Clinical management of twin reversed arterial perfusion cases: insights into a complex and challenging twinning.

Twin reversed arterial perfusion (TRAP) sequence occurs in approximately 1% of monozygotic pregnancies. The proposed pathogenesis is the association of paired artery-to-artery and vein-to-vein anastomoses through the placenta combined with delayed cardiac function of one of the embryos early in pregnancy. Presently the most commonly used technique for TRAP sequence is intrauterine radiofrequency ablation (RFA) of the cord of the recipient twin. This report shares the authors' experience in managing similar cases, the rationale leading to clinical decisions, the timing of the RFA procedure, the potential complications associated with TRAP, and the out-come of these two cases.

The amniotic fluid index in normal twin pregnancies.

OBJECTIVE: We sought to investigate the amniotic fluid index for individual gestational sacs of twin pregnancies. STUDY DESIGN: Four hundred eighty-eight patients with normal diamniotic twins were examined between 14 and 40 weeks' gestation. The dividing membrane between twin fetuses was identified. An amniotic fluid index was then obtained for each gestational sac. RESULTS: The median amniotic fluid index in individual twin gestational sacs rises slowly from 14 to 16 weeks' gestation to 23 to 28 weeks' gestation and then gradually declines. The median amniotic fluid index values by gestational age for twin A and twin B are not statistically different. Although twin pregnancies have a slightly lower median amniotic fluid index value than singleton pregnancies, the difference is also not statistically significant. CONCLUSION: Individual amniotic fluid indices can be obtained in twin pregnancies, and the values are comparable with those of singleton gestations.

The severity of polyhydramnios, estimated fetal weight and preterm delivery are independent risk factors for the presence of congenital malformations.

OBJECTIVE: To evaluate maternal and fetal factors associated with congenital malformations in patients with polyhydramnios. STUDY DESIGN: The study group consisted of 275 singleton pregnancies with an amniotic fluid index (AFI) >25.0 cm. An equal number of controls were matched for maternal age, gravidity, parity and gestational age. The proportion of cases and controls with malformations was compared. Polyhydramnios cases were categorized into three groups by severity: mild (AFI 25-30 cm), moderate (AFI: 30.1-35.0 cm) and severe (AFI >35.1 cm). Among cases, logistic regression analysis was utilized to estimate the risk for fetal congenital malformations in relation to severity of polyhydramnios, estimated fetal weight, maternal diabetic status and gestational age at delivery. RESULTS: Congenital malformations were detected in 40 of 275 cases (14.5%) with polyhydramnios and in 9 cases (3.3%) of the control group (p < 0.01). The relative risks of congenital malformations increased with the severity of polyhydramnios: 3.2 (95% CI 1.5-6.8), 5.7 (95% CI 2. 4-13.3) and 13.1 (95% CI 5.8-29.5) for mild, moderate and severe polyhydramnios, respectively. Congenital malformations among polyhydramnios cases were present in 54.5% of small-for-gestational age fetuses, in contrast to 12.7% for average-for-gestational age fetuses and 10.8% for large-for-gestational age fetuses (p < 0.001). Maternal diabetic status did not significantly affect the fetal anomaly rate once polyhydramnios was detected. Premature newborns in the polyhydramnios group had a higher malformation rate (24%) than did term newborns (11.3%) (p < 0.02). In the study group, multiple logistic analysis confirmed the significance of severe polyhydramnios, small-for-gestational age status and preterm delivery as independent contributors to the malformation risk. CONCLUSIONS: Polyhydramnios (AFI >35 cm), small-for-gestational age fetus and preterm delivery are independent risk factors for congenital malformations.

Insights into the pathogenesis and natural history of fetuses with multicystic dysplastic kidney disease.

