Sarah J. Kilpatrick

Fetal acidemia and electronic fetal heart rate patterns: Is there evidence of an association?

Objective. Despite the ubiquity of electronic fetal monitoring, the validity of the relationship between various fetal heart rate (FHR) patterns and fetal acidemia has not yet been established in a large unselected series of consecutive pregnancies. The aim of this study was to examine the published literature for evidence of such a relationship. Methods. Four hypotheses based on assumptions in common clinical use were examined. The literature was searched for relationships between certain aspects of FHR patterns (e.g., degree of FHR variability, depth of decelerations), and fetal acidemia, or fetal vigor (5-minute Apgar score ≥7). We also attempted to relate duration of these patterns to the degree of acidemia. Using standardized FHR nomenclature we defined patterns based on baseline FHR variability, baseline rate, decelerations, and accelerations. Results. The following relationships were observed: (1) Moderate FHR variability was strongly associated (98%) with an umbilical pH >7.15 or newborn vigor (5-minute Apgar score ≥7). (2) Undetectable or minimal FHR variability in the presence of late or variable decelerations was the most consistent predictor of newborn acidemia, though the association was only 23%. (3) There was a positive relationship between the degree of acidemia and the depth of decelerations or bradycardia. (4) Except for sudden profound bradycardia, newborn acidemia with decreasing FHR variability in combination with decelerations develops over a period of time approximating one hour. Most studies identified were observational and uncontrolled (grade III evidence of US Preventive Services Task Force); however, there was general agreement amongst the various studies, strengthening the validity of the observations. Conclusions. The validity of the relationship between certain FHR patterns and fetal acidemia and/or vigor, is supported by observations from the literature. In addition four assumptions commonly used in clinical management are supported. These conclusions need to be confirmed by a prospective examination of a large number of consecutive, unselected FHR patterns, and their relationship to newborn acidemia. Pending the completion of such studies, these observations can be used to justify certain aspects of current clinical management, and may assist in standardizing the diversity of opinions regarding FHR pattern management.

The clinical utility of serum uric acid measurements in hypertensive diseases of pregnancy.

OBJECTIVE Our purpose was to evaluate the clinical utility of serum uric acid measurements in the hypertensive diseases of pregnancy. STUDY DESIGN We performed a nested case-control study to assess the clinical utility of serum uric acid measurements in women with hypertensive diseases of pregnancy. We identified 344 women who had serum uric acid measurements at term and categorized them into five diagnostic groups according to definitions of hypertensive diseases in pregnancy published by the National Working Group on Hypertension in Pregnancy: transient hypertension of pregnancy (n = 69), preeclampsia (n = 130), chronic hypertension (n = 23), chronic hypertension with superimposed preeclampsia (n = 29), and normal (n = 93). We compared the mean uric acid concentration for each group with use of a one-way analysis of variance and Scheffes post hoc test and calculated the sensitivities and specificities in diagnosing preeclampsia as well as the likelihood ratios for serum uric acid values of 5.5, 6.0, and 6.5 mg/dl. We also examined the correlation between serum uric acid levels and several clinical outcome measures in women with hypertensive diseases of pregnancy. RESULTS The mean serum uric acid values for women with preeclampsia (6.2 +/- 1.4 mg/dl) and transient hypertension (5.6 +/- 1.7 mg/dl) were significantly higher than those of controls (4.3 +/- 0.8 mg/dl, p < 0.05). The difference in mean serum uric acid values between women with chronic hypertension (4.9 +/- 1.0 mg/dl) and superimposed preeclampsia (5.8 +/- 1.4 mg/dl) were not statistically significant. The likelihood ratio of having preeclampsia with a serum uric acid value of 5.5 mg/dl was 1.41 in gestational hypertension of pregnancy and 2.5 in chronic hypertension. With use of a receiver-operator characteristic curve, we were unable to identify a serum uric acid value that could be used to differentiate various hypertensive diseases of pregnancy. There was a weak correlation between serum uric acid values and several clinical outcome measures of preeclampsia (r = 0.06 to 0.26). CONCLUSION Although mean serum uric acid values are elevated in women with preeclampsia, the clinical utility of serum uric acid values in differentiating various hypertensive diseases of pregnancy appears to be limited. In the setting of chronic hypertension, however, a serum uric acid level of > or = 5.5 mg/dl could identify women with an increased likelihood of having superimposed preeclampsia.

