Managing nonreassuring fetal heart rate patterns before cesarean delivery. Compliance with ACOG recommendations

OBJECTIVE

To determine the rate of compliance with current American College of Obstetricians and Gynecologists (ACOG) recommendations for management of parturients undergoing cesarean delivery for persistent nonreassuring fetal heart rate (FHR) tracings.

STUDY DESIGN

We performed a retrospective chart review (July 1995-June 1998) of all parturients who underwent cesarean delivery for nonreassuring FHR tracings. Outcome measures included maneuvers for fetal assessment (scalp stimulation or scalp blood pH) and therapeutic interventions (tocolytic agents for reducing uterine activity or amnioinfusion). Patients with multiple gestations and cesarean delivery for other indications were excluded. Student's t test, chi 2 and Fisher's exact tests were used; odds ratio and 95% confidence interval were calculated. P < .05 was considered significant.

RESULTS

Cesarean delivery for persistent nonreassuring FHR patterns included 134 (3.6%) of the 3,671 deliveries during three years. Thirty patients produced intrapartum FHR tracings containing persistent variable decelerations; 12 (40%) of these patients received amnioinfusion. In only 37% (50/134) of cases was there a documented attempt at scalp or acoustic stimulation prior to delivery. Scalp pH was obtained in 15% (15/98) of patients whose cervix was at least 3 cm dilated. Tocolytic agents were used for intrauterine resuscitation in 25% (34/134) of cases; their use varied significantly (P = .006) with the type of FHR abnormality.

CONCLUSION

At our tertiary center, ACOG recommendations for management of nonreassuring intrapartum FHR tracings were used in a limited number of cases.

Neonatal acidemia with trial of labor among parturients with prior cesarean delivery: a case-control study

OBJECTIVE

To determine the risk factors for neonatal acidemia with trial of labor among parturients with a prior cesarean delivery.

METHODS

From a prospectively collected database on all parturients attempting a trial of labor, newborns with umbilical arterial pH < 7.15 were selected as cases and the controls (1:4) were the next four patients who delivered nonacidotic (pH > or = 7.15) neonates. Exclusion criteria were no prior cesarean delivery, anomalous fetus, and nonavailability of umbilical arterial blood gas analysis. Student's t-test, chi2, and Fisher's exact tests were utilized and odds ratio (OR) and 95% confidence intervals (CI) were calculated. P < 0.05 was considered significant.

RESULTS

The frequency of neonatal acidemia among patients undergoing trial of labor was 12% (28/234). The cases and controls (n = 112) were similar (P > 0.05) with regards to maternal age, frequency of more than one prior cesarean delivery (11% vs. 8%), gestational age, cervical exam on admission (3.0 +/- 1.5 vs. 3.4 +/- 1.7 cm), usage of oxytocin, and duration of first or second stage of labor. The mean birthweight was significantly higher among acidotic (3,758 +/- 670 g) than nonacidotic (3,470 +/- 545 g; P = 0.018) newborns. Compared to the controls, the cases had a significantly higher frequency of unsuccessful trial of labor (19% vs. 50%; OR: 4.09; 95% CI: 1.70, 9.82) and separation of the uterine scar (0.8% vs. 14%; OR: 18.50; 95% CI: 1.98, 173.05).

CONCLUSIONS

Acidotic newborns with trial of labor tend to be heavier. Parturients have a failed attempt at vaginal birth after cesarean, and have separation of the uterine scar during labor.

Oral contraceptives and epithelial ovarian cancer. Does dose matter?

OBJECTIVE

To determine the risk of ovarian cancer among women who use low-estrogen-dose oral contraceptives.

STUDY DESIGN

The study used data on white women under 70 years of age who had been enrolled in a population-based case-control study conducted between 1986 and 1988 in three western Washington counties. Women with ovarian cancer (n = 276) were ascertained through a population-based cancer registry, and controls (n = 391) were selected by random digit dialing. Unconditional logistic regression was used to estimate the risk of ovarian cancer associated with oral contraceptive use.

RESULTS

After adjustment for age and parity, women who took oral contraceptives for at least three months were at decreased risk of ovarian cancer (odds ratio [OR] 0.8, 95% confidence interval [CI] 0.5-1.1) relative to women who never used this form of contraception. The reduced risk of ovarian cancer was present among women whose only preparation contained a low (< 50 micrograms ethinyl estradiol or < 80 micrograms mestranol) (OR 0.6, 95% CI 0.3-1.1) and high (OR 0.8, 95% CI 0.5-1.2) estrogen dose.

