The predictive value of maternal serum testing for detection of fetal anemia in red blood cell alloimmunization.

OBJECTIVE: Current management protocols for pregnancies complicated by red blood cell alloimmunization use the maternal antibody titer to predict the need for invasive testing for detection of fetal anemia. We investigated the use of three maternal serum tests to assess their usefulness in predicting fetal disease: indirect Coombs' titer, Marsh score, and monocyte monolayer assay. STUDY DESIGN: Forty-seven serum samples from pregnant women with red blood cell antibodies associated with fetal anemia were analyzed at cordocentesis. Fetal blood was analyzed for hematocrit (corrected for gestational age) and antigen status. Fetal anemia was defined as a hematocrit value of < 2 SD from the mean value for gestational age. Fetuses were classified into three groups: Antigen positive with anemia (n = 19), antigen positive without anemia (n = 17), antigen negative (n = 11). Statistical methods included Kruskal-Wallis test, Newman-Keuls test, Spearman's rank correlation, and receiver-operator characteristic curves; p < 0.05 was considered significant. RESULTS: The median monocyte monolayer assay (phagocytosis, adherence, and association) did not differ among the three groups. Both maternal titers and Marsh scores were significantly higher in fetuses with anemia compared with the other two groups of fetuses (256 vs 64 vs 64, p < 0.001, and 86 vs 69 vs 64, p = 0.02, respectively). Both titer and Marsh score exhibited significant correlations with corrected fetal hematocrit (r = -0.70, p < 0.001; r = -0.63, p < 0.001, respectively). Comparison of the overall receiver-operator characteristic curves for titer and Marsh score revealed no statistical difference; however, a Marsh score of 57 was noted to have a superior specificity than a titer of 16 (p = 0.02). CONCLUSION: The maternal Marsh score can be performed in conjunction with standard indirect Coombs' titers to enhance the predictability of fetal anemia.

Erythropoietin in human fetuses with immune hemolytic anemia and hydrops fetalis.

OBJECTIVE: To determine whether plasma erythropoietin is increased in fetuses with anemia due to Rh isoimmunization. METHODS: Hemoglobin and erythropoietin were measured in samples obtained by funipuncture from 15 fetuses with Rh isoimmunization (gestational age 26.2 +/- 5.0 weeks, mean +/- standard deviation) and from 13 control fetuses (23.1 +/- 6.7 weeks). Hemoglobin and erythropoietin also were determined in umbilical cord blood collected at birth from 20 term fetuses delivered by elective cesarean. RESULTS: Fetuses with Rh isoimmunization had lower hemoglobin and higher plasma erythropoietin measurements than mid-gestation controls (6.1 +/- 3.9 versus 10.7 +/- 1.5 g/dL and 105.5 +/- 168.1 versus 12.5 +/- 3.1 mU/mL, P < .05, respectively). Hemoglobin and plasma erythropoietin increased with gestational age in control fetuses. There was an inverse association between hemoglobin and plasma erythropoietin in control and Rh-isoimmunized fetuses (r = -0.56, P < .005). Using multiple linear regression, hemoglobin and gestational age were associated independently with plasma erythropoietin (overall F2,25 = 12.3, multiple r2 = 0.49, P < .001). Despite marked decreases in hemoglobin, fetuses below 24 weeks' gestation had minimal increases in plasma erythropoietin compared to fetuses above that gestational age. Mildly anemic Rh-isoimmunized fetuses (hemoglobin 11.6 +/- 2.0 g/dL) delivered vaginally had significantly higher erythropoietin levels in umbilical cord plasma than Rh-isoimmunized fetuses with comparable hemoglobin (10.9 +/- 3.5 g/dL) delivered by elective cesarean without labor (1246 +/- 856 versus 106 +/- 66 mU/mL, respectively, P < .05). CONCLUSION: Fetuses with anemia at mid to late gestation respond with increases in plasma erythropoietin, but these changes are substantially attenuated before 24 weeks' gestation.

