Prenatal recognition of central nervous system complications of alloimmune thrombocytopenia

Pregnant Women at Low Risk of Having a Child with Fetal and Neonatal Alloimmune Thrombocytopenia Do Not Require Treatment with Intravenous Immunoglobulin

Fetal and neonatal alloimmune thrombocytopenia (FNAIT) is a rare condition in which maternal alloantibodies to fetal platelets cause fetal thrombocytopenia that may lead to intracranial hemorrhage (ICH). Off-label intravenous immunoglobulin (IVIg) has for 30 years been the standard of care for pregnant women who previously have had a child with FNAIT. The efficacy of this treatment has never been tested in a placebo-controlled clinical trial. Although IVIg treatment may improve the neonatal outcome in women who previously have had a child with FNAIT-associated ICH, the question is whether IVIg is necessary for all immunized pregnant women at risk of having a child with FNAIT. The results from some recent publications suggest that antenatal IVIg treatment is not necessary for women who are (1) HPA-1a-immunized and HLA-DRB3*01:01-negative, (2) HPA-1a-immunized with a previous child with FNAIT but without ICH or (3) HPA-5b-immunized. If IVIg is not used for these categories of pregnant women, the amount of IVIg used in pregnant women with platelet antibodies would be reduced to less than ¼ of today's use. This is important because IVIg is a scarce resource, and the collection of plasma for the treatment of one pregnant woman is not only extremely expensive but also requires tremendous donor efforts.

Outcome of antenatally diagnosed intracranial hemorrhage: case series and review of the literature

OBJECTIVES

Prenatal diagnosis of intracranial hemorrhage (ICH) has been widely reported. Hemorrhages may occur either within the cerebral ventricles, subdural space or infratentorial fossa. The aim of this study was to determine the sonographic criteria for the diagnosis of fetal ICH, the role of in utero magnetic resonance imaging (MRI) and the outcome of this condition.

METHODS

The archives of our ultrasound laboratory and the literature were searched for all cases of antenatally diagnosed ICH. A grading system was used to classify the intraventricular lesions as suggested in postnatal sonographic studies.

RESULTS

Adding our series of 16 fetuses to the 93 cases identified in the literature, a group of 109 fetal ICHs was obtained: 89 were intracerebral (79 intraventricular and 10 infratentorial) and 20 were subdural hemorrhages. Intraventricular lesions were mostly classified as severe (32 each for Grades III and IV). In 27 cases antenatal MRI was performed additionally to ultrasound and confirmed the sonographic findings. Of the entire group, 65 infants (59%) were reported to be alive 1 month after birth (51 intraventricular hemorrhages, three infratentorial hemorrhages, 11 subdural hematomas). At 12 months, of the 48 infants whose follow-up was available, 25 or 52% were judged neurologically normal (17/36 or 47% among the intraventricular hemorrhages, 6/9 or 66% among the hematomas, and 2/3 or 66% among the infratentorial hemorrhages).

CONCLUSIONS

Fetal ICH may be accurately identified and categorized by antenatal sonography. The outcome is usually poor, especially for those fetuses affected by higher-grade intraventricular hemorrhages.

Will it ever be possible to balance the risk of intracranial haemorrhage in fetal or neonatal alloimmune thrombocytopenia against the risk of treatment strategies to prevent it?

BACKGROUND AND OBJECTIVES

Intracranial haemorrhage (ICH) of the fetus or newborn is a severe complication of fetal or neonatal alloimmune thrombocytopenia (FNAIT). In order to attain management decisions to prevent ICH, the risk of ICH in successive pregnancies with thrombocytopenia, with or without a history of ICH, must be established.

MATERIALS AND METHODS

We performed a search of medline for ICH cases in untreated FNAIT pregnancies. After exclusion of cases with confounding factors, 24 reports, describing 62 pregnancies of 27 mothers, were eligible. In addition, two mothers with five pregnancies were included from our own case records. Observational studies were examined to estimate the risk of ICH in subsequent FNAIT pregnancies without a history of ICH. Finally, medline was searched for complication rates in the treatment of FNAIT pregnancies.

RESULTS

In 52% of the ICH cases, a previous sibling suffered from ICH. The recurrence rate of ICH in the subsequent offspring of women with a history of FNAIT with ICH was 72%[confidence interval (CI): 46-98%] without inclusion of fetal deaths and 79% (CI: 61-97%) with inclusion of fetal deaths. In 48% of the ICH cases, the previous sibling had thrombocytopenia but not ICH. Population studies revealed an overall ICH risk in thrombocytopenic infants of 11% (CI: 0.8-23%) without inclusion of fetal deaths and 15% (CI: 1.5-19%) with inclusion of fetal deaths. Assuming occurrence in 48%, the risk of ICH in a subsequent pregnancy following a history of FNAIT without ICH, was estimated to be 7% (CI: 0.5-13%). Invasive treatment strategies carry a risk of 2.8% (CI: 1.2-4.4%) on complications.

CONCLUSIONS

The number of eligible publications on ICH in untreated FNAIT pregnancies is strikingly limited. The recurrence rate is high. As sufficient data on successive FNAIT cases without ICH are lacking, the occurrence of ICH in pregnancies with thrombocytopenia, but without ICH in a previous sibling, cannot be predicted. We estimate this risk to be 7%. This risk must be balanced against the risk of interventions in treatment strategies.

