Elevated maternal serum alpha-fetoprotein with normal ultrasound: is amniocentesis always appropriate? A review of 26,069 screened patients

We reviewed our experience with a policy of revising the estimated probability of an open neural tube defect for those cases in which maternal serum alpha-fetoprotein (MSAFP) was elevated and the ultrasound examination was normal. Assuming a sensitivity for the ultrasound diagnosis of neural tube defects of 90%, the risk estimate derived from the MSAFP was reduced by that amount when ultrasound was adequate and normal. When counseled regarding this revised risk estimate, 67% of our patients declined amniocentesis. The sensitivity for the ultrasound diagnosis of anencephaly in our series was 100%; for open spine defects, 80%; and for all open neural tube defects, 91%. The two patients in whom an open spine defect was not detected with ultrasound had elevated revised risk estimates. When appropriate criteria are met, the estimated sensitivity of ultrasound in diagnosing open neural tube defects may be used for counseling patients at risk for a fetus with an open neural tube defect.

The effect of human amniotic fluid on the isolated perfused rat heart

To test the hypothesis that amniotic fluid directly affects cardiac function, isolated rat hearts were perfused with varying concentrations of centrifuged and filtered human amniotic fluid. The most consistent change seen was a dose-dependent decrease in coronary flow rate. With 10% concentrations, a wide spectrum of changes was seen in both a positive and a negative direction for left ventricular pressure and change in pressure with respect to time, which were closely correlated with the degree of decrease in coronary flow rate. If amniotic fluid has a direct role in depressing cardiac function in amniotic fluid embolism, it may act by decreasing coronary flow rather than by directly suppressing myocardial activity.

Single-probe spectrophotometry in the assessment of fetal oxygenation

Six sheep fetuses were monitored with a single-probe tissue spectrophotometer. This spectrophotometer provides continuous digital output of the index of hemoglobin that is saturated with oxygen. To vary the fetal pO2, each maternal ewe was given room air, 100% oxygen, 12% oxygen, and 100% nitrogen via rebreathing bag. Fetal venous (N = 4) or arterial (N = 2) blood was analyzed for pO2. There was excellent correlation between the index of hemoglobin saturated with oxygen and the fetal pO2. The single-probe spectrophotometer overcomes two of the technical problems encountered when a double-probe spectrophotometer is used.

Atenolol and short umbilical cords

Umbilical cord length may be a function of fetal movement. Agents that cause decreased fetal movement may cause short umbilical cords. This investigation examined the effect of the beta-blocker atenolol on umbilical cord length in rabbits. Fetuses of rabbits treated with atenolol had significantly shorter cords than control animals (p less than or equal to 0.0005). Since short cords are associated with problems in labor, low Apgar scores, and abruption, we recommend careful surveillance of mothers and fetuses who are given beta-blocking agents in the first 30 weeks of pregnancy.

Effects of plasma on the platelet antiaggregatory action of prostacyclin in pregnancy

Platelet-poor plasma from 13 nonpregnant, 33 normally pregnant, and eight preeclamptic women was incubated with prostacyclin. The ability of platelet-poor plasma to diminish the antiaggregatory effect of prostacyclin was assessed by measuring this effect on arachidonic acid-induced platelet aggregation. Platelet aggregation greater than 95% in response to arachidonic acid was observed when incubated plasma without exogenous prostacyclin was assayed. When prostacyclin and platelet-poor plasma were preincubated together, subsequent arachidonic acid-induced platelet aggregation measured 9.6% in samples from nonpregnant patients, 40.3% in samples from normally pregnant patients, and 78.2% in samples from patients with preeclampsia. The ability of exogenous prostacyclin to inhibit arachidonic acid-induced platelet aggregation was significantly different in the presence of plasma from nonpregnant, normally pregnant, and preeclamptic women. These observations suggest that a plasma factor may affect the action of prostacyclin during pregnancy.

Preconceptional health promotion: a focus for obstetric care

Women contemplating pregnancy generally dream of a healthy infant yet are unaware of the critical significance of the weeks of organogenesis that precede entry into prenatal care. Programs of preconceptional health promotion provide women with information on the potential relatedness of prepregnancy lifestyle choices, health status, and pregnancy outcomes. We review the significance of this relationship and offer a framework for exploring preconceptional issues with women contemplating pregnancy.

