Serial Amniocenteses Research Articles

RAPID MOLECULAR DETERMINATION OF FETAL RHESUS E TYPE

The successful prophylaxis of RhD disease has brought attention to other Rh antigens, such as RhE antigen, that can cause hydrops fetalis. Our purpose was to develop simple molecular techniques to permit fetal RhE genotyping. We obtained amniotic fluid, villi, and fetal blood from two RhE-sensitized pregnancies, performed the Polymerase Chain Reaction (PCR), and made a presumptive fetal genotype diagnosis. The restriction enzyme MnlI was used to determine the E/e subtypes. DNA sequencing was used to demonstrate base-pair differences between the mother and fetus in one case. Conventional serology was used to confirm the fetal blood type. Maternal, paternal, and fetal genotypes were identified using molecular techniques. The presence of the fetal E allele was correctly predicted in both cases. Sequencing of maternal and fetal PCR products in one case demonstrated one base-pair substitution associated with the E/e polymorphism. Prenatal diagnosis of the fetal RhE genotype is now possible by PCR. The use of amniocytes obtained in one procedure of amniocentesis for RhE genotyping in sensitized pregnancies is less invasive than currently accepted techniques of cordocentesis, or serial amniocenteses done for ΔOD450 measurement.

Modern management of rhesus disease

The cloning of the RhDCcEe complex has made it likely that the polymerase chain reaction will be incorporated into the modern management of rhesus sensitization. Currently, the accuracy of this technique is under evaluation. Its specific role in management protocols is not yet clear. The use of this technology will hopefully avoid the need for cordocentesis or serial amniocenteses in some patients.

Amniotic fluid pressure in twin-to-twin transfusion syndrome: an objective prognostic factor.

Severe twin-to-twin transfusion syndrome presenting before 28 weeks' gestation is associated with a high neonatal mortality and morbidity due to polyhydramnios-related very premature delivery or intrauterine death of one or both twins. Management options include serial amniodrainages or laser coagulation of the intertwin placental anastomoses; however, early antenatal prognostic factors are lacking. Serial amniocenteses were performed in 9 pregnancies with twin-to-twin transfusion syndrome presenting with second-trimester polyhydramnios, and serial measurements of amniotic fluid pressure were made. Although in 8 cases the pre-drainage pressure was above the 95th centile of the normal range for singleton pregnancies, the pressures were lower in the pregnancies resulting in two livebirths than in the cases where one or both babies died. This study suggests that patients presenting with intraamniotic pressure > 17 mm Hg cannot be safely managed by serial amniodrainages.

OCCASIONAL REVIEW: Twin‐Twin Transfusion Syndrome: Intraamniotic Pressure Measurement in the Assessment of Volume Reduction at Serial Amniocenteses

EDITORIAL COMMENT: We accepted this paper for publication because we consider it contains important information on management of patients with acute polyhydramnios. However the editorial committee considers that there is still doubt regarding how commonly fetofetal transfusion is the aetiological mechanism of the acute polyhydramnios syndrome seen in uniovular twins. We have reviewed the clinical data of the 13 cases reported by Steinberg and colleagues(A) with a particular emphasis on the haemoglobin discrepancies between the twins and whether or not the polyhydramnios was associated with the recipient twin. The findings were that there were only 4 cases where there were haemoglobin measurements performed on both twins; in only 2 of the 4 was the difference more than 4 g/dL and in both cases the smaller twin had a higher haemoglobin value. In 1 of the cases the haemoglobin values of the twins were 5.5 and 9.8 g/dL respectively and the smaller twin had the higher haemoglobin value; there was polyhydramnios in both sacs. In the other case where there was a haemoglobin discrepancy of more than 4 g/dL the smaller twin had the higher haemoglobin (20.7 g/dL) and the larger twin had a haemoglobin value of 16.6 g/dL and only this larger twin had a polyhydramniotic sac. It seems to us that the mechanism of acute polyhydramnios may not be the same in all cases and it is not proven that fetofetal haemorrhage is a convincing explanation for all cases. One of the problems in elucidating the problem is that these patients are often incompletely documented because of stillbirth or uncertainty as to whether the small or large twin occupied the polyhydramniotic sac. Summary: Two cases of severe twin‐twin transfusion syndrome are described. In both, serial amniocenteses were followed by resolution of the disordered inter‐twin haemodynamics with 4 intact term survivors. In all reports to date of aggressive reduction with or without successful outcome, volume reduction has been dictated by subjective or semiquantitative ultrasonic estimates of liquor volume. With the use of intraamniotic pressure estimation we describe a more rational basis for the removal of these large volumes of amniotic fluid.

