Elimination of antithrombin III concentrate in healthy pregnant and preeclamptic women with an acquired antithrombin III deficiency

The activity elimination half-life of heat-treated antithrombin III (AT III) concentrate was studied in 5 healthy pregnant and 5 preeclamptic women with a documented AT III deficiency. Healthy pregnant women received 1500 units over 20 minutes. Serial blood specimens were obtained over the next 12 hours. The mean (+/- SEM) activity elimination half-life of AT III was 29.4h +/- 3.4h. Preeclamptic subjects had a mean baseline AT III activity of 70.5 +/- 2% (range 61 to 75%). Their activity eliminator half-life after 3000 units of AT III concentrate was 8.5 +/- 1.2h. There was a direct relationship between the pre-concentrate AT III activity level and the AT III activity elimination half-life (r = 0.79, p = 0.01) for all subjects. Based upon parameters calculated from the first infusion, the AT III activity of preeclamptic subjects was maintained by a constant infusion at approximately 100% for 96h. At the conclusion of the infusion, the activity elimination half-life was again measured. A dramatic increase in the activity elimination half-life was demonstrated (433.6h). We conclude that the activity elimination half-life of AT III concentrate is increased during normal pregnancy and further increased in preeclamptic women with an acquired deficiency.

The relationship between the umbilical artery systolic/diastolic ratio and umbilical blood gas measurements in specimens obtained by cordocentesis

The purpose of this investigation was to prospectively determine the relationship between the umbilical artery systolic/diastolic ratio and the umbilical blood gases in samples obtained from 165 fetuses during diagnostic cordocenteses. In each instance the sample was the umbilical vein. The systolic/diastolic ratio was measured in a midsection of the umbilical cord. Analyses used stepwise, multiple linear regression. The mean +/- SEM gestation was 29 +/- 0.4 weeks; 72% of fetuses were greater than or equal to 25 weeks and were considered potentially viable. There was no relationship between the umbilical artery systolic/diastolic ratio and pH, PCO2, or PO2 in fetuses either less than 25 weeks' gestation or greater than or equal to 25 weeks' gestation but with systolic/diastolic ratios greater than or equal to the 95th percentile for control fetuses at 25 weeks' gestation with normal blood gas values (3.5). In fetuses greater than or equal to 25 weeks' gestation with systolic/diastolic ratios that exceeded 3.5 (n = 37), there was a strong relationship between the systolic/diastolic ratio and the umbilical venous PO2 (r = -0.68, p less than 0.0001), which was independent of gestational age. Each fetus with repetitively absent-reversed umbilical artery diastolic blood flow and a heart rate greater than 90 beats/min (n = 6) had blood gas measurements consistent with hypoxia and acidosis. This investigation suggests that factors that lead to an increase in the umbilical artery systolic/diastolic ratio are associated with a progressive impairment of placental gas exchange and that by the time diastolic flow is lost, hypoxemia is present.

Relationship between renal histology and plasma antithrombin III activity in women with early onset preeclampsia

Renal biopsy was performed in 12 women with the clinical diagnosis of severe, early-onset preeclampsia at the time of cesarean delivery for the express purpose of aiding future counseling on the risk of recurrence. The mean gestation at delivery was 30 +/- 3 weeks. The mean birthweight was 1090 +/- 505 gm. Four women (33%) were multiparous. Antithrombin III activity was determined immediately prior to delivery unrelated to clinical care and as part of other protocols. The biopsy was performed without difficulty in each, although the sample was inadequate in one patient. The clinical diagnosis of preeclampsia was confirmed in nine (82%). However, three of the nine had underlying renal disease, as did the two women without histologic evidence of preeclampsia (42% of the total). Correlations between laboratory parameters with the histopathologic diagnoses were sought. Neither uric acid, creatinine, blood urea nitrogen, platelet count, or 24-hour urinary protein measurements aided the differentiation of the various subgroups. Antithrombin III activity in women with biopsy-supported preeclampsia (77% +/- 12%) was significantly lower than that in women without histologic evidence of preeclampsia (116% +/- 8%). Antithrombin III activity correctly predicted biopsy findings in at least 9 of 11 (82%). These preliminary findings confirm the high frequency of underlying disease in women with early-onset preeclampsia. Although low antithrombin III activity does not differentiate between "pure" preeclampsia and superimposed disease, a normal antithrombin III activity is reassuring and more consistent with a nonpreeclamptic renal complication than with preeclampsia.

Does ritodrine worsen maternal hypotension during epidural anesthesia in gravid ewes?

The purpose of this study was to determine whether prior administration ritodrine worsens maternal hypotension during epidural anesthesia in gravid ewes. Twenty-four experiments were performed in nine chronically instrumented animals between 0.8 and 0.9 of timed gestation. The experimental sequence included the following: 1) at time-zero, intravenous (iv) administration of ritodrine, 0.004 mg.kg-1.min-1, or normal saline (NS) for 2 h; 2) at 120 min discontinuation of ritodrine, and administration of a 500 ml iv bolus of NS over 15 min; and 3) at 135 min epidural injection of 2% lidocaine or NS. There were three groups of experiments: 1) iv ritodrine-epidural lidocaine (n = 9); 2) iv NS-epidural lidocaine (n = 8); and 3) iv ritodrine-epidural NS (n =7). Epidural injection of lidocaine resulted in a median sensory level of T9 in both the ritodrine-lidocaine and NS-lidocaine groups. At 165 min (i.e., 30 min after the epidural injection of lidocaine), maternal mean arterial pressure was 19 +/- 3% below baseline (P = 0.0001) in the ritodrine-lidocaine group and 22 +/- 7% below baseline (P = 0.0001) in the NS-lidocaine group (NS between groups). At 120 min ritodrine had increased maternal cardiac output 45 +/- 6% above baseline (P = 0.0001) in the ritodrine-lidocaine group and 39 +/- 6% above baseline (P = 0.0001) in the ritodrine-NS group. Cardiac output remained above baseline (P less than 0.01) after epidural injection of lidocaine in the ritodrine-lidocaine group. In contrast, in the NS-lidocaine group cardiac output was 13 +/- 5% below baseline (P = 0.005) at 150 min. Fetal arterial pH did not change significantly in either the ritodrine-lidocaine or ritodrine-NS group.(ABSTRACT TRUNCATED AT 250 WORDS)

Fetal gastroschisis complicated by bowel dilation: an indication for imminent delivery?