The cardiorespiratory effects of perfluorochemicals on acute carbon monoxide poisoning in the pregnant ewe

Studies in nonpregnant animal models of carbon monoxide poisoning have demonstrated the protective effect of perfluorochemicals. Anesthetized pregnant ewes were exposed to carbon monoxide. After symptoms of toxicity were demonstrated, group 1 animals were respired with room air. Group 2 animals respired room air and were given intravenous perfluorochemicals. Group 3 animals were administered 100% oxygen. Group 4 animals were given intravenous perfluorochemicals and respired 100% oxygen. In all ewes exposure to carbon monoxide resulted in increased cardiac output, heart rate, and carboxyhemoglobin level without a significant change in arterial oxygen tension. After carbon monoxide exposure, there was no significant difference in the carboxyhemoglobin to oxyhemoglobin conversion between groups 1 and 2 although the conversion rates were more rapid in groups 3 and 4. Fetal oxygenation was improved in groups 3 and 4. All fetal lambs exhibited a progressive increase in carboxyhemoglobin and a decrease in venous pH regardless of the maternal postexposure treatment. There was no significant increase in the fetal venous oxygen content of group 4 as compared with that of group 3, suggesting that the adjunctive administration of limited quantities of perfluorochemicals to the mother offers no apparent advantage over 100% oxygen alone for acute fetal resuscitation.

Elevated second trimester maternal serum alpha-fetoprotein and cytomegalovirus infection

A case is presented of intrauterine cytomegalovirus infection. Initially, the infection was most probably manifested by elevated second trimester maternal serum alpha-fetoprotein levels. Placental involvement by the infectious agent may have produced the elevations in maternal serum. Alpha-fetoprotein elevation unrelated to fetal anatomic abnormalities, twins, or incorrect dates may represent a potential marker of placental pathology.

The relationship between mean abdominal diameter and femur length in normal and impaired fetal growth

The relationship of fetal mean abdominal diameter (MAD) to fetal femur length (FL) in clinically normal pregnancies and 37 cases of intrauterine growth retardation (IUGR) was studied. The normal relationship of FL to MAD is closely described by the equation: log (MAD) = 3.326 + (0.185 X FL). r = .953, P less than .001. In the growth retarded infants, 59% of the abdominal measurements fell below the lower 75% confidence limit. Of the abdominal measurements derived from infants with birthweight greater than 2 SD below the mean for gestational age, 86% fell below the lower 75% confidence limit. These data show the MAD is selectively depressed in many, but not all cases of IUGR and particularly in the more severely affected infant, but the technique is not sufficiently discriminant to be used by itself for the detection of IUGR. Detection of an anomaly of this relationship would be strong supportive evidence of IUGR independent of gestational age and possibly identifies infants growth retarded specifically due to chronic deprivation.

Fatal influenza A pneumonia in pregnancy

Today, influenza A infections are an uncommon cause of maternal morbidity and mortality. This is a report of a 20-year-old pregnant woman who died from pneumonia caused by influenza A/Philippines/1982. The decreased immune system and respiratory functions of pregnancy make pregnant women especially susceptible to having a complicated influenza infection, though such infections probably do not directly threaten the fetus. The use of influenza immunizations and antiviral medication during pregnancy is discussed.

Femur length versus biparietal diameter for estimating gestational age in the third trimester

It is well established that ultrasound measurement of femur length and biparietal diameter are comparably accurate estimators of gestational age when obtained in the first half of pregnancy. Both estimators, however, become less accurate later in pregnancy. The present study compares the relative accuracy of these estimators when obtained in the third trimester. It is concluded from linear regression analysis that the correlation between gestational age estimated from femur length and the actual gestational age is stronger than that between gestational age estimated from biparietal diameter and actual gestational age. Furthermore, gestational age calculated from femur length is significantly more likely to be within 2 weeks (P less than or equal to .01) and 3 weeks (P less than or equal to .05) of actual gestational age than is gestational age calculated from biparietal diameter. Estimating gestational age from the mean of the gestational age based on biparietal diameter and that based on femur length is less accurate than estimating gestational age from femur length alone.

The effects of fetal exchange transfusion with a red blood cell substitute

Isovolemic exchange transfusion in the fetal lamb in utero was performed with the use of Fluosol-DA (20%), a perfluorochemical erythrocyte substitute. With maternal hyperoxygenation, a physiologic PO2 was maintained in the fetal lambs, although the total fetal oxygen content decreased as the hematocrit dropped. Because of the oxygen-carrying properties of the perfluorochemical emulsion, the fraction of fetal oxygen carried in the dissolved state increased significantly when compared with that in controls that received saline solution.