To better delineate the natural history of multicystic displastic kidney disease (MCDKD) and provide insights into the pathogenesis of this condition, we report our experience in 102 prenatally detected cases. MCDKD is most commonly an incidental finding on prenatal ultrasound examination. The abnormality may be unilateral (76 per cent) or bilateral (24 per cent). In unilateral cases, abnormality of the contralateral kidney is common (33 per cent). Associated non-renal abnormalities occur frequently with both unilateral (26 per cent) and bilateral (67 per cent) MCDKD, and increase the risk for an abnormal chromosome study. Males are more likely to be affected than females with a ratio of 2.4:1, but females are twice as likely to have bilateral MCDKD and associated non-renal abnormalities, and four times more likely to have an abnormal chromosome study. We suggest that the option of chromosomal analysis should be discussed with all patients diagnosed with MCDKD in their fetus, if there is bilateral renal involvement or if an associated non-renal abnormality is present. Unilateral MCDKD without associated renal or non-renal abnormalities was not associated with an abnormal chromosome study, and resulted in favourable outcomes. While unilateral MCDKD, lack of associated anomalies, normal chromosome study and adequate amniotic fluid are all reassuring findings, a complete neonatal urologic work-up should be performed in all newborns. We believe the evaluation should include voiding cystourethrography to rule out vesicoureteral reflux. Our findings allow more precise counselling of patients regarding prognosis, and subsequent management of the fetus found to have MCDKD.

The floating harbor syndrome with cardiac septal defect.

The Floating Harbor syndrome of short stature, very delayed bone age, expressive language delay, and characteristic facial changes has not been associated with cardiac anomalies, except for one patient with pulmonic stenosis. We report on a 10-year-old boy with the syndrome and tetralogy of Fallot with atrial septal defect.

Vibroacoustic stimulation enhances visualization of the four-chamber cardiac view in the third trimester.

The objective of this study was to determine whether vibroacoustic stimulation would improve the visualization rate of the four-chamber cardiac view. Patients between 26 and 42 weeks' gestation were considered to be candidates for this study if the amniotic fluid index (AFI) was between 8.0 and 24.0 cm, no malformations were detected on a careful fetal anatomical survey and a four-chamber cardiac view was not obtainable. Once a four-chamber view was considered to be not obtainable due to fetal position, the patient was asked to withdraw a sealed envelope and was assigned to either the study or the control group. The 164 study patients received one to three 3-s vibroacoustic stimulations. Five minutes later a second attempt was made to visualize the four-chamber view adequately. The control group consisted of another 198 subjects in whom a four-chamber view could not be obtained. The control group did not receive vibroacoustic stimulation. A similar 5-min time interval was allowed to elapse before an attempt was made to visualize the four-chamber view. The study and control groups were similar with respect to fetal presentation, placental location, fetal weight category, biophysical profile score, gestational age, AFI and estimated fetal weight. The rate of the four-chamber view was significantly higher among fetuses receiving vibroacoustic stimulation (20.1%), in comparison to the control group (11.1%) (p = 0.019). Successful repositioning was more likely among fetuses with estimated fetal weight between 2251 and 3050 g, and at a gestational age between 33.1 and 37.0 weeks. We conclude that in a selected group of patients vibroacoustic stimulation can be used to enhance visualization of the four-chamber view.

45,X/46,XY mosaicism: the role of ultrasound in prenatal diagnosis and counselling.

The purpose of this study was to assess the benefit of ultrasound evaluation for fetuses with prenatally diagnosed 45,X/46,XY mosaicism. The charts of all patients who underwent chorionic villus sampling and/or amniocentesis between 1 March 1990 and 31 October 1995 were screened for 45,X/46,XY mosaicism. Cases were divided on the basis of the results of the confirmatory amniocentesis into two groups: (1) confined placental mosaicism (n = 4); and (2) true fetal 45,X/46,XY mosaicism (n = 4). All patients underwent high-resolution detailed ultrasound study between 16 and 22 weeks. If the initial ultrasound study failed to visualize fetal genitalia, scanning was repeated in 2 weeks. Chromosome analysis was carried out on the newborn's skin to confirm the prenatal result. Six cases were found to have 45,X/46,XY mosaicism on chorionic villus sampling. Amniocentesis indicated a normal 46,XY male karyotype for three fetuses and true fetal 45,X/46,XY mosaicism for two cases. One patient declined follow-up amniocentesis. At birth, this newborn was documented to have normal male genitalia and a 46,XY karyotype. An additional two cases underwent amniocentesis only and were documented to have 45,X/46,XY mosaicism. High-resolution detailed ultrasound study between 16 and 22 weeks revealed seven fetuses with normal male genitalia and one fetus with ambiguous genitalia. Of the four neonates with true 45,X/46,XY mosaicism this was the only one found to have ambiguous genitalia. We conclude that the work-up of patients with 45,X/46,XY mosaicism should include ultrasound study to look for ambiguous genitalia. This allows appropriate counselling regarding the natural history of the condition and aids in the planning for management in the postnatal period.

