Effect of MgSO4 on heart rate monitoring in the preterm fetus.

OBJECTIVE: To evaluate in a controlled, blind fashion, using both subjective and objective criteria, whether MgSO4 is associated with clinically significant changes in fetal heart rate monitoring. STUDY DESIGN: Fetal heart rate tracings were prospectively collected before and after MgSO4 loading in 50 preterm labor patients. Three obstetricians, blind to treatment status, graded the tracings using both subjective and objective criteria. RESULTS: The baseline fetal heart rate declined slightly after therapy. Subjective, but not objective, evaluation demonstrated a greater likelihood of decreased variability after MgSO4 loading. There was no difference in periodic changes after MgSO4 loading. Multiple regression analysis showed a greater likelihood of decreased variability at earlier gestational ages but no relationship to the serum magnesium level. CONCLUSION: Magnesium sulfate tocolysis is associated with a subjective decrease in fetal heart rate variability in the preterm fetus.

Puerperal emergency. Vaginal and vulvar hematomas.

Puerperal hematoma is an uncommon complication of childbirth with a potential for serious morbidity and possible mortality. Prevention, using good surgical technique with attention to hemostasis in the repair of lacerations and episiotomies, should limit the occurrence of this complication. Puerperal hematomas, however, are not unavoidable. Thus, one must be alert to the possibility so that the hematoma can be diagnosed early and treated aggressively. This includes correcting hypovolemia and intervening with active surgical management if the hematoma is large or expanding.

Resolution of unilateral fetal hydrothorax with associated non-immune hydrops after intrauterine thoracentesis.

Congenital hydrothorax has been successfully managed in utero by two different treatment modalities: thoracentesis and pleuroamniotic shunting. Unfortunately, there is a paucity of data as to which method is better for the management of this problem. This case report supports the use of thoracentesis as the initial procedure for primary fetal hydrothorax. We report a pregnancy complicated by primary fetal hydrothorax with non-immune hydrops that completely resolved after two thoracenteses in the early third trimester. Complete resolution was maintained throughout pregnancy without the need for further antenatal or neonatal intervention, i.e. further thoracentesis, pleuroamniotic shunt placement, intubation, or chest and/or abdominal tube placement. The child was delivered at 42 weeks and is doing well without problems at 1 year of age. We believe that intrauterine thoracentesis should be the initial procedure of choice for the treatment of primary fetal hydrothorax with mediastinal shift, and pleuroamniotic shunting should be reserved for cases that require repetitive thoracenteses.

Magnesium sulfate loading: preeclampsia vs preterm labor (a clinical pearl).

OBJECTIVE: To measure the apparent volume of distribution (AVOD) for magnesium (Mg) in preeclampsia and preterm labor and determine if a standard 4 gm loading dose of magnesium sulfate (MgSO4) is sufficient to attain therapeutic levels. METHODS: Twenty-five patients with preeclampsia and 25 with preterm labor received 4 g of MgSO4 intravenously over 15 minutes. Serum Mg levels were determined before and one minute after loading and the AVOD for Mg was calculated. Stepwise linear regression with AVOD as the dependent variable was performed and comparisons between the groups were made. RESULTS: Preeclamptics were heavier, had greater surface areas, and presented at a later stage of pregnancy than did patients with preterm labor. Despite these differences AVOD did not differ between the groups. Predose magnesium levels were slightly higher in the preeclamptic group (p = .04). Post-loading levels were nearly identical due to similar AVOD's and, because of the lower levels required for seizure prevention as opposed to tocolysis, were therapeutic 88% of the time in preeclampsia but only 12% of the time in preterm labor (p < .001). Multivariate analysis revealed that only ideal body weight, degree of underweight, and current therapy with betamimetics were significantly related to AVOD. CONCLUSION: AVOD was found to be similar in preeclamptic and preterm labor patients. A 4 g loading dose of MgSO4 is usually adequate to achieve therapeutic levels in preeclampsia but not in preterm labor.

Meconium-stained amniotic fluid: increased risk for adverse neonatal outcome.

OBJECTIVE: To determine the risk of adverse neonatal outcome associated with meconium-stained amniotic fluid independent of that related to antepartum or intrapartum abnormalities. METHODS: A cohort of 2200 consecutive deliveries was examined and the fetal heart rate (FHR) tracings analyzed independently. Singleton term pregnancies without fatal malformations were stratified by the consistency of meconium and compared. RESULTS: Moderate or thick meconium increased the risk for adverse outcome more than threefold (relative risk 3.2, 95% confidence interval 2.0-5.2). This risk was independent of fetal heart tracing abnormalities or maternal hypertensive, kidney, or heart disease. CONCLUSION: Thick meconium alone should alert the physician to a high-risk fetal condition. This phenomenon requires continuous FHR monitoring and reassurance of fetal well-being by acid-base assessment or the equivalent, regardless of maternal disease status or the presence of abnormal FHR tracings.