Detection of smoking-related covalent DNA adducts in human placenta

The presence of covalent DNA chemical addition products (adducts) in human term placentas was investigated by recently developed immunologic and 32P-postlabeling assays. DNA from placental specimens of smokers showed a small but not statistically significant increase in adduct levels when tested by antibodies to DNA modified with a benzo[a]pyrene dihydrodiol epoxide (BPDE-I), the ultimate carcinogenic derivative of benzo[a]pyrene. The postlabeling assay detected several modified nucleotides, one of which (adduct 1) strongly related to maternal smoking during pregnancy. This adduct was present in placental tissue from 16 of 17 smokers, but only 3 of 14 nonsmokers. Among smokers, levels of adduct 1 in general were only weakly related to questionnaire and biochemical measures of the intensity of smoking exposures, which suggests modulation by individual susceptibility factors. The adduct seemed to be derived from an aromatic carcinogen, but it may not result from several of the most intensely studied polycyclic aromatic hydrocarbons or aromatic amines in tobacco smoke. The data show the association of cigarette smoking with covalent damage to human DNA in vivo.

Thrombotic thrombocytopenic purpura in early pregnancy

Thrombotic thrombocytopenic purpura during pregnancy in which both mother and fetus have survived has been an exceedingly rare occurrence, due at least in part to the difficulty in distinguishing this uncommon disease from hematologic complications of preeclampsia. In the nonpregnant patient, the use of plasma infusion or exchange plasmapheresis as therapy of choice has resulted in a dramatic increase in survival. By using more specific criteria than the classical clinical pentad, the diagnosis of thrombotic thrombocytopenic purpura during pregnancy can be made with greater accuracy. The first known instance of the successful use of exchange plasmapheresis leading to the survival of both mother and fetus in thrombotic thrombocytopenic purpura clearly not secondary to preeclampsia is reported.

Amniotic fluid embolism. Three case reports with a review of the literature

Amniotic fluid embolism is a catastrophic event of the intra- and early postpartum period which may also be seen with cesarean delivery and during abortions. Presenting symptomatology includes respiratory distress with cyanosis, shock, and possibly tonic-clonic seizures. DIC frequently occurs. The pathogenesis may include entry of amniotic fluid through lacerations or ruptures of the uterus or cervix, through endocervical veins and through abnormal uteroplacental sites, such as with placental abruption, placenta previa, or placenta accreta. Amniotic fluid probably causes cardiovascular-respiratory symptoms by pulmonary vascular obstruction and through a vasoactive substance causing pulmonary vascular constriction. The lethality of amniotic fluid may be enhanced by a high particulate content or meconium staining. The diagnosis of amniotic fluid embolism may be made ante mortem by demonstrating amniotic fluid debris in central blood samples or expectorated sputum. Postmortem diagnosis often requires meticulous examination of the pulmonary microvasculature with the utilization of special stains. Treatment is directed towards symptoms of shock, arterial hypoxemia, and DIC. Acute renal failure may complicate the picture after shock. If the patient survives the embolic and coagulative problems, recovery is usually complete without long-term sequelae.

Effect of maternal intravenous infusions on fetal extracellular fluid composition in pregnant ewes

Infusion of intravenous solutions to women in labor is common clinical practice. Since these infusions may change the volume and electrolyte balance between the mother and fetus, we investigated the influence of acute maternal volume expansion upon fetal and maternal fluid and electrolyte equilibrium in the chronically catheterized fetal lamb. Paired measurements of maternal and fetal plasma sodium and potassium concentrations, osmolality, and colloid osmotic pressure (COP), plus measurements in the fetal-placental plasma volume were obtained following rapid maternal infusions with saline, dextrose, and dextran solutions. Maternal infusions resulted in changes in fetal electrolyte concentrations as well as alterations in transplacental COP differences. Despite these changes, however, no changes in fetal plasma volume were noted.

Prenatal detection of intraamniotic bands: implications and management

The prenatal diagnosis of intraamniotic bands with confirmation at delivery is presented, and the pertinent literature is reviewed. The significance of intrauterine membranes or bands detected during pregnancy is not known. Direct fetal involvement by these structures has been reported in only one instance, but malformations apparently unrelated to amniotic bands have been common among reported cases. Serial ultrasound examinations are recommended both to exclude pseudosac, extrachorionic hemorrhage, blighted twin, and other possible causes of membranous structures and to search for fetal abnormalities.

Fulminant hepatic failure in the third trimester of pregnancy. A case report

There is a paucity of information regarding fulminant hepatic failure during pregnancy, in part because it is such an uncommon event. We encountered a case of fatal hepatic failure secondary to viral hepatitis occurring during the third trimester.