CONCLUSION

While our results are limited in their statistical precision and by the inability of many subjects to recall the brands of oral contraceptives that they took, they suggest that the newer, low-estrogen-dose oral contraceptives confer a benefit regarding ovarian cancer risk similar to that conferred by earlier, high-estrogen-dose formulations.

Cesarean delivery for suspected fetal distress among preterm parturients

OBJECTIVE

Among preterm parturients (< 37 weeks) who underwent cesarean delivery for suspected fetal distress, to determine the factors associated with decision-incision time (DIT) of < or = 30 minutes and to assess if umbilical arterial pH < 7.10 is more common with DIT < or = 30 or > 30 minutes.

STUDY DESIGN

The peripartum course of all patients who had cesareans for suspected fetal distress over three years was reviewed. The inclusion criteria were reliable gestational age < 37 weeks and a single indication for cesarean delivery, suspected fetal distress. Twenty antepartum and intrapartum factors were used in a univariate analysis.

RESULTS

The mean DIT among the 84 parturients was 30.5 +/- 21.2 minutes, and 63% of patients had surgery started within 30 minutes. The incidence of pH < 7.10 was 20%. Multivariate analysis indicated that the two factors significantly associated with prolonged time to surgery were tachycardia with decreased variability (odds ratio [OR] 5.9, 95% confidence interval [CI] 1.6-21.6) and use of spinal anesthesia (OR 6.2, 95% CI 1.1-35.0). Though none of the 20 variables had significant univariate associations with neonatal acidosis at alpha = .05, those with P < .20 were considered in multiple logistic regression analysis. None of the 20 factors were associated with pH < 7.10, including DIT of > or = 30 minutes (OR 0.26, 95% CI 0.06-1.03).

CONCLUSION

DIT is likely to be > 30 minutes if cesarean delivery is due to decreased fetal heart variability or if spinal anesthesia is utilized; neonatal acidosis, however, is not significantly associated with a prolonged interval.

Antepartum detection of macrosomic fetus: clinical versus sonographic, including soft-tissue measurements

OBJECTIVE

To compare clinical and sonographic estimates of birth weights with five new estimation techniques that involve measurements of soft tissue, for identifying newborns with birth weights of at least 4000 g.

METHODS

Over 1 year, each woman at or after 36 weeks' gestation and suspected of having a macrosomic fetus had clinical and sonographic estimates of fetal weight (EFW) based on femur length (FL) and head and abdominal circumference, followed by five additional ways to identify excessive growth: cheek-to-cheek diameter, thigh soft tissue, ratio of thigh soft tissue to FL, upper arm subcutaneous tissue, and EFW derived from it. Areas (+/- standard error) of receiver operating characteristic (ROC) curves were calculated and compared with the area under the nondiagnostic line. P <.05 was considered statistically significant.

RESULTS

Among 100 women recruited, 28 newborns weighed 4000 g or more. The areas under the ROC curves with clinical (0.72 +/- 0.06) and sonographic predictions using biometric characteristics (0.73 +/- 0.06) had the highest but similar accuracies (P.05). Three of the five newer methods (upper arm or thigh subcutaneous tissue and ratio of thigh subcutaneous tissue to FL) were poor diagnostic tests (range of areas under ROC 0.52 +/- 0.06 to 0.58 +/- 0.07). Estimated fetal weight based on upper arm soft tissue thickness and cheek-to-cheek diameter (areas 0.70 +/- 0.06 and 0.67 +/- 0.06, respectively) were not significantly better than clinical predictions (P.05) for detecting macrosomic fetuses. About 110 macrosomic and nonmacrosomic infants combined would be needed to have 80% power to detect a difference between ROC curves with areas of 0.58 (thigh subcutaneous tissue) and 0.72 (clinical estimate).

CONCLUSION

ROC curves indicated that measurements of soft tissue are not superior to clinical or sonographic predictions in identifying fetuses with weights of at least 4000 g.

Clinical vs. sonographic estimate of birth weight in term parturients. A randomized clinical trial

OBJECTIVE

To determine the relative accuracy of clinical and sonographic birth weight estimation among term parturients (> or = 37 weeks) and to assess the performance of the two techniques in identifying newborns with weights of < 2,500 g vs. > or = 2,500 g or < 2,500 g vs. at least 4,000 g.