In utero diagnosis and management of fetal subdural hematoma.

The in utero ultrasonographic diagnosis of a fetal subdural hematoma is presented. The value of percutaneous umbilical blood sampling, transvaginal ultrasonography, and magnetic resonance imaging for diagnosis and management is discussed.

Isolated fetal ascites: prenatal diagnosis and management.

The perinatal outcomes of four patients with isolated fetal ascites were evaluated. The ascites disappeared prior to delivery in 50% of the cases and was resolved shortly after delivery in the remainder. Excellent neonatal outcomes were observed. Thus, isolated fetal ascites may represent a separate condition that significantly differs from the general category of nonimmune hydrops in both perinatal courses and prognoses. The prenatal diagnosis and management of this condition are discussed.

Atrial natriuretic factor in hydrops fetalis caused by Rh isoimmunisation.

Plasma concentrations of atrial natriuretic factor were determined by radioimmunoassay in 16 human fetuses of between 19 and 38 weeks' gestation. Fifteen fetuses had varying degrees of anaemia as a result of Rh isoimmunisation, and one fetus was normal. Eight fetuses had ultrasonographic evidence of severe hydrops fetalis and an additional three fetuses had mild hydrops. Severely hydropic fetuses were more anaemic and immature than those with mild or no hydrops. Among fetuses from which samples were taken before in utero transfusion, concentrations of atrial natriuretic factor were higher in those with severe hydrops than in the other groups. An inverse relationship between the haemoglobin concentration and that of atrial natriuretic factor was found. In four fetuses in which severe hydrops resolved after intravascular transfusions in utero, there were significant decreases in plasma atrial natriuretic factor concentrations; in the fifth fetus the decrease was less pronounced. Raised concentrations of atrial natriuretic factor in fetuses with severe anaemia and hydrops may be the result of atrial natriuretic factor release induced by hypoxia.

Invasive fetal assessment in the antepartum period.

Access to the fetus as a true patient is a recent development in maternal-fetal medicine. We review the major invasive techniques currently available for establishing diagnoses and providing treatments to the fetus. These include fetoscopy, fetal blood sampling, fetal transfusions, and fetal shunts. Indications, techniques, and complications are discussed.

Invasive fetal procedures.

The development of the subspecialty of maternal-fetal medicine has been hampered by the inability to gain direct access to the fetus. With the development and improvement of high-resolution real-time ultrasound, access to the fetus and its intravascular compartment has become a reality. This article presents a description of the invasive procedures used in the prenatal diagnosis and treatment of fetal medical and surgical conditions.

Pulsed Doppler flow-velocity waveforms in the prediction of fetal hematocrit of the severely isoimmunized pregnancy.

We previously reported a significant relationship between the hematocrit levels of anemic fetuses and information derived from ultrasonographic and Doppler flow-velocity waveforms. In this study we prospectively tested two formulas for the prediction of hematocrit values, by use of gestational age, presence or absence of hydrops, and Doppler indices. Although one of the two formulas predicted hematocrit values significantly, the only component of the formula that made a significant contribution was fetal hydrops. We conclude that currently available fetal Doppler measurements are unable to be applied in the prospective prediction of hematocrit values in anemic fetuses of isoimmunized pregnancies.

Fetal cardiac output in the isoimmunized pregnancy: a pulsed Doppler-echocardiographic study of patients undergoing intravascular intrauterine transfusion.

The mechanism of development of hydrops fetalis in severe isoimmunization has been subject to speculation. We performed pulsed Doppler assessment of cardiac output in 13 severely isoimmunized fetuses before and after intravascular transfusion and compared the results with 37 control fetuses between 20 and 34 weeks' gestation. The cardiac index of the anemic fetuses was significantly greater than that of the control group. A significant (right ventricle, p less than 0.01; left ventricle, p less than 0.02) increase in indexed output was noted from both ventricles and in the combined ventricular output (mean +/- SEM 644 +/- 35.3 ml/kg/min in control fetuses versus 879 +/- 86.0 ml/kg/min in anemic fetuses, p less than 0.006). An increase in cardiac output was also noted when anemic fetuses were compared with gestational age-specific norms. We conclude that severely anemic fetuses of isoimmunized pregnancies tend to have significantly higher cardiac output than do unaffected fetuses and that this high output state may play a part in the development of hydrops fetalis.