Early prenatal sonographic appearance of rare thoraco-abdominal eventration

Fetal ventral wall malformations may be diagnosed prenatally with ultrasound. These include omphalocele, gastroschisis, or even thoracic defects with or without ectopia cordis. It is important whenever such a defect is found to carefully define the full extent of the lesion prior to parental counselling. Described and illustrated here is the prenatal diagnosis with real-time ultrasound at 17 weeks gestation of a rare thoraco-abdominal ventral wall defect including omphalocele, bifid sternum, diaphragmatic aplasia, and pericardial aplasia with incomplete ectopia cordis. The technique is described and the importance of the complete, accurate delineation of anatomic malformations is emphasized.

Recurrent idiopathic fetal hydrops: results of prenatal therapy

A case of nonimmune hydrops recurring within a sibship is reported. Progressive severe fetal ascites and hydramnios at 31 weeks' gestation led to fetal paracentesis for both therapeutic and diagnostic purposes. A successfully placed indwelling peritoneal-amniotic diversion shunt functioned well but became dislodged, and rapid recurrence of ascites and hydramnios required two subsequent drainage procedures. Neonatal death occurred from pulmonary failure after delivery at 34 weeks' gestation, as had happened in the similarly affected sibling. Amniotic and fetal peritoneal pressures, biochemical analysis, and bacteriologic studies of fluid samples are reviewed. Although this experience adds to the knowledge of fluid dynamics in fetal ascites and hydramnios, it does not clearly support or refute such therapy in the care of fetal hydrops from nonimmunologic causes. Management issues are discussed.

Hydramnios and maternal renal failure: relief with fetal therapy

Hydramnios and maternal renal compromise are described in a singleton pregnancy with a large fetal abdominal cystic mass. Both the hydramnios and the renal failure resolved after percutaneous drainage of the fetal cyst. Rapid reaccumulation of the mass resulted in redrainage and placement of an indwelling cyst/amniotic cavity diversion shunt. Successful continuous decompression and uneventful continuation of the pregnancy were observed for four weeks. The relationship between fetal abdominal masses and hydramnios is discussed.

The relationship of intracranial infrared light absorbance to fetal oxygenation. I: Methodology

Current clinical methods for assessing fetal oxygenation in labor are indirect and remain somewhat imperfect. Since infrared light passes through the cranium and infrared light absorbance by tissues has been shown in adult animals to vary with oxygenation, monitoring of infrared light absorbance may serve as the basis for a new, more direct technique for the assessment of fetal condition. Described here is the application of infrared reflectance spectrophotometry to a fetal sheep model and the precision of the relationship between fetal arterial or venous PO2 and infrared light absorbance at selected wavelengths. A very strong, linear correlation (r = 0.915) was found between fetal arterial PO2 and intracranial infrared light absorbance according to an algorithm developed for selective monitoring of the state of hemoglobin oxygenation in tissue. With further development, this method holds promise for a more direct, noninvasive assessment of fetal condition in labor than is currently available.

Maternal and fetal effects of exchange transfusion with a red blood cell substitute

Recent reports have demonstrated the efficacy of Fluosol-DA (20%) as a temporary erythrocyte substitute. We investigated two groups of pregnant ewes that underwent exchange transfusion. In group 1, the animals underwent a nearly total isovolemic exchange of Fluosol-DA (20%) for maternal whole blood; in group 2, the red blood cells were removed and the plasma along with Ringer's lactate was replaced isovolumetrically. Although group 1 animals received 100% oxygen and Fluosol-DA (20%), the maternal arterial P02 increased to 350 to 400 torr. However, the maternal blood oxygen content decreased during the exchange, with no change in fetal pH, Pco2, or hematocrit. Maternal blood pressure remained stable and there was a 40% to 50% increase in cardiac output and mean pulmonary arterial pressure. During the exchange, the maternal hematocrit decreased from a mean of 32% to 5.5%; the maternal fluorocrit at the end of the exchange was 9%. Throughout the Fluosol-DA (20%) exchange, the proportion of fetal brain oxyhemoglobin as estimated from infrared transcranial transmittance increased, as did the fetal blood P02 and oxygen content. In group 2, the maternal mean blood pressure decreased, and the hematocrit decreased from a mean of 32% to 8%. Despite an increase in the maternal P02 to 250 torr, the fetal P02 and oxygen content decreased in group 2. This investigation demonstrated that Fluosol-DA (20%) exchange of the mother does not impair delivery of oxygen to the fetus under the conditions of the study.