Arnold L. Medearis

Risk factors associated with uterine rupture during trial of labor after cesarean delivery: A case-control study

OBJECTIVEnThe purpose of our study was to thoroughly investigate the risk factors of uterine rupture in patients undergoing trial of labor after cesarean section.nnnSTUDY DESIGNnWe conducted a case-control study of 70 patients with prior cesarean delivery with uterine rupture during trial of labor between January 1983 and June 1990. The risk factors of uterine rupture were identified, and the estimates of the relative risks were reported.nnnRESULTSnThe risk of uterine rupture was increased in patients who had an excessive amount of oxytocin, who had experienced dysfunctional labor, and who had a history of two or more cesarean deliveries. Epidural anesthesia, macrosomia, history of successful vaginal delivery after cesarean section, unknown uterine scar, and history of cesarean delivery because of cephalopelvic disproportion were not associated with uterine rupture.nnnCONCLUSIONSnWe recommend that all patients with a history of cesarean delivery be observed closely for progression of labor. Recognition of an active-phase arrest disorder, despite adequate augmentation with oxytocin, requires operative delivery.

Uterine rupture during trial of labor after previous cesarean section

This study was undertaken to determine the incidence and associations of uterine rupture and dehiscence with an attempted vaginal birth after cesarean section. The charts from 137 patients who had uterine scar separation after a previous cesarean section from 1983 to 1989 were examined. Approximately 9.3% of the 119,395 women who were delivered in that interval had a prior cesarean section. Of those, 68.8% underwent a trial of labor with a 79.2% success rate. The uterine rupture rate in this latter group was 0.8%, while an additional 0.7% had a bloodless dehiscence. Bleeding and pain were unlikely findings with a uterine scar separation (3.4% and 7.6%, respectively). The most common manifestation of a scar separation was a prolonged fetal heart rate deceleration leading to operative intervention (70.3%). We conclude that, although the incidence of uterine rupture was low, the event is most often seen as an acute emergency. Prevention should be directed toward timely diagnosis and prompt management of labor dystocias. Staff and facilities for safe management of a uterine scar separation are a requisite for the conduct of a vaginal birth after previous cesarean section.

Qualitative assessment of maternal uterine and fetal umbilical artery blood flow and resistance in laboring patients by Doppler velocimetry

The purpose of this study is to evaluate the effect of uterine contractions during labor on both the uterine and the umbilical circulations. Twenty-seven patients in active labor were studied by continuous-wave Doppler velocimetry. Umbilical, left uterine, and right uterine arterial waveforms were obtained before, during, and after peak uterine contractions, and the ratio of maximum systolic and minimum diastolic velocities was calculated. Fifteen patients showed absent flow in end diastole on the uterine artery waveform and had significantly higher intra-amniotic pressures (64.5 +/- 3.5 mm Hg) during the peak amplitude of the uterine contraction compared with the 12 patients with maintained end diastolic flow (46.5 +/- 2.6 mm Hg; p less than 0.05). During the peak amplitude of the uterine contractions the 12 patients maintaining end-diastolic flow had significantly higher systolic/diastolic ratios in the uterine artery (6.5 +/- 1.5) compared with either before or after a contraction (2.1 +/- 0.15 and 2.0 +/- 0.2, respectively; p less than 0.05). Also, these 12 patients showed a linear relationship between the systolic/diastolic ratio and the intrauterine pressure. However, no differences were observed in the umbilical artery systolic/diastolic ratios before, during, or after a contraction in the intensity range studied. On the contrary, during contractions an increase in uterine artery resistance occurs with decreased or absent end-diastolic flow, which bears an inverse linear relationship to the intensity of the contraction. This suggests that during uterine contractions the human fetus continues to have uninterrupted fetoplacental blood flow, whereas the degree of interruption or reduction in uteroplacental blood flow is dependent on the intensity of uterine contraction.

