Congenital infection

The past year has shed much new light on congenital infection. A key development has been the application of polymerase chain reaction technology to the diagnosis of intrauterine infection. This technique appears to be the diagnostic tool of choice for toxoplasmosis and cytomegalovirus. Pharmacologic treatment appears to reduce the sequellae of toxoplasmosis when treated either in utero or postnatally. Obstetric interventions may reduce vertical transmission. Education has been shown to reduce the incidence of seroconversion for toxoplasmosis, and HIV-positive women treated with zidovudine have a dramatically reduced rate of transmission to their offspring.

Growth deficient fetuses with absent or reversed umbilical artery end-diastolic flow are metabolically compromised

Controversy continues regarding the clinical relevance of absent or reversed umbilical artery blood flow during diastole. The purpose of this study was to characterize the blood gas and lactate measurements of growth deficient fetuses with absent (ADF) or reversed (RDF) umbilical artery (UA) diastolic flow. In a descriptive study from February 1988 through October 1991, 42 consecutive structurally and karyotypically normal growth deficient fetuses identified to have either ADF or RDF diastolic flow in the UA were studied. Heparinized blood specimens were obtained from them and the pH, PCO2, PO2 and lactate measured. Fourteen of these specimens were obtained from the umbilical vein by cordocentesis and 28 at the caesarean delivery of non-labouring patients. Statistical analyses were performed using Fisher's exact test, Student t-test and linear correlation. All measured parameters in fetuses with ADF or RDF undergoing cordocentesis were significantly abnormal compared to gestational age corrected norms. Both the mean venous and arterial pH of fetuses with RDF were significantly lower than that of fetuses with ADF. With few exceptions, preoperative maternal oxygenation failed to correct the fetal hypoxaemia associated with either ADF or RDF. In the setting of severe fetal growth deficiency secondary to uteroplacental dysfunction, ADF and RDF are clinically reliable indicators of fetal compromise as determined by the umbilical blood gases. RDF is associated with a greater impairment of placental gas exchange than ADF.

Regionalization of endothelium-dependent relaxation in the thoracic aorta of pregnant and nonpregnant guinea pigs

Regional variation in the response of the thoracic aorta to contractile agonists has previously been demonstrated. Since the net contractile response reflects the interaction between smooth muscle activation and the release of endothelial substances, we hypothesize that agonist-stimulated release of endothelium-derived nitric oxide (NO) also varies along the length of the thoracic aorta. The distribution of thoracic aorta estrogen receptors is also regionalized. Since pregnancy augments the release of endothelium-derived NO by acetylcholine (ACh) in some arterial beds, we further hypothesize that pregnancy enhances the stimulated release of NO from the thoracic aorta. Aortae were removed from nonpregnant and near term pregnant guinea pigs and cut into ring segments numbered sequentially proximal to distal. The rings were suspended at their optimal passive tension and submaximally contracted with prostaglandin F2 alpha. Endothelium-derived NO-dependent relaxation to ACh increased moving proximal to distal along the aorta independent of pregnancy and ACh relaxation was unaffected by pretreatment with physostigmine to inhibit cholinesterase. The magnitude of the relaxation to carbachol among the different segments was similar to ACh. Pregnancy decreased the ED50 for ACh of segments from the middle and distal segments of the thoracic aorta. Relaxation to the NO donor sodium nitroprusside and the nonreceptor-mediated endothelium-dependent relaxing agent A23187 was uniform along the length of the aorta and independent of pregnancy. These experiments demonstrate regional variation in the stimulated release of endothelium-derived NO in the guinea pig thoracic aorta which is increased by pregnancy.

Pregnancy increases guanosine 3',5'-monophosphate in the myometrium independent of nitric oxide synthesis

The mechanism for myometrial quiescence during pregnancy is unknown. cGMP plays an integral role in the relaxation of smooth muscle, and nitric oxide (NO) is the most important endogenous activator of soluble guanylate cyclase. The purpose of this study was to determine the effect of gestational age on myometrial cGMP and NO synthase (NOS) activity in the guinea pig. Myometrial cGMP content (measured by RIA) rose slowly until 0.49 (fraction of pregnancy completed) gestation before abruptly increasing to 200 times the non-pregnant control value. It then declined precipitously after 0.87 gestation. Of the known isoenzymes of NOS, the messenger RNAs coding for both endothelial and neuronal NOS could be amplified from the myometrium of pregnant and nonpregnant animals using reverse transcriptase-polymerase chain reaction, but inducible NOS messenger RNA was not found. Myometrial calcium-dependent NOS activity (measured by the conversion of L-[U-14C]arginine to [U-14C]citrulline) declined slowly with advancing gestation (r2 = 0.096; slope = -0.34; P = 0.01), but never differed significantly from the activity in nonpregnant animals [31.1 +/- 11 (term pregnancy) vs. 56.9 +/- 16 (nonpregnant) pmol/min.g; P = NS]. Calcium-independent activity declined shortly after conception, and then rose toward the nonpregnant level (r2 = 0.19; slope = 0.45; P = 0.0009). However, at no time was it significantly different from that in the nonpregnant animal. Pregnancy had no effect on myometrial L-arginine and L-citrulline content. The administration of L-nitro-arginine methyl ester (200 mg/kg) to inhibit NOS dramatically increased blood pressure and reduced fetal renal NOS activity, but had no effect on the myometrial cGMP content. Estradiol (500 micrograms/kg for 5 days) modestly increased cGMP, but in contrast to many tissues in which estradiol increases NOS, it had no effect on myometrial NOS activity. We conclude that pregnancy dramatically increases cGMP by a mechanism independent of NOS. The stimulus remains to be identified. The temporal change in cGMP concentration is consistent with the hypothesis that cGMP mediates myometrial quiescence during pregnancy.

First trimester three-dimensional ultrasound volumetry of the gestational sac

First trimester amniotic fluid is an ultrafiltrate of maternal plasma and constitutes the major component of gestational sac volume (GSV). We hypothesized that GSV, assessed by 3-dimensional (3-D) ultrasound volumetry, would reflect function of the early uteroplacental unit and therefore provide a basis for predicting pregnancy outcome. We tested this hypothesis in 38 pregnancies which had first trimester GSV measurements by two investigators thus allowing determination of interobserver variation. Gestational age (GA) was based on a careful history and conventional 2-dimensional ultrasound measurements. Serum for beta-hCG, estradiol (E2) and progesterone (P) was obtained at the time of ultrasound examinations. "Normal" outcome was defined as confirmation of a viable fetus. "Abnormal outcome" was defined as either a "blighted ovum" or embryonic demise. Statistical analysis was performed by Independent t-test and regression analysis. There were 31 "normal" and 7 "abnormal" pregnancies studied between 5 and 11 weeks gestation (mean +/- SD 8.3 +/- 1.3 weeks). GSV was significantly correlated to GA (r = 0.74, P < 0.001), higher than to beta-hCG (r = 0.40, P = 0.034), E2 (r = 0.70, P < 0.001) and P (r = 0.21, P = 0.334), respectively. In the abnormal group 2/2 pregnancies with a twin sac had a GSV within 1 SD of the mean. 3/5 cases of missed abortions or blighted ovum had a GSV < 2 SD of the mean. The interobserver correlation was high (r = 0.99, P < 0.00f2p4This is the first clinical study investigating the diagnostic use of 3-D ultrasound volumetry in first trimester pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Nitric oxide: an autocrine regulator of human granulosa-luteal cell steroidogenesis