Antenatal diagnosis of fetal gastroschisis permits study of bowel appearance throughout gestation. Fetal bowel dilation has been regarded as a 'high-risk' condition requiring imminent cesarean delivery. We report 2 cases of gastroschisis with onset of bowel dilation in the third trimester. At surgery, the bowel was patent. Neither fetus had evidence of acute bowel damage following expectant management and vaginal delivery. Both underwent a one-stage repair. We conclude that antenatal bowel dilation does not necessarily reflect bowel injury or a poorer neonatal prognosis. In our experience, bowel dilation in fetal gastroschisis does not represent a separate indication for cesarean delivery and can be associated with a good outcome following vaginal delivery.

The role of serotonin in the preeclampsia-eclampsia syndrome

The cause of preeclampsia, a syndrome unique to human pregnancy, is unknown. There is presently no effective pharmacologic therapy once the symptoms have appeared. Only delivery is curative. Preeclampsia likely has multiple etiologies, each of which activates a common pathway, culminating in diffuse endothelial damage, vasospasm, and hypertension. Current investigation suggests that serotonin has a pivotal role in the genesis of preeclamptic hypertension. The evidence, as obtained from human and animal study, is reviewed in this article, and areas in need of further study are highlighted. A modified series of Koch's postulates is employed for a framework. Serotonin is the agent but does not directly cause the hypertension. Rather, it is suggested that in a milieu characterized by a reduction in endothelial-derived relaxing factor and prostacyclin, serotonin augments the smooth muscle response to normally occurring concentrations of endogenous vasopressors. It is delivered to the site of action (the microvasculature) by the platelet, whose aggregation is encouraged by dysfunctional endothelium. Either inhibition of the delivery mechanism by a low, daily dose of aspirin, or inhibition of the peripheral serotonin type 2 (5HT2) receptor, effectively controls the hypertension.

The effect of intravascular transfusion on umbilical venous pressure in anemic fetuses with and without hydrops

Human fetal umbilical venous pressure was measured during 20 intravascular transfusions performed for treatment of hemolytic anemia. The mean (+/- 1 SEM) gestational age at the time of transfusion was 29.3 +/- 1 weeks and the mean beginning hematocrit was 27% +/- 2%. The mean volume of infused packed red blood cells (70% hematocrit) was 90.3 +/- 7 ml. The mean hematocrit at completion of the procedure was 48% +/- 1%. In nonhydropic fetuses umbilical venous pressure rose progressively from 6.7 +/- 1 mm Hg at the start of transfusion to 10.9 +/- 1 mm Hg at the completion of transfusion (p less than 0.002). However, most fetuses who began the infusion with a normal umbilical venous pressure ended the transfusion with a normal umbilical venous pressure (less than 10 mm Hg). Fetuses with immune hydrops (n = 2) had elevated umbilical venous pressure values before the initiation of transfusion therapy when compared with the first transfusion of nonhydropic fetuses (12.5 +/- 0.5 vs. 5.7 +/- 1 mm Hg, p = 0.01). However, the umbilical venous pressure measurements declined into the normal range within 24 hours of the first transfusion; this normalization was too rapid to be explained by the reversal of liver hypertrophy or portal hypertension. There was no demonstrable relationship between the rise in umbilical venous pressure and either the gestational age, the volume transfused, or the rise in hematocrit. This study demonstrated: (1) In terms of the umbilical venous pressure, direct intravenous infusion of the human anemic fetus is well tolerated; (2) the elevated umbilical venous pressure associated with immune hydrops can correct rapidly with red blood cell replacement.

Effect of acute intravascular volume expansion on human fetal prostaglandin concentrations

Direct fetal intravascular transfusion is well tolerated by the human fetus. However, the rapid transfusion of high-hematocrit blood should increase vessel distention and the flow shear force. Each is known to stimulate the release of prostacyclin. We measured prostaglandins E2 and F2 alpha and the stable metabolite of prostacyclin, 6-keto-prostaglandin F1 alpha, by radioimmunoassay before, at the estimated midway point of, and at the completion of 40 umbilical venous transfusions performed because of immune hemolytic anemia. Umbilical venous pressures corrected for amniotic fluid pressure were measured at similar intervals during nine of the procedures. The mean (+/- SEM) length of gestation at transfusion was 29 +/- 1 week, opening hematocrit 23% +/- 1%, and total volume of 70% hematocrit red blood cells transfused 83 +/- 5 ml. 6-Keto-prostaglandin F1 alpha was the principal circulating fetal prostanoid and its concentration was unrelated to gestational age. Intravenous transfusion was associated with an 84% increase in 6-keto-prostaglandin F1 alpha (p = 0.03) and a 68% increase in prostaglandin E2 (p less than 0.05). The rise for each strongly correlated with the rise in the fetal umbilical venous pressure (6-keto-prostaglandin F1 alpha, r = 0.94, p = 0.0005; prostaglandin E2, r = 0.81, p less than 0.03). We conclude that 6-keto-prostaglandin F1 alpha is the principal circulating prostaglandin in the human fetus and that the release of venodilator prostaglandins may be one reason the human fetus can tolerate a large increase in intravascular volume without obvious sequelae.

Effect of pregnancy on uterine and carotid artery response to norepinephrine, epinephrine, and phenylephrine in vessels with documented functional endothelium

The effect of pregnancy on arterial sensitivity to vasoconstrictors is controversial. Some of the controversy may reflect methodologic differences. Vessel reactivity in vitro is altered by both the tension placed on the segment and the presence or absence of functional endothelium. We investigated the effect of pregnancy on guinea pig uterine and carotid arteries to norepinephrine, epinephrine, and phenylephrine. Each vessel segment was stretched to the optimal point along its length-tension curve, and functional endothelium was documented by acetylcholine-stimulated relaxation. A significant dose-response relationship was observed in each vessel for each agent (each p less than 0.0001). Pregnancy was demonstrated to be associated with a significant reduction in both uterine artery response and sensitivity to norepinephrine, epinephrine, and phenylephrine. However, there was no consistent pregnancy-associated effect on carotid artery response and sensitivity.

Does furosemide alter the hemodynamic response to rapid intravascular transfusion of the anemic fetal lamb?

