Percutaneous umbilical blood sampling: indication changes and procedure loss rate in a nine years' experience

The promise of fetal cells in maternal blood

Delaying childbirth increases the proportion of advanced maternal age pregnancies. This increases the number of pregnancies requiring invasive prenatal testing. Prenatal diagnosis of chromosomal aneuploidies and monogenic disorders requires fetal cells obtained through invasive procedures (i.e. chorionic villus sampling and amniocentesis). These procedures carry a risk of fetal loss, which causes anxiety to at-risk couples. Intact fetal cells entering maternal circulation have raised the possibility of non-invasive prenatal diagnosis. Rarity of fetal cells, however, has made it challenging. Fetal nucleated red blood cells are ideal candidate target cells because they have limited lifespan, contain true representation of fetal genotype, contain specific fetal cell identifiers (embryonic and fetal globins), and allow interrogation with chromosomal fluorescence in-situ hybridisation and possibly with array comparative genomic hybridisation. The utility of fetal nucleated red blood cells in non-invasive prenatal diagnosis has not reached clinical application because of the inconsistencies in enrichment strategies and rarity of cells.

Effect of cord puncture site in cordocentesis at mid-pregnancy on pregnancy outcomes

OBJECTIVES

To compare the procedure and pregnancy outcomes of pregnancies undergoing cordocentesis between a group of cord insertion puncture and that of free loop puncture.

MATERIALS AND METHODS

Pregnancies undergoing cordocenteses meeting the following inclusion criteria were recruited: (1) singleton pregnancies at gestational ages of 18-22 weeks; (2) no fetal abnormalities; (3) the procedures performed by experienced operators; and (4) the procedures of no placenta penetration. The recruited cases were classified into two groups: a group of cordocenteses with puncture site at placental cord insertion (Group 1) and those with puncture site at cord free loop (Group 2). The primary outcomes to be compared were rates of fetal loss, newborns with low birth weight and preterm birth. The secondary outcomes included a rate of successful procedures, umbilical cord bleeding, fetal bradycardia, maternal blood contamination, and duration of the procedure time.

RESULTS

Of 6147 cordocenteses recruited, 2214 met inclusion criteria. The mean duration to complete the procedure in Group 1 was significantly shorter than that in Group 2 (4.5 ± 5.4 vs. 6.7 ± 8.5 min, Student's t-test; p = 0.001). The mean birth weight and gestational age at delivery were comparable between the two groups. No significant differences between the two groups were seen in rates of fetal loss, low birth weight, preterm birth, successful procedures, umbilical cord bleeding, or fetal bradycardia. However, the rate of maternal blood contamination was significantly higher in the group of puncture at the cord insertion site.

CONCLUSION

Of cordocenteses performed based on accessibility and quality of visualization, cord insertion puncture may cause more maternal blood contamination but free loop puncture may be associated with more difficult procedures, while the safety was comparable.

Prenatal diagnosis: update on invasive versus noninvasive fetal diagnostic testing from maternal blood

The modern obstetrics care includes noninvasive prenatal diagnosis testing such as first trimester screening performed between 11 and 14 weeks' gestation and second trimester screening performed between 15 and 20 weeks. In these screening tests, biochemical markers are measured in the maternal blood with or without ultrasound for fetal nuchal translucency with reported accuracy of up to 90%. Invasive procedures, including amniocentesis or chorionic villi sampling, are used to achieve over 99% accuracy. During these procedures direct fetal material is examined and, therefore, these tests are highly accurate with the caveat of a small risk for pregnancy loss. Much research now focuses on other noninvasive highly accurate and risk-free tests that will identify fetal material in the maternal blood. Fetal cells and fetal DNA/RNA provide fetal information but are hard to find in an overwhelming background of maternal cells and in the absence of specific fetal cell markers. The most experience has been accumulated with fetal rhesus and fetal sex determination from maternal blood, with an accuracy of up to 100% by using gene sequences that are absent from maternal blood. Although not clinically applicable yet, fetal cells, fetal DNA/RNA and fetal proteomics in combination with cutting edge technology are described to prenatally diagnose aneuploidies and single-gene disorders.