Antepartum surveillance in diabetic pregnancies: Predictors of fetal distress in labor

OBJECTIVEnOur purpose was to evaluate an antepartum testing program based on twice-weekly nonstress testing and amniotic fluid evaluation in pregnancies complicated by diabetes mellitus and to weight the test components in the prediction of fetal distress requiring cesarean delivery.nnnSTUDY DESIGNnDuring the 4-year period of 1987 through 1990, 2134 women with pregnancies complicated by diabetes underwent antepartum testing. Of these 1501 women (class A1, n = 505; A2-diet, n = 305; A2-insulin, n = 580; B, n = 71; C to D, n = 29; R to F, n = 11) were delivered within 4 days of their last test. Categoric analysis of data was performed according to diabetic class, fetal heart rate results, and the presence of decreased, normal, or increased amniotic fluid assessment. A univariate logistical regression was first conducted with cesarean delivery for fetal distress as outcome variable by use of the following variables: fetal weight and sex, diabetic class, gestational age at delivery, presence of additional indications for antepartum testing, largest vertical pocket, amniotic fluid index (summation of the four quadrants of the largest vertical pocket), nonstress test reactivity (two accelerations of > or = 15 beats/min of 15 seconds duration), presence of decelerations (> or = 15 beats/min for 15 seconds) during the nonstress test, and the interactions of the nonstress test with deceleration, largest vertical pocket, and amniotic fluid index. Multivariate analysis was then applied to predict the best model.nnnRESULTSnNo stillbirths occurred within 4 days of the last antepartum test. However, the corrected stillbirth rate of the entire tested population was 1.4 per 1000. Eighty-five women required cesarean delivery for fetal distress. The factors most predictive of cesarean delivery for fetal distress (p < 0.05, odds ratio and 95% confidence interval) were a deceleration (3.60, 2.14 to 6.06), nonreactive nonstress test (2.68, 1.60 to 4.49), and the interaction of both a nonreactive nonstress test and decelerations (5.63, 2.67 to 11.9). Amniotic fluid assessment by largest vertical pocket or amniotic fluid index were not statistically significant. The multivariate analysis selected the interaction of nonstress test and deceleration as the best significant predictor for cesarean delivery for fetal distress.nnnCONCLUSIONnAn antepartum fetal surveillance program using twice-weekly nonstress test and fluid index assessment in pregnancies complicated by diabetes was successful in preventing stillbirth. The absence of fetal heart rate reactivity and the presence of decelerations were predictive of the diagnosis of fetal distress in labor requiring cesarean delivery. Ultrasonographic assessment of amniotic fluid volume was not a significant predictor of fetal distress in labor in the diabetic pregnancy.

The use of transvaginal sonography for evaluation of postmenopausal ovarian size and morphology

Ultrasonic evaluation has been suggested as a possible screening tool for early changes in ovarian morphology. This study uses transvaginal sonography to evaluate the ovaries in postmenopausal women who were scheduled for gynecologic surgery unrelated to adnexal disease. The findings of ultrasonic ovarian examination are compared with the findings at surgery and the pathologic evaluation of the ovaries. Nine (17.3%) abnormal ovaries were identified by ultrasonography and at surgery and were confirmed at pathologic examination. Among the abnormal ovaries there were one malignancy (10%) and two neoplasms with known malignant potential (20%). One ovary that was identified to have microscopic areas of Brenner tumor cells at pathologic examination was described as normal by both ultrasound and surgical evaluation. The sensitivity (90%) and specificity (100%) of vaginal sonography were the same as that of gross examination of the ovary at the time of surgery. We conclude that vaginal sonography is a reliable tool in the detection of early abnormalities in the postmenopausal ovary.

Ultrasonographic estimation of fetal weight in the clinically macrosomic fetus

The purpose of this study is to evaluate models for the prediction of birth weight in fetuses suspected of being macrosomic. A total of 141 patients with standard measurements of the head, abdomen, and femur were studied. Linear regressions were performed with single parameters, squares, and all possible cross products in the generation of models with log (birth weight) and birth weight as dependent variables. These models were then compared with a group of previously published equations. Clinically, all models performed poorly. However, two models were significantly less accurate in the prediction of birth weight (p less than or equal to 0.05). The best results were obtained by equations that used abdominal circumference and femur length measurements. There was no improvement in models that contained log (birth weight) or birth weight as dependent variables or models with complex variables such as squares or cross products of measured parameters. In conclusion, when evaluating patients at risk of macrosomia, the best estimates of fetal weight can be obtained by models that contain abdominal circumference and femur length.