The use of polymerase chain reaction to determine fetal RhD status

Objective: Our purpose was (1) to establish the accuracy of a deoxyribonucleic acid amplification method in determination of RhD status in adult blood samples, including weak D variants (previously referred to as Du) and a D mosaic, and (2) to apply the method to determine fetal RhD status in alloimmunized pregnancies.Study Design: Twenty-five adult blood samples, including five weak D variants and one D mosaic, were analyzed with a polymerase chain reaction to determine RhD type. The method was then applied to amniotic fluid samples obtained by amniocentesis from three RhD-negative women with known RhD sensitization.Results: RhD type determined by polymerase chain reaction for all adult blood samples agreed with serologic typing results. All weak D variants and the D mosaic gave results consistent with RhD positivity. Fetal RhD status was determined in each of the three alloimmunized pregnancies, and obstetric management decisions were made on the basis of these results.Conclusions: This polymerase chain reaction method allows rapid and accurate determinations of fetal RhD status by amniocentesis. Fetal blood sampling or serial amniocenteses may be avoided when the fetus is RhD negative, and plans for surveillance and intervention can be confidently made if the fetus is RhD positive. However, before the widespread use of this assay, its sensitivity and specificity must be established. Because weak D variants and a D mosaic demonstrated RhD-positive status by polymerase chain reaction, the method described is applicable to these RhD variants.

Prenatal determination of fetal RhD type by DNA amplification

Background An RhD-negative woman whose partner is heterozygous may have preexisting anti-RhD antibodies that may or may not affect a subsequent fetus, depending on whether it is heterozygous. A safe method of determining fetal RhD type early in pregnancy would eliminate the risks to an RhD-negative fetus of fetal-blood sampling or serial amniocenteses. Methods We determined the RhD type in 15 fetuses using the polymerase chain reaction in amniotic cells and serologic methods in fetal blood collected simultaneously. In another 15 fetuses, the RhD type determined from chorionic-villus samples was compared with that identified by typing of DNA from the fetus itself. Results RhD typing of DNA from amniotic cells correctly indicated the serologic type in every fetus. Of 10 fetuses with RhD-negative mothers, 4 were identified as RhD-negative and 6 as RhD-positive. Of five fetuses with RhD-positive mothers, four were identified as RhD-positive and one as RhD-negative. There was also complete agreement between th...

Stuck twin syndrome: Outcome in thirty-seven consecutive cases

Our purpose was to further evaluate the role of serial amniocentesis in pregnancies complicated by the "stuck twin" syndrome. A cohort of 37 consecutive cases of stuck twin syndrome was followed up from 1986 through 1992. Evaluations included gestational age at diagnosis and at delivery, mean number of amniocenteses, volume of amniotic fluid withdrawn, placentation, perinatal complications, fetal survival, and neonatal follow-up. Five pregnancies were terminated, five had no intervention, and 27 underwent serial amniocenteses. The mean number of amniocenteses was 3.4 (range 1 to 6), and mean total amniotic fluid volume withdrawn was 5.8 L (range 0.75 to 4.0). In the serial amniocentesis group mean gestational age was 23.1 weeks (range 16 to 30) at diagnosis and 31.5 weeks (range 20 to 38) at delivery. Eighty-two percent had monochorionic placentas, and 36% had marginal or velamentous cord insertions. Infant survival was 39 of 54 (74%) in the serial amniocentesis group compared with four of 10 (40%) in the nonintervention group (relative risk 0.46, 95% confidence interval 0.24 to 0.90). Serial amniocentesis was associated with a 54% reduction in fetal and neonatal death in cases of stuck twin syndrome.

Prenatal determination of fetal RhD type by DNA amplification.

An RhD-negative woman whose partner is heterozygous may have preexisting anti-RhD antibodies that may or may not affect a subsequent fetus, depending on whether it is heterozygous. A safe method of determining fetal RhD type early in pregnancy would eliminate the risks to an RhD-negative fetus of fetal-blood sampling or serial amniocenteses. We determined the RhD type in 15 fetuses using the polymerase chain reaction in amniotic cells and serologic methods in fetal blood collected simultaneously. In another 15 fetuses, the RhD type determined from chorionic-villus samples was compared with that identified by typing of DNA from the fetus itself. RhD typing of DNA from amniotic cells correctly indicated the serologic type in every fetus. Of 10 fetuses with RhD-negative mothers, 4 were identified as RhD-negative and 6 as RhD-positive. Of five fetuses with RhD-positive mothers, four were identified as RhD-positive and one as RhD-negative. There was also complete agreement between the results of RhD typing of DNA from chorionic-villus samples and the results of typing of DNA from fetal tissue. Eleven fetuses were RhD-positive, and 4 were RhD-negative. Four RhD-positive fetuses had RhD-negative mothers. Three RhD-negative fetuses had RhD-positive mothers. There was no contamination by maternal RhD-positive DNA of the samples from RhD-negative fetuses. Determining fetal RhD type in amniotic cells without invading the fetomaternal circulation is a reliable method that will be valuable in the management of Rh alloimmunization.

