmune thrombocytopenia (FMAIT) in previously affected families is of great clinical importance. We report here our experience in the prenatal treatment of 15 severely thrombocytopenic fetuses. Thrombocytopenia was in 13 cases due to immunization to HPA-1a, in one case to HPA-5b, and in one case to HPA-6b. Thirteen fetuses received altogether 34 intrauterine platelet transfusions, seven of them in combination with maternal-administered intravenous gammaglobulin (IVIG) and two in combination with IVIG and prednisone. Six of the 13 fetuses had only one transfusion just prior to delivery. In our experience, IVIG seemed to be less effective than reported; only two fetuses of eight treated initially with weekly maternal-administered IVIG responded, and these were the mildest affected cases in the study. On the other hand, owing to the short survival time, weekly platelet transfusions could only partly maintain a safe platelet count in the four fetuses treated with serial intrauterine platelet transfusions. The number of transfusions needed to be limited because of the high cumulative risk associated with repeated procedures. Three of 34 intrauterine platelet transfusions were associated with near-loss of three different fetuses due to prolonged fetal bradycardia after the transfusion. In conclusion, overall neonatal outcome was good, with no mortality; among the study group there was no intracranial haemorrhage (evaluated by postnatal ultrasonography) compared with one case in their untreated siblings. However, the problem of the optimal treatment of FMAIT remains to be solved. For the moment, the treatment of choice is a combination of maternal IVIG and platelet transfusions in severely affected cases. Serial fetal blood samplings (FBS) are needed in order to monitor the fetus with sufficient care.

Alloimmune thrombocytopenia

For the fetuses who are at risk for antenatal or postnatal sequelae from AIT, prevention and treatment are now possible. This requires the attention of the obstetrician to factors in the patient's history and early referral to a center experienced in the diagnosis and management of fetal AIT.

Clinical uses of intravenous immunoglobulin in pregnancy

The obstetric literature contains numerous reports of IVIG therapy for various conditions encountered during pregnancy. The mechanisms of action of IVIG are uncertain and may vary depending on the specific disorder. Immunoglobulin G infusions appear to be well tolerated by the parturient. The occurrence of major and minor side effects is uncommon, and infectious morbidity is low. Further research will be necessary to elucidate the specific mechanisms of action of IVIG in certain disease states. Determining the exact "therapeutic agent" in IVIG for each specific disease state may allow for a more tailored approach to treatment (i.e., isolation or production of the particular antibody). Outcome assessment, long-term positive and negative effects, cost-benefit analysis, and effects on fetal and neonatal immune function require further study through randomized trials.

Clinical aspects and typing of platelet alloantigens

Platelet alloantigens can induce the formation of corresponding alloantibodies when exposed to phenotypically negative individuals. These antibodies are responsible for fetal and neonatal alloimmune thrombocytopenia, posttransfusion purpura, passive alloimmune thrombocytopenia and transplantation-associated thrombocytopenia and may contribute to platelet transfusion refractoriness together with HLA antibodies. Besides antibody detection laboratory diagnosis of the clinical syndromes requires alloantigen typing. Furthermore, typed platelet donors are a prerequisite for effective platelet transfusion therapy. Different techniques for phenotyping are well established and easy to perform but they rely on the availability of antisera. Since the molecular genetic background of the clinically most relevant alloantigens has been elucidated during the last years various genotyping methods have been applied to the platelet membrane polymorphisms and thus facilitated widespread platelet alloantigen typing. Generation of antibodies from phage display libraries and of lymphoblastoid cell lines from donors with all genetic variants will allow further developments.

Prenatal diagnosis and management of neonatal alloimmune thrombocytopenia

Neonatal alloimmune thrombocytopenia (NAIT) is an uncommon (1 in 2,000 livebirths) but serious disorder characterized by marked thrombocytopenia in the fetus and neonate. Platelet destruction is caused by a maternal antibody directed against a fetal platelet antigen inherited from the father and lacking in the mother's platelets. Intracranial hemorrhage (ICH) is the most devastating complication of NAIT, affecting approximately 20% of all proven cases, up to 50% of which occur antenatally. Because close to 100% of subsequent pregnancies will be equally or more severely affected, antenatal management directed at preventing ICH in utero has assumed great clinical importance. In recent years, considerable progress has been made in this regard, and although clinical uncertainties still exist, the natural history of this disease and its response to various antenatal interventions have become reasonably well understood. This review will focus on the diagnosis and current management of NAIT, including controversies surrounding current treatment modalities and future prospects for treatment and prevention.