The purpose of this study was to define the hemodynamic response to rapid intravascular transfusion of the anemic fetal lamb and to determine whether furosemide alters that response. Sixteen experiments were performed in nine chronically instrumented gravid ewes between 0.8 and 0.9 of timed gestation. On day 1 of each experiment, each fetus was subjected to hemorrhage (40 ml/kg of estimated fetal weight) over 1 hour. On day 2, plasma was withdrawn from the stored fetal blood until the hematocrit was approximately 70%, and the packed red blood cells were returned to the fetus intravenously over 10 minutes. Each fetus received either furosemide (2 mg/kg) or control saline solution intravenously at time zero and again at 5 minutes. The order of experiments was randomly determined for each animal. Hemorrhage resulted in a similar decrease in fetal hematocrit in the two groups. The mean +/- SEM fetal hematocrit before hemorrhage was 38 +/- 3% in the furosemide group (n = 8) and 36 +/- 2% in the control group (n = 8). On day 2, the mean +/- SEM fetal hematocrit before transfusion was 28 +/- 2% in the furosemide group and 25 +/- 1% in the control group. There was no significant difference between groups in the fetal hemodynamic response to transfusion. At the end of the transfusion, the fetal central venous pressure had increased from 4.9 +/- 0.5 to 6.2 +/- 0.5 mm Hg in the furosemide group (p = 0.01) and from 3.9 +/- 0.2 to 5.8 +/- 0.3 mm Hg in the control group (p = 0.0001). Fetal mean arterial pressure increased from 42 +/- 1 to 50 +/- 1 mm Hg in the furosemide group (p = 0.0001) and from 40 +/- 1 to 46 +/- 1 mm Hg in the control group (p = 0.0007). Fetal heart rate decreased from 187 +/- 2 to 169 +/- 5 beats/min in the furosemide group (p = 0.004) and from 188 +/- 4 to 170 +/- 5 beats/min in the control group (p = 0.0008). Transfusion did not significantly change fetal pH in either group. At 120 minutes, the fetal PO2 had increased from 17 +/- 1 to 19 +/- 1 mm Hg in the furosemide group (p = 0.03) and from 19 +/- 1 to 21 +/- 2 mm Hg in the control group (p = 0.05). We conclude that rapid transfusion of the anemic fetal lamb resulted in modest increases in fetal central venous pressure and mean arterial pressure.(ABSTRACT TRUNCATED AT 400 WORDS)

Sonographic diagnosis of intrauterine growth retardation using the postnatal ponderal index and the crown-heel length as standards of diagnosis

One hundred twenty-one patients underwent an ultrasound examination within 48 hours of delivery to assess prospectively the reliability of the diagnosis of intrauterine growth retardation. Sonographic parameters examined included the abdominal circumference, sonographic estimate of fetal weight, the head to abdominal circumference ratio, and the femur length to abdominal circumference ratio. The best obstetric estimate of gestational age was used. The diagnosis of growth retardation was based on the postnatal ponderal index, and or the birthweight and crown-heel length percentiles. Seventeen infants were growth retarded. Fifteen infants had a birthweight less than the 10th percentile, but only nine (60%) were either asymmetrically growth retarded (by their ponderal index) or symmetrically growth retarded (by virtue of a birthweight and length less than the 10th percentile). All sonographic parameters were better able to predict a birthweight below the 10th percentile for gestational age than growth retardation. An abdominal circumference less than the 2.5 percentile for gestational age had the highest sensitivity for growth retardation (88.0%) of the parameters studied. Only the abdominal circumference centile identified all infants with either symmetric growth retardation or asymmetric growth retardation associated with a birthweight below the 10th percentile. A sonographic estimate of fetal weight below the 10th percentile had the highest positive predictive value for growth retardation--38%. In contrast to the overall poor positive predictive values, the negative predictive values for all parameters studied exceeded 90%. Combining the abdominal circumference percentile with one of the three remaining techniques did not significantly improve diagnostic accuracy.(ABSTRACT TRUNCATED AT 250 WORDS)

Normal values for human umbilical venous and amniotic fluid pressures and their alteration by fetal disease

Umbilical venous and amniotic fluid pressures were measured in 68 human pregnancies at the time that cordocentesis was performed. Normal umbilical venous pressure was unrelated to gestational age and remained within a tight range (5.3 +/- 2.3 mm Hg, mean +/- SD). Fetuses with an elevated umbilical venous pressure had disorders consistent with either hepatomegaly or congestive heart failure. Umbilical venous pressure was significantly increased before treatment in two fetuses with immune hydrops; it rapidly declined with treatment. Neither gestational age nor umbilical venous pressure was significantly different in the groups that received and did not receive pancuronium. There was a strong relationship between amniotic fluid pressure and gestational age in normal pregnancy (r = 0.54, p less than 0.0001). Women with hydramnios had amniotic fluid pressures greater than control subjects (p = 0.0007). This investigation documents normal human amniotic fluid and fetal umbilical venous pressures. These measurements are altered by disease and may prove to be of diagnostic and therapeutic value in the future.

The plasma renin-angiotensin system in preeclampsia: effects of magnesium sulfate

Two groups of women were studied in a prospective longitudinal fashion to determine the effects of a 2.5-hour infusion of magnesium sulfate upon the renin-angiotensin system. Serum magnesium concentration, angiotensin-converting enzyme concentration, and plasma renin activity were measured at uniform intervals in women with either preeclampsia or preterm labor. Plasma renin activity was significantly lower (3.9 +/- 2.2 versus 6.1 +/- 1.8 ng/mL/minute; P = .004) and angiotensin-converting enzyme significantly higher (47.1 +/- 14 versus 34.0 +/- 10 U/mL; P = .008) in women with preeclampsia than in those with preterm labor. Magnesium infusion was associated with a sustained decline in plasma renin activity in preeclamptic women (P = .003). A transient decline in angiotensin-converting enzyme (P = .009) was observed in women with preeclampsia, but not with preterm labor. In contrast to the sustained change in plasma renin activity, angiotensin-converting enzyme concentration returned to baseline activity levels by 2.5 hours. A nonsignificant negative relationship (P = .06) was noted between angiotensin-converting enzyme and gestational age in subjects with preeclampsia. We conclude that a short-term infusion of magnesium sulfate leads to a sustained decline in plasma renin activity in preeclamptic women, but exerts no sustained effect on angiotensin-converting enzyme in women with either preeclampsia or preterm labor.