The effect of amniotic sheet orientation on subsequent maternal and fetal complications.

The purpose of this investigation was two-fold, first, to determine the incidence of amniotic sheets in our obstetric population; and, second, to elucidate the maternal and fetal complications associated with this particular finding. In this retrospective study, we searched the computerized records of the ultrasound department for the presence of amniotic sheets in singleton pregnancies from 1 March 1991 to 17 September 1993. Sonographic criteria for an amniotic sheet included the findings that (1) a reflective membrane attached to the placenta at one end or the other, with measurable thickness, was identified traversing the amniotic fluid; and (2) the fetus was not attached to the membrane, and fetal ability to move without restriction was ascertained. An amniotic sheet was identified in 79 of 17,553 examinations (0.45%) performed between 12 and 28 weeks' gestation. Two subsets of amniotic sheets were identified: perpendicular and not perpendicular. The sheets in the first subset were orientated perpendicular to the placental surface and were more likely to be associated with an abnormal presentation at delivery (p < 0.001) and a history of pelvic inflammatory disease, but not with a history of prior Cesarean section, or previous dilatation and curettage. The second subset of amniotic sheets were non-perpendicular, either oblique or parallel, in orientation to the placental surface and were associated with fewer maternal complications. Of the study group, 40.7% had a history of vaginal bleeding. The incidence of vaginal bleeding was not significantly different between those patients with perpendicular or those with non-perpendicular amniotic sheets. We conclude that perpendicular, in contrast to non-perpendicular, amniotic sheets are more commonly associated with breech presentation at term and a past history of pelvic inflammatory disease.

Severity of polyhydramnios does not affect the prevalence of large-for-gestational-age newborn infants.

The purpose of this study was to evaluate the relationship between the severity of polyhydramnios with or without maternal diabetes and the prevalence of large-for-gestational-age newborn infants. A case control design was used. The study group consisted of 275 singleton pregnancies with an amniotic fluid index > or = 25.0 cm. An equal number of controls was matched for maternal age, gravidity, parity, and gestational age. Polyhydramnios was categorized into three groups by severity: mild (amniotic fluid index 25 to 30 cm.); moderate (amniotic fluid index, 30.1 to 35.0 cm); and severe (amniotic fluid index > or = 35.1 cm). Among our study group, 72.7%, 19.7%, and 7.6% of cases had mild, moderate, and severe polyhydramnios, respectively. Patients with polyhydramnios had a significantly higher prevalence of large-for-gestational-age neonates (27%) than did controls (10%) (P < 0.001). No correlation was seen between the severity of polyhydramnios and neonatal delivery weight. The prevalence of gestational and class > or = B diabetes mellitus was significantly higher among patients with polyhydramnios (17.7%) than among controls (7%) (P < 0.003). Once polyhydramnios was diagnosed sonographically, however, maternal diabetic status did not affect the prevalence of large-for-gestational-age newborn infants. We conclude that the prevalence of large-for-gestational-age neonates is 2.7 times greater when polyhydramnios is present than when the amniotic fluid volume is normal. Neither the severity of polyhydramnios nor the presence of maternal diabetes mellitus strengthens the relationship between polyhydramnios and large-for-gestational-age newborn infants.

Effect of indomethacin on individual amniotic fluid indices in multiple gestations.

To determine the effect of indomethacin on the amniotic fluid index of individual fetuses in multiple gestations, we evaluated seven sets of twins and two sets of triplets in preterm labor (eight cases) or with polyhydramnios (one case). The dose of oral indomethacin was either 25 mg every 12 hours or 25 mg every 6 hours. The amniotic fluid volume of individual amniotic sacs was estimated serially by the amniotic fluid index. When an oral dose of indomethacin of 25 mg every 6 hours was used, oligohydramnios eventually occurred in five of eight amniotic sacs and a subjective decrease in amniotic fluid occurred in one sac. Oligohydramnios was detected in only one of 13 amniotic sacs when the dose of indomethacin was 25 mg every 12 hours. The amniotic fluid volume returned to normal in these seven amniotic sacs within 4 days of discontinuing indomethacin. We conclude that maternal indomethacin therapy has a variable effect on the individual amniotic fluid volumes in multiple gestations.

