Jason A. Pates

Elective Induction of Labor Compared With Expectant Management of Nulliparous Women at 39 Weeks of Gestation: A Randomized Controlled Trial.

OBJECTIVE: To evaluate whether the elective induction of labor in nulliparous women with an unfavorable cervix affects the cesarean delivery rate. METHODS: We conducted a randomized controlled trial at a tertiary care medical center. Nulliparous woman between 38 0/7 and 38 6/7 weeks of gestation who were least 18 years of age with a singleton gestation and a Bishop score of 5 or less were randomized to elective induction of labor or expectant management. The induction of labor group was induced within 1 week of enrollment but not before 39 0/7 weeks of gestation. The control group continued routine prenatal care with admission for labor or obstetric indication. The primary outcome was cesarean delivery. Assuming a 20% rate in women in a control group, 80% power, and a goal to detect a twofold increase to 40% in the induction of labor group, 162 patients were needed. RESULTS: From March 2010 to February 2014, 82 patients were randomly allocated to induction of labor and 80 to expectant management. Baseline characteristics were similar between groups. The cesarean delivery rate in the induction of labor group was 30.5% (25/82) compared with 17.7% (14/79) in the expectant management group (relative risk 1.72, 95% confidence interval 0.96–3.06). CONCLUSION: In nulliparous women with a Bishop score of 5 or less, elective induction after 39 0/7 weeks of gestation compared with expectant management of pregnancy did not double the rate of cesarean delivery. CLINICAL TRIAL REGISTRACTION: ClinicalTrials.gov, www.clinicaltrials.gov, NCT01076062. LEVEL OF EVIDENCE: I

The appendix in pregnancy: Confirming historical observations with a contemporary modality

OBJECTIVE: To estimate the position of the appendix in term pregnancy using magnetic resonance imaging (MRI) technique. METHODS: Appendiceal distance from the iliac crest and axis rotation were determined in women between 39 and 40 weeks of gestation who were undergoing scheduled repeat cesarean delivery. A single-shot fast spin-echo MRI sequence of the maternal pelvis was performed without gadolinium contrast. A board-certified radiologist interpreted the MRIs and measured the distance from the base of appendix (or cecum) to the iliac crest in centimeters as well as the axis of the appendix using clock position annotation. RESULTS: Seventy-two women had optimal imaging for interpretation. The mean displacement of the appendix above the iliac crest was 45 mm and was significantly higher than previously described in the term pregnant woman (P<.001). CONCLUSION: Despite recent studies supporting the contrary view, the upward displacement of the appendix in term pregnancy is confirmed in this study. LEVEL OF EVIDENCE: II

Determining uterine blood flow in pregnancy with magnetic resonance imaging

OBJECTIVE The purpose of this study is to determine the feasibility of measuring total uterine blood flow in pregnancy using magnetic resonance imaging (MRI) technique. METHODS Uterine blood flow was determined in pregnant women in whom MRI was being carried out to assess a fetal anomaly. A two-dimensional time-of-flight magnetic resonance (MR) angiogram sequence was performed. Scout images and a peripherally gated phase contrast MR sequence were planned to study simultaneous blood flow in the uterine and ovarian arteries. RESULTS The MR pelvic angiogram sequence was completed in 13 women. The uterine arteries were visualized and their cross-sectional area determined. The complexity of the pelvic blood supply prevented the calculation of blood flow velocity and, thus, total uterine blood flow. CONCLUSION The measurement of total uterine blood flow during pregnancy was not possible using our MR technique. The ovarian vessels were not consistently visualized. Doppler ultrasonography remains the best modality by which to estimate total uterine blood flow in pregnancy.

Postpartum cerebral venous thrombosis.

BACKGROUND: Cerebral venous thrombosis is a rare entity in pregnancy and the postpartum period, with an incidence of 1:10,000 to 1:25,000. CASE: A 19-year-old woman, gravida 1, para 1, presented to the emergency department on postpartum day 7, having experienced seizures. Severe preeclampsia had been diagnosed during the antepartum period. The patient initially was diagnosed with postpartum eclampsia and started on magnesium sulfate for seizure prophylaxis. Magnetic resonance imaging later showed cerebral venous thrombosis of the left transverse sinus and right frontal and left frontoparietal cortical veins. CONCLUSION: Cerebral venous thrombosis and eclampsia may manifest in a similar manner. Physicians can optimize the care of patients presenting with seizures by considering etiologies rarer than eclampsia and pursuing tests that may distinguish them.

