The cost-effectiveness of targeted or universal screening for vasa praevia at 18-20 weeks of gestation in Ontario.

OBJECTIVES: To estimate the cost-effectiveness of targeted and universal screening for vasa praevia at 18-20 weeks of gestation in singleton and twin pregnancies. DESIGN: Cost-utility analysis based on a decision-analytic model comparing relevant strategies and life-long outcomes for mother and infant(s). SETTING: Ontario, Canada. POPULATION: A cohort of pregnant women in 1 year. METHODS: We constructed a decision-analytic model to estimate the lifetime incremental costs and benefits of screening for vasa praevia. Inputs were estimated from the literature. Costs were collected from the London Health Sciences Centre, the Ontario Health Insurance Program, and other sources. We used one-way, scenario and probabilistic sensitivity analysis to determine the robustness of the results. MAIN OUTCOME MEASURES: Incremental costs, life expectancy, quality-adjusted life-years (QALY) and incremental cost-effectiveness ratio (ICER). RESULTS: Universal transvaginal ultrasound screening of twin pregnancies has an ICER of $5488 per QALY-gained. Screening all singleton pregnancies with the risk factors low-lying placentas, in vitro fertilisation (IVF) conception, accessory placental lobes, or velamentous cord insertion has an ICER of $15,764 per QALY-gained even though identifying some of these risk factors requires routine use of colour Doppler during transabdominal examinations. Screening women with a marginal cord insertion costs an additional $27,603 per QALY-gained. Universal transvaginal screening for vasa praevia in singleton pregnancies costs $579,164 per QALY compared with targeted screening. CONCLUSIONS: Compared with current practice, screening all twin pregnancies for vasa praevia with transvaginal ultrasound is cost-effective. Among the alternatives considered, the use of colour Doppler at all transabdominal ultrasound examinations of singleton pregnancies and targeted use of transvaginal ultrasound for IVF pregnancies or when the placenta has been found to be associated with one or more risk factors is cost-effective. Universal screening of singleton pregnancies is not cost-effective compared with targeted screening.

Contrast sonography, video densitometry and intervillous blood flow: a pilot project.

PURPOSE: To examine the feasibility of constructing time-intensity (TI) curves from the intervillous space with an intravascular ultrasound contrast agent and computer assisted video densitometry. STUDY DESIGN: We sedated nine pregnant baboons, optimized the grey scale and color Doppler images of their placentas, and then fixed the transducers in place. For each injection of contrast, we recorded images on videotape without changing the ultrasound image processing functions. Video images were captured using a Macintosh personal computer equipped with a video-capture board using image analysis software (Image 1.4, W Rasband, NIH). For each injection, we sampled digitized images of a fixed region of interest at regular intervals. After computing the mean video density of each image, we used the sampling frequency to construct TI curves depicting any change over time as the contrast agents washed into and out of the intervillous space. RESULTS: Three of four agents tested produced changes in the video density of the placenta. TI curves were established using both grey scale and color Doppler signal augmentation. As expected, intra-arterial agents produced rapid accumulation and decay. Intravenous agents produced more protracted effects secondary to bolus dilution and transit through the right heart and pulmonary vascular bed. CONCLUSION: TI curves may be generated from the intervillous space with the use of a transpulmonary ultrasound contrast agent and video densitometry. If validated by further study, this may allow investigators to apply ultrasound and indicator-dilution theory to intervillous blood flow.

Oxytocin labor stimulation of twin gestations: effective and efficient.

OBJECTIVE: To test the hypothesis that oxytocin labor stimulation of twin gestations is similar to that of singletons regarding dosage, time, complications, and ability to achieve vaginal delivery. METHODS: This retrospective investigation included 124 gravidas receiving oxytocin for augmentation or induction of labor. Sixty-two women with twin gestations were matched by parity, cervical dilation at initiation of oxytocin, gestational age, oxytocin dosage regimen, and indications for oxytocin to controls with singleton pregnancies. Outcome variables included maximum dosage of oxytocin, incidence of hyperstimulation and fetal heart rate (FHR) abnormalities, time from oxytocin to delivery, cesarean deliveries, and maternal and neonatal outcomes. Statistical analysis was done using McNemar test, paired t test, and Wilcoxon signed-rank test for paired samples. RESULTS: Women with twin pregnancies and those with singletons responded similarly regarding maximum oxytocin dosage (21 +/- 1.5 and 18 +/- 2.4 mU/minute, respectively, P = .1), time from oxytocin to delivery (7.0 +/- 0.8 and 6.7 +/- 0.6 hours, respectively, P = .88), and successful vaginal delivery (90% and 90%, respectively). Oxytocin stimulation of twins resulted in fewer interruptions of the infusion for FHR abnormalities (5% compared with 26%, odds ratio [OR] 0.27, 95% confidence interval [CI] 0.16, 0.47) and hyperstimulation (6% compared with 18%, OR 0.19, 95% CI 0.36, 0.99). CONCLUSION: Twin gestation has no adverse impact on the effectiveness or efficiency of oxytocin labor stimulation. Twin pregnancy seems to be associated with fewer side effects.

Adrenal suppression induced by betamethasone in women at risk for premature delivery.