Magnetic resonance imaging of anomalous fetuses

Magnetic resonance imaging (MRI) has been used sparingly in obstetrics. The reasons for this relate mainly to cost, availability, difficulty obtaining clear images because of fetal movement, and the convenience and utility of ultrasound. However, MRI use is expanding and has the potential to play an important role in selected problem pregnancies. We studied the pregnancies of five women whose fetuses showed anomalies by ultrasound. These included cases of a large body wall defect, a diaphragmatic hernia, hydrocephalus, Meckel-Gruber syndrome, and iniencephaly with a diaphragmatic hernia (the iniencephaly sequence). Three of these examinations followed fetal neuromuscular blockade, and two were associated with oligohydramnios without fetal paralysis. Paralysis provided superior images. The fetal central nervous system, subcutaneous tissue, and liver imaged particularly well. This study illustrates that MRI can enhance and even clarify certain information provided by ultrasound.

Antenatal diagnosis and palliative treatment of non-immune hydrops fetalis secondary to fetal parvovirus B19 infection

Hydrops fetalis was diagnosed at 22 weeks. An ultrasound examination demonstrated cardiomegaly and a fetal blood specimen obtained by cordocentesis revealed thrombocytopenia, anaemia, and neutropenia. Fetal paracentesis yielded straw-coloured fluid with electrolytes indicative of a transudate. Non-enveloped icosahedral viral particles approximately 23 mm in diameter were visualized in the ascitic fluid by electron microscopy. Immune electron microscopy confirmed human parvovirus B19. Direct fetal digitalization led to a reduction in umbilical artery resistance, a decline in the abdominal circumference from 20.3 to 17.8 cm, and resolution of the ascites within 72 h. Despite this dramatic response to therapy, fetal death occurred on day 5 of treatment. The initial maternal serum was positive for anti-B19 IgM and IgG antibodies. Electron microscopy of fetal cardiac tissue obtained post-mortem revealed intranuclear viral particles typical of B19, confirming the antenatal diagnosis of myocarditis. This case demonstrates that direct viral identification is applicable to prenatal diagnosis. To our knowledge, this is the first reported case of the antenatal diagnosis and palliative treatment of fetal viral infection.

The effect of intravenously administered 2-chloroprocaine upon uterine artery blood flow velocity in gravid guinea pigs

The purpose of the present study was to assess the effect of intravenously administered 2-chloroprocaine upon uterine artery blood flow velocity (UBFV) in gravid guinea pigs. Ten experiments were performed in ten chronically instrumented animals between 0.7 and 0.9 of timed gestation. Each animal received four solutions of 2-chloroprocaine in random order: 1) 0.67 mg/kg; 2) 1.34 mg/kg; 3) 2.0 mg/kg; and 4) 1.34 mg/kg, with epinephrine 0.2 microgram/kg. Six animals received a fifth solution, 0.2 ml of saline control. 2-Chloroprocaine 1.34 mg/kg significantly increased maternal mean arterial pressure (MMAP) at 30 s after injection, and 2-chloroprocaine 2.0 mg/kg significantly increased MMAP through 2 min. 2-Chloroprocaine 1.34 mg/kg, with epinephrine 0.2 microgram/kg, also significantly increased MMAP through 2 min. No other solution significantly altered MMAP. 2-Chloroprocaine 2.0 mg/kg significantly decreased UBFV at 30 s after injection. 2-Chloroprocaine 1.34 mg/kg, with epinephrine 0.2 microgram/kg, significantly decreased UBFV through 2 min. No other solution significantly altered UBFV. The authors conclude that iv administration of 2-chloroprocaine with epinephrine significantly decreased UBFV in pregnant guinea pigs. In contrast, only the largest dose (i.e., 2.0 mg/kg) of 2-chloroprocaine alone transiently decreased UBFV. These data suggest that, in doses up to 1.34 mg/kg, 2-chloroprocaine alone may not decrease uterine blood flow when used as a marker for intravenous injection in obstetric patients.

Intravenous administration of d-tubocurarine and pancuronium in fetal limbs

The purpose of this study was to assess the effects of intravenous administration of d-tubocurarine and pancuronium in fetal lambs. Eighteen experiments were performed in seven chronically instrumented pregnant ewes between 0.8 and 0.9 of timed gestation. Each fetus received 6 ml of study drug intravenously at 1.2 ml/min over 5 minutes (d-tubocurarine 3.0 mg/kg, pancuronium 0.5 mg/kg, or saline solution control). Pancuronium (n = 7) significantly increased both fetal heart rate and mean arterial pressure. d-Tubocurarine (n = 5) significantly decreased both fetal heart rate and mean arterial pressure. Saline solution control (n = 6) did not significantly alter fetal heart rate or mean arterial pressure. The present study suggests that pancuronium is preferable to d-tubocurarine for those intrauterine procedures when an increase in fetal heart rate is desired.

The acute effect of cordocentesis with or without fetal curarization and of intravascular transfusion upon umbilical artery waveform indices

The systolic/end-diastolic ratio (S/D) and pulsatility and resistance indices were calculated before and after diagnostic cordocentesis in 46 fetuses, after 19 intravascular transfusions in eight fetuses, and on two occasions 45 minutes apart in eight controls. The fetus was paralyzed with pancuronium (0.3 mg/kg sonographic estimate of fetal weight) for diagnostic cordocentesis on 19 occasions (intravascularly in 17 and intramuscularly [IM] in two). Pancuronium (intravascularly in 16; IM in three) and furosemide (4 mg/kg intravenously) were administered during each transfusion. There were no significant differences between the first and second measurements for any of the three indices in the control group. Significant reductions were documented in the S/D ratio (P less than .0001), the pulsatility index (P = .043), and the resistance index (P less than .0001) after diagnostic cordocentesis. Pancuronium administration did not alter the magnitude of the decline, nor was there an association between the decline and the volume of blood removed. Significant relationships were observed between the magnitude of the decline and several respiratory blood gas measurements. As in the diagnostic cordocentesis group, there were significant reductions in each Doppler index after transfusion (S/D ratio, P = .003; pulsatility index, P = .002; resistance index, P = .0001). In addition, there was a significant relationship between gestational age and S/D ratio (r = 0.70, P = .002) in fetuses undergoing intravascular transfusion. The S/D ratio was most sensitive to changes in fetal oxygenation. We conclude that both diagnostic cordocentesis and intravascular transfusion as performed at the University of Iowa acutely lower the studied Doppler waveform indices.