STUDY DESIGN

The sample size for this randomized clinical trial was based on the assumption that 50% of clinical predictions are within 10% of birth weight. Thus, 700 parturients were necessary to show a difference of 10% with sonographic estimates (alpha = .05, beta = .02). Inclusion criteria were singletons with a reliable gestational age of > or = 37 weeks, admitted for delivery and with no known fetal anomalies. Physicians who were unaware of previous sonographic estimates obtained the estimates. Student t and chi 2 tests were used; relative risk (RR) and 95% confidence intervals (CIs) were calculated. Receiver-operating characteristic (ROC) curves were constructed to compare the two techniques' ability to differentiate between abnormal (birth weight < 2,500 g and > 4,000 g) and normal (2,500-3,999 g). P < .05 was considered significant.

RESULTS

Over 30 months, 758 term parturients were recruited; of them, 391 had clinical estimates and 367, sonographic. The two groups were similar in gestational age, prepregnancy and intrapartum body mass index, station of the presenting part, actual birth weight and frequency of newborns with weights < 2,500 g or > or = 4,000 g. Predictions based on clinical examination were significantly more likely to be within 10% of actual weight (58%) than those derived from ultrasound examination (32%; P < .0001; RR, 1.65; 95% CI, 1.43, 1.69). The areas under the ROC curves indicated that both techniques had a similar ability to differentiate normally and abnormally grown fetuses (P > .05).

CONCLUSION

Among term parturients, clinical estimates had significantly higher accuracy than ones derived sonographically.

Predicting the success of a trial of labor with a simple scoring system

OBJECTIVE

To determine the applicability of a simple scoring system, by Troyer and Parisi, in predicting the success of a trial of labor among parturients with prior cesarean delivery.

STUDY DESIGN

Retrospectively, all patients who underwent a trial of labor over six consecutive years were reviewed. chi 2, Fisher's exact test and analysis of variance followed by the Turkey or Dunn test were used when appropriate. P < .05 was considered significant.

RESULTS

There were 263 trials of labor, of which 63% (167) ended in vaginal delivery. While 21% had a score of 0, 40%, 28% and 11% had a score of 1, 2 and at least 3, respectively. The frequency of vaginal birth was significantly different between the four groups (P < .001): 98% for a score of 0, 69% for 1, 40% for 2 and 33% for 3-4. Occurrence of cesarean delivery for cephalopelvic disproportion (2%, 24%, 39%, 56%; P < .001) or for a nonreassuring fetal heart rate tracing (0%, 7%, 21%, 11%; P < .001) was significantly different between the four groups.

CONCLUSION

In our population, we confirmed the inverse relationship between the Troyer-Parisi scoring system and a successful trial of labor.

Perinatal outcome and amniotic fluid index in the antepartum and intrapartum periods: A meta-analysis

OBJECTIVE

Our purpose was to perform a meta-analysis of studies on the risks of cesarean delivery for fetal distress, 5-minute Apgar score <7, and umbilical arterial pH <7.00 in patients with antepartum or intrapartum amniotic fluid index >5.0 or <5.0 cm.

STUDY DESIGN

Using a MEDLINE search, we reviewed all studies published between 1987 and 1997 that correlated antepartum or intrapartum amniotic fluid index with adverse peripartum outcomes. The inclusion criteria were studies in English that associated at least one of the selected adverse outcomes with an amniotic fluid index of </=5.0 cm versus >5.0 cm. Contingency tables were constructed for each study, and relative risks and standard errors of their logs were calculated. Fixed-effects pooled relative risks were calculated for groups of studies that were homogeneous, whereas random-effects pooled relative risks were calculated for significantly heterogeneous groups of studies.

RESULTS

Eighteen reports describing 10,551 patients met our inclusion criteria. An antepartum amniotic fluid index of </=5.0 cm, in comparison with >5.0 cm, is associated with an increased risk of cesarean delivery for fetal distress (pooled relative risk, 2.2; 95% confidence interval, 1.5-3.4) and an Apgar score of <7 at 5 minutes (pooled relative risk, 5.2; 95% confidence interval, 2.4-11.3). An intrapartum amniotic fluid index of </=5.0 cm is also associated with an increased risk of cesarean delivery for fetal distress (pooled relative risk, 1.7; 95% confidence interval, 1.1-2.6) and an Apgar score <7 at 5 minutes (pooled relative risk, 1.8; 95% confidence interval, 1.2-2.7). A poor correlation between the amniotic fluid index and neonatal acidosis was noted in the only study that examined this end point. More than 23,000 patients are necessary to demonstrate that the incidence of umbilical arterial pH <7.00 is 1.5 times higher among those with oligohydramnios in labor than among those with adequate amniotic fluid index (alpha = 0.05; beta = 0.2)

CONCLUSIONS

An antepartum or intrapartum amniotic fluid index of </=5.0 cm is associated with a significantly increased risk of cesarean delivery for fetal distress and a low Apgar score at 5 minutes. There are few reports linking amniotic fluid index and neonatal acidosis, the only objective assessment of fetal well-being. A multicenter study with sufficient power should be undertaken to demonstrate that a low amniotic fluid index is associated with an umbilical arterial pH <7.00.