Prenatal diagnosis of partial trisomy 1q using fluorescent in situ hybridization.

We report the use of fluorescent in situ hybridization (FISH) with a DNA library of chromosome 1-specific probes to confirm the karyotype, 46,XY,15+der15,t(1;15)(q32.1; q26.3), obtained by prenatal periumbilical blood sampling from a fetus who exhibited multiple abnormalities by ultrasound examination. GTG-banding of chromosomes obtained from the mother showed a normal karyotype, while the father was unavailable for study. The propositus was born at 37 weeks gestation and survived for several weeks. Cytogenetic analysis performed after the birth of the male infant with multiple anomalies verified partial trisomy 1q. This patient is compared with other partial trisomy 1q patients reported in the literature. The usefulness of FISH is demonstrated in situations where fetal abnormalities are present with de novo chromosomal rearrangements where paternal chromosomes are unavailable for study.

The development and testing of new instruments for operative vaginal delivery.

OBJECTIVE: Little innovation has occurred in recent years in the instruments available for operative vaginal delivery. The purpose of this study is to develop a technique to test the utility of an investigational device, the obstetric bonnet, and measure the forces it places on the fetal head. STUDY DESIGN: We constructed a model of the fetal head capable of measuring both compression and vacuum created by an applied device. A total of 18 devices were tested to a maximum traction of 60 pounds. RESULTS: A significant linear relationship exists between the traction applied and the compression (R2 = 0.42, p = 0.0004) and vacuum (R2 = 0.85, p = 0.0001) created. Compression and vacuum recorded at maximum recommended traction were 1.1 lb/sq in and 31 cm Hg, respectively. CONCLUSION: These findings explain the mechanics of this interesting device, and demonstrate forces that compare favorably with those known to occur with forceps or vacuum extraction.

Pregnancy complicated by chronic cardiomyopathy and an automatic implantable cardioverter defibrillator.

The dismal prognosis of dilated cardiomyopathy and its resulting tachyarrhythmias has recently been improved by technical advances such as the automatic implantable cardioverter defibrillator. We report a successful pregnancy in a patient with chronic cardiomyopathy and malignant tachyarrhythmias necessitating use of this device, with a documented defibrillator discharge and monitored fetal response.

Combination antibiotics and indomethacin in idiopathic preterm labor: a randomized double-blind clinical trial.

Subclinical infection may play a role in the failure of magnesium sulfate tocolysis. Using a double-blind randomized study design, we administered a combination of ampicillin-sulbactam and indomethacin or corresponding placebos to patients in preterm labor who were receiving intravenous magnesium sulfate tocolysis. The mean gestational age at enrollment was 30.1 weeks, and mean cervical dilatation was 2.15 cm. No differences were noted between placebo (n = 43) and study patients (n = 43) in gestational age at delivery, term deliveries, days gained, or neonatal outcome. Preterm delivery (less than 36 weeks) occurred in 61% of the total population. The likelihood of a beta error was 0.07 to 0.23 on the basis of outcome analysis. In our population adjunctive ampicillin-sulbactam with indomethacin did not improve the success of magnesium sulfate tocolysis.

Acute gestational pyelonephritis: the impact on colloid osmotic pressure, plasma fibronectin, and arterial oxygen saturation.

Acute gestational pyelonephritis infrequently leads to nonhydrostatic permeability pulmonary edema known clinically as acute respiratory distress syndrome (ARDS). In this form of ARDS, sepsis is considered the primary cause of pulmonary dysfunction. Decreases in colloid osmotic pressure, plasma fibronectin, and arterial oxygen saturation are associated with a worsening prognosis in septic conditions. We sought to investigate the changes in these parameters with acute gestational pyelonephritis to gain insight into the factors that may place the patient at risk for sepsis-related morbidity. Colloid osmotic pressure, plasma fibronectin, and arterial oxygen saturation via pulse oximetry were prospectively measured during the inpatient treatment of 17 pregnant patients with acute gestational pyelonephritis. All three parameters achieved their nadir within 24 hours of hospitalization and the initiation of therapy. Although no patient developed significant pulmonary dysfunction, we believe that patient susceptibility for pulmonary edema and general morbidity could be maximal in the first 24 hours after therapy. Future studies using a larger number of patients may identify one or more of these laboratory parameters as helpful in identifying gravid patients who are at risk of developing gestational ARDS.