Evaluation of severe growth retardation using cordocentesis--hematologic and metabolic alterations by etiology

Hematologic and respiratory blood gas parameters were studied in 21 fetuses with severe or early-onset (at or before 34 weeks) growth retardation and in 44 age-matched control fetuses. Diagnostic categories included uteroplacental insufficiency (N = 7) and uteroplacental insufficiency with associated fetal structural abnormality (N = 7), aneuploidy (N = 5), and congenital infection (N = 2). The mean (+/- 1 SEM) gestational age was 29.3 +/- 1 week. Compared with the control group matched for gestational age, the growth-retarded fetuses had higher hematocrits regardless of etiology. The platelet count was reduced in growth-retarded fetuses with aneuploidy (P less than .05). Leukopenia was observed in a fetus with congenital infection and in the group of fetuses with uteroplacental insufficiency unassociated with a structural abnormality (P less than .05). Leukocytosis was seen in growth-retarded aneuploid fetuses (P less than .01). The pH, pO2, and percent oxygen saturation were each lower in growth-retarded fetuses with either uteroplacental insufficiency or aneuploidy, and the pCO2 and bicarbonate were higher compared with controls (each P less than or equal to .05). Appropriately grown aneuploid fetuses had normal hematologic and respiratory blood gas measurements but were significantly more likely not to be trisomic (P = .04). Fetuses with uteroplacental insufficiency unassociated with a structural anomaly had significantly higher umbilical artery systolic/diastolic ratios than both the control group (P = .0002) and the group with uteroplacental insufficiency and a structural anomaly (P less than .008). This investigation confirms previous studies of fetuses suffering uteroplacental insufficiency and extends the observations to other etiologies.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of exogenous prostacyclin on central and uterine hemodynamics in the chronically instrumented pregnant guinea pig before and after indomethacin administration

The effect of prostacyclin before and after pretreatment with indomethacin was studied in the chronically instrumented pregnant guinea pig. Twenty-six animals were studied between 45 and 65 days' gestation. Prostacyclin (6.25, 12.5, 25, 50, and 125 micrograms/kg/min) produced a dose-dependent decrease in arterial pressure (r = -0.915, p less than 0.0001) and uterine artery blood flow velocity, as measured by a miniaturized Doppler flow probe (r = -0.850, p = 0.0001), and an increase in heart rate (r = 0.745, p = 0.0335). Uterine resistance increased at each dose, with 125 micrograms/kg/min generating an increase greater than all others (p less than 0.02). The hypotensive effect of prostacyclin was blunted by indomethacin (p = 0.018). Rather than blunting the expected changes in the remaining parameters, pretreatment with indomethacin followed by prostacyclin significantly decreased uterine blood flow velocity further and increased uterine resistance. We conclude that prostacyclin infusion can have adverse effects on uterine blood flow and that these are altered by pretreatment with a prostaglandin synthetase inhibitor. Prostacyclin should be avoided in women with preeclampsia until further animal studies are available.

Arginine vasopressin and acute, intravascular volume expansion in the human fetus

There is presently no information concerning the ontogeny and control of arginine vasopressin (AVP) in the human fetus. AVP was measured in 22 nonanemic control fetuses and 7 fetuses with hemolytic anemia undergoing 13 intravascular transfusions. Each transfused fetus received pancuronium (0.3 mg/kg) and furosemide (2 mg/kg). Compared to the control group of nonanemic fetuses with hemolytic disease, AVP was significantly lower in the anemic fetus prior to transfusion (2.6 +/- 0.4 microU/ml versus 10.4 +/- 4.1 microU/ml, p less than 0.05). This suggests that hemolytic anemia is associated with a relative increase in fetal intravascular volume. Intravascular transfusion was associated with a significant increase in AVP (p less than 0.05). These findings could not be explained by changes in either blood pressure, plasma osmolality, or fetal oxygenation.

Prolonged elevation of alphafetoprotein and detectable acetylcholinesterase after death of an anomalous twin fetus

Persistence of elevated alphafetoprotein (AFP) levels and the presence of an acetylcholinesterase (AChE) band in amniotic fluid have been reported to occur up to 11 weeks following intrauterine fetal demise (IUFD) of one twin (Bass et al., 1986). We now report a case where such prolongation of these findings was observed in a case of unrecognized monochorionic, monoamniotic twinning, in which case cord entanglement resulted in IUFD at an estimated 10-12 weeks and 25-26 weeks. The fetus suffering early demise (Fetus B) had multiple congenital anomalies, including a neural tube defect. The presence of this defect and/or fetal demise and bleeding into the amniotic sac is entertained as continuing sources of documented elevated AChE and AFP 9-11 weeks after the initial fetal death. We re-emphasize the possibility of unrecognized twinning as a cause of abnormal maternal serum and amniotic fluid study results in the face of one apparently normal fetus.

Atrial natriuretic factor, digoxin-like immunoreactive substance, norepinephrine, epinephrine, and plasma renin activity in human fetuses and their alteration by fetal disease

We measured five hormones presumably involved in fetal homeostasis in specimens obtained by cordocentesis for clinical indications from 106 fetuses. Norms for atrial natriuretic factor, digoxin-like immunoreactive substance, plasma renin activity, norepinephrine, and epinephrine were derived from fetuses ultimately shown to be free of detectable abnormality. Atrial natriuretic factor, digoxin-like immunoreactive substance, and plasma renin activity were unrelated to umbilical vessel source or gestational age. Digoxin-like immunoreactive substance was directly related to PCO2 (r = 0.63, p = 0.02). Digoxin-like immunoreactive substance level was elevated in all fetal disease states studied except isoimmunization. The level of atrial natriuretic factor was elevated in fetuses with immune hydrops (NS). Norepinephrine and epinephrine levels were higher in the umbilical artery than in the vein (p = 0.05 and 0.006, respectively). There was a significant correlation between norepinephrine and gestational age in normal fetuses (r = 0.7637, p less than 0.025) and between both catecholamines and many of the respiratory blood gas measurements, with pH and PCO2 being the major determinants. Most disease states were associated with an elevated norepinephrine concentration. There was a negative correlation between plasma renin activity and base deficit (p less than 0.0001). Plasma renin activity was elevated in fetuses with idiopathic growth retardation and nonimmune hydrops (p less than 0.05 for each). In summary, fetal homeostasis as reflected by these five hormones was altered by a variety of disorders. With these baseline values the effects of direct or indirect fetal therapy can begin to be studied.