A new funipuncture technique: two-needle ultrasound- and needle biopsy-guided procedure.

A new technique is presented for funipuncture under ultrasound guidance using a biopsy guide and a 20/25-gauge needle combination. The 20-gauge needle was used for uterine entry and the 25-gauge needle for the actual cord puncture. The method was used for sampling fetal blood in 262 pregnancies with 264 fetuses (two sets of twins) between 17-39 weeks, at risk for beta-thalassemia, chromosomal disorders, TORCH infection, fetal hypoxia, and Rh-isoimmunization. Pure fetal blood was aspirated from 241 fetuses (91.3%), including the twins. The procedure lasted less than 5 minutes in 76.5% of the cases and less than 10 minutes in 90.1% of the cases. Intra-amniotic bleeding was seen in only 23.1% of the cases, and fetal bradycardia was not noted. Forty-four pregnancies were terminated after the diagnosis of genetic or infectious disease. Seven fetuses at risk for Rh-isoimmunization, found to be Rh-positive and anemic, were transfused immediately after blood sampling using the same needle. Of the 220 continuing pregnancies, there were 14 fetal losses (three before 28 weeks and 11 after 28 weeks or during the perinatal period). A probable etiology for the loss was found in 11 cases. These included one severely Rh-isoimmunized hydropic fetus who died in utero after transfusion at 26 weeks, one fetus who died in utero at 31 weeks following a car accident, and nine malformed newborns. The corrected rate for fetal losses probably related to the procedure was thus 0.9% before 28 weeks and 0.8% after 28 weeks. This new funipuncture technique seems to have several advantages over the freehand and/or biopsy-guided single-needle techniques.

The use of percutaneous umbilical blood sampling in immune thrombocytopenic purpura.

Maternal immune thrombocytopenic purpura has been associated with profound fetal and neonatal thrombocytopenia. Percutaneous umbilical blood sampling offers a reliable method of determining the fetal platelet count antenatally and optimizing obstetric management. We present our experience with this technique in 19 gestations.

Diagnostic fetal umbilical blood sampling in the management of isoimmunization.

Current management of isoimmunization in pregnancy is predicted on the assumption that all sensitized women carry antigen-positive fetuses. In addition, management is based on indirect predictors of the magnitude of the fetal hemolytic disease. We present a preliminary report using a new approach of direct fetal blood sampling for the diagnosis and treatment of these patients. This form of evaluation provides specific information about fetal red blood cell antigen status and the degree of fetal anemia at an earlier gestational age than that validated by the Liley curves and eliminates empiricism from both the diagnosis and treatment of the isoimmunized pregnancy. The use of such a management protocol reduces the need for multiple invasive procedures in fetuses at little risk for disease and provides specific information about the status of those fetuses truly at risk.

Prevention of Rh isoimmunization and treatment of the compromised fetus.