Sources of variability in umbilical artery systolic/diastolic ratios: implications of the Poiseuille equation.

The Poiseuille equation of fluid flow suggests that umbilical cord length and cord blood viscosity may affect resistance to flow and thus affect the systolic/diastolic ratio. In this prospective study of 40 uncomplicated term pregnancies, we sought to define the relationship of umbilical cord length and cord blood hematocrit level (as an index of viscosity) to the umbilical artery systolic/diastolic ratio. To focus on these factors, we minimized known sources of systolic/diastolic ratio variability and controlled for fetal heart rate. Linear regression revealed that fetal heart rate contributed 18% of the systolic/diastolic ratio variability. Conversely, umbilical cord length and cord blood hematocrit level were not related to umbilical artery systolic/diastolic ratio. We conclude that normal variations in cord blood hematocrit level and umbilical cord length do not significantly affect systolic/diastolic ratio.

Angiographic arterial embolization and computed tomography-directed drainage for the management of hemorrhage and infection with abdominal pregnancy.

Hemorrhage during or after surgery, pelvic abscess, bowel obstruction, and prolonged febrile morbidity can complicate the puerperal course of the gravida after removal of an extrauterine fetus with nondisturbance of the extrauterine placenta. In this report we describe the successful angiographic arterial gelfoam embolization of the placental vascular bed to control heavy postoperative hemorrhage in a mother suffering adult respiratory distress syndrome after removal of the fetal portion of her abdominal pregnancy. Six weeks later, computed tomography (CT)-directed drainage by catheter of a placental abscess was performed. Selective angiographic transcatheter embolization with gelfoam is a useful tool for the control of hemorrhage in the gravida who is an unfavorable operative candidate or who may present technical hemostasis problems peculiar to the placenta with abdominal pregnancy. Later use of CT-directed catheter drainage of the infected residual placental mass provided a nonoperative means of treatment.

Effect of tocolytic agents on fetal umbilical velocimetry.

In this prospective study, we sought to examine the changes in umbilical vascular resistance induced by tocolytic therapy. Umbilical artery velocimetry was performed in 46 patients with preterm labor before tocolysis and at 1 hour and 24 hours after tocolysis was initiated. Raw systolic/diastolic ratios were corrected for concomitant changes in fetal heart rate. Thirty patients received subcutaneous terbutaline and 16 were treated with intravenous magnesium. Systolic/diastolic ratios decreased in patients treated with terbutaline. This decline persisted after correction for increases in fetal heart rate. No significant changes in systolic/diastolic ratios were seen in patients treated with magnesium. We conclude that terbutaline may affect umbilical vascular resistance. Possible clinical implications of these findings are discussed.

A prospective randomized comparison of oral terbutaline and magnesium oxide for the maintenance of tocolysis.

We compared oral magnesium oxide with oral terbutaline sulfate in a prospective, randomized manner to determine efficacy and side effects. Preterm labor patients whose labor was arrested with parenteral tocolysis were randomized to oral tocolysis with either magnesium oxide, 200 mg every 3 to 4 hours (n = 23), or terbutaline, 2.5 to 5 mg every 3 to 4 hours (n = 27). The number of patients who were delivered of infants before 36 weeks' gestation was similar between groups (18.5% receiving terbutaline versus 17.4% receiving magnesium). At least one side effect occurred in 81.5% of patients in the terbutaline group and 47.8% in the magnesium group (p less than 0.01). Finally, the cost for 1 day of magnesium (20 cents) is approximately one third the cost of terbutaline (56 cents). These data suggest that oral magnesium oxide is as effective as terbutaline for the maintenance of tocolysis, with fewer side effects and at a lower cost.

Adjusting the loading dose of magnesium sulfate for tocolysis.

The purpose of this prospective study was to establish a method to calculate a loading dose of magnesium sulfate so as to achieve therapeutic levels of tocolysis more quickly. Fifty patients in preterm labor were enrolled. In the first phase 25 patients were studied so that the apparent volume of distribution for the loading dose of magnesium sulfate could be estimated and an adjusted loading dose could be calculated. The efficacy of this adjusted loading dose was then tested on a further 25 patients in the second phase. We found that the apparent volume of distribution could be accurately estimated and an adjusted loading dose calculated, with the use of ideal body weight, degree of underweight, and current use of beta-sympathomimetics. In the adjusted loading dose group therapeutic levels were achieved more often, with higher postloading magnesium levels and a greater decrease in contraction index immediately after the loading dose. We conclude that an adjusted loading dose can be calculated for magnesium sulfate to optimize tocolytic therapy.