Sterilization and its consequences

The purpose of this review is to analyze critically the two techniques of sterilization (bilateral tubal ligation [BTL] and vasectomy) so that a physician may provide informed consent about methods of sterilization. A MEDLINE search and extensive review of published literature dating back to 1966 was undertaken to compare preoperative counseling, operative procedures, postoperative complications, procedure-related costs, psychosocial consequences, and feasibility of reversal between BTL and a vasectomy. Compared with a vasectomy, BTL is 20 times more likely to have major complications, 10 to 37 times more likely to fail, and cost three times as much. Moreover, the procedure-related mortality, although rare, is 12 times higher with sterilization of the woman than of the man. Despite these advantages, 300,000 more BTLs were done in 1987 than vasectomies. In 1987, there were 976,000 sterilizations (65 percent BTLs and 35 percent vasectomies) with an overall cost of $1.8 billion. Over $260 million could have been saved if equal numbers of vasectomies and BTLs had been performed, or more than $800 million if 80 percent had been vasectomies, as was the case in 1971. The safest, most efficacious, and least expensive method of sterilization is vasectomy. For these reasons, physicians should recommend vasectomy when providing counseling on sterilization, despite the popularity of BTL.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians

LEARNING OBJECTIVES

After completion of this article, the reader will be able to predict the failure rates and likelihood of successful reversal of tubal ligation and vasectomy; to recall the difference in cost between the two sterilization procedures, and to describe the short-term and long-term complications associated with each of the two methods of sterilization.

Accuracy of sonographically estimated fetal weight with and without oligohydramnios. A case-control study

OBJECTIVE

To determine the accuracy of sonographically estimated fetal weight among women with and without oligohydramnios (amniotic fluid index [AFI] < or = 5.0 cm) and to ascertain the ability to detect fetal growth restriction (FGR) (estimated birth weight < 10th percentile for gestational age [GA]) among patients in two groups.

STUDY DESIGN

Assuming that 50% of sonographic predictions are within 10% of the birth weight in the study group, 300 parturients are necessary to show a difference of 15% among controls (alpha = .05, beta = .02). The study group consisted of parturients with a reliable GA of > or = 24, no known anomalies and known AFI of < or = 5.0 cm. The control (1:1) was the next patient with the same GA but AFI between 5.1 and 23.9 cm. The paired t test was used, and the odds ratio (OR) and 95% confidence interval (CI) were calculated. P < .05 was considered significant.

RESULTS

Among the study and control groups (N = 162 each), maternal demographics, mean estimate (P = .078) and actual birth weight (P = .091) were similar. Sonographic estimates within 10% of weight were not significantly different among those with (57%) and without oligohydramnios (59%; OR 0.92; 95% CI 0.59, 1.44). The frequency of FGR was higher among those with inadequate fluid (18%) than controls (9%; OR 2.13; 95% CI 1.10, 4.16). Sensitivity, positive predictive value and likelihood ratio were higher among those with oligohydramnios (76%, 78% and 16) than controls (53%, 42% and 7).

CONCLUSION

The accuracy of sonographic estimates of fetal weight is not influenced by whether the parturient has oligohydramnios. Moreover, the accuracy of identifying FGR is not diminished among those with AFI < or = 5.0 versus > 5.0 cm.

Fetal acoustic stimulation in early labor and pathological fetal acidemia: a preliminary report

OBJECTIVE

To determine if a nonreactive response to fetal acoustic stimulation in early labor can predict a significantly higher risk of umbilical arterial pH <7.10 or <7.00.

METHODS

Fetal acoustic stimulation was applied to the fetuses of term parturients (gestational age > or =37 weeks) with cervical dilation of < or =5 cm. The responses to stimulation were correlated with cesarean delivery for fetal distress and umbilical arterial pH. Student's t-test, Chi-square, and Fisher exact test were used; P < 0.05 was considered significant. Relative risks (RR) and 95% confidence intervals (CI) were calculated.