Intrauterine intravascular transfusion for the treatment of severe erythroblastosis fetalis has resulted in a number of benefits: (a) Direct access to the fetal vasculature allows an accurate assessment and prompt correction of anemia, albeit temporary. In contrast, intraperitoneally transfused blood may be absorbed erratically, especially in the face of ascites. (b) Intravascular treatments can be performed, in general, as early as 17 weeks of gestation, earlier than intraperitoneal approaches permit. (c) Reversal of hydrops along with the correction of anemia and hypoproteinemia has significantly reduced neonatal morbidity and mortality. None of the surviving neonates in our series required either thoracentesis or paracentesis following delivery, and 40% did not require neonatal exchange transfusion. (d) Treatments may be safely performed until pulmonic maturity has been established and/or an EFW of greater than 2,000 g has been reached, reducing problems of prematurity. (e) Central vein and umbilical vein hypertension may be arrested or prevented, thereby allowing fetal liver function to return to normal. While isoimmunization stands as a disease that has been quite successfully reduced in frequency and severity by the careful attention and treatment by obstetricians, cases still occur. Due to the reduced frequency of severe disease, fewer physicians are trained and experienced in performing this difficult procedure. As fewer transfusions are required, the value of regionalized treatment centers will have to be considered carefully, in order to maximize the experience and efficiency of the intravascular intrauterine transfusion treatment teams.

The reversal of hydrops fetalis by intravascular intrauterine transfusion in severe isoimmune fetal anemia.

Seventy-two intrauterine intravascular transfusions were performed on 26 patients with severe erythroblastosis fetalis. Twenty of the 26 fetuses were hydropic at the time of referral. Of the 20 hydropic fetuses, 16 (80%) survived. Hydrops was completely reversed in 13 of the 16 fetuses (81%). Total protein of less than 3 gm/dl, albumin less than 2 gm/dl, and a hematocrit level of less than 15% were associated with hydrops fetalis. After hydrops was reversed, total protein greater than 3 gm/dl, albumin greater than 2 gm/dl, along with a sustained hematocrit level of greater than 15%, were found. Only three neonates were born with minimal ascites, two of whom had had intraperitoneal transfusions before intravascular treatments. There were 21 survivors of the total group, giving an overall survival rate of 82%. There was one neonatal death from severe respiratory distress syndrome. Thirty-eight percent of the neonates did not require exchange transfusions in the newborn period. Intrauterine intravascular transfusions appear to be an effective mode of therapy in severe erythroblastosis fetalis and not only increase survival rates but also decrease neonatal morbidity and mortality.

Pulsed Doppler flow-velocity waveforms before and after intrauterine intravascular transfusion for severe erythroblastosis fetalis.

Pulsed Doppler studies of the fetal and maternal circulations were carried out before and after 64 intrauterine transfusions performed on 24 fetuses. A model was derived for the prediction of hematocrit before the first transfusion: Hematocrit = 7.778 - (0.088 x peak velocity in descending aorta) + (0.968 x gestational age [weeks]) - (10.911 if hydrops present) (r = 0.876, p less than 0.0001). An alternative formula, excluding hydrops, was slightly less predictive: Hematocrit = 45.312 - (56.261 x umbilical cord Pourcelot index) - (0.128 x peak velocity in descending aorta) + (1.042 x gestational age) r = 0.822, p less than 0.001). Neither model was accurate in the prediction of hematocrit before second or subsequent transfusions. A third model was derived from second-transfusion data: Hematocrit = 40.524 - (0.045 x peak velocity in descending aorta) - (10.693 x pulsatility index of maternal uterine artery) (r = 0.81, p less than 0.003). However, this model was unable to predict hematocrit before third or later transfusions. No changes in Doppler parameters before and after transfusion were found. We conclude that pulsed Doppler ultrasound may be helpful in the evaluation of isoimmunized pregnancies, in differentiating anemic from normal fetuses. It does not appear to be useful in determining the timing of later transfusions. The lack of change before and after transfusions suggests that these vessels will not provide significant information concerning the effect of rapid volume and hematocrit changes in the fetus.

The use of intravenous pancuronium bromide to produce fetal paralysis during intravascular transfusion.

Intravascular fetal transfusion can be complicated by difficulty in maintaining vascular access because of fetal movements. Treatment by intramuscular pancuronium bromide has been proposed as a means of arresting fetal movements, although this treatment requires a separate puncture for injection. We report in this article our experience with intravenous fetal injection of pancuronium bromide to produce muscular paralysis during fetal transfusion.