The mechanism of reduced antithrombin III activity in women with preeclampsia

The cause(s) of the low plasma antithrombin III activity in women with preeclampsia is unknown. The purpose of this study was to evaluate the relationship between plasma antithrombin III activity and both clotting parameters (platelet count and fibrinopeptide A) and renal parameters (serum creatinine and uric acid concentration). Forty-seven preeclamptic women were studied within the 2-day interval before delivery. Creatinine did not correlate significantly with any of the other study parameters. However, there were significant correlations between antithrombin III activity and platelet count (r = 0.53, P less than .005) and between antithrombin III and fibrinopeptide A (r = -0.29, P less than .05). The correlation between platelet count and fibrinopeptide A was not significant. These findings support the hypothesis that antithrombin III consumption by fibrin generation is initiated by platelet activation, and is at least one cause of the low activity level known to occur in women with preeclampsia.

Does the intravenous infusion of ritodrine or magnesium sulfate alter the hemodynamic response to hemorrhage in gravid ewes?

The purpose of this study was to determine whether the intravenous infusion of ritodrine or magnesium sulfate alters the hemodynamic response to maternal hemorrhage in gravid ewes. Twenty-seven experiments were performed in 12 chronically instrumented animals at 0.8 of timed gestation. Each animal was subjected to hemorrhage (20 ml/kg over 60 minutes) during infusion of ritodrine (0.004 mg/kg/min), magnesium sulfate (4 gm/hour), or saline solution control. Infusion of magnesium sulfate increased the mean (+/- SEM) maternal serum magnesium concentration to 4.8 +/- 0.2 mg/dl before hemorrhage and 5.3 +/- 0.3 mg/dl after hemorrhage. At the end of hemorrhage maternal mean arterial pressures were 63% +/- 4%, 82% +/- 2%, and 79% +/- 6% of baseline in the magnesium sulfate, ritodrine, and control groups, respectively. The maternal mean arterial pressure response in the magnesium sulfate group differed significantly from the maternal mean arterial pressure responses in the ritodrine and control groups (p less than 0.01). Fetal pH was decreased significantly only in the magnesium sulfate group (p = 0.0001). Fetal PO2 was decreased significantly in the magnesium sulfate and ritodrine groups (p less than 0.001) but not in the control group. We conclude that magnesium sulfate but not ritodrine, worsened the maternal hypotensive response to hemorrhage in gravid ewes.

Transplacental passage and hemodynamic effects of esmolol in the gravid ewe

Using a chronic maternal-fetal sheep preparation, the authors determined the transplacental passage and the hemodynamic changes consequent to maternal administration of esmolol. Fifteen experiments were performed in six chronically instrumented pregnant ewes near term. Each animal received esmolol iv, 500 micrograms.kg-1.min-1, for 4 min and then 300 micrograms.kg-1.min-1 for 6 min. Maternal and fetal blood esmolol concentrations (mean +/- SEM) were 1.2 +/- 0.28 and 0.1 +/- 0.03 micrograms/ml, respectively, at the completion of the infusion, and 0.03 +/- 0.01 microgram/ml in the mother and not detectable in the fetus 10 min after stopping the infusion. Despite the relatively low blood esmolol concentration in the fetus compared to the mother, the hemodynamic effects in the fetus were similar to those in the mother. The maximal decrease of maternal mean arterial pressure (MAP) and heart rate (HR) were 7 +/- 2 and 14 +/- 3% (mean +/- SEM), respectively (P less than .05). The maximal decrease of fetal MAP and HR were 7 +/- 2 and 12 +/- 3%, respectively (P less than .05). No changes were seen in maternal or fetal acid-base variables, and intra-amniotic pressure was not affected. The authors conclude that esmolol has a rapid but relatively small transplacental passage, and it is eliminated rapidly from both maternal and fetal plasma.

Effect of varying degrees of "normal" glucose metabolism on maternal and perinatal outcome

Prior studies concerning effects of varying degrees of normal glucose metabolism on pregnancy have reported an increase in the incidence of a variety of pregnancy complications in women with normal oral glucose tolerance test results as the glucose concentration after a standardized meal rose. However, these investigations have neglected to include a control group of women with gestational diabetes for comparison. We theorized that if the adverse outcomes noted were indeed a reflection of glucose concentration, women with gestational diabetes should have an even higher incidence of these complications. Mother and infant charts of 312 consecutive women undergoing an oral glucose tolerance test were reviewed. A glucose challenge test preceded the oral glucose tolerance test in 310. The glucose challenge test value was less than 140 mg/dl in 64 and greater than or equal to 140 mg/dl in 246. There were 63 abnormal oral glucose tolerance test results (2.7% of the population studied). Among all patients, the relationship between glucose challenge test and oral glucose tolerance test values followed a gradient with a progressive rise in mean oral glucose tolerance test values when the glucose challenge test result was greater than or equal to 160 mg/dl. However, the incidence of an abnormal oral glucose tolerance test result did not rise significantly until the glucose challenge test result exceeded 180 mg/dl. A wide variety of outcome parameters were studied; none were related to the glucose challenge test value. Similar analysis of the 2-hour oral glucose tolerance test value revealed an increase in the incidence of nonelective operative deliveries and a decrease in the percentage of infants discharged home with their mother where values were greater than 180 mg/dl. However, when women with gestational diabetes were excluded from analysis, neither the glucose challenge test nor the 2-hour glucose tolerance test measurements were related to adverse outcome. When analysis was limited to women with gestational diabetes, there was no clinically significant relationship between either glucose challenge test or 2-hour glucose tolerance test and the outcome parameters. Finally, when analysis was repeated according to diagnosis, women with gestational diabetes had a significantly higher risk of having nonelective operative delivery, premature delivery, growth-retarded neonate, 1-minute Apgar score less than 7, and neonatal hypoglycemia than women with normal oral glucose tolerance test results.(ABSTRACT TRUNCATED AT 400 WORDS)

The therapeutic efficacy and cost-effectiveness of aggressive tocolysis for premature labor associated with premature rupture of the membranes

