Yoshio Yoneyama

Clinical Trial of Induction of Labor versus Expectant Management in Twin Pregnancy

Objective: The appropriate date of delivery in twin pregnancies is supposed to be earlier than that in singleton pregnancy. The aim of this study was to compare two strategies for managing twin pregnancies (i.e., immediate induction and expectant management). Methods: Seventeen patients underwent immediately induced labor by administration of oral prostaglandin E2 at 37 weeks, while 19 patients underwent expectant management. Results: The average gestational age at delivery in the induction group was 37.5 ± 0.4 weeks, significantly earlier than that in the expectant management group (39.0 ± 1.1 weeks). However, there were no significant differences in the average birth weight between the two groups (2,700 ± 330 g in the induction group vs. 2,672 ± 392 g in the expectant management group). The cesarean delivery rate in the induction group was 18%, not significantly different from that in the expectant management group (32%). The most common indication for cesarean section in the expectant management group was maternal infection, while there was no maternal infection in the induction group (p = 0.08). Conclusion: It may be acceptable do intervene in twin pregnancies earlier than in singleton pregnancies during term.

Iatrogenic monoamniotic twin gestation with progressive twin-twin transfusion syndrome.

Objective: Intentional puncture of the membrane has been reported to be a promising new method for the management of twin-twin transfusion syndrome. Case Report: Treatment of twin-twin transfusion syndrome with serial amniocenteses resulted in unintentional puncture of the dividing membrane at 24 weeks of gestation. Fetal growth discordance increased, and twin-twin transfusion did not improve following the puncture. Intrauterine death of both fetuses at 27 weeks of gestation occurred. Conclusion: Amniotic septostomy for the treatment of twin-twin transfusion sydnrome should be performed with serious consideration.

Regulation of platelet aggregation in vitro by plasma adenosine in preeclampsia.

The aim of this study was to evaluate the possible role of plasma adenosine in platelet aggregation in preeclampsia. We measured the plasma adenosine concentration [ADO] and in vitro platelet aggregation in the third trimester of normal pregnant (n = 15) and preeclamptic women (n = 15). The mean plasma [ADO] in preeclampsia was 0.68 ± 0.08 µM (means ± SEM), significantly higher than in normal pregnancy (0.42 ± 0.09 µM) (p < 0.05). In preeclampsia, platelet aggregation in response to collagen was approximately 40% lower than that in normal pregnancy (p < 0.05). There was an inverse correlation between the plasma [ADO] and platelet aggregation in vitro (r = –0.27, p < 0.05). These results suggest reduced platelet aggregation in preeclampsia may be at least in part attributed to an elevation of the the plasma [ADO].

Fetal Middle Cerebral Artery Doppler Waveforms in Twin–Twin Transfusion Syndrome

The aim of this study was to compare the fetal middle cerebral artery (MCA) Doppler waveforms in growth-retarded twin fetuses with (n = 11) and without (n = 24) twin–twin transfusion syndrome (TTTS). Umbilical artery (UA) and fetal MCA Doppler velocity waveforms were recorded on admission. The mean values of the UA pulsatility index (PI) of smaller twin fetuses with and without TTTS were significantly higher than those of normal singleton pregnancies. The mean values of the MCA PI of smaller twin fetuses in the TTTS group (+0.7 ± 1 SD) were significantly higher than those of normal singleton pregnancies on admission, and these levels did not markedly change following amniocentesis. On the other hand, the values of the MCA of the growth-retarded fetuses without TTTS (–0.9 ± 1 SD) were significantly lower than those of normal singleton pregnancies. Our findings suggest that measurement of fetal MCA PI is a useful method to assess growth-retarded fetuses in monochorionic twin pregnancies.

Umbilical Venous Pulsation Indicating Tight Cord Entanglement in Monoamniotic Twin Pregnancy

Increased risks in monoamniotic twin pregnancies are due primarily to cord entanglement,1 leading to compression and fetal asphyxia. Unfortunately, the prevalence of this condition has been reported to be 40 to 70% in monoamniotic twin pregnancies.1,2 Therefore, when cord entanglement is diagnosed, we must be able to predict whether or not fetal asphyxiation will occur. In singleton pregnancies, umbilical venous pulsations have been observed in abnormal fetuses with heart failure or in normal fetuses using pulsations of the umbilical arteries.3 We present a case of monoamniotic twin pregnancy in which umbilical venous pulsations suggested tight cord entanglement leading to progressive preloading of the fetal heart.

Relation between serum uric acid and plasma adenosine levels in twin pregnancies.