The significance of recurrent polyhydramnios.

A study of 30 women who had polyhydramnios in more than 1 pregnancy revealed that 8 of the 36 resultant pregnancies (22.2%) were associated with diabetes mellitus, 14 (37.8%) with fetal macrosomia, and the perinatal mortality was 16.2% (6 of 37). The incidence of major fetal malformations or abnormalities was 18.9% (7 of 37); 4 of the 6 deaths resulted from malformations (anencephalus (2), hydrocephalus (1), nonimmune hydrops (1)), and the other 2 deaths were from hyaline membrane disease associated with prematurity. Recurrent polyhydramnios occurred in 1 in 1,720 pregnancies. The onset was acute in 3, subacute in 2 and chronic in 31, the perinatal deaths in these categories being 2, 1 and 3 respectively. The risk of recurrent polyhydramnios is the risk of fetal malformation and premature delivery. The latter may be preventable by prompt therapy with indomethacin, and serial amniocentesis if this therapy fails.

The Stuck Twin Phenomenon: Experience with Serial Therapeutic Amniocentesis

Expectant management of the “stuck” twin phenomenon is usually associated with a dismal prognosis for both fetuses. Improved outcomes have been reported following serial amniocentesis of the sac of the co-twin. We therefore reviewed our experience with this therapy. Six consecutive sets of affected twins were managed over a 3-year period. Six of 12 (50%) fetuses survived the neonatal period, five of whom (42%) exhibited no long-term sequelae. Hydrops resolved completely in one and partially in two of the six co-twins. All co-twins and two of six “stuck” twins had karyotypes performed which were all normal. Other diagnostic evaluations ruled out fetal infection, fetomaternal hemorrhage, and blood group incompatibility. Autopsies were performed in all cases of stillbirth and neonatal death, revealing no anomalies. This suggested an extreme form of twin-twin transfusion as the etiology of the phenomenon in these cases. Our observations agree with those of others in supporting serial amniocentesis in the mana...

The ‘stuck twin’ phenomenon: Ultrasonographic findings, pregnancy outcome, and management with serial amniocenteses

Thirteen consecutive pregnancies affected by the twin phenomenon were reviewed to determine the potential benefit of serial amniocenteses. The fetal survival rate for the eight pregnancies that underwent serial amniocenteses was 69% (11 of 16 fetuses). This is significantly improved compared with a fetal survival rate of 20% among the five preceding pregnancies managed without serial amniocenteses at the same institution (p = 0.01). It is also markedly improved compared with a combined fetal survival rate of 16% among 48 previously reported pregnancies with the stuck phenomenon managed without serial amniocenteses (p < 0.0001). Survival correlated with the absence of concomitant pregnancy complications (Le., maternal hypertension or intractable labor) and with the absence of severe fetal structural abnormalities. Procedural complications occurred in three of eight pregnancies (37.5%) managed with serial amniocenteses and was attributed as a cause of fetal death in one case. Two of 11 survivors (18%) had complications after serial amniocenteses including brain infarction and renal tubular necrosis. Serial amniocenteses may significantly improve the survival rate of gestations affected by the stuck phenomenon but may be associated with complications among survivors. (AM J OBSTET GVNECOL 1990;163:1513-22.)

The “stuck twin” phenomenon: Ultrasonographic findings, pregnancy outcome, and management with serial amniocenteses

Thirteen consecutive twin pregnancies affected by the “stuck twin” phenomenon were reviewed to determine the potential benefit of serial amniocenteses. The fetal survival rate for the eight pregnancies that underwent serial amniocenteses was 69% (11 of 16 fetuses). This is significantly improved compared with a fetal survival rate of 20% among the five preceding pregnancies managed without serial amniocenteses at the same institution (p = 0.01). It is also markedly improved compared with a combined fetal survival rate of 16% among 48 previously reported pregnancies with the stuck twin phenomenon managed without serial amniocenteses (p<0.0001). Survival correlated with the absence of concomitant pregnancy complications (i.e., maternal hypertension or intractable labor) and with the absence of severe fetal structural abnormalities. Procedural complications occurred in three of eight pregnancies (37.5%) managed with serial amniocenteses and was attributed as a cause of fetal death in one case. Two of 11 survivors (18%) had complications after serial amniocenteses including brain infarction and renal tubular necrosis. Serial amniocenteses may significantly improve the survival rate of twin gestations affected by the stuck twin phenomenon but may be associated with complications among survivors. (Am J Obstet Gynecol 1990;163:1513-22.)