We investigated the presence of nitric oxide (NO) synthase in ovarian follicular cells obtained from women undergoing in vitro fertilization procedures. Endothelial NO synthase messenger RNA was demonstrated by polymerase chain reaction amplification of reverse transcribed RNA. NO synthase was localized to granulosa-luteal cells by immunocytochemistry, using a monoclonal antibody. Ovarian follicular cell NO synthase enzyme activity was confirmed by measuring the conversion of L-arginine to citrulline. To investigate the effect of NO on granulosa-luteal cell steroidogenesis, NO synthase inhibitors and NO donors were added to cell cultures. NG-Monomethyl-L-arginine and N-nitro-arginase methyl ester, selective inhibitors of NO synthase, significantly increased estradiol secretion by granulosa-luteal cells. S-Nitroso-L-acetyl penicillamine (S-NAP) and S-nitroso glutathione, NO donors, caused a dose-dependent decrease in both estradiol and progesterone secretion. The decrease by S-NAP was reversed by hemoglobin, which binds free NO. Although S-NAP increased the concentration of cGMP in granulosa-luteal cells, cGMP analogs had no effect on steroidogenesis in cell cultures. S-NAP and native NO in solution decreased cellular and microsomal aromatase activities. We conclude that NO synthase is present in human granulosa-luteal cells and that NO inhibits estradiol secretion independent of cGMP by directly inhibiting aromatase.

Diagnosis, pathophysiology, and treatment of chronic twin-to-twin transfusion syndrome

The discovery of a 'stuck twin' during an ultrasound examination has often been equated with twin-to-twin transfusion based to a great extent on postnatal confirmation of discordant fetal size and hemoglobin concentration. However, the diagnosis of twin-to-twin transfusion cannot be made with certainty after birth since virtually all monochorionic gestations have placental anastomoses and there are many causes of growth deficiency and abnormal hemoglobin concentration. The purpose of this study is to investigate the pathophysiology of chronic twin-to-twin transfusion syndrome and apply the findings to the development of a management algorithm. In 42 twin gestations with stuck twin associated with acute hydramnios, we performed targeted ultrasound cordocentesis in each fetus and therapeutic amniocentesis. The diagnosis of chronic twin-to-twin transfusion syndrome required: sonographic evidence of monochorionicity; rapid reaccumulation of fluid after amniocentesis; discordant fetal size, and divergent fetal hematocrit measurements with at least one above or below the 95% confidence interval for gestational age. These criteria were met in 20 of 42 (48%) pregnancies. The mean gestation was 23.8 +/- 2 weeks (range 21-27 weeks). In 4 pregnancies, the transfer of adult RBCs from the donor to the recipient was documented. Monochorionicity was confirmed in all postnatally. All recipients had polycythemia and hyperproteinemia. Hydrops developed only in the recipient twin (6 of 20) and was associated with an elevated umbilical venous pressure. All pregnancies were treated with aggressive serial therapeutic amniocenteses. There was no objective evidence that amniocentesis altered the magnitude of the shunt.(ABSTRACT TRUNCATED AT 250 WORDS)

Induction of nitric oxide synthases early in pregnancy

OBJECTIVE

We have previously demonstrated that calcium-dependent nitric oxide synthase is induced by estrogen and that by the end of pregnancy nitric oxide synthase of both endothelial and neuronal origin is increased in various maternal tissues. This rise in activity may be crucial for the alterations in muscle activity necessary for a successful pregnancy. If so, the increase in nitric oxide synthase activity must occur early in gestation.

STUDY DESIGN

We tested the hypothesis that pregnancy increases nitric oxide synthase activity early in gestation by measuring in heart, kidney, skeletal muscle, and esophagus of time-mated guinea pigs the conversion by nitric oxide synthase of carbon 14-labeled L-arginine to carbon 14-labeled citrulline and the concentration of cyclic guanosine monophosphate, the second messenger of nitric oxide.

RESULTS

Calcium-dependent nitric oxide synthase activity was increased twofold to fourfold by pregnancy in each tissue examined. The rise began by 0.14 gestation (9 of 63 +/- 2 days) and reached a plateau by 0.30 gestation (19 days), which was then maintained until term. The treatment of pregnant animals with tamoxifen decreased nitric oxide synthase activity to nonpregnant values in the heart, where tamoxifen is an estrogen receptor antagonist, but not in kidney, skeletal muscle, and esophagus. Cyclic guanosine monophosphate also rose progressively in each tissue studied until about 0.70 gestation before declining in skeletal muscle, kidney, and heart. It remained elevated in the esophagus.

CONCLUSION

These studies demonstrate that nitric oxide synthase activity in maternal tissues rises early in pregnancy and is associated with an increase in cyclic guanosine monophosphate, the second messenger of nitric oxide. These findings are consistent with the hypothesis that an increase in nitric oxide synthase plays a role in smooth muscle adaptations of pregnancy.

Effect of pregnancy on contraction and endothelium-mediated relaxation of renal and mesenteric arteries

We have hypothesized that differences in the effect of pregnancy on mechanisms modulating vascular reactivity underlie the redistribution of cardiac output. Because pregnancy increases mesenteric blood flow by 75% and renal blood flow by only 10% in the guinea pig, we investigated the effect of pregnancy on vascular reactivity in these two beds. Relaxation in response to acetylcholine (ACh), an endothelium-dependent relaxing agent, and contraction induced by the thromboxane mimetic U-46619 were measured in ring segments of mesenteric and renal arteries from pregnant and nonpregnant guinea pigs. To determine the role of the endothelium, nitric oxide (NO), and vasodilator prostaglandins in modulating vascular response, rings were denuded, treated with N omega-nitro-L-arginine (L-NNA) to inhibit NO synthase, or treated with indomethacin to inhibit cyclooxygenase. Pregnancy increased ACh-stimulated relaxation of mesenteric arteries but not renal arteries. L-NNA significantly reduced ACh sensitivity (based on the concentration that produced 50% of the maximal response) in arteries from pregnant and nonpregnant animals, and indomethacin slightly decreased maximal relaxation only in the renal artery of nonpregnant animals. ACh sensitivity of mesenteric arteries was still increased after L-NNA or indomethacin. Pregnancy reduced the threshold concentration of U-46619 in mesenteric artery but had no effect on contraction of renal artery. Contraction of both arteries was enhanced by denudation. L-NNA and indomethacin were less effective than denudation in arteries from pregnant and nonpregnant animals, which suggests that pregnancy alters thromboxane contraction by endothelium-dependent mechanisms other than NO and prostaglandins. Thus, pregnancy differentially alters vascular reactivity of mesenteric and renal arteries in the guinea pig.