Perinatal mortality in twins and singletons matched for gestational age at delivery at ≥30 weeks

OBJECTIVE Our purpose was to compare perinatal mortality between twins and singletons matched for gestational age at delivery with the hypothesis that perinatal mortality would be similar. STUDY DESIGN A retrospective cohort study compared perinatal mortality in twins (790 babies) matched for gestational age at delivery at > or = 30 weeks with the next singleton. Perinatal mortality was also compared by expected growth (small and average for gestational age) and by the cause of the preterm delivery (medical indication, spontaneous preterm delivery, or preterm premature rupture of membranes with preterm delivery. RESULTS Uncorrected perinatal mortality was significantly greater in singletons (56/1000) than in twins (26/1000) (p = 0.004). After major congenital anomalies were excluded, perinatal mortality remained significantly higher in singletons (25/1000) than in twins (11/1000) (p = 0.04). In preterm deliveries perinatal mortality was significantly greater in singletons (72/1000) than in twins (19/1000) (p = 0.0002). Perinatal mortality was significantly greater in small- compared with average-for-gestational-age neonates, whether singletons or twins (p = 0.005), and singleton small-for-gestational-age neonates had a significantly greater perinatal mortality (105/1000) than did twin small-for-gestational-age neonates (36/1000) (p = 0.02). Perinatal mortality was not significantly different between preterm singletons and twins delivered by spontaneous preterm labor. However, perinatal mortality in preterm singletons delivered for a medical indication (156/1000) was significantly greater than for twins (20/1000) (p = 0.0006). CONCLUSIONS At > or = 30 weeks at delivery, twins either had a perinatal mortality similar to, or less than singletons matched for gestational age at delivery. This suggests that when preterm delivery is controlled for perinatal mortality is not greater in twins. In twins, without risk factors for perinatal death, routine antepartum testing may not be indicated.

Misoprostol is more efficacious for labor induction than prostaglandin E2 , but is it associated with more risk?

OBJECTIVE Our purpose was to compare the efficacy and safety of misoprostol with dinoprostone (Prepidil) for labor induction. STUDY DESIGN In a randomized, controlled trial of labor induction, patients were randomly assigned to receive either 50 microgram of intravaginal misoprostol every 4 hours or 0.5 mg of intracervical prostaglandin E2 every 6 hours. Eligibility criteria included gestation of >/=31 weeks, Bishop score <6, and fewer than 12 contractions per hour. Primary outcomes were cesarean section, induction to delivery time, oxytocin use, and fetal distress requiring delivery. RESULTS One hundred fifty-nine women were randomly assigned to receive misoprostol (n = 81) or Prepidil (n = 78). There were no differences in the indication for induction, preinduction Bishop score, epidural use, or cesarean section rate. Mean time to delivery was significantly shorter in the misoprostol group (19 hours 50 minutes) than in the Prepidil group (28 hours 52 minutes) (P =.005). Only 58% of women in the misoprostol group required oxytocin augmentation, in comparison with 88% of women receiving Prepidil (P =.00002). However, 41% of women receiving misoprostol and 17% receiving Prepidil had late decelerations or bradycardias (P =.001), and 20% of the misoprostol group and 5% of the Prepidil group had deliveries for fetal distress (P =.05). CONCLUSIONS Misoprostol is more efficacious than Prepidil for labor induction. However, the significantly increased incidence of abnormal fetal heart rate tracings and the trend in increased deliveries for fetal distress with misoprostol dosing of 50 microgram every 4 hours are of concern. These data suggest that either a lower dose of misoprostol or less frequent dosing of misoprostol should be considered.