Determining cervical ripeness and labor outcome: the efficacy of magnetic resonance T2 relaxation times.

OBJECTIVE: To determine whether the magnetic resonance assessment of cervical water content using the T2 relaxation time correlated with cervical ripening, as evidenced by the time to onset of spontaneous labor, need for induction, and the incidence of cesarean delivery in women whose pregnancy reached 41 weeks of gestation. METHODS: The cervical T2 relaxation time was calculated from magnetic resonance data obtained in a previous study of magnetic resonance pelvimetry. After consent was obtained, the patients underwent a magnetic resonance imaging (MRI) protocol consisting of a dual fast spin echo T2-weighted scan. From images of a single slice, the cervical T2 relaxation time was calculated from two different regions of interest (anterior and posterior) on the cervix. The average cervical T2 relaxation time was then correlated to obstetric outcomes linked with cervical ripening. RESULTS: A total of 119 patients gave their consent for the study. Of these patients, 93 had optimal imaging of the cervical stroma and were included in the analysis. There was no significant correlation between the cervical T2 relaxation time and any individual component of the Bishop score or the total score. The cervical T2 relaxation time did not predict whether labor was spontaneous or induced and whether or not a woman underwent cesarean delivery. CONCLUSION: Cervical magnetic resonance T2 relaxation times did not correlate with the clinical Bishop score or predict labor outcome in our series of women whose pregnancies reached 41 weeks of gestation. Quantifying the magnetic resonance T2 relaxation time does not appear to be useful in the assessment of cervical ripening. LEVEL OF EVIDENCE: III

Elective Induction of Nulliparous Labor at 39 Weeks of Gestation: A Randomized Clinical Trial

INTRODUCTION: Elective induction of labor is common despite the paucity of prospective data on maternal and neonatal outcomes. The objective of this study was to investigate the effect of induction of labor, at 39 weeks of gestation, on the frequency of cesarean delivery in nulliparous women with an unfavorable cervix compared with expectant management. METHODS: Nulliparous women aged 18–40 years with an uncomplicated pregnancy and a Bishop score of 5 or less receiving care at single medical center were assigned to induction of labor at 39 weeks of gestation or to expectant management in a parallel group randomized clinical trial. Maternal and neonatal outcome data were analyzed for 156 women. RESULTS: Cesarean delivery occurred in 24 of 78 (30.7%) patients in the induction of labor group and in 14 of 78 (18%) patients in the expectant management group (relative risk 1.7, 95% confidence interval 0.96–3.06, P=.07). Time from admission to delivery was longer in the induction of labor group. Meconium-stained amniotic fluid occurred more often in the expectant management group. There were no differences observed in the frequency of other outcomes. CONCLUSIONS: Cesarean deliveries in nulliparous women with an unfavorable cervix were not increased in those electively induced at 39 weeks of gestation compared with those expectantly managed. Further investigation into the clinical use of elective induction is warranted in larger multicenter trials. Based on this study, concern over maternal and neonatal outcomes including mode of delivery should not be perceived as stumbling blocks to further study of this commonly used yet understudied intervention.

Magnetic Resonance Signal Characteristics of the Cervix as Pregnancy Advances

The objective of this study is to describe magnetic resonance (MR) signal intensity (SI) changes in the cervix during pregnancy. This is an observational cohort study of women with a history of preterm delivery. MR imaging sequences were performed every 3 to 4 weeks. Using 8 regions of interest, the SIs are quantified and analyzed with respect to gestational age. Twenty-seven MR studies were performed on a cohort of 8 women. The SIs of the external os are significantly greater than those of the internal os ( P = .035). Similarly, the SIs of the outer stroma are greater than those of the inner stroma (P = .002). As gestational age advances, the inner to outer stromal SI ratio increases, primarily because of a decreasing SI in the outer stromal layer (P = .03). The MR SIs of the cervical stromal zones display variability during pregnancy and decrease with advancing gestation.