Outcome of alloimmunized fetuses managed solely by cordocentesis but not requiring antenatal transfusion

A published algorithm for the frequency of fetal blood sampling in the management of fetal hemolytic disease allows many pregnancies to continue 1-3 months after the last sample until delivery at term. Though the positive predictive value for antenatal anemia is known, the likelihood of either neonatal hyperbilirubinemia or an unexpected anemia (< 30%) is not. The perinatal records of 51 antigen-positive neonates who did not require treatment antenatally were abstracted. As fetuses, these neonates had been prospectively coded as either low risk (pattern 1), moderate risk (pattern 2) or high risk (patterns 3 and 4) for antenatal anemia (hematocrit < 30%) based on their hematocrit, reticulocyte count, and the strength of the direct Coombs' test performed on their first sample. Delivery occurred at 38 +/- 2 weeks. Neonatal complications of hemolytic disease were common. Sixty-four percent required phototherapy, 17% one or more double-volume exchange transfusions, and 13% one or more simple transfusions for late-developing anemia. In all, 29% of neonates received postnatal transfusion therapy. The only correlation between the antenatal hematologic/serologic studies and the need for postnatal transfusion therapy was the strength of the indirect Coombs' test performed on the first fetal blood sample. Two neonates unexpectedly had anemia (4% risk). In the first, the hematocrit at 35 weeks was 40% and the ultrasound 1 week later normal. In one, the algorithm had been erroneously applied. Stability of the hematocrit in fetuses at risk to develop antenatal anemia can be accurately predicted by fetal blood tests performed weeks prior to delivery.(ABSTRACT TRUNCATED AT 250 WORDS)

Direct relationship of fetal carboxyhemoglobin with hemolysis in alloimmunized pregnancies

Because carbon monoxide (CO) is a byproduct of heme degradation and because placental diffusing capacity of CO is limited, we hypothesized that the concentration of CO transported in fetal blood as carboxyhemoglobin (HbCO) would correlate with the severity of fetal hemolytic disease. Fetal blood was obtained by cordocentesis and HbCO was measured by gas chromatography. The two primary study groups included control fetuses (n = 26) and fetuses of Coombs-positive mothers before in utero transfusion (n = 15). Compared with controls, fetuses with hemolytic disease had higher HbCO levels (0.0111 +/- 0.0014 versus 0.0159 +/- 0.0072 fraction of total Hb, mean +/- SD, p < 0.002). In contrast, HbCO levels in simultaneously sampled maternal blood samples were not different in the control and alloimmune groups [0.0110 +/- 0.0025 (n = 20) versus 0.0115 +/- 0.0021 (n = 11)]. There was a significant inverse correlation observed between fetal HbCO and Hb concentrations in the group with hemolytic disease (r = -0.73, p < 0.002) but not in controls. In fetuses with hemolytic disease, HbCO and bilirubin were highly correlated (r = 0.88, p < 0.0001). Data from four anemic fetuses who were Coombs negative, three of whom had no evidence of hemolysis, indicated normal HbCO and normal plasma bilirubin levels. A fourth fetus with anemia had viral sepsis and elevated HbCO and plasma bilirubin levels. We conclude that elevated HbCO levels detected in fetuses of nonsmoking mothers with erythrocyte alloimmunization are likely the result of accelerated hemolysis.

Induction of calcium-dependent nitric oxide synthases by sex hormones

We have examined the effects of pregnancy and sex hormones on calcium-dependent and calcium-independent nitric oxide synthases (NOSs) in the guinea pig. Pregnancy (near term) caused a > 4-fold increase in the activity of calcium-dependent NOS in the uterine artery and at least a doubling in the heart, kidney, skeletal muscle, esophagus, and cerebellum. The increase in NOS activity in the cerebellum during pregnancy was inhibited by the estrogen-receptor antagonist tamoxifen. Treatment with estradiol (but not progesterone) also increased calcium-dependent NOS activity in the tissues examined from both females and males. Testosterone increased calcium-dependent NOS only in the cerebellum. No significant change in calcium-independent NOS activity was observed either during pregnancy or after the administration of any sex hormone. Both pregnancy and estradiol treatment increased the amount of mRNAs for NOS isozymes eNOS and nNOS in skeletal muscle, suggesting that the increases in NOS activity result from enzyme induction. Thus both eNOS and nNOS are subject to regulation by estrogen, an action that could explain some of the changes that occur during pregnancy and some gender differences in physiology and pathophysiology.

MR of fetal central nervous system abnormalities

PURPOSE

To investigate whether MR can provide additional information on fetuses with central nervous system abnormalities as demonstrated by ultrasonography.

METHODS

Fetal MR examinations were studied prospectively in 22 pregnant women whose fetuses showed evidence of anomalies on ultrasound performed in the High-Risk Obstetric Clinic.

RESULTS

In 19 of 22 cases, postpartum confirmatory diagnoses were obtained by MR or CT examinations, autopsy, or surgery. In general, the image quality of MR is comparable with that of ultrasound. However, in six of 22 cases (27%), MR provided additional information that altered the ultrasound diagnosis; these included cases of infarction, diastematomyelia, normal hemimegalencephaly with early myelination, Dandy-Walker variant, and lipoma. All of these cases had postpartum confirmation. The additional information changed the treatment in three of six patients (no intervention or elective abortion).

CONCLUSIONS

In certain situations MR can add valuable information to that obtained by sonography in the evaluation of the fetal central nervous system.

Fetal echogenic bowel on ultrasound: is there clinical significance?

Though echogenic fetal bowel has been associated with meconium ileus and/or peritonitis, it may be a normal finding in the second trimester. The purpose of this study is to determine which characteristics might distinguish fetuses ultimately having abnormal outcomes in a population at low risk for cystic fibrosis. Seven fetuses with echogenic bowel were identified: 5 fetuses < or = 20 weeks gestation (group 1) and 2 fetuses 20-25 weeks gestation (group 2) at diagnosis. Four of 5 group 1 fetuses had resolution of the echogenic bowel during the second trimester. One group 2 fetus had a persistent mass associated with growth deficiency and trisomy 18. The neonatal bowel evaluation was normal in the remaining 2 fetuses although echogenic findings persisted into the third trimester. In a low-risk population, echogenic bowel usually resolves without neonatal sequelae. Even when persistent into the third trimester, echogenic bowel does not uniformly herald an abnormal outcome. Echogenic bowel coexistent with other abnormalities (such as growth deficiency or structural malformations) may be a comarker for aneuploidy.

Effect of intravenous beta-sympathomimetic tocolysis on human fetal serum erythropoietin levels

OBJECTIVE

The major stimulus for erythropoietin production is tissue hypoxia. We sought to investigate the relationship of beta-sympathomimetic administration for tocolysis and fetal serum erythropoietin.