Maternal Fertility Is Not Affected by Fetal Surgery

The purpose of this report is to assess the impact of fetal surgery on future maternal fertility, subsequent pregnancy outcome, and the incidence of pregnancy complications. Retrospective data were collected on 70 mothers who underwent fetal surgery between April 1981 and June 1996. Indications for open hysterotomy fetal surgery included congenital diaphragmatic hernia (n = 44), congenital cystic adenomatoid malformation of the lung (n = 11), urinary obstruction (n = 9), sacrococcygeal teratoma (n = 4), heart block (n = 1), and acardiac-acephalic twin reduction (n = 1). The following data were obtained: number of pregnancy attempts, number of successful pregnancies, pregnancy outcome including obstetrical and neonatal complications, and infertility after fetal surgery. There were 45 respondents, of whom 35 attempted subsequent pregnancies. Thirty-two were successful, resulting in 31 livebirths. Two women had a strong prefetal surgery history of infertility, 1 has only attempted to conceive for 3 months. We report this experience because the effect of open fetal surgery on futrue fertility is such an important question for our patients and referring physicians. This analysis suggests that hysterotomy and open fetal surgery has a negligible impact on maternal fertility.

Pulmonary edema in obstetric patients is rapidly resolved except in the presence of infection or of nitroglycerin tocolysis after open fetal surgery

OBJECTIVES This study was designed to determine the etiology, course, and severity of pulmonary edema in obstetric patients in a tertiary care center. STUDY DESIGN A retrospective study was carried out on 16,810 deliveries from University of California, San Francisco, 1985-1995. Diagnosis and severity of lung injury were defined by a 4-point system that was based on the chest radiograph, oxygenation, positive end-expiratory pressure, and lung compliance. Resolution of pulmonary edema was defined by improvement in the chest radiograph and hypoxemia (ratio of arterial oxygen tension to inspired oxygen concentration) scores or by extubation. RESULTS Pulmonary edema developed in 86 patients, or 0.5% of all obstetric cases. It usually showed extensive air space consolidation on the chest radiograph and arterial hypoxemia. Although 43% of the patients had severe pulmonary dysfunction, the average time to resolution of pulmonary edema was 2.4 days. Only 45% of patients required admission to the intensive care unit and only 15% required intubation and positive-pressure ventilation. Patients with infection (mean of 7.2 days) or fetal surgery (mean of 3.8 days) had the most severe, protracted course. CONCLUSION Although obstetric pulmonary edema is associated with extensive radiographic infiltrates and severe hypoxemia, resolution occurs rapidly in most patients, limiting the need for intensive care support.

Is there a benefit to episiotomy at spontaneous vaginal delivery? A natural experiment

OBJECTIVE Our purpose was to examine the association between maternal vaginal and perineal morbidity and episiotomy performed at spontaneous vaginal delivery. STUDY DESIGN We obtained data from 17,483 consecutive spontaneous vaginal deliveries and compared the yearly rates of episiotomy, lacerations, and potential confounders with linear regression and stratified analyses. RESULTS Between 1976 and 1994 the use of episiotomy fell significantly (86.8% to 10.4%, R2 = 0.92, p = 0.0001). This change was associated with a fall in the rate of third- and fourth-degree lacerations (9.0% to 4.2%, R2 = 0.59, p = 0.0001) and a rise in the rate of intact perinea (10.3% to 26.5%, R2 = 0.68, p = 0.0001) and vaginal lacerations (5.4% to 19.3%, R2 = 0.77, p = 0.0001). These associations held in separate analyses stratified by parity and birth weight, except for the subgroup of nulliparous women with macrosomic infants. CONCLUSION At our institution a large reduction in the use of episiotomy in spontaneous vaginal deliveries was associated with a significant reduction in perineal trauma in all groups of women except for nulliparous women with macrosomic infants.