Developing recombinant HPA-1a-specific antibodies with abrogated Fcgamma receptor binding for the treatment of fetomaternal alloimmune thrombocytopenia

Fetomaternal alloimmune thrombocytopenia (FMAIT) is caused by maternal generation of antibodies specific for paternal platelet antigens and can lead to fetal intracranial hemorrhage. A SNP in the gene encoding integrin beta3 causes a clinically important maternal-paternal antigenic difference; Leu33 generates the human platelet antigen 1a (HPA-1a), whereas Pro33 generates HPA-1b. As a potential treatment to prevent fetal intracranial hemorrhage in HPA-1a alloimmunized pregnancies, we generated an antibody that blocks the binding of maternal HPA-1a-specific antibodies to fetal HPA-1a1b platelets by combining a high-affinity human HPA-1a-specific scFv (B2) with an IgG1 constant region modified to minimize Fcgamma receptor-dependent platelet destruction (G1Deltanab). B2G1Deltanab saturated HPA-1a+ platelets and substantially inhibited binding of clinical HPA-1a-specific sera to HPA-1a+ platelets. The response of monocytes to B2G1Deltanab-sensitized platelets was substantially less than their response to unmodified B2G1, as measured by chemiluminescence. In addition, B2G1Deltanab inhibited chemiluminescence induced by B2G1 and HPA-1a-specific sera. In a chimeric mouse model, B2G1 and polyclonal Ig preparations from clinical HPA-1a-specific sera reduced circulating HPA-1a+ platelets, concomitant with transient thrombocytopenia. As the Deltanab constant region is uninformative in mice, F(ab')2 B2G1 was used as a proof of principle blocking antibody and prevented the in vivo platelet destruction seen with B2G1 and polyclonal HPA-1a-specific antibodies. These results provide rationale for human clinical studies.

Fetal and neonatal alloimmune thrombocytopenia: progress and ongoing debates

Fetal and neonatal alloimmune thrombocytopenia (AIT) is a result of a parental incompatibility of platelet-specific antigens and the transplacental passage of maternal alloantibodies against the platelet antigen shared by the father and the fetus. It occurs in approximately 1 in 1000 live births and is the most common cause of severe thrombocytopenia in fetuses and term neonates. As screening programs are not routinely performed, most affected fetuses are identified after birth when neonatal thrombocytopenia is recognized. In severe cases, the affected fetus is identified as a result of suffering from an in utero intracranial hemorrhage. Once diagnosed, AIT must be treated antenatally as the disease can be more severe in subsequent pregnancies. While there have been many advances regarding the diagnosis and treatment of AIT, it is still difficult to predict the severity of disease and which therapy will be effective.

HPA-1a antibody potency and bioactivity do not predict severity of fetomaternal alloimmune thrombocytopenia

BACKGROUND

The antenatal management of fetomaternal alloimmune thrombocytopenia (FMAIT) due to HPA-1a antibodies remains controversial, and a test identifying pregnancies that do not require therapy would be of clinical value.

STUDY DESIGN AND METHODS

The statistical correlation was analyzed between clinical outcome and 1) anti-HPA-1a potency in maternal serum samples determined by a monoclonal antibody immobilization of platelet (PLT) antigen assay with an international anti-HPA-1a potency standard and 2) anti-HPA-1a biological activity measured by a monocyte chemiluminescence (CL) assay.

RESULTS

A total of 133 pregnancies with FMAIT due to anti-HPA-1a were analyzed. In 97 newly diagnosed cases, there was no difference in antibody potency or CL signal between cases with intracranial hemorrhage (ICH; n = 15), those with no ICH but a PLT count of less than 20 x 10(9) per L (n = 52), and those with a PLT count of at least 20 x 10(9) per L (n = 30). In 22 previously known pregnancies, the positive predictive value of maternal anti-HPA-1a of greater than 30 IU per mL for a PLT count of less than 20 x 10(9) per L was 90 percent, but the negative predictive value was only 66 percent. Antibody potency tended to stay stable throughout pregnancy (n = 16) and from one pregnancy to the next (n = 16).

CONCLUSION

Neither severe thrombocytopenia nor ICH in HPA-1a-alloimmunized pregnancies can be predicted with sufficient sensitivity and specificity for clinical application from maternal anti-HPA-1a potency or bioactivity.