STUDY DESIGN

Umbilical cord blood was obtained from infants whose mothers received intravenous beta-sympathomimetic tocolysis and who were delivered at < or = 34 weeks' gestation. Serum erythropoietin was measured by radioimmunoassay. On the basis of the presumed 2- to 4-hour half-life of fetal erythropoietin, the infants were divided into two groups. In group 1 (n = 16) beta-sympathomimetic therapy was discontinued < 24 hours before delivery; in group 2 (n = 11) it was discontinued > or = 24 hours before delivery.

RESULTS

Group 1 fetuses had significantly higher erythropoietin levels than did group 2 fetuses (37.3 vs 13.9 mU/ml, p = 0.02). The duration of beta-sympathomimetic tocolysis and the maximum infusion rate were not different. The two groups did not differ in gestational age, birth weight, route of delivery, presence of labor, or duration of first or second stage of labor.

CONCLUSIONS

We speculate that intravenous beta-sympathomimetic tocolytic therapy stimulates fetal erythropoietin production by decreasing fetal oxygenation as a result of the reversible fetal metabolic effects of the tocolysis. These data suggest that beta-sympathomimetic tocolysis should be undertaken cautiously if fetal compromise is suspected, fetal well-being should be assessed carefully if tocolysis is undertaken, and treatment should be discontinued promptly if a clear benefit is not realized.

Endothelium-derived relaxing factor inhibits norepinephrine contraction of fetal guinea pig arteries

As in the adult circulation, the endothelium may play an important role in determining fetal vascular tone. The purpose of this study was to determine the influence of the endothelium on norepinephrine- and phenylephrine-induced contraction of pulmonary and carotid arteries from near-term fetal guinea pigs. Isometric contractions of isolated rings to the cumulative addition of norepinephrine (10(-9)-10(-5) M) were measured before and after 1) endothelium removal, 2) NG-monomethyl-L-arginine (L-NMMA; 10(-4) M) to inhibit endothelium-derived relaxing factor (EDRF), 3) methylene blue (10(-5) M) to inhibit guanylate cyclase, 4) oxyhemoglobin (3 x 10(-6) M) to bind EDRF, and 5) indomethacin (10(-5) M) to inhibit cyclooxygenase. All treatment effects were measured in endothelium-intact segments. The maximal norepinephrine contraction of fetal pulmonary (40 +/- 8% KCl, n = 7) and carotid (13 +/- 7% KCl, n = 7) arteries was much less (P < 0.05) than the maximal contraction to 120 mM KCl. Treatments that inhibit the action of EDRF increased contraction of both fetal pulmonary and carotid arteries. L-NMMA also increased contraction to phenylephrine. Indomethacin had no effect on the contractile responses to norepinephrine of either artery. Thus EDRF inhibits alpha-adrenoceptor-stimulated contraction of fetal pulmonary and carotid arteries and may attenuate the constrictor responsiveness of the fetal circulation in vivo.

Umbilical pressure measurement in the evaluation of nonimmune hydrops fetalis

OBJECTIVE

Nonimmune hydrops fetalis continues to have a perinatal mortality rate > 50%. Although many abnormalities are associated with nonimmune hydrops fetalis, the direct mechanism by which the hydrops occurs is often obscure, even after delivery. There are at least three possible mechanisms for hydrops: heart failure (whether primary or a secondary effect of obstructed venous return), lymphatic malformation, and liver or peritoneal disease. The development of safe access to the fetal circulation by cordocentesis allows for the measurement of the umbilical venous pressure, which is closely related to the fetal central venous pressure. The premise that nonimmune hydrops fetalis of cardiac origin could be distinguished from that of noncardiac origin was examined by measuring the umbilical venous pressure.

STUDY DESIGN

Umbilical venous pressure was measured during indicated diagnostic cordocentesis in three groups of fetuses: 20 with nonimmune hydrops fetalis, four with a cardiac malformation but without nonimmune hydrops fetalis, and eight with immune hydrops (fetal hemolytic disease). In 16 of 20 fetuses with nonimmune hydrops fetalis the serum total protein and albumin concentrations were also measured.

RESULTS

Presumed inadequate cardiac output, as indicated by an elevated umbilical venous pressure, was the mechanism of nonimmune hydrops fetalis in 13 of 20 (65%). The pathologic condition included arrhythmia, cardiothoracic abnormalities, severe polycythemia and hyperviscosity, viral infection, and severe anemia. Successful antenatal treatment normalized the umbilical venous pressure. Nonimmune hydrops fetalis secondary to noncardiac mechanisms did not progress in severity and was not amenable to antenatal therapy. Hypoproteinemia and hypoalbuminemia were found in only six of 16 cases and were similarly distributed between cardiac and noncardiac mechanisms.

CONCLUSIONS

This is the first report where the measurement of umbilical venous pressure was applied to the evaluation of nonimmune hydrops fetalis. Cardiac dysfunction was the most common mechanism causing hydrops. The finding of a normal umbilical venous pressure greatly reduces the likelihood that the heart is the cause of the hydrops, even when there is a coexistent heart malformation. This immediate information allows the practitioner either to focus on therapeutic interventions that might lower the umbilical venous pressure or to look for noncardiac causes for the hydrops.

"Normal" umbilical arterial and venous acid-base and blood gas values

Study groups often considered representative of entire populations inevitably do not consider normal fetuses because nonpathologic events can alter the study parameters. Therefore, the term "normal" and its range, when used for comparisons, must be scrutinized by the obstetrician, pediatrician, and those with medicolegal concerns.

Diagnosis of fetal infection in the patient with an ultrasonographically detected abnormality but a negative clinical history

Unsuspected fetal infection (viral or parasitic) is often overlooked as a possible cause of abnormalities revealed on ultrasonographic examination during pregnancy. Infectious agents can produce a wide spectrum of ultrasonographic findings. Our objective was to highlight those findings and review the rationale and method of antenatal investigation. No ultrasonographic findings are pathognomonic for a particular agent. The search for possible fetal infection consists of both direct and indirect techniques. Methods to directly demonstrate fetal infection include maternal-fetal serologic studies, culture, electron microscopy, and polymerase chain reaction. Emerging evidence strongly suggests that prior assumptions concerning the sensitivity of both maternal and fetal-neonatal serologic studies are incorrect. Serologic studies alone are inadequate to exclude fetal infection as a cause of an ultrasonographically detected abnormality. Indirect techniques suggestive of fetal infection include fetal hematologic and biochemical measurements. New approaches and methods for the detection of fetal infection are needed. The evaluation should be initiated antenatally. Needless delay until after delivery increases the likelihood that the diagnosis will be missed. Antenatal diagnosis provides the opportunity for therapy and often leads the practitioner to modify the obstetric and neonatal care plan. A protocol used by the University of Iowa Fetal Diagnosis and Treatment Unit for the diagnosis and management of unsuspected fetal infection is offered as an example of a protocol that has been successful in the past.