The underlying cause of polyhydramnios determines prematurity.

The preterm delivery rate in polyhydramnios is higher than in the normal population. We conducted this study to determine if different aetiologies for polyhydramnios have different frequencies of preterm delivery. Three hundred and forty women with a singleton pregnancy and polyhydramnios were included in the study group. A delivery was considered premature if it occurred before 37 weeks' gestation. Preterm deliveries occurred in 14.1 per cent of patients with unexplained polyhydramnios, 27.7 per cent of patients with insulin-dependent diabetes mellitus (IDDM), and in 36 per cent of pregnancies with congenital malformations. The prevalence of preterm delivery was significantly greater for the subgroups with IDDM (P = 0.02) and congenital malformations (P = 0.001), when compared with patients with idiopathic polyhydramnios. The prevalence of preterm delivery in patients with gestational diabetes mellitus was no greater than for the population at large. The underlying cause of polyhydramnios is a major factor in determining when delivery will occur.

Resolving polyhydramnios: clinical significance and subsequent neonatal outcome.

The objective of this study was to determine the clinical significance and neonatal outcome of patients with polyhydramnios that subsequently resolved prior to delivery. A retrospective review of 275 cases of polyhydramnios, defined as an amniotic fluid index of > or = 25.0 cm, identified 41 cases in which the amniotic fluid volume returned to normal prior to delivery. A total of 40 out of 41 patients with resolving polyhydramnios had a mild to moderate excess of amniotic fluid. There was a significant difference in the distribution of neonatal delivery weights between the study group and a matched control group. Twelve of 41 (29.3%) neonates from the study vs. none of the neonates in the control group were large for gestational age (p < 0.001). A total of 21 of 41 patients (51.2%) in the study group vs. three of 41 (7.3%) patients in the control group had at least minimal glucose intolerance (p < 0.01). We conclude that patients with resolving polyhydramnios have a significantly higher prevalence of glucose intolerance and fetal macrosomia than patients with normal pregnancies.

The association between polyhydramnios and preterm delivery.

OBJECTIVE: To determine whether an association exists between the severity of polyhydramnios and the frequency of preterm delivery. METHODS: The study group consisted of 275 singleton pregnancies with polyhydramnios as defined by an amniotic fluid index (AFI) of at least 25 cm. Polyhydramnios was arbitrarily categorized into three groups by severity: mild (AFI 25-30 cm), moderate (AFI 30.1-35 cm), and severe (AFI greater than 35.1 cm). A delivery was considered preterm if it occurred before 37 weeks' gestation. RESULTS: Fifty-two of 275 (18.9%) women delivered before 37 weeks' gestation. Preterm delivery occurred in 37 of 199 (18.5%) cases with mild polyhydramnios, 12 of 55 (21.8%) with moderate polyhydramnios, and three of 21 (14.3%) with severe polyhydramnios (no statistically significant difference). Fetuses with congenital malformations (16 of 41, 39%) and those of diabetic mothers (ten of 45, 22.2%) had a significantly higher incidence of preterm delivery than did cases with unexplained polyhydramnios (24 of 190, 12.6%; P < .001). The prematurity rate in cases with idiopathic polyhydramnios was no higher than the overall rate for our hospital. CONCLUSION: The underlying cause of polyhydramnios, rather than the relative excess of amniotic fluid as defined by this study, appears to determine when preterm labor will occur.

The relationship between placental cadmium, zinc, and copper.

A number of interactions between the essential metals zinc (Zn) and copper (Cu), and the toxic metal cadmium (Cd), have been described in animal, but not in human tissues. The purpose of this study was to determine whether Cd levels are directly related to Zn or Cu levels in the human placenta at term, and whether this relationship is affected by parity or smoking. Atomic absorption spectroscopy was used to determine Cd, Zn and Cu in perfused placental cotyledons from 292 low-risk parturients. Plasma thiocyanate levels were used to determine smoking status. Linear regression and repeated measures analysis of variance (ANOVA) were used to examine relationships between the elements and the effects of parity and smoking status. Results show significant correlations between placental Cd and both Zn (r-0.41; p < 0.01) and Cu (r-0.35; p < 0.01), but only in multiparous patients. These relationships were not altered by smoking. These results suggest that Cd-Zn and Cd-Cu interactions occur in the placenta at "normal" levels of Cd exposure and over a very short time period.