Cordocentesis in multifetal pregnancies

OBJECTIVE

To describe the experiences in diagnostic cordocentesis in twin pregnancies at midpregnancy

METHODS

The database and medical records of pregnant women attending Maternal Fetal Medicine Unit of the hospital for diagnostic cordocentesis at midpregnancy between January 1989 and September 2006 were retrospectively reviewed.

RESULTS

During 17 years of experience, 4,241 cordocenteses at midpregnancy were performed for prenatal diagnosis, including 59 procedures in 30 multiple pregnancies (29 twins and 1 triplet). The mean gestational age at the time of cordocentesis was 19.5 +/- 1.6 weeks. Success rate of the samplings was 98.3% with one sample was maternal blood contamination. Averaged-time used of the procedures was 8.2 minutes (range 1-45 minutes). The procedure-related complications included transient bleeding at puncture site (8.5%) and transient fetal bradycardia (22.0%). The total fetal loss rate was 10.5% but there was no cordocentesis-related fetal loss (0.0%), defined as a fetal loss within 2 weeks after the procedure.

CONCLUSION

This study may provide a new insight on the safety of cordocentesis in multifetal pregnancies at midpregnancy. The procedure-related fetal loss is not as high as reported in the past. This study suggests cordocentesis be a relatively safe and highly successful in obtaining fetal blood samples.

Antenatal noninvasive treatment of patients at risk for alloimmune thrombocytopenia without a history of intracranial hemorrhage

OBJECTIVE

The purpose of this study was to evaluate noninvasive management of alloimmune thrombocytopenia that included only the blind administration of immunoglobulin.

STUDY DESIGN

Seventeen women with 30 pregnancies that were at risk of neonatal alloimmune thrombocytopenia were included. Except for 6 cases, in which the women refused treatment, 24 pregnancies were managed by the weekly administration of intravenous immunoglobulin without monitoring platelet count.

RESULTS

The mean platelet count at birth after intravenous immunoglobulin treatment was 118,000/microL, compared with 25,000/microL among the 17 first affected infants and 24,000/microL among the 6 infants whose mothers refused treatment (P < .05). Only 8% of the treated fetuses had platelet counts of <30,000/microL at birth, compared with 70% of the untreated infants (P < .05). None of the treated and nontreated fetuses had an intracranial hemorrhage.

CONCLUSION

Noninvasive management of alloimmune thrombocytopenia that consists of only immunoglobulin administration is highly effective and seems safe in women without a history of fetal/neonatal intracranial hemorrhage.

Genetic counseling issues in urea cycle disorders

The goal of counseling families that have a urea cycle disorder (UCD) is to facilitate the process of scientific understanding, emotional acceptance, and decision-making in a nondirective way. A proper understanding of the genes involved, inheritance patterns, available testing, and complicating factors is critical to serving the families' needs. This article summarizes the needed information, in particular describing the complexities of prenatal testing and counseling issues for each UCD. Included case histories illustrate the genetic counseling process and the decision-making scenarios for two families.

European collaborative study of the antenatal management of feto-maternal alloimmune thrombocytopenia

The aims of this study were to determine whether the severity of fetomaternal alloimmune thrombocytopenia (FMAIT) in the current pregnancy could be predicted from the history of FMAIT in previous pregnancies, and to assess the effects of different types of antenatal intervention. Fifty-six fetuses were studied that all had a sibling affected by FMAIT due to human platelet antigen 1a (HPA-1a) alloimmunization. Cases with a sibling history of antenatal intracranial haemorrhage (ICH) or severe thrombocytopenia (platelet counts of < 20 x 109/l) had significantly lower pretreatment platelet counts than cases whose siblings had less severe thrombocytopenia or postnatal ICH. Maternal therapy resulted in a platelet count exceeding 50 x 109/l in 67% of cases. None of the fetuses managed by serial platelet intrauterine transfusions (IUT) suffered ICH following treatment. However, several serious complications arose with fetal blood sampling (FBS). Overall, intervention improved outcome, as three study cases suffered from antenatal ICH and three others died whereas 15 study cases had a sibling with an ICH, eight of whom died. The results of this study suggest that the start of therapy can be stratified on the basis of the sibling history of FMAIT, and support the use of maternal therapy as first-line treatment.