Pregnancy reduces serotonin-induced contraction of guinea pig uterine and carotid arteries

Because platelet activation and serotonin have been implicated in preeclamptic hypertension, we investigated the effect of pregnancy on the contractile response to this agent. Prior studies have shown that the vascular contractions to norepinephrine, angiotensin II, and thromboxane are reduced during normal pregnancy by the altered release of endothelium-derived vasoactive substances. We hypothesized that the contraction to serotonin would also be reduced during pregnancy by an endothelium-dependent mechanism. Isolated ring segments from uterine and carotid arteries of near-term pregnant and nonpregnant guinea pigs were studied after stimulating a small amount of active tone with prostaglandin F2 alpha. Serotonin (10(-8) to 10(-5) M) contractile responses of both arteries were reduced by pregnancy. Regardless of pregnancy status, the contractile responses of the uterine artery to serotonin were severalfold greater than that of the carotid artery whose maximum averaged only 10% of the 120 mM KCl contraction. Denudation of uterine artery abolished acetylcholine-stimulated relaxation in vessels from pregnant and nonpregnant animals. However, serotonin-induced contractions were enhanced by denudation only in ring segments obtained from pregnant animals. Nitric oxide synthase inhibition by either NG-monomethyl-L-arginine (L-NMMA) or N omega-nitro-L-arginine and cyclooxygenase inhibition by indomethacin had no effect on serotonin-induced contraction of intact uterine artery regardless of pregnancy. L-NMMA modestly enhanced the intact carotid arterial response to 10(-5) M serotonin independent of pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Antenatal treatment of fetal alloimmune thrombocytopenia

OBJECTIVE

To review our experience with, and to evaluate the efficacy of, antenatal pharmacologic treatment of pregnancies complicated by alloimmune thrombocytopenia.

METHODS

We reviewed the records of six pregnancies complicated by alloimmune thrombocytopenia recently cared for at the University of Iowa Fetal Diagnosis and Treatment Unit. All patients had a history consistent with alloimmune thrombocytopenia in a previous gestation. All fetuses had thrombocytopenia on funipuncture at 20-32 weeks' gestation, and all patients and fetuses demonstrated a platelet antigen incompatibility. Three women initially received weekly gamma globulin infusions, two received gamma globulin and dexamethasone, and one had no initial treatment but was given gamma globulin and dexamethasone at 32 weeks' gestation. Repeat funipuncture was performed at 3.5- to 7-week intervals, and therapeutic modifications were made as necessary.

RESULTS

In five cases, the last funipuncture before delivery documented platelet counts adequate for vaginal delivery. One woman, who received gamma globulin alone with good initial response, was delivered by cesarean for a platelet count of 25,000/microL at 39 weeks. Following delivery, all infants were thoroughly evaluated, and none had evidence of intracranial hemorrhage or other alloimmune thrombocytopenia-associated morbidity. All had normal platelet counts at discharge from the hospital.

CONCLUSIONS

Our experience confirms the efficacy of gamma globulin treatment, but indicates that not all fetuses will respond to it alone. Serial funipunctures are essential to evaluate patient response and allow appropriate therapeutic modifications. Randomized studies are needed to determine the optimal antenatal pharmacologic therapy for this disease.

The effect of fetal age upon normal fetal laboratory values and venous pressure

Eighty fetuses referred because of maternal alloimmunization or maternal infection underwent umbilical venipuncture and were found to be unaffected. Norms for hematologic, biochemical, and pressure measurements were constructed from 18 weeks until term. Total red blood cell (RBC) count (p less than .0001), hemoglobin (p less than .0001), white blood cell count (p less than .0001), and platelet count (p = .04) and volume (p less than .03) each rose with advancing gestation. The number of nucleated RBCs declined significantly (p less than .0001). Umbilical vein carbon dioxide pressure rose (p less than .009) and oxygen pressure declined (p = .005) with advancing gestation. Total protein and albumen rose (each p less than .0001). Aspartate aminotransferase (p less than .02), alanine transferase (p less than .0001), and gamma-glutamyl transpeptidase (p less than .0001) each rose with gestation, independent of any other measured value. The rise in lactic dehydrogenase with gestation was found to depend on pH (p = .0002) rather than gestational length. Paired maternal-fetal serum samples were obtained from an additional 50 abnormal fetuses; there was no significant relationship between mother and fetus for the concentrations of any of the studied enzymes. Umbilical vein pressure rose progressively with gestational age (p less than .004). These studies reveal new information on fetal development and provide a baseline from which to evaluate either fetal disease or the response to therapy.

Human fetal bilirubin levels and fetal hemolytic disease

The development of secondary fetal anemia in association with maternal red blood cell alloimmunization requires hemolysis. In specimens obtained at the time of a clinically indicated cordocentesis, total and direct umbilical venous bilirubin was measured and the indirect umbilical venous bilirubin calculated in 43 antigen-positive and 30 control fetuses. Twenty-two (51%) of the antigen-positive fetuses had or subsequently developed severe anemia (hematocrit less than 30%). Umbilical venous total bilirubin (r = 0.47, p = 0.0008) and direct bilirubin (r = 0.520, p = 0.04) levels each rose with gestation. Indirect bilirubin did not vary significantly with gestation. Bilirubin was unrelated to hemoglobin. In contrast to the control fetuses, umbilical venous total bilirubin for antigen-positive fetuses was inversely related to hemoglobin (r = -0.57, p less than 0.0001) independent of gestational age (r = 0.53, p less than 0.0001) (multiple R of hemoglobin and gestational age for umbilical venous total bilirubin = 0.76, p less than 0.0001). Eighteen of 22 (82%) fetuses in whom anemia developed had an umbilical venous total bilirubin greater than or equal to 97.5 percentile compared with only eight of 21 (38%) fetuses in whom anemia did not develop (p = 0.009). In longitudinal study the umbilical venous total bilirubin frequently rose above normal weeks before the development of anemia. An umbilical venous total bilirubin greater than 3 mg/dl represented the warning line. Fifteen of 16 (94%) fetuses in whom either severe antenatal anemia or significant postnatal hyperbilirubinemia developed had an umbilical venous total bilirubin greater than 3 mg/dl. We conclude that the normal placental capacity for the transport of fetal bilirubin is exceeded in the face of enhanced fetal hemolysis. An elevated fetal bilirubin often precedes the development of antenatal anemia. The antigen-positive fetus with an elevated bilirubin is at high risk to develop anemia antenatally.

Endothelium-derived relaxing factor and indomethacin-sensitive contracting factor alter arterial contractile responses to thromboxane during pregnancy

OBJECTIVES

Pregnancy reduces uterine artery contractile responses to norepinephrine and angiotensin II in many species, including the human and the guinea pig, by release of endothelium-derived relaxing substances. We hypothesized that vascular reactivity to thromboxane during pregnancy would also be reduced by a similar mechanism.

STUDY DESIGN

Isolated ring segments of uterine and carotid arteries from nonpregnant and near-term pregnant guinea pigs were suspended in a myograph for the measurement of isometric tension.