Maternal-fetal substrate relationships in the third trimester in human pregnancy.

The maternal-fetal relationship of metabolic substrates was examined in 12 mothers undergoing cordocentesis for clinical reasons between 23 and 36 weeks' gestation. Twenty cordocentesis procedures were performed. Blood glucose, insulin, beta-hydroxybutyrate, glycerol and lactate were measured in simultaneously obtained maternal and fetal samples. There was a linear correlation between fetal and maternal concentration of glucose (y = 0.687x + 0.756, R2 = 0.65 and p = 0.001), and beta-hydroxybutyrate (y = 0.443x + 0.16, R2 = 0.938 and p = 0.0001). No relation between fetal insulin and glucose concentration was observed. No correlation was seen between maternal and fetal lactate concentration. The data on glycerol could be divided into two groups. When the fetal glycerol levels were below 100 mumol/l, the fetal glycerol concentration was always less than the simultaneously obtained maternal level. However, when the fetal glycerol levels were greater than 100 mumol/l, the corresponding maternal levels were lower than that in the fetus. The exact mechanism or significance of higher fetal glycerol levels remains unknown. These data demonstrate the usefulness of cordocentesis in the understanding of fetal metabolism. In correlation with isotopic tracer, cordocentesis could provide detailed insight into human fetus in the future.

Normal blood gases in fetuses with absence of end-diastolic umbilical artery velocity.

Five fetuses with absent end-diastolic umbilical artery velocity had normal fetal acid-base status assessed by cordocentesis. Each fetus, despite widely differing pathologic conditions, deteriorated over the next several days. These cases confirm an earlier report of normal gases with absent umbilical artery end-diastolic velocity. Normal blood gases on cordocentesis cannot provide extended reassurance in fetuses with absent end-diastolic velocity.

Response of fetal heart rate to scalp stimulation related to fetal acid-base status.

The correlation of the response of the fetal heart rate (FHR) to scalp stimulation and the acid-base status of the fetal scalp blood (FSB pH) was studied in 104 term fetuses during labor. The mean FHR was determined for the 5-minute period before the preparation for fetal scalp blood pH determination and 1 minute following FSB pH. The analysis was performed for three pH groups: (a) Normal (pH more than 7.25, = 73); (2) preacidotic (pH 7.20 to 7.25, = 16); and (3) acidotic (pH less than 7.20, = 15). The pH was confirmed at delivery by determination of umbilical cord blood acid-base status. Regression analysis of the number of fetuses responding by changing their heart rate against time was significant only for the nonacidotic fetuses. There was no significant difference in the number of subjects whose mean FHR increased, decreased, or remained unchanged between the three pH groups. Furthermore, there was no difference between the three pH groups in the number of fetuses who demonstrated significant mean heart rate changes (p less than 0.05) following the stimulation compared to those who did not. Further analysis between fetuses in the three pH groups who increased FHR 15 beats/min or more following stimulation did not discriminate between groups. We conclude that scalp stimulation results in a FHR response in all three pH categories. However, the net change in the mean heart rate following the stimulation may be negative or positive. The magnitude and the direction of this change in FHR is not significantly related to FSB pH.(ABSTRACT TRUNCATED AT 250 WORDS)

Smoking alters the relationship between maternal zinc intake and biochemical indices of fetal zinc status.

Maternal smoking impairs fetal zinc status. This study was designed to clarify the effect of smoking on the relationship between maternal zinc intake and zinc status in mother and fetus. Zinc was measured with atomic-absorption spectroscopy. Statistical analyses consisted of descriptive statistics, simple correlations, and stepwise multiple regression. The results suggest that maternal plasma zinc, red blood cell zinc, and alkaline phosphatase at term are not related to maternal zinc intake. In the nonsmoking parturient both cord-vein plasma zinc and cord-vein alkaline phosphatase activity are positively related to maternal zinc intake. In the smoking parturient there is no relationship between maternal zinc intake and fetal zinc status except for a negative relation with cord-vein plasma zinc. Relations between maternal zinc intake and placental zinc can be shown with stepwise-multiple-regression techniques. The data suggests that maternal zinc intake is related not to maternal zinc status but to fetal zinc status in a normal pregnancy. The relation is altered in the pregnancy complicated by smoking.