A classification of pregnancy losses after invasive prenatal diagnostic procedures: an approach to allow comparison of units with a different case mix

OBJECTIVE

Pregnancy loss rates after prenatal invasive procedures such as amniocentesis (Amnio), chorionic villous sampling (CVS) and fetal blood sampling (FBS) vary with an underlying indication for the procedure and due to different background risk of miscarriage. Loss rates need to be quantified and available for counselling. We developed a classification of pregnancy losses that will help in calculating procedure-related pregnancy loss rates and allow comparison between units with a different case mix.

METHODS

The procedure-related pregnancy loss rate was obtained by subtracting the losses in pregnancies with known lethal conditions and those occurring more than two weeks after the procedure from total pregnancy losses.

RESULTS

Out of 436 CVSs, there were 18 losses. Of these, 14 had a known lethal condition and 3 occurred after 2 weeks of CVS. In only one case, there was no known lethal abnormality and the loss occurred within 2 weeks. Thus, the total pregnancy loss rate was 4.1% and the procedure-related loss rate was 0.23% (95% CI; 0.0061-1.28). The procedure-related loss rates for Amnio 0.7% (95% CI; 0.2-1.8) and FBS 1.19 (95% CI; 0.14-4.23) were calculated in a similar way.

CONCLUSIONS

We present a method of recording pregnancy loss after prenatal invasive procedures, which would be useful for benchmarking comparison between units and pre-procedural counselling.

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.

A less invasive treatment strategy to prevent intracranial hemorrhage in fetal and neonatal alloimmune thrombocytopenia

OBJECTIVE

The purpose of this study was to evaluate whether a less invasive treatment strategy results in a higher platelet count of the neonate and prevents intracranial hemorrhage in pregnant women who are at risk for fetal or neonatal alloimmune thrombocytopenia.

STUDY DESIGN

Between March 1989 and August 2000, 48 women with 56 pregnancies were treated. The population was divided into groups. A diagnostic fetal blood sample was taken in 7 cases that had a history of a sibling with an intracranial hemorrhage (group I; n = 8); treatment was provided, when necessary, with platelet transfusions and maternal administration of immunoglobulin. The other 48 cases, with a history of a sibling with severe thrombocytopenia but without intracranial hemorrhage, were retrospectively divided into group IIa (n = 16) and IIb (n = 32). In group IIa, at least 2 diagnostic fetal blood samples were taken, and when necessary, intrauterine platelet transfusion and immunoglobulin were administered (invasive treatment). In group IIb, no initial diagnostic fetal blood sampling was performed (noninvasive treatment). In 23 cases, immunoglobulin was administered, which was followed by predelivery fetal blood sampling in 8 cases. In 9 cases, only predelivery fetal blood sampling was performed, when necessary, followed by intrauterine platelet transfusion.

RESULTS

Results of our noninvasive treatment strategy were comparable to results of the invasive method in the prevention of intracranial hemorrhage (intracranial hemorrhage was not observed). In addition, there was an increasing trend in median platelet count and a lower number of cases with severe thrombocytopenia (<50 x 10(9)/L) in the noninvasive compared with the invasive treatment group (median platelet count, 92 and 31 x 10(9)/L, respectively).

CONCLUSION

Our results indicate that a less invasive treatment strategy in patients who are at risk for fetal or neonatal alloimmune thrombocytopenia and who have no history of a previous child who was affected with intracranial hemorrhage seems justified.

The new obstetrics: its integration into neonatal clinical practise, teaching and research

Most neonatologists have not yet incorporated into their teaching, clinical service and research the advances in high risk obstetrics particularly as it relates to fetal surveillance. This brief review emphasizes some of the "new obstetrics" from the viewpoint of perinatal medicine, particularly in terms of neonatal teaching and the design of future neonatal research. The information that can be obtained about an infant prenatally by the use of ultrasound. power doppler, computerized fetal heart rate monitoring, cordocentesis, etc is extensive and yet, has rarely been utilized in the design of neonatal research protocols. It is becoming imperative that the "new obstetrics" be recognized and utilized in modern neonatal thinking if a truly "perinatal medicine" is to be practised.