RESULTS

Uterine but not carotid artery sensitivity to cumulative addition of the thromboxane analog U46619 was decreased during pregnancy. The maximal contractile responses of both vessels were unaltered by pregnancy. N omega-nitro-L-arginine (10(-4) mol/L), an inhibitor of nitric oxide endothelium-derived relaxing factor synthesis, increased the sensitivity of uterine and carotid arteries to U46619 in both pregnant and nonpregnant animals. The maximal contractile response of uterine arteries from pregnant guinea pigs was also increased, but that of nonpregnant ones was not. The maximal U46619 contractile response of the carotid artery was not significantly altered by N omega-nitro-L-arginine. Indomethacin (10(-5) mol/L), a cyclooxygenase inhibitor, reduced both the sensitivity and the maximal response of U46619 in each vessel group. Removal of the endothelium from uterine artery of pregnant animals enhanced both sensitivity and maximal response to U46619. Pretreatment of the denuded segments with indomethacin reduced the sensitivity to U46619. However, indomethacin-treated denuded segments were still more sensitive to U46619 than controls.

CONCLUSION

The sensitivity of guinea pig uterine artery but not carotid artery to thromboxane is reduced during pregnancy. Although the precise mechanism remains unclear, both endothelium-derived relaxing factor and an indomethacin-sensitive contracting factor are involved. If indomethacin-sensitive contracting factor is released by humans and disease alters that release, it is possible that any enhanced contractile response to thromboxane resulting from the loss of endothelium-derived relaxing agents such as prostacyclin and endothelium-derived relaxing factor would be offset by the loss of indomethacin-sensitive contracting factor.

Fetal survival after human parvovirus B19 infection: spectrum of intrauterine response in a twin gestation

We report the first known symptomatic survivors of congenital parvovirus infection. One fetus was hydropic and the other was growth retarded. There was no evidence of anemia. The antenatal diagnosis of congenital infection requires a multifaceted approach, which includes serology, cultures, and electron microscopy.

Does magnesium sulfate alter the maternal cardiovascular response to vasopressor agents in gravid ewes?

Magnesium sulfate (MgSO4) attenuates the maternal compensatory response to hemorrhage in gravid ewes, perhaps by decreasing the response to endogenous vasopressors. The purpose of this study was to determine whether MgSO4 alters the cardiovascular response of gravid ewes to vasopressor agents. Sixteen gravid ewes underwent a series of experiments consisting of administration of two exogenous and two endogenous vasopressors, each with and without a concurrent MgSO4 infusion. Dose-response curves were constructed for phenylephrine (an alpha 1-adrenergic agonist), ST-91 (an alpha 2-adrenergic agonist), angiotensin II, and arginine vasopressin (AVP). MgSO4 significantly attenuated the increase in maternal mean arterial pressure and systemic vascular resistance and the decrease in cardiac output during ST-91 infusion but not during phenylephrine, angiotensin II, or AVP infusions. MgSO4 significantly attenuated the increase in uterine vascular resistance during phenylephrine, ST-91, and angiotensin II infusions and the decrease in uterine blood flow during phenylephrine and angiotensin II infusions. MgSO4 also appeared to attenuate the decrease in uterine blood flow during ST-91 infusion (P = 0.067). The present study suggests that MgSO4 antagonizes the effects of alpha 1-adrenergic agonists, alpha 2-adrenergic agonists, and angiotensin II on the uterine vasculature, thus providing a level of protection for the fetus in situations of maternal stress.

Preeclampsia-eclampsia syndrome and coagulation

In balance, available studies employing sophisticated coagulation assays demonstrate enhanced thrombin generation in women with preeclampsia. The etiology is unknown but likely stems from the damage of vascular endothelium. Although activation of the clotting cascade does not cause preeclampsia, it likely contributes to the manifestations by obstruction and trauma of the microvasculature. Markers of clotting cascade activation such as AT III may be useful in the hypertensive preterm patient in whom the diagnosis is unclear.

The association between fetal karyotype and mean corpuscular volume

To determine whether elevated fetal mean corpuscular volume is characteristic of a chromosome abnormality or fetal disease, 22 fetuses with chromosome abnormalities, 31 with uteroplacental insufficiency, 50 undergoing their first cordocentesis for hemolytic disease, and 50 control fetuses were identified. Chromosomally abnormal fetuses had a significantly higher mean corpuscular volume than the control fetuses. Among fetuses with chromosome abnormalities, the mean corpuscular volume for trisomic or triploid fetuses was significantly higher than for fetuses with other chromosome abnormalities. An elevated mean corpuscular volume was also associated with uteroplacental insufficiency, intrauterine growth retardation, and hemolytic disease. It correlated significantly with gestational age (p less than 0.002 in all cases) in all groups except trisomy or triploidy. In addition, it correlated with hematocrit in the hemolytic disease group (r = -0.60, p less than 0.0001) and with PO2 in fetuses with intrauterine growth retardation (r = -0.43, p = 0.005) from all causes including uteroplacental insufficiency. Trisomic or triploid fetuses showed no such relationships and therefore appear to have escaped the normal control mechanisms for erythropoiesis. One in 12 fetuses with an elevated mean corpuscular volume had trisomy or triploidy, whereas no fetus with trisomy or triploidy had a normal mean corpuscular volume. Thus an unexpectedly elevated fetal mean corpuscular volume in a patient undergoing cordocentesis for reasons other than evaluation of fetal chromosomes would appear to warrant further karyotypic analysis.

Management of fetal hemolytic disease by cordocentesis. II. Outcome of treatment

Forty-eight of 128 pregnancies complicated by maternal red blood cell alloimmunization (49%) received a total of 142 intravascular transfusions (range, 1 to 7) for treatment of severe anemia (hematocrit, less than or equal to 30%). Thirteen fetuses (27%) had hydrops when therapy was initiated. The overall survival rate was 96%. Eighty-five percent of survivors received two or more transfusions before delivery. The mean gestational age at initiation of therapy was 28 weeks (range, 18 to 36 weeks). Bleeding from uterine and umbilical cord puncture sites was not of clinical significance. The most common complication was fetal bradycardia (8%). Simple intravascular transfusion resulted in the replacement of fetal red blood cells with adult red blood cells and suppression of fetal erythropoiesis. By the completion of the second transfusion, on average, less than 1% of circulating red blood cells were fetal. Within 3 weeks of the second transfusion, the mean reticulocyte count was less than 1%. The rate at which the fetal hematocrit declined after a transfusion (exclusive of the first) was inversely related to gestational age (r = -0.84, p less than 0.0001), permitting a 4- to 5-week interval between transfusions after 32 weeks' gestation. A total of 78% of surviving neonates were delivered at term. Neonates transfused more than once antenatally required less phototherapy (75.8 +/- 54 vs 165 +/- 101 hours, p less than 0.003) and, when delivered at term, fewer hospital days (4.8 +/- 2 vs 8.6 +/- 6 days, p = 0.01) compared with those transfused once. We conclude that the treatment of fetal anemia by intrauterine simple intravascular transfusion permits a term delivery in the majority of cases and is associated with high perinatal survival and low perinatal morbidity.