We conducted a randomized trial comparing bed rest with tocolysis to determine the therapeutic efficacy, safety, and cost-effectiveness of tocolysis for the treatment of preterm labor after membrane rupture. One hundred nine women participated over a 26-month interval. Treatment groups did not differ significantly in terms of gestational age at membrane rupture, gestational age at delivery, birth weight, maternal or fetal infectious morbidity, respiratory distress syndrome, necrotizing enterocolitis, or perinatal mortality. Prolongation of intrauterine time after the onset of uterine contractions was seen in women receiving tocolysis (105.2 +/- 157 hours versus 62.1 +/- 77 hours, p = 0.06). This prolongation was not associated with a significant reduction in the total cost per surviving infant (tocolysis, $38,593 +/- $40,887 versus bed rest, $43,158 +/- $37,116; p = 0.445). The cost difference was artifactual. The number of very premature infants born (less than 28 weeks' gestation) was unequal in the two groups (12 in the bed rest group and 5 in the tocolysis group) and skewed the results. Before 28 weeks' gestation tocolysis was associated with a significant increase in intrauterine time after the onset of regular contractions (p = 0.05). However, there was no identifiable perinatal benefit garnered from the additional 5 days. After 28 weeks there were no significant differences between treatment groups in terms of intrauterine time after the onset of regular contractions and total cost per surviving infant. Because tocolysis does not improve perinatal outcome and can itself be associated with major maternal morbidity, it should be avoided after 28 weeks' gestation. Before 28 weeks' gestation tocolysis may greatly increase intrauterine time, but the benefit of this prolongation is not clear.

Cordocentesis

The development of cordocentesis has permitted for the first time safe and direct evaluation of our second patient. The information garnered from the specimens obtained by cordocentesis will lay the groundwork for the development of primary-care fetal medicine--fetology.

The effect of vasopressor agents upon uterine artery blood flow velocity in the gravid guinea pig subjected to ritodrine infusion

The purpose of the present study was to assess the effects of intravenously administered vasopressors upon uterine artery blood flow velocity (UBFV) in the gravid guinea pig subjected to ritodrine infusion. Fourteen experiments were performed in 14 chronically instrumented pregnant guinea pigs near term. Immediately following a 1-h intravenous infusion of ritodrine (0.05-0.20 mg.kg.min-1), each animal received an intravenous bolus of vasopressor solution: 1) epinephrine, 0.001 mg/kg; 2) phenylephrine, 0.01 mg/kg; 3) mephentermine, 1.0 mg/kg; 4) ephedrine, 1.0 mg/kg; or 5) placebo. The experimental sequence was performed five times, so that each animal received all five solutions. The vasopressor sequence was randomly altered between animals. Infusion of ritodrine increased maternal heart rate 18 +/- 1% (P less than .0001), decreased maternal mean arterial pressure (MMAP) 4 +/- 1% (P less than .01), and decreased UBFV 5 +/- 1% (P less than .001). The four active vasopressor solutions resulted in similar, though not equivalent, increases in MMAP. Further, the MMAP response to each active vasopressor differed from the response to placebo (P less than .0001). Epinephrine and phenylephrine each significantly decreased UBFV (P less than .002). Ephedrine clearly preserved UBFV, whereas mephentermine appeared to result in an intermediate response.

Direct treatment of fetal supraventricular tachycardia after failed transplacental therapy

Digitalization by direct intramuscular injection of the fetus successfully controlled supraventricular tachycardia at 24 weeks' gestation after more traditional intensive trials of transplacental therapy with digoxin, verapamil, and procainamide, either separately or in combination, had failed. The fetal pharmacokinetics were calculated from fetal blood samples obtained by cordocentesis. No clear evidence of placental transfer of digoxin administered to the mother could be found despite a digoxin concentration in the mother that ranged from 1.8 to 2.6 ng/ml for 4 days. After direct fetal digitalization we calculated that the coefficient of elimination for digoxin from the fetus was 0.0463 h-1, and digoxin elimination half-life was 15.9 hours. The latter time span is substantially less than the 50-hour half-life previously reported in newborn infants with low birth weight. The fetal/maternal concentration ratio of procainamide was 0.914. However, maternal clearance of procainamide (9.7 ml/kg-1/min-1) was twice as long as the clearance reported for nonpregnant patients undergoing fast acetylation. We conclude first, that at least in the dose of this ill fetus, little digoxin administered to the mother crossed the placentae; and second, that while direct fetal therapy with digoxin is effective, the necessary frequent number of injections render this therapy impractical. Direct fetal digitalization should probably be reserved for the preterm fetus who has evidence of heart failure and has not responded to maternally administered therapy other than digoxin.

MR imaging of pregnancy in bicornuate uterus

We report a case of incarcerated bicornuate pregnancy diagnosed by magnetic resonance. In this unusual case both CT and sonography suggested an abdominal pregnancy. Magnetic resonance may be a valuable adjunct to sonography in the management of the complicated pregnancy in spite of nonvisualization of the fetal parts due to fetal movement.

Cordocentesis for diagnostic indications: two years' experience

Cordocentesis was performed 96 times over a two-year interval, for a variety of diagnostic indications, in 55 completed pregnancies of 16-40 weeks' duration. There were four unsuccessful procedures, two associated with severe hydramnios and posterior placentas in which the available needles were too short. Sixty-three percent of procedures were successful on the first try; 95% succeeded within three attempts. Sixty-four percent of the samples were obtained from the placental cord origin, 27% from a free-floating loop, and 9% from the fetal cord origin. There were no maternal or significant fetal complications, and bleeding from the puncture site was not a problem. The present series confirms previous reports suggesting that in the proper hands, cordocentesis for diagnosis is a safe, rapid, and efficient means of obtaining access to the fetal circulation.