OBJECTIVE: To determine whether betamethasone administered to women at risk of preterm delivery causes adrenal suppression. METHODS: Ten women at risk of preterm delivery had three weekly low-dose (1 microg) ACTH stimulation tests with the first one between 24 and 25 weeks' gestation. Immediately after the first and second ACTH stimulation tests, we gave each woman a 12-mg betamethasone dose intramuscularly and repeated it 24 hours later. The third ACTH stimulation test was 1 week after the second course of betamethasone. Serum cortisol levels were measured before (baseline) and 30 minutes after ACTH administration. RESULTS: All subjects had normal baseline and stimulated cortisol levels for the first ACTH stimulation test. Mean baseline serum cortisol levels decreased with each ACTH stimulation test, from 25.4 +/- 4.8 microg/dL (before betamethasone) to 4.3 +/- 4.0 microg/dL (1 week after the second course of betamethasone) (P <.001). The mean stimulated cortisol levels also decreased from 33.0 +/- 4.3 microg/dL (before betamethasone) to 11.8 +/- 6.4 microg/dL (1 week after the second course of betamethasone) (P <.001). Compared with initial ACTH stimulation tests, laboratory evidence of adrenal suppression occurred in four patients 1 week after the first course of betamethasone and in seven patients after the second course. No signs or symptoms of Addisonian crisis occurred antepartum or intrapartum. CONCLUSION: Antenatal administration of betamethasone produced measurable adrenal suppression in women at risk of preterm delivery. The number of women with adrenal suppression increased each week that antenatal betamethasone was repeated. (Obstet Gynecol 2000;96:287-90.)

The effect of indomethacin tocolysis on maternal coagulation status.

OBJECTIVE: To investigate the effect of indomethacin tocolysis on maternal coagulation. METHODS: Twenty gravidas at 24-32 weeks' gestation were treated for preterm labor with 50 mg indomethacin orally, followed by 25 mg every 6 hours for 3 days. Bleeding time, prothrombin time (PT), and activated partial thromboplastin time (aPTT) were measured before and 48 hours after initiation of therapy. Statistical analysis was performed by paired t test and Fisher exact test. RESULTS: The typical participant was 22 years old, nulliparous, and 26.2 weeks' gestational age at enrollment. The mean bleeding time was 4.5 minutes before therapy and 8.8 minutes after therapy (P < .0001, mean difference 4.3 minutes, 95% confidence interval 2.9-5.8). Nineteen of the 20 subjects experienced an increase in bleeding time and 13 had abnormal bleeding times. No clinically significant changes in PT or aPTT were noted. The mean period from treatment to delivery was 60.2 days. No cases of neonatal intraventricular hemorrhage or maternal postpartum hemorrhage were noted. CONCLUSION: Oral indomethacin treatment for tocolysis has no impact on PT and aPTT; however, profound acute changes in maternal bleeding time occur.

Ultrasound detection of fetal aneuploidy in patients with elevated maternal serum alpha-fetoprotein.

Increasing confidence in the ability of high-resolution ultrasound to detect neural tube and ventral wall defects has enabled us to offer a revised risk estimate to the patient with an elevated maternal serum alpha-fetoprotein (MSAFP) level, such that amniocentesis may not be necessary. Recent authors have suggested that a reduced emphasis on follow-up amniocentesis fails to consider an increased risk for chromosomal anomalies in pregnancies with an elevated MSAFP, and that amniocentesis should still be performed. We reviewed our ultrasound findings from patients who underwent amniocentesis for evaluation of an elevated MSAFP and who had a karyotype prepared from the amniotic fluid sample. Four abnormal karyotypes were detected among 313 amniocenteses, and three of these were correctly predicted based on an abnormal ultrasound. The risk of an unexpected fetal aneuploidy after a normal consultative ultrasound in our series was one in 310. This is comparable to the risk of detecting abnormal chromosomes in the fetus of a 32-year-old woman, an age at which amniocentesis is not routinely offered.

Severe glottic stenosis in a parturient with ectodermal dysplasia.

Airway stenosis in pregnancy is challenging and the literature does not offer consensus regarding its evaluation and anesthetic management. A 21-year-old nulliparous woman with ectodermal dysplasia and severe glottic stenosis was referred to the obstetric anesthesia team for evaluation and peripartum management recommendations. She had a history of a congenital complete glottic web that required a tracheostomy at birth. After decannulation at age four, she was lost to follow-up. On examination in early pregnancy, she was found to have a dangerously narrow airway with fixed vocal cords and a glottic aperture of 2-3mm. At nine weeks of gestation an elective tracheostomy was performed under local anesthesia. She later underwent an uneventful cesarean delivery under spinal anesthesia. Ultimately, early interdisciplinary planning for an elective tracheostomy helped assure patient safety during advancing pregnancy and delivery.

Emergent cerclage.

Emergent cerclage may be defined as that performed in the setting of advanced cervical dilation with bulging or "hourglass" membranes. During a five year period, 15 patients with bulging or hourglass membranes and marked cervical dilation in the second trimester were treated with emergent cerclage. Included were two triplet gestations. Complications were limited to intraoperative rupture of fetal membranes in two patients and chorioamnionitis either in the early postoperative period (two) or later in pregnancy (three). Pregnancy was prolonged for a sufficient time to deliver viable fetuses in 11 of 15 patients. Eleven of 13 neonates of a gestational age of 24 weeks or more survived. The lack of significant maternal morbidity combined with the results for the fetus-infant supports further efforts in this area.

Trial of labor: a disciplined approach to labor management resulting in a high rate of vaginal delivery.

A disciplined approach to labor management has resulted in a low cesarean rate (9%) in our population. We wondered if this management scheme was applicable and safe applied to women with previous cesareans. Women with a previous cesarean delivering in a 5-year period were included. Labor management included encouragement of trial of labor, labor stimulation with oxytocin when indicated, epidural analgesia only after entering the active phase, and continuous monitoring. Demographic, labor and delivery, and neonatal data were electronically stored and analysis performed using SPSS release 4.1 for VAX/VMS. Statistical analysis was performed using chi-square and Fisher's exact test where appropriate. Multiple logistic regression was performed to control for potentially confounding variables. A previous cesarean had been