Risk factors for cordocentesis and fetal intravascular transfusion

There is little information on the impact of technical aspects or patient characteristics on the risks of accessing the fetal circulation. We performed 594 diagnostic cordocenteses and 156 intravascular transfusions over 6 years. Pancuronium was administered during 52% of procedures. The number of needle punctures per successful procedure was unrelated to the placental location. However, the number of punctures required was lower if the placental cord origin rather than a midsegment was targeted (p less than 0.0001). Bleeding from either the uterine or umbilical cord puncture site was not believed to be clinically significant, although the duration of bleeding was greater after arterial puncture than after venous puncture (p = 0.01) and after intravascular transfusion than after diagnostic cordocentesis (p less than 0.0001). Amnionitis (suspected plus verified) complicated 0.5% of procedures. Preterm premature rupture of membranes (with or without amnionitis) followed 0.4% of procedures. Fetal bradycardia occurred in 6.6% (6.6 +/- 0.8 minutes; range, 0.1 to 35 minutes). There were five perinatal losses after a diagnostic procedure, yielding an uncorrected loss rate of 0.8% (5/594). Each was associated with a prolonged bradycardia; each fetus was ultimately demonstrated to have been unsalvageable. Two independent risk factors for bradycardia were identified--arterial puncture and severe, early onset intrauterine growth retardation. The administration of pancuronium reduced the incidence of bradycardia in appropriately grown fetuses (6% to 1.5%; p less than 0.05), but did not alter the incidence in growth-retarded fetuses. We conclude that cordocentesis performed with a needle guide is a safe procedure but that its risk varies with both the indication and the vessel punctured.

A five-year statewide experience with congenital diaphragmatic hernia

Antenatal in utero surgery for congenital diaphragmatic hernia has been justified by reported perinatal mortality rates of 77% to 80%. Such rates may have been subject to bias of ascertainment and may include fetuses with additional severe malformations who would not be surgical candidates. We used the Iowa Birth Defects Registry to conduct a complete population survey to determine the incidence of congenital diaphragmatic hernia, the frequency of associated severe malformations, and the morbidity and mortality of infants with isolated congenital diaphragmatic hernia who were not subjected to antenatal surgery. The incidence of congenital diaphragmatic hernia was 1 in 3715. Twenty-eight percent of affected fetuses had associated severe malformations that were potentially identifiable prenatally and that would have precluded antenatal surgery. Of those with isolated congenital diaphragmatic hernia, 55% survived in spite of delivery (88.5%) and/or surgical repair (44%) in a level I or II hospital. Any decision for in utero surgery to repair congenital diaphragmatic hernia must be based on this or similarly obtained information.

Management of fetal hemolytic disease by cordocentesis. I. Prediction of fetal anemia

Between January 1985 and November 1990, 128 pregnancies complicated by maternal red blood cell alloimmunization were referred to our Fetal Diagnosis and Treatment Unit. We examined the premise that an evaluation of fetal blood would accurately identify fetuses at risk of requiring antenatal transfusion therapy. Two hundred seventy-two diagnostic cordocenteses were performed. Criteria for the timing of repeat cordocenteses were developed retrospectively on the basis of the fetal hematocrit values, reticulocyte counts, and direct Coombs' test results of the first 84 pregnancies. These criteria were tested and confirmed prospectively on the next 44 pregnancies. On the basis of the first blood sample, four hematologic patterns (and their distributions) were identified in the 98 antigen-positive fetuses. Pattern 1: fetuses at low risk of having significant antenatal anemia (hematocrit less than 30%) (n = 11, 11%). These fetuses had normal hematocrit values and reticulocyte counts coupled with negative or trace-positive direct Coombs' test. No fetus in this group had significant antenatal anemia. Pattern 2: fetuses at intermediate risk of having anemia (n = 29, 31%). Pattern 2 fetuses had normal hematocrit values and either direct Coombs' titers of more than trace less than or equal to 2+ and normal reticulocyte counts or low reticulocyte counts (less than 2.5th percentile for gestation). Twenty-one percent (n = 6) of fetuses in pattern 2 had significant antenatal anemia. Patterns 3 and 4: fetuses at greatest risk of having severe anemia. These fetuses had normal hematocrit values associated with either reticulocyte counts greater than 97.5th percentile for gestation or a direct Coombs' test greater than or equal to 3+ (pattern 3, n = 49, 50%) or both, or a mild anemia (greater than 30% but less than 2.5th percentile for gestation) (pattern 4, n = 9, 10%). Eighty percent (n = 39) of fetuses with pattern 3 and 90% (n = 8) with pattern 4 developed a hematocrit value less than 30%. We conclude that evaluation of fetal hemolytic disease with a fetal blood specimen permits the identification of fetuses at high risk of having antenatal anemia.

Relationship between second trimester maternal serum alpha-fetoprotein and umbilical artery Doppler velocimetry and their association with preterm delivery

One explanation for an abnormal maternal serum alpha-fetoprotein (MSAFP) may be an abnormal placenta. A specimen for MSAFP and a series of umbilical artery waveforms were obtained prior to amniocentesis from 144 consecutive women referred for either maternal age (n = 85), a persistently elevated MSAFP unassociated with a structural abnormality (n = 42), or a low MSAFP (n = 17). Almost 50% of deliveries before 37 weeks and 60% of neonatal birthweights below the tenth percentile occurred in the high MSAFP group. We observed that the systolic-diastolic ratio (S/D), pulsatility index, and resistance index tended to be higher in women referred for an elevated MSAFP. Confining analyses to the elevated MSAFP group, the MSAFP in multiples of the median correlated with birthweight independent of the gestational age at delivery (p less than 0.001). In addition, the S/D related directly to MSAFP (p less than 0.03) and indirectly to the gestational age at delivery (p less than 0.04). None of these relationships was observed in the groups of women referred for either maternal age (who had a normal MSAFP) or a low MSAFP. Employing a stepwise multiple linear regression, we found that the gestational age at delivery could be predicted during the midsecond trimester using a combination of the umbilical artery S/D and MSAFP. When the analyses and predictions were limited to subjects whose MSAFP still exceeded 2 multiples of the median at the time of amniocentesis, the positive predictive value for preterm delivery was 100% and the negative predictive value was 93%.(ABSTRACT TRUNCATED AT 250 WORDS)

Intrauterine transfusion treatment of nonimmune hydrops fetalis secondary to human parvovirus B19 infection

Congenital human parvovirus B19 infection presented in this case as nonimmune hydrops fetalis that resulted from aplastic anemia at 20 weeks' gestation. Intravascular transfusion therapy led to resolution of the hydrops and a term delivery of an appropriately grown neonate.