Ultrasonography versus amniotic fluid spectral analysis: Are they sensitive enough to predict neonatal complications associated with isoimmunization?

The modern management of pregnancy complicated by erythroblastosis fetalis is based on serial amniocenteses followed by either intrauterine transfusions or early delivery of affected infants, depending on the gestational age. A retrospective study was undertaken involving 92 isoimmunized pregnancies in which ultrasonography and amniotic fluid analyses were used to assess the relative predictive values for neonatal complications. Our data demonstrated that ultrasonography and optical density analyses were comparable in the evaluation of the isoimmunized pregnancy. The combined information from both these modalities did not increase the predictive value over that observed with either one alone. Both instruments were found to have high negative predictive values. However, neither method, used singly or in combination, was highly predictive of neonatal complications. In light of the low positive predictive values, caution should be exercised in using the results of amniotic fluid spectral analyses and/or ultrasound examinations for predicting perinatal complications.

Midtrimester amniotic fluid delta optical density at 450 nm in normal pregnancies

Spectrophotometric analysis of amniotic fluid has become the standard for assessing the fetal condition in Rh-immunized pregnancies. Serial amniocentesis is usually started at 28 to 29 weeks of gestation unless the antibody titer or history indicates it should be done earlier. This study presents the values from 14 to 20 weeks in normal pregnancies, which will also assist in evaluating pathologically elevated values.

Severe erythroblastosis fetalis secondary to anti-Kpb sensitization

As a consequence of the reduced occurrence of maternal sensitization to Rh antigens, the relative clinical importance of irregular red blood cell antigen sensitization has increased. While such sensitization is reported to account for 5% of all neonatal immune hemolytic disease, most information concerning the more than 40 antigens that can cause hemolytic disease has been derived from sporadic case reports.’ Recommendations so based are subject to error and require updating when new information is obtained. Sensitization to members of the subgroups of the Kell (K) antigen (Kp”, Kpb, Js”, Jsb) has been reported to occur only occasionally and to result in mild hemolytic disease. Expectant management without serial amniocentesis has been suggested.’ This report details the occurrence of severe erythroblastosis fetalis resulting from anti-Kpb sensitization.

Changes in amniotic fluid optical density at 450 mμ in Rh-sensitized patients after maternal hydrocortisone treatment

In anticipation of elective premature delivery (32 to 34 weeks of gestation), five Rh-sensitized pregnant women were given hydrocortisone succinate for enhancement of fetal lung maturation. Serial amniocenteses were performed and an abrupt drop in the optical density at 450 mμ (OD450) was observed in all cases immediately after administration of the steroid. Two infants in whom the OD450 remained low were followed safely to term. The others were delivered prematurely. All infants were Rh-sensitized and required one or more exchange transfusions, and all survived. It is tempting to speculate that glucocorticoids alter the antigen-antibody affinity and inhibit splenic macrophage sequestration, thus reducing erythrocyte destruction. Maternal steroid administration may prove to be therapeutic in the management of Rh-sensitization, but until its mechanisms are further delineated, extreme caution must be used in the interpretation of OD450 changes.

The lecithin/sphingomyelin ratio in Macaca arctoides.

The amniotic fluid lecithin/sphingomyelin ratio (L/S ratio) of stumptail macaque monkeys (Macaca arctoides) was investigated by means of serial amniocenteses during the second half of pregnancy. Ten dated pregnancies were studied in 9 individual monkeys. The mean number of successful amniocenteses per pregnancy was 4. A rapid increase in the L/S ratio suggesting maturation of lung surfactant synthesis occurred as early as 130--140 days of pregnancy in some animals, and as late as 150--160 days in others. The earliest and latest times at which the L/S ratio first exceeded 2.0 were 135 and 164 days, respectively. These observations indicate that the L/S ratio of M. arctoides follows a course similar to that observed in human pregnancy, with a rise at 0.7--0.8 of term gestation. M. arctoides thus appears to be a useful model for the study of factors affecting fetal lung maturity, on the basis of the amniotic fluid L/S ratio. In particular, a rapid rise in L/S ratio before 130 days of pregnancy would be highly suggestive of accelerated maturation of pulmonary surfactant production.

Transferrin concentration in human amniotic fluid

The concentration of transferrin in human amniotic fluid was measured by single radial immunodiffusion. In the 52 amniotic fluid samples studied, the mean transferrin concentration was 29.9 mg. per 100 ml. and was not observed to vary greatly during gestation. Significant differences occurred between the mean values of gestational age groups with respect to early and late third trimester. In nine patients on whom serial amniocenteses were performed, six patients showed increasing concentrations of transferrin as gestation progressed, although these increases were relatively small. The values observed in this study represent the largest group of amniotic fluids studied with respect to transferrin concentration and are comparable to those of a previously reported study.