Subchorionic hemorrhage: sonographic diagnosis and clinical significance

Twenty-one pregnancies with sonographic evidence of subchorionic hemorrhage were evaluated clinically and sonographically. Clinical evaluation included maternal age, gravidity, parity, gestational age, presence of pain, presence and amount of bleeding, and pregnancy outcome. Sonographic evaluation included the relative and absolute size of the hematoma, its echogenicity and location in relation to the placenta, the presence of marginal placental abruption, and progress on follow-up examinations. The outcome of these pregnancies was unfavorable in 15 cases (71%) and correlated well with the relative and absolute size of the hematoma, severity of vaginal bleeding, change in hematoma size on follow-up examination, and presence of pain. There was no significant correlation between the outcome and the echogenicity of the hematoma, presence of placental margin elevation, gestational and maternal age, gravidity, or parity. All hematomas extended to the margin of the placenta. Subchorionic hemorrhage is a frequent cause of first and second trimester bleeding and has a grave prognosis. Familiarity with the varied sonographic appearances and meticulous sonographic examination with special attention to the placental margins can be helpful in the diagnosis.

Digoxin-like immunoreactive substance in fetuses with and without cardiac pathology

The concentration of digoxin-like immunoreactive substance was measured by immunoassay in umbilical venous blood from six normal and 19 fetuses with a variety of cardiac and noncardiac disorders. Fetal blood was obtained either by percutaneous umbilical blood sampling (n = 13) or at delivery (n = 12). Three women received digoxin for fetal indications. Healthy control fetuses had significantly less digoxin-like immunoreactive substance measured (mean concentration below the limit of the assay sensitivity) than was found in ill fetuses whose mothers received digoxin (p less than 0.005). However, the fetal concentrations of immunoreactive digoxin in fetuses with a cardiac abnormality were similar whether the mother had (0.93 +/- 0.4 ng/ml) or had not (1.27 +/- 0.4 ng/ml) received digoxin (p = 0.1452). Although there was a significant negative correlation between digoxin concentration and gestational age (R = -0.5079, p less than 0.01), the youngest fetuses examined were generally the sickest. The correlation with gestational age was not significant if the normal control fetuses were excluded. One fetus with a cardiac tachyarrhythmia was examined during and after transplacental therapy. There was no change. It is possible that previously measured "digoxin" in "treated" fetuses represents digoxin-like immunoreactive substance and that only small amounts of maternally administered digoxin actually reach the ill fetus. Our findings suggest that a randomized trial of maternal digitalization for the treatment of fetal supraventricular tachycardia is essential prior to its acceptance as effective therapy.

Diagnosis of gestational diabetes by capillary blood samples and a portable reflectance meter: derivation of threshold values and prospective validation

Paired capillary-venous samples were obtained from 255 women undergoing a glucose challenge test and 116 women undergoing an oral glucose tolerance test. The capillary equivalents for the venous threshold values were calculated by regression analysis. The glucose challenge test predictions of either normal or abnormal agreed in 82%. The sensitivity, specificity, and positive and negative predictive values for the capillary oral glucose tolerance test were 89%, 90%, 62%, and 98%, respectively. These capillary equivalents were then applied prospectively to 147 women undergoing a glucose challenge test and 141 women undergoing an oral glucose tolerance test. The concurrence rate of the glucose challenge test in the prospective group was 90%. The sensitivity, specificity, and positive and negative predictive values for the capillary oral glucose tolerance test were 64%, 95%, 75%, and 92%. When the venous threshold recommendations of the American Diabetes Association were used instead of those standard at our institution, these values increased to 75%, 98%, 83%, and 96%, respectively. The recommended capillary values of the American Diabetes Association were 100% sensitive but had a positive predictive value of only 20%. Based on the prospective group, the cost per case of gestational diabetes identified would decline 63% if both a capillary glucose challenge test and an oral glucose tolerance test were used and 25% if the capillary glucose challenge test and venous oral glucose tolerance test were used. Combining the data set for new regression equations, the following venous-capillary threshold sets emerged: glucose challenge test, 140 mg/dl/150 mg/dl; fasting oral glucose tolerance test, 105 mg/dl/114 mg/dl; 1 hour, 190 mg/dl/211 mg/dl; 2 hours, 165 mg/dl/183 mg/dl; 3 hours, 145 mg/dl/157 mg/dl. The sensitivity, specificity, and negative predictive values for the capillary oral glucose tolerance test with these thresholds were 80%, 97%, 80%, and 97%. In conclusion, capillary glucose testing for diabetes during pregnancy is feasible and cost-effective.

Heparin-neutralizing activity in the plasma of women with gynecologic malignancy: the effect of tumor stage on heparin concentration and fibrin generation after low-dose heparin

The relationship between tumor stage and the concentration of circulating heparin achieved after subcutaneous administration and its effect on fibrin generation were studied in 24 women with gynecologic malignancy. A single subcutaneous injection of 5000, 7500, and 10,000/U of sodium heparin was given in random order on different days. Plasma specimens for antithrombin III, fibrinopeptide A, and heparin were obtained serially over an 11-hour interval. Women with a Stage III or IV malignancy had significantly lower circulating heparin after the 5000 and 10,000/U doses. There was a significant decline in fibrinopeptide A as the concentration of circulating heparin increased. Thirty-three percent of women with a Stage III or IV malignancy had no detectable circulating heparin at any point examined over the 11 hours after 5000/U of heparin. Likewise, 16.7% and 8.4% had no detectable circulating heparin after 7500 and 10,000/U, respectively. A similar percentage was noted in a smaller group of women with Stage II malignancy. Next, a known quantity of heparin was added to the plasma from these patients and the concentration of heparin was determined. A significant amount of heparin-neutralizing activity was documented. We conclude that a large percentage of women with an advanced gynecologic malignancy are able to neutralize heparin administered for the prevention of thromboembolic disease. This heparin-neutralizing activity may account for the failure of low-dose heparin to prevent thromboembolic complications in this patient population.

The role of serotonin in the genesis of hypertension in preeclampsia

While it is generally accepted that preeclampsia is a disease of the microvasculature characterized by an imbalance between prostacyclin and thromboxane and that the evidence for enhanced responsiveness to some vasopressors is present weeks before clinical disease, the specific cause of the hypertension characterizing the syndrome is unknown. A number of endogenous vasopressor substances have been examined without conclusive findings. Pharmacologic and methodologic advances over the last decade have resulted in a body of information implicating serotonin as a mediator in the genesis of preeclamptic hypertension. This information is summarized and a possible mechanism of delivery and action is suggested.

The clinical spectrum of preeclampsia

Though classically a disease of the near term nullipara, the chameleonlike presentation of preeclampsia makes the diagnosis at times difficult and in most circumstances presumptive. A high index of suspicion is important. Early and frequent prenatal examinations coupled with laboratory parameters should reduce diagnostic error.