Magnetic resonance imaging of fetuses with intracranial defects

Thirteen women whose fetuses had intracranial defects on ultrasound examination were offered magnetic resonance imaging (MRI) without charge. All fetuses were paralyzed with pancuronium before the study, which lasted approximately 1 hour. With the mother in the left lateral decubitus position to minimize transmitted maternal aortic pulsation, T1-weighted images were obtained using a Picker 0.5-tesla superconductive unit. Magnetic resonance imaging provided excellent detail of intracranial anatomy in all cases. In four of the 13 fetuses, the MRI diagnosis differed from that of ultrasound and ultimately proved correct. In another three, MRI added greatly to the ultrasound diagnosis by delineating intracranial anatomy more precisely. In the remaining six cases, MRI confirmed the ultrasound impression. For circumstances in which the ultrasound diagnosis is unclear or antenatal intervention might require exact knowledge of anatomical detail, the additional information provided by MRI may justify its cost.

Diverse maternal and fetal pathology associated with absent diastolic flow in the umbilical artery of high-risk fetuses

Twenty-two of approximately 450 high-risk pregnancies referred to a regional center for a level II sonographic examination after 20 weeks' gestation were characterized by absent or reversed diastolic flow in the umbilical artery. Ten fetuses had congenital malformations or were aneuploid. Ten were growth-retarded in association with other problems: maternal hypertension, preeclampsia, cyanotic heart disease, elevated maternal serum alpha-fetoprotein levels, or twin gestation. In two cases, no etiology could be identified. Knowledge of the fetal karyotype, fetal anatomy, gestational age, maternal disease, and fetal status as determined by other tests of fetal well-being was required to optimize outcome in each case. In view of the heterogeneous etiologies of absent or reversed diastolic flow, management of such cases must be individualized.

Does indomethacin alter the hemodynamic response to magnesium sulfate infusion and hemorrhage in gravid ewes?

The purpose of this study was to determine whether indomethacin alters the maternal and fetal hemodynamic response to magnesium sulfate (MgSO4) infusion and hemorrhage in gravid ewes. We studied seven chronically instrumented animals between 0.8 and 0.9 of timed gestation. The experimental sequence included: 1) at time 0, indomethacin, 2 mg/kg, or vehicle only intravenously (IV) over 5 minutes; 2) at 60 minutes, MgSO4 4 g IV over 5 minutes; 3) at 65 minutes, MgSO4 infusion at 4 g/hour; 4) at 150 minutes, maternal hemorrhage, 20 mL/kg, over 60 minutes; and 5) at 215 minutes, reinfusion of maternal blood over 60 minutes. Each animal was studied with and without indomethacin. Indomethacin, but not vehicle only, transiently increased maternal and fetal mean arterial pressure (MAP), decreased maternal and fetal heart rate, and decreased maternal cardiac output. Magnesium sulfate significantly decreased uterine vascular resistance and increased uterine blood flow both with and without indomethacin. Hemorrhage significantly decreased maternal MAP, heart rate, cardiac output, and uterine blood flow in both groups. The magnitude of each change was similar between the groups. For example, at the end of hemorrhage, maternal MAP was 36 +/- 7% below baseline (P = .0001) with indomethacin and 41 +/- 2% below baseline (P = .0001) in the vehicle-only group (P = not significant between groups). Hemorrhage significantly decreased fetal heart rate, pH, and PO2, and increased fetal MAP and PCO2 in both groups. We conclude that indomethacin did not alter the maternal or fetal hemodynamic response to MgSO4 infusion and hemorrhage in gravid ewes.

Prenatal diagnosis of congenital cytomegalovirus infection by virus isolation from amniotic fluid

Cytomegalovirus was isolated antenatally from the amniotic fluid of two pregnant women. In both cases prenatal diagnosis of the fetal virus infection aided the subsequent management of the mother and newborn infant.

Effect of intrauterine growth retardation on renal function on day one of life

We measured inulin clearance per kilogram, fractional sodium excretion per kilogram, osmolality, and urinary prostaglandin concentration in seven growth-retarded neonates and six appropriately grown neonates matched for gestational age during the first 24 hours of life to determine the effect of fetal growth retardation on renal function. There was a nonsignificant reduction in inulin clearance per kilogram in the growth-retarded neonates (p = 0.11). Inulin clearance correlated with gestational age in both groups. It was significantly correlated with birthweight in the growth-retarded group (p less than 0.05) but did not reach significance in the control group (p less than 0.06). Fractional sodium excretion was significantly higher in the growth-retarded fetuses (p less than 0.05). This increase was not explainable by differences in mean blood pressure and intravenous fluid intake, although differences in urinary prostaglandin concentrations during the study interval may be involved. In conclusion, we have demonstrated that growth retardation is associated with impaired renal maturation, which during the first 24 hours of life is manifest as decreased glomerular filtration rate and increased sodium excretion.

Prenatal diagnosis of fetal hyperthyroidism using funipuncture

Women with Graves disease who are euthyroid as a result of ablative therapy still produce thyroid-stimulating antibodies that can cross the placenta. The fetuses of such patients are at risk of hyperthyroidism. We found that fetal blood sampling for the measurement of fetal endocrine function was useful in two patients for both diagnostic and therapeutic purposes. It may be especially helpful for situations in which maternal and fetal endocrine functions are dissimilar.

Prenatal diagnosis of congenital cytomegalovirus infection: two decades later

Cytomegalovirus is the most common cause of congenital infection in the United States, yet there has been little progress in the prenatal diagnosis of this intrauterine infection. We present evidence that viral culture of amniotic fluid may be a useful adjunct procedure, when performed as part of the antenatal evaluation of suspected fetal cytomegalovirus infection.

Gastroschisis and omphalocele: does either antenatal diagnosis or route of delivery make a difference in perinatal outcome?

The route of delivery for the fetus with an abdominal wall defect is controversial. This investigation proposed two null hypotheses: 1) The prognosis for the fetus with an abdominal wall defect is not affected by the timing of the diagnosis (antenatal or postnatal); and 2) the route of delivery does not affect fetal outcome. Sixty-one pregnancies complicated by either fetal gastroschisis (33) or omphalocele (28) delivered between December 1979 and January 1989 were reviewed. Seventy-one percent of the fetuses with gastroschisis and 59% with omphalocele were born vaginally. Gestational age at delivery, incidence of meconium staining, days to first neonatal oral feeding, percentage of neonates with one-stage closure of their defect, and percent of neonates with a birth weight less than the tenth percentile for gestational age were similar in fetuses with gastroschisis and with omphalocele, whether diagnosed antenatally or at birth. Significantly lower birth weights and longer neonatal hospitalizations were noted in the infants with omphalocele diagnosed antenatally compared with those diagnosed at birth (P less than .03), but no such differences were seen with gastroschisis. The route of delivery did not affect outcome for either defect. All fetuses born with gastroschisis and 87% with omphalocele free of associated lethal abnormalities were discharged alive. We conclude that the antenatal diagnosis of gastroschisis is not associated with either worse disease or a poorer outcome, though this may not be true for omphalocele. The good outcome with a high vaginal delivery rate suggests the need for a randomized trial of vaginal and cesarean delivery for fetal gastroschisis and omphalocele.