RESULTS

The study population contained 271 subjects, of which 90% (244) had a reactive response following acoustic stimulation and 10% (27) a nonreactive response. The maternal demographics, time interval from stimulation to delivery (8.3 +/- 8.7 vs. 8.3 +/- 8.4 h; P = 1.00) were similar in the two groups. Compared to those with a reactive response, patients with a nonreactive response had a significantly greater risk for: 1) cesarean delivery for fetal distress (2.0% vs. 11.1%; P = 0.03, RR 4.1, 95% Cl 1.5, 60.5), 2) umbilical arterial pH <7.10 (2.0% vs. 14.8%; P = 0.007, RR 5.0, 95% CI 2.2, 11.6), and 3) umbilical arterial pH <7.00 (0.8% vs. 7%; P = 0.05, RR 5.0, 95% CI 1.8, 15.2).

CONCLUSION

A nonreactive response to fetal acoustic stimulation in early labor is associated with a significantly increased risk for cesarean delivery for fetal distress and neonatal acidosis. This finding extends the potential value of acoustic stimulation as an intrapartum admission screening test.

Risk factors associated with blood transfusion in ectopic pregnancy

OBJECTIVE

To determine the risk factors associated with blood transfusion in ectopic pregnancy.

STUDY DESIGN

A retrospective chart review of the presentation and hospital course of ectopic pregnancies managed over five years at two hospitals was undertaken. Thirty-two variables, including demographics, presenting signs and symptoms, and intraoperative findings, were examined with univariate and multivariate logistic modeling.

RESULTS

Among 185 patients with histologically confirmed ectopics who were managed surgically, 8.6% (16 women) required transfusion. Multivariate analysis of risk factors for blood transfusion demonstrated a statistically significant association with (1) initial hemoglobin < 10 g/dL (odds ratio [OR] 38.8, 95% confidence interval [CI] 6.0-356.8); (2) human chorionic gonadotropin levels > or = 6,500 mIU (OR 18.1, 95% CI 3.6-158.1); and (3) abnormal bleeding on presentation (OR 0.08, 95% CI 0.007-0.42). The presence of two of these factors had a sensitivity of 82% (95% CI 48-98%) and a positive predictive value of 33% (95% CI 16-54%). No case had all three factors.

CONCLUSION

This study was, to our knowledge, the first regression analysis of risk factors for transfusion associated with ectopic pregnancy. It demonstrated that initial hemoglobin and human chorionic gonadotropin levels as well as abnormal bleeding on presentation are independent risk factors for blood transfusion in ectopic pregnancy.

Detection of growth-restricted fetuses in preeclampsia: a case-control study

OBJECTIVE

To determine the diagnostic accuracy of detecting growth-restricted fetuses in women with and without preeclampsia.

METHODS

Over 2 years, parturients with reliable gestational ages, preeclampsia, and sonographic estimates of birth weights were matched (1:1) for gestational age with women without preeclampsia. Paired and unpaired t tests were used; P < .05 was significant. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated.

RESULTS

Two hundred eighty-seven preeclamptic women were identified and matched. In each group, mean (+/- standard deviation [SD]) gestational age was 34.9 +/- 4.2 weeks, and 166 (57.8%) infants were born preterm. Fetal growth restriction (FGR) was significantly more common among women with preeclampsia (14.9%) than among controls (5.6%; OR 2.98, 95% CI 1.64, 5.44). The percentage of sonographic estimates within 10% of actual birth weight (57.5% versus 53.6%) was similar in the two groups (OR 1.16; 95% CI 0.84,1.62). Compared with normal growth, the mean (+/- SD) standardized absolute error was significantly higher among those with FGR regardless of group (preeclampsia 109 +/- 100 versus 158 +/- 152 g/kg; P = .009; control 117 +/- 103 versus 233 +/- 206 g/kg; P < .001). Fetal growth restriction was detected more commonly among preeclamptic women than among controls (11.6% versus 0%; OR 4.74 95% CI 0.25, 90.31). The sensitivity and positive predictive value of FGR detection were 10% and 50%, respectively, among women with preeclampsia and 0% each among controls.

CONCLUSION

Although FGR was detected more frequently in fetuses of women with preeclampsia than in those of controls, the ability to predict it with sonography remained poor.