Is there a benefit to episiotomy at operative vaginal delivery? Observations over ten years in a stable population

Abstract OBJECTIVE: Our purpose was to examine the association between maternal vaginal and perineal morbidity and episiotomy performed at operative vaginal delivery. STUDY DESIGN: We obtained data from 2041 consecutive operative vaginal deliveries and compared yearly rates of episiotomy, lacerations, and potential confounders with linear regression and stratified analyses. RESULTS: Between 1984 and 1994 the use of episiotomy for operative vaginal deliveries fell significantly (93.4% to 35.7%, R 2 = 0.85, p = 0.0001). This change was associated with a rise in the rate of vaginal lacerations (16.1% to 40.0%, R 2 = 0.80, p = 0.0002), a decrease in the rate of fourth-degree lacerations (12.2% to 5.4%, R 2 = 0.62, p = 0.004), but no significant change in the rate of third-degree lacerations. These associations held in separate analyses stratified by parity and type of instrument used for delivery. The prevalence of other previously reported risks for perineal morbidity did not change during the study period. CONCLUSION: At our institution a statistically and clinically significant reduction in the use of episiotomy for operative vaginal deliveries was not associated with a change in the rate of third-degree lacerations but was associated with an increase in the rate of vaginal lacerations and a decrease in the rate of fourth-degree lacerations.(Am J Obstet Gynecol 1997;176:411-4.)

Chorioamnionitis and uterine function

Objective To clarify the relationships between intrapartum chorioamnionitis and abnormalities of uterine function, including labor abnormalities, cesarean delivery, and hemorrhage during parturition. Methods We did a retrospective cohort study on 16,226 deliveries between 1986 and 1996 that were identified from the University of California, San Francisco Perinatal Database. Variables included maternal age, parity, birth weight, gestational age, epidural usage, oxytocin usage, cesarean delivery, labor abnormalities, length of labor stages, estimated blood loss, and chorioamnionitis status. Analyses included χ2, Student t test, and logistic regression. Results In the chorioamnionitis group, there was a statistically significantly higher proportion of women with labor abnormalities (relative risks [RRs] 2.6–4.1), cesarean delivery (RR 3.3; 95% confidence interval [CI] 3.0, 3.5), hemorrhage after cesarean (RR 1.2; 95% CI 1.1, 1.3), and hemorrhage after vaginal delivery (RR 2.1; 95% CI 1.9, 2.4) compared with the nonchorioamnionitis group. Those findings stayed significant after multivariate analysis for various labor abnormalities (adjusted odds ratios [ORs] ranged 1.3–2.1), cesarean delivery (adjusted OR 1.8; 95% CI 1.5, 2.1), hemorrhage after cesarean (adjusted OR 1.5; 95% CI 1.2, 1.8), and hemorrhage after vaginal delivery (adjusted OR 1.8; 95% CI 1.5, 2.1). Conclusion Adverse associations between chorioamnionitis and labor abnormalities, cesarean rate, and hemorrhage during parturition appear to be significant, suggesting a deleterious effect of chorioamnionitis on uterine function.

Standardized Severe Maternal Morbidity Review: Rationale and Process

Severe maternal morbidity and mortality have been rising in the United States. To begin a national effort to reduce morbidity, a specific call to identify all pregnant and postpartum women experiencing admission to an intensive care unit or receipt of 4 or more units of blood for routine review has been made. While advocating for review of these cases, no specific guidance for the review process was provided. Therefore, the aim of this expert opinion is to present guidelines for a standardized severe maternal morbidity interdisciplinary review process to identify systems, professional, and facility factors that can be ameliorated, with the overall goal of improving institutional obstetric safety and reducing severe morbidity and mortality among pregnant and recently pregnant women. This opinion was developed by a multidisciplinary working group that included general obstetrician–gynecologists, maternal–fetal medicine subspecialists, certified nurse–midwives, and registered nurses all with experience in maternal mortality reviews. A process for standardized review of severe maternal morbidity addressing committee organization, review process, medical record abstraction and assessment, review culture, data management, review timing, and review confidentiality is presented. Reference is made to a sample severe maternal morbidity abstraction and assessment form.