Fetal choroid plexus cysts in the second trimester of pregnancy: A cause for concern

Controversy surrounds the issue of recommending cytogenetic studies in second-trimester fetuses with fetal choroid plexus cysts. To assist in clarifying this issue, a prospective study was designed to describe the association between fetal choroid plexus cysts and aneuploidy in a large population. During a 3-year period 7350 women at 15 to 22 weeks gestation underwent an ultrasonographic evaluation. Fetal choroid plexus cysts were diagnosed in 71 (0.96%) of these pregnancies. Sixty-two of the 71 patients elected to undergo amniocentesis. An abnormal karyotype was identified in four (6.4%) of these fetuses. One fetus had trisomy 21, and three fetuses were diagnosed with trisomy 18. These data indicate that it is reasonable to offer genetic counseling and cytogenetic studies in those patients identified as having a fetal choroid plexus cyst.

The use of a neural network for the ultrasonographic estimation of fetal weight in the macrosomic fetus

The error associated with regression analysis methods for the ultrasonographic estimation of fetal weight in the suspected macrosomic fetus, approximately 10%, is clinically unacceptable. This study was undertaken to evaluate the applicability of an emerging technique, biologically simulated intelligence, to this problem. One hundred patients with suspected macrosomic fetuses underwent ultrasonographic measurements of biparietal diameter, head and abdominal circumference, femur length, abdominal subcutaneous tissue, and amniotic fluid index. The biologically simulated intelligence model included gestational age, fundal height, age, gravidity, and height. The model was then compared with results obtained from previously published formulas relying on the abdominal circumference and femur length. The biologically simulated intelligence yielded an average error of 4.7% from actual birth weight, statistically better (p = 0.001) than the results obtained from regression models.

Characteristics of ovarian follicular development in Norplant users

Daily transvaginal ultrasound (US) scanning of the ovaries to assess follicular development and daily blood sampling were performed on 19 Norplant (Leiras, Turku, Finland) subdermal contraceptive implant users who had regular menstrual cycles and on 10 normally cycling women. Three groups were identified in the implant users based on US finding. Six (31.6%) of the implant users had US findings that were consistent with a normal ovulatory pattern. However, their mean peak luteinizing hormone levels and peak midluteal phase progesterone (P) levels were significantly lower than control values. Eleven (57.9%) users had persistent follicles, and 2 users (10.5%) had no follicular development. These data suggest that after 2 to 4 years of use, about one third of Norplant users with regular bleeding patterns may ovulate but most have deficient luteal P levels. In this small study, the presence of persistent follicular enlargement in implant users was common.

Maternal and fetal blood flow velocity waveforms in patients with preterm labor prediction of successful tocolysis

Umbilical and uterine artery velocimetry was performed using continuous-wave Doppler ultrasound (Angioscan III) in 60 patients in preterm labor. Peak-systolic/end-diastolic ratios were calculated according to previously described techniques. All measurements were made before tocolytic therapy was begun: magnesium sulfate (n = 40) or ritodrine (n = 20). The mean gestational age was 33.1 +/- 1.5 weeks (range 29 to 36 weeks). Twelve (20%) patients had elevated (greater than 2.6) pretherapy uterine peak-systolic/end-diastolic ratios, 10 (16.7%) patients had elevated (greater than 3.5) pretherapy umbilical peak-systolic/end-diastolic ratios, and in eight (13.3%) patients both ratios were elevated. In seven (58.4%) of the 12 patients with elevated uterine peak-systolic/end-diastolic ratios, six (60%) of the 10 patients with elevated umbilical peak-systolic/end-diastolic ratios, and five (62.5%) of the eight patients with both ratios elevated tocolytics failed and the women were delivered within 48 hours, compared with seven (14.6%) of 48, eight (16%) of 50, and six (13.0%) of 46 with normal ratios, respectively (p less than 0.05). We conclude that patients in preterm labor with elevated pretherapy uterine and/or umbilical peak-systolic/end-diastolic ratios are more likely to fail tocolysis therapy and be delivered preterm than those with normal ratios. It may therefore be useful to include umbilical and uterine velocimetry in the initial evaluation of preterm labor.