Intrapartum amniotic fluid index: a poor predictor of abnormal fetal size

OBJECTIVE

Using receiver-operating characteristic (ROC) curves, we tried to determine the diagnostic threshold of amniotic fluid index (AFI) that will identify abnormal fetal size (birth weights under 2500 g or at least 4000 g) at 37 weeks or beyond.

METHODS

We analyzed prospectively over 2 years all parturients with intact membranes and known AFI in early labor. Patients with the following conditions were excluded: pregestational or gestational diabetes, known anomalies, and preterm labor. Two ROC curves were constructed, and the areas (+/- standard error of the mean [SE]) under the curves were calculated. P < .05 was considered significant.

RESULTS

Of the 1038 subjects meeting study criteria, 3.6% and 11.5% gave birth to infants who were small for gestational age (SGA) or macrosomic, respectively. Overall, 28.7% had oligohydramnios (AFI at most 5.0 cm) and 3.6% had hydramnios (AFI at least 24.0 cm). Small for gestational age was more common in patients with AFI at most 5.0 cm (6.4%) than in those with adequate fluid (AFI 5.1-23.9; 2.5%), or hydramnios (2.7%; P = .012). Macrosomic newborns were less likely to be born to women with oligohydramnios (7.7%) than to those with adequate amniotic fluid (13.1%) or hydramnios (13.5%). Areas under ROC curves are not significantly different from the area under the nondiagnostic line, indicating that AFI (0-34 cm) cannot differentiate between newborns under 2500 g and at or over 2500 g or under 4000 and at or more 4000 g.

CONCLUSION

Intraparterium AFI appears to be a poor screening test to identify risk for delivery of SGA or macrosomic fetus.

Ultrasonographic estimate of birth weight at 24 to 34 weeks: a multicenter study

OBJECTIVE

The study was intended to compare the accuracies of ultrasonographic estimates of birth weights among infants born between 24 and 34 weeks' gestation at 3 tertiary centers.

STUDY DESIGN

In this retrospective study subjects were matched for gestational age (1:1); all underwent ultrasonographic examination within 2 weeks of delivery. The estimates of birth weight were obtained according to 26 published regression equations and their accuracies were assessed with the mean standardized absolute error. For each center the equation with the lowest error was selected to generate (1) receiver-operating characteristic curves for an estimate to identify actual weight < 1500 g and (2) prediction limit calculations to determine the estimate that ensures at 70% confidence a birth weight > 1500 g.

RESULTS

One hundred seventy-one cases were analyzed at each center. Comparison of the 26 mean standardized errors at each center indicated that (1) the range was rather wide (eg, 89 +/- 87 to 365 +/- 313 g/kg) and (2) 73% (19/26) of the equations had significantly (P < .05) different accuracies. Receiver-operator characteristic curves show that fetal weight estimates of > or = 1600 g at 2 centers and > or = 1700 g at the third center are required to predict actual birth weight < 1500 g. Prediction limit calculation suggests that different fetal weight estimates (> 1600 g at center 1, > 1900 g for the center II, and > 1800 g at center III) are needed to predict actual weight > 1500 g with a 70% accuracy.

CONCLUSIONS

Ultrasonographic estimates of weight for preterm infants, as obtained from 26 equations, are characterized by a rather wide range of accuracy; for most of the equations the accuracies of estimates differ markedly among centers.

Sonographic examination of twins. From first trimester to delivery of second fetus

Sonographic examination is essential in the diagnosis and management of twin gestation. It assists in determining the zygosity, assessing fetal anomalies, and is integral to amniocentesis if it is necessary, determining the growth and ruling out discordance, and in intrapartum management. The management of uncommon complications with twins also requires ultrasonic survey. Considering that the incidence of multiple gestation is increasing, it would be prudent to become familiar with the use and benefit of ultrasound with twins.

An analysis of risk factors associated with blood transfusion in ectopic pregnancy

Objective: To determine the risk factors associated with blood transfusion in ectopic pregnancy.Methods: A retrospective chart review of the presentation and hospital course of ectopic pregnancies managed over 5 years at two hospitals was undertaken. Thirty-two variables, including demographics, presenting signs and symptoms, and intraoperative findings, were examined in univariate and multivariate logistic modeling.Results: Among 185 patients with histologically confirmed ectopic pregnancies who were managed surgically, 8.6% or 16 women required transfusion. Multivariate analysis of risk factors for blood transfusion demonstrated a statistically significant association with 1) initial hemoglobin <10 g/dL (odds ratio [OR] 38.8, 95% confidence interval [CI] 6.0-356.8) and 2) hCG levels >/= 6500 mIU (OR 18.1, 95% CI 3.6-158.1), as well as 3) abnormal bleeding on presentation (OR 0.08, 95% CI 0.007-0.42. Presence of two of these factors has a sensitivity of 82% (95% CI 48-98%) and a positive predictive value of 33% (95% CI 16-54%). No case had all three factors present.Conclusion: This report is, to our knowledge, the first regression analysis of risk factors for transfusion associated with ectopic pregnancy. It demonstrates that initial hemoglobin and hCG levels as well as abnormal bleeding on presentation are independent risk factors for blood transfusion in ectopic pregnancy.