Objective To examine the relationship between plasma adenosine and serum uric acid levels in women with singleton and twin pregnancies. Methods We sampled maternal arterial blood and measured serum uric acid and plasma adenosine levels in 22 singleton pregnancies and nine twin pregnancies at 33 to 38 weeks gestation. Results The average plasma adenosine levels were 0.31 ± 0.12 μmol/L in the singleton pregnancy group and 0.45 ± 0.09 μmol/L in the twin pregnancy group (P < .001). The mean serum uric acid level in women with twin pregnancy was 5.7 ± 0.44 mg/dL which was higher than that in the singleton pregnant women (4.4 ± 0.69 mg/dL, P < .001). Positive correlations were found between serum uric acid and plasma adenosine levels in both the singleton (r2 = 0.54, P < .001) and the twin pregnancy groups (r2 = 0.65, P = .009). Moreover, there was also a significant correlation between serum uric acid and plasma adenosine levels overall (r2 = 0.66, P < .001). Conclusion Our results suggest that higher adenosine levels are a contributing source of hyperuricemia in twin pregnancies.

BRAIN TEMPERATURE AND METABOLIC RESPONSES DURING UMBILICAL CORD OCCLUSION IN FETAL SHEEP

Abstractu2002The purpose of this study was to compare core body and brain temperatures after complete but intermittent occlusions of the umbilical cord. Thermocouple probes were placed in the parasagittal parietal cortex, ascending aorta, and jugular vein of eight near-term fetal sheep and in the maternal descending aorta. Three days later, after an initial control period, the umbilical cord was occluded for 5 min, followed by a 30-min recovery period, and this cycle was repeated 4 times. Temperature changes, blood gases, and plasma glucose, lactate and adenosine were measured. In the first occlusion period, body core temperature increased 0.12°C over control, and then declined to baseline after cord release, and this pattern was repeated with subsequent occlusions. Brain temperature, however, did not increase in response to any of the cord occlusions. Plasma adenosine increased 2.4-fold during the first occlusion, but not during subsequent occlusions, despite a continuing pattern of constant brain temperature, a result which minimizes adenosine’s importance as a continuing regulator of cerebral metabolism. We conclude that brain temperature fails to increase because of diminished heat production by the brain and increases in cerebral blood flow, responses which delay complete depletion of adenosine 5′-triphosphate stores in brain tissue.

Evidence for mechanisms of the acute-phase response to endotoxin in late-gestation fetal goats

OBJECTIVEnThe aim of this study was to evaluate the relationship between febrile response to fetal endotoxin administration and fetal plasma endogenous pyrogen, tumor necrosis factor-alpha, the possible putative pyrogen mediator prostaglandin E2, and the endogenous antipyretic arginine vasopressin in late-gestation pregnant goats.nnnSTUDY DESIGNnChanges in fetal core temperature, plasma tumor necrosis factor-alpha, prostaglandin E2, and arginine vasopressin levels were measured after administration of Escherichia coli endotoxin (70 microg/kg of fetal weight) to 10 fetal goats in late gestation.nnnRESULTSnFetal body temperature did not rise after endotoxin administration. Fetal plasma tumor necrosis factor-alpha and arginine vasopressin increased to 87.5 +/- 15.2 pg/mL and 25.1 +/- 4.8 pg/mL, respectively, after 1 to 2 hours (P < .05). Fetal plasma prostaglandin E2 levels did not change significantly throughout the study.nnnCONCLUSIONnThe absence of a febrile response to endotoxin in late-gestation fetal goats is accompanied by a deficient responses in prostaglandin generation in the periphery and increased activity of the antipyrogen arginine vasopressin.

Fetal brain death and Dandy–Walker malformation

The diagnosis of brain death by Doppler ultrasonography and magnetic resonance imaging is reported in a fetus at 23 weeks gestation. This is believed to be the first instance in which brain death has been shown in a premature fetus with a brain‐stem anomaly. Copyright

Maternal plasma adenosine levels in pregnancies complicated by toxemia

Summary The aim of this study was to evaluate the relationship between uteroplacental circulatory insufficiency and the maternal release of adenosine in pregnancies complicated by toxemia. Uterine artery Doppler velocimetry was performed immediately before maternal arterial blood sampling in 16 pregnant women complicated by toxemia and 6 normal pregnant women. Maternal arterial blood was then analyzed for plasma adenosine levels. The mean maternal arterial plasma adenosine level in pregnant women complicated by toxemia was 0.85±0.18 μmol/L, significantly higher than in normal pregnant women 0.54±0.12 μmol/L. Furthermore, the evaluation of plasma adenosine levels was related to the presence of a protodiastolic notch in the uterine artery waveform. The results suggest that increased maternal adenosine levels are associated with placental blood flow in pregnancies complicated by toxemia.