Cervical spinal cord hemorrhage secondary to neonatal alloimmune thrombocytopenia

Neonatal alloimmune thrombocytopenia with intracranial hemorrhage is a reported phenomenon. While most of the hemorrhages are noted to be either intraventricular or intraparenchymal, the authors describe the case of a fourth-ventricle hemorrhage with extension into the spinal column down the cervical spinal cord secondary to maternal anti-human platelet antigen (HPA-1a) antibody.

The management of alloimmune neonatal thrombocytopenia

Neonatal alloimmune thrombocytopenia (NAITP), defined as thrombocytopenia (platelet count < 150 x 10(9)/l) due to transplacentally acquired maternal platelet alloantibodies, occurs in approximately 1 per 1200 live births in a Caucasian population. In such a population, the majority (> 75 percent) of cases are due to fetomaternal incompatibility for the platelet specific alloantigen, HPA-1a (P1A1, Zwa). Incompatibility for the HPA-5b (Bra) alloantigen is the next most frequent cause of NAITP in Caucasians; much less common is NAITP due to incompatibility for HLA, blood group ABO or other platelet-specific antigens. In non-Caucasian populations (e.g. Orientals) HPA-1a incompatibility is a rare cause of NAITP and other alloantigens e.g. HPA-4b (Penb, Yuka) are implicated. The greatest clinical challenge relates to the antenatal management of pregnant women alloimmunized to the HPA-1a (P1A1, Zwa) antigen, and particularly the subset of such women who have a history of a previously affected infant with severe thrombocytopenia and/or intracranial hemorrhage (ICH). The risk of antenatal ICH in the fetus of such women is high enough to merit intervention, either weekly infusion of high-dose intravenous immunoglobulin G (IVIG) with or without corticosteroids given to the mother (the preferred approach in North American centres), or repeated in-utero fetal platelet transfusions (the preferred treatment approach in some European centres). Post-natal management of severely affected infants centres on the rapid provision of compatible antigen-negative platelets harvested from the mother or a phenotyped donor. The value of antenatal screening programs to detect 'at risk' alloimmunized women during pregnancy continues to be debated.

Clinical significance of fetal intracranial hemorrhage

OBJECTIVE

We reviewed our experience with six consecutive cases of fetal intracranial hemorrhage and the cases published in the English literature in an attempt to devise an original prognostic scoring system for antenatal intracranial hemorrhage.

STUDY DESIGN

The series included the cases of fetal intracranial hemorrhage detected at our institution between 1992 and 1994 by transabdominal ultrasonography. In addition, we performed an English literature search (Medline computer search, National Library of Medicine) of all reported cases of a prenatal diagnosis of intracranial hemorrhage. The prenatal ultrasonographic findings were correlated with the clinical outcome, which was divided into (1) normal outcome or mild neurologic sequelae and (2) poor outcome (severe neurologic impairment and fetal or neonatal death).

RESULTS

Six cases of intracranial hemorrhage were detected in a population of 6641 pregnancies (0.9/1000) at our institution. Parenchymal involvement was present in three cases. Review of the English literature revealed 35 additional cases with prenatal ultrasonographic findings and postnatal follow-up. The total cases (n = 41) were divided into three groups: (1) isolated intraventricular hemorrhage (n = 20), (2) parenchymal hemorrhage (n = 13), and (3) subdural or subarachnoid hemorrhage (n = 8). Overall, poor outcome was present in 68% of cases, including 45% (9/20) of intraventricular hemorrhage, 92% (12/13) of parenchymal hemorrhage, and 88% (7/8) of subdural or subarachnoid hemorrhage. The heterogeneity of the intraventricular hemorrhage group in both severity of antenatal findings and outcome prompted us to devise a prognostic scoring system based on prenatal ultrasonographic lesions, grouping cohorts with similar outcomes. Outcome was favorable in 100% (5/5) of grade 1 intraventricular hemorrhage cases, in 50% (6/12) of grade 2 cases, and in 0% (0/3) of grade 3 cases.

CONCLUSIONS

Fetal intracranial hemorrhage can be classified on the basis of the anatomic location of the intracranial bleeding. The prognosis is poor in nearly 90% of parenchymal and subdural hemorrhages, whereas it is better in the subgroup with intraventricular hemorrhage. The prognostic scoring system we propose for intraventricular hemorrhage may assist the physician in providing patients with prognostic information.

Nature of the brain lesion in fetal allo-immune thrombocytopenia

Study of three fetuses with allo-immune thrombocytopenia, one with autopsy findings, and comparison with existing data have permitted speculation on the nature of the initial lesion within the brain. The commonest first bleeding site is probably underneath the molecular layer of the cerebral cortex, often within the temporal lobe. Small haemorrhages may appear to be (sub)pial, but expansion will lead to so-called subarachnoid haematoma. Communication with the adjacent lateral ventricle will contribute to post-haemorrhagic hydrocephalus. Occasionally, the initial haemorrhage is within the ventricle; such a pattern may lead to post-haemorrhagic hydrocephalus, often with a porencephalic component. In utero follow-up of fetuses at risk for allo-immune thrombocytopenia will have to focus on superficial cerebral haemorrhage for early detection of brain involvement.