Ectopic pregnancy in sterilized and nonsterilized women. A comparison

OBJECTIVE

To assess whether differences occurred in the presentation, treatment and postoperative outcomes of ectopic pregnancy in sterilized and nonsterilized women.

STUDY DESIGN

All cases of ectopic pregnancy admitted over five years at two hospitals were reviewed. Using a case-control method, patients with ectopic pregnancy and prior tubal sterilization were compared with the next nonsterilized patient with ectopic pregnancy admitted within 30 days. Statistical comparison, utilizing t tests, chi 2 tests of Fisher's exact test, when appropriate, was performed.

RESULTS

Thirty-eight (18%) of 208 patients with ectopics during the study period had undergone prior sterilization. This group, when compared with the 38 nonsterilized patients with ectopics, was similar for gestational age at diagnosis, frequency of pelvic inflammatory and sexually transmitted diseases, and mean human chorionic gonadotropin (hCG) level; the preoperative sonographic findings were also similar in the two groups. Sterilized patients were less likely than controls to have had serial hCG levels, while their mean duration of symptoms at admission was shorter. Although both groups had a similar distribution of surgical management (laparoscopy, laparotomy or both) and postoperative complications, there were trends toward a higher risk of ectopic rupture and hemoperitoneum in sterilized patients.

CONCLUSION

Ectopic pregnancies following tubal sterilization have clinical manifestations and surgical outcomes similar to those occurring without prior sterilization, except for less frequent determination of serial hCGs, probably related to a shorter duration of reported preceding symptoms. The trend toward more frequent rupture and hemoperitoneum in this group suggests that sterilized patients are less likely to heed the early warnings of this complication.

Bishop score: a poor diagnostic test to predict failed induction versus vaginal delivery

BACKGROUND

We evaluated the accuracy of the Bishop score in predicting the likelihood of successful labor induction (entry into active phase) in nulliparous and multiparous women.

METHODS

During an index year, all patients having induction of labor and a preinduction Bishop score were included in a standard protocol for cervical ripening and use of oxytocin. Receiver-operating characteristic (ROC) curves were constructed for Bishop scores (0 to 11) to predict abdominal delivery for failed induction (final cervical dilation <4 cm) versus vaginal delivery.

RESULTS

Parturients who had vaginal delivery (n = 253) and those in whom attempted induction failed (n = 38) did not differ significantly with respect to maternal demographics, length of gestation, Bishop score and its distribution, and infant birth weight. The area under the ROC curve did not differ significantly from the area under the nondiagnostic line.

CONCLUSION

The Bishop score appears to be a poor predictor of the outcome of labor induction.

Limitations of clinical and sonographic estimates of birth weight: experience with 1034 parturients

OBJECTIVE

To compare the accuracy of clinical and sonographic estimates of fetal weight made throughout the third trimester of pregnancy.

METHODS

Patients in early labor had fetal weight estimated by two approaches: 1) clinical evaluation and palpation followed by 2) sonographic mensuration of fetal biparietal diameter, abdominal circumference, and femur length applied to Hadlock's formula. The accuracy of these two methods of estimating fetal weight was compared using Student t test, Wilcoxon test, and chi2 tests. P < .05 was considered significant. Prediction limits (50th, 90th, and 95th percentiles) were calculated for both techniques by obtaining the range of actual weights associated for a particular estimated fetal weight (EFW).

RESULTS

We enrolled 1034 parturients whose clinical EFWs yielded significantly higher mean (+/- standard deviation) simple error (48.2 +/- 411 g) and standardized absolute error (130 +/- 122 g/kg) than were obtained by use of sonographic formulas for EFW (-6.6 +/- 381 g and 104 +/- 89 g/kg, respectively). When the population was partitioned by gestational age, we found that sonographic EFW was more accurate than clinical EFW in preterm (n = 373) but not in term (n = 460) or post-term (n = 201) pregnancies. Prediction limits indicate that for a given EFW, for example, 800 g, the 90% ranges of actual weight based on clinical and sonographic EFW are 566-1829 g and 469-1667 g, respectively.

CONCLUSION

The apparent superiority of sonographic EFW over clinical EFW applies principally to preterm pregnancies. The prediction limitation calculation suggests that either method, for any particular estimate between 500 and 4500 g, has limited value in the estimation of actual birth weight, because this outcome is highly variable and frequently lies outside of the useful bandwidth (+/- 10%) for prospective management.

Ultrasonographic assessment of amniotic fluid does not reflect actual amniotic fluid volume

OBJECTIVE

Our objective was to compare the ability of two methods of amniotic fluid assessment (two-diameter amniotic fluid pocket versus the amniotic fluid index) to predict oligohydramnios (actual amniotic fluid volume < 500 ml) or polyhydramnios (actual amniotic fluid volume > 1500 ml).

STUDY DESIGN

The amniotic fluid index and the two-diameter amniotic fluid pocket were assessed before amniocentesis and determination of amniotic fluid volume with the dye (aminohippurate sodium)-dilution technique. To assess the detection of either oligohydramnios or polyhydramnios, the areas under the receiver-operator characteristic curves (+/-SE) were estimated by the point-to-point trapezoidal method of integration. Prediction limits were calculated by regression analysis of amniotic fluid index or two-diameter amniotic fluid pocket versus actual amniotic fluid volume and determination of 95th percentile ranges for amniotic fluid volume.

RESULTS

We studied 144 patients with a mean (+/-SD) gestational age of 31.7 +/- 5.5 weeks; mean (+/-SD) amniotic fluid index and two-diameter amniotic fluid pocket were 12.6 +/- 6.1 cm and 21.2 +/- 18.4 cm2, respectively. Mean (+/-SD) actual amniotic fluid volume was 722 +/- 735 ml (range 101 to 4318 ml). The areas under the four receiver-operator characteristic curves were not significantly different from the nondiagnostic line (p < 0.05). Regression slopes (r values) for amniotic fluid index and two-diameter amniotic fluid pocket versus actual amniotic fluid volume were 0.34 and 0.23, respectively. Calculation of the prediction limit for 95% confidence that oligohydramnios is absent requires that the amniotic fluid index be 30 cm and the two-dimension amniotic fluid pocket be 90 cm2, both thresholds of which are currently considered to represent clinical polyhdramnios.

CONCLUSIONS

Both amniotic fluid index and two-dimension amniotic fluid pocket appear to be inaccurate predictors of actual oligohydramnios or polyhydramnios when compared with dye-dilution calculations of actual amniotic fluid volume.

Intrapartum oligohydramnios does not predict adverse peripartum outcome among high-risk parturients

OBJECTIVE

Oligohydramnios can be defined by an amniotic fluid index < 5th percentile for gestational age or an amniotic fluid index < or = 5.0 cm regardless of gestational age. The purpose of this prospective study was to determine whether oligohydramnios by either definition predicts accurately, in a high-risk population, the risks for cesarean section for fetal distress, Apgar score < 7 at 5 minutes, and neonatal acidosis.

STUDY DESIGN

An amniotic fluid index was obtained in 490 consecutive parturients with medical or obstetric complications and a reliable gestational age. After each delivery, an umbilical arterial blood gas analysis was obtained. Both measures of amniotic fluid index were rated as screening tests with use of sensitivity, specificity, predictive values, and receiver-operator characteristic curves.

RESULTS

The incidences of cesarean section for fetal distress and umbilical arterial pH < 7.00 were 14% and 1.8%, respectively. The 70 neonates delivered by cesarean section for distress, compared with the 420 without, had a significantly higher incidence of pH < 7.00 (8.5% vs 0.7%, p = 0.0004, relative risk 5.0, 95% confidence interval 2.9 to 8.4). Sensitivity and positive predictive values of an amniotic fluid index < 5th percentile for gestational age to predict pH < 7.00 were 0.8% and 22%, respectively, and for an amniotic fluid index < or = 5.0 cm, 0.5% and 11%, respectively. Receiver-operator characteristic curves indicate that an amniotic fluid index between 0 and 20 cm cannot predict accurately which parturients will have cesarean sections for distress or be delivered of a newborn with a low Apgar score at 5 minutes or a pH < 7.10.

CONCLUSION

Both criteria for oligohydramnios are poor predictors of adverse outcome for high-risk intrapartum patients.