Clinical uses of intravenous immunoglobulin in pregnancy

Intravenous immunoglobulin was licensed for use in the United States in 1981. Currently, there are only a few Food and Drug Administration-labeled indications for intravenous immunoglobulin, but up to 50 "off-label" uses are reported in the literature. The obstetric literature contains numerous reports on intravenous immunoglobulin therapy during pregnancy. This article reviews the properties, pharmacokinetics, mechanisms of action, and side effects of intravenous immunoglobulin, as well as the reported uses of intravenous immunoglobulin during pregnancy.

Fetal transfusion therapy

Rapid advances are occurring in the diagnosis and treatment of the fetus with a red blood cell or platelet cytopenia. Noninvasive methods of monitoring the alloimmunized pregnancy, invasive methods such as amniocentesis and cordocentesis, and intrauterine transfusion therapy of both red cells and platelets, are being further refined to allow the prompt recognition and treatment of fetal cytopenias. Specialized centers have now accrued a large experience in the management of the fetus severely affected by alloimmunization. Advances in ultrasound, blood banking techniques, and genetic engineering technology have spurred the most recent advances. The indications for diagnosis, timing and frequency of invasive procedures for treatment, and technical considerations regarding preparation of blood products and volume of transfusion, are outlined in this review. Polymerase chain reaction (PCR) determination of fetal Rh(D) genotype by chorionic villus sampling or amniocentesis in the first or second trimesters is a recent clinically useful advance. The advent of hematopoietic stem cell transplantation and the potential for gene therapy are exciting advances in the treatment and prevention of hematopoietic diseases, including, but not limited, to the fetal cytopenias.

Medical fetal therapy

Medical fetal therapy describes any therapy in which a pharmacological agent is administered to a woman or her fetus in order to avoid or alleviate fetal disease. Treatment of the fetus with blood products or injection of other agents can also be considered to be medical fetal therapy. This chapter reviewed the application of medical fetal therapy to the prevention of NTDs, treatment of endocrinological and metabolic disorders, such as CAH, thyroid disease and others, and the medical management of cardiac arrhythmias. Several haematological disorders and reviews of recent advances in genetic manipulation involving the use of stem-cell implantation were discussed. The field of medical fetal therapy has been extremely exciting and continues to evolve at a rapid pace. No doubt, future advances involving genetic manipulation or the use of molecular genetic techniques for diagnosis will continue to keep this field at the forefront of treatment and prevention of fetal disorders.

Monitoring anti-HPA-1a platelet antibody levels during pregnancy using the MAIPA test

Anti-HPA-1a platelet antibody levels in pregnant women with a history of fetomaternal alloimmune thrombocytopenia (FMAIT) were monitored longitudinally using the monoclonal antibody immobilisation of platelet antigens (MAIPA) assay, in order to examine any variation in optical density (OD) readings obtained over the course of pregnancy and after delivery. Seven women were selected; 4 were studied retrospectively and 3 prospectively (the latter being treated with intravenous gammaglobulin; IVGG). Levels of anti-HPA-1a were measured at various intervals after delivery of the first affected infant, to post delivery of the following affected infant. A decrease in MAIPA OD was demonstrated in all patients during the course of these pregnancies. This assay is a useful tool for monitoring anti-HPA-1a in women with a history of infants affected with FMAIT. A maternal antibody 'resting' level prior to, or early in the first trimester, must be established for comparison.

Antenatal management of fetomaternal alloimmune thrombocytopenia--report of 15 affected pregnancies

The recognition that spontaneous intracranial haemorrhage (ICH) may occur in utero in fetomaternal alloimmune thrombocytopenia (FMAIT) led us to attempt to prevent this in 15 pregnancies of 11 women who had previously affected infants with FMAIT due to anti-HPA-1a. The antenatal management included fetal platelet transfusions and maternal steroids and/or high-dose intravenous immunoglobulin (IVIgG). In the first pregnancy, ICH occurred between 32 and 35 weeks' gestation before any treatment had been given, emphasizing the need for earlier intervention. Five of the 14 subsequent pregnancies in this study were considered to be severely affected (severe haemorrhagic complications in a previous infant and initial fetal platelet count < 20 x 10(9)/L in this study); four were managed successfully with weekly fetal platelet transfusions started between 18 and 29 weeks and continued until delivery at 33-35 weeks, and one severely affected case who was referred at 36 weeks was managed successfully with a single platelet transfusion prior to delivery. Five pregnancies were considered to be mildly affected (previous infants were unaffected by severe bleeding and initial fetal platelet count > 50 x 10(9)/L in this study). The platelet counts were maintained in one case with steroids and in three with IVIgG without the need for repeated platelet transfusions, but in the fifth the fetal platelet count fell despite steroids and IVIgG and serial platelet transfusions were required. Four pregnancies were unsuccessful; two pregnancies were terminated after severe ICH occurred at an early stage before fetal blood sampling had been carried out, one fetus died after the mother had a severe fall despite the successful initiation of fetal platelet transfusions and one died due to a cord haematoma which occurred at the time of the initial fetal blood sampling. The optimal management of FMAIT to reduce the risk of antenatal ICH remains uncertain. Steroids and IVIgG may be effective in some mildly affected cases but serial fetal platelet transfusions are the preferred therapy for those who are severely affected.

Maternal intravenous immunoglobulin treatment does not prevent intracranial haemorrhage in fetal alloimmune thrombocytopenia

In fetal alloimmune thrombocytopenia (FAIT) the fetus is threatened by intracranial haemorrhage (ICH); therefore early diagnostic and therapeutic intervention is required. We followed the clinical course of a 30-year-old woman during her fifth pregnancy after she had given birth to a child with alloimmune thrombocytopenia due to anti-Zwa. The fetus was monitored by 13 fetal blood samplings (FBS) always followed by transfusion of either maternal or compatible donor platelets. Intravenous immunoglobulin (ivIg) treatment of the mother was begun at 20 weeks of gestation when the fetal platelet count was 36 x 10(9)/l. The fetal platelets were typed Zwa positive by DNA analysis. Despite 11 weeks of maternal ivIg treatment fetal platelet counts progressively declined to 6 x 10(9)/l and ICH occurred. Subsequently, the fetus was successfully managed by intrauterine platelet transfusions at shorter intervals (3-5 days) and elective Cesarean section was carried out at 35 weeks of gestation. We conclude that maternal ivIg treatment does not prevent ICH in FAIT. The treatment of choice for severely affected cases is serial FBS combined with transfusion of compatible platelets.

Neonatal alloimmune thrombocytopenia. A case report and a review of the literature

A 32-year-old woman in her third pregnancy underwent fetal blood sampling because of a previous child with neonatal thrombocytopenia. At 33 weeks' gestation, fetal thrombocytopenia was diagnosed. Treatment was instituted antenatally with serial fetal platelet transfusions and corticosteroid therapy. Delivery was by Caesarean section at 37 weeks' gestation. Neonatal treatment included further platelet transfusion and immunoglobulin infusion. Recovery of the neonate was complete on discharge from hospital 10 days after birth. The aetiology, diagnosis, clinical presentations and therapeutic options in cases of alloimmune thrombocytopenia are discussed.

Neonatal alloimmune thrombocytopenia due to anti-P1A1 (anti-HPA-1a): importance of paternal and fetal platelet typing for assessment of fetal risk

Neonatal alloimmune thrombocytopenia (NAIT), which usually involves sensitization to P1A1 (HPA-1a), may have devastating complications for the fetus. These may be prevented by antenatal treatment of severe cases with either maternally administered high-dose gamma-globulin and/or repeated intrauterine platelet transfusions. Determination of the paternal platelet phenotype is useful for counseling parents who have had one or more affected pregnancies. This report of an unaffected pregnancy in a woman with a history of previous pregnancies complicated by NAIT illustrates the role of paternal and fetal platelet phenotyping in managing existing pregnancies at risk of NAIT.

The effect of intravenous immunoglobulin on placental transfer of a platelet-specific antibody: anti-P1A1

The isolated perfused lobule of human placenta was used as an in-vitro model to study the effect of intravenous immunoglobulin (IVGG) on the placental transfer of a human platelet-specific antibody (anti-P1A1). Normal human IgG was shown to transfer from the maternal to the fetal circulation of the placental model after a lag period of 2-3 h. IVGG also transferred across the placenta but only after a longer lag period (3-4 h) than normal human IgG at the same concentration, which suggests that IVGG may contain a factor that inhibits the transfer of its own component IgG. The sensitive Western immunoblotting technique was used to demonstrate progressive transfer of anti-P1A1 antibody to the fetal circulation after a 2-3 h lag period. When IVGG and anti-P1A1 antibody were added simultaneously to the maternal circulation, the transfer of platelet-specific antibody was strongly inhibited by IVGG. The inhibitory effect of IVGG on anti-P1A1 antibody transfer was consistent for three different batches of the same IVGG product (Sandoglobulin). These studies provide the first scientific data to support the use of IVGG to inhibit antiplatelet antibody transfer as part of the antenatal management of neonatal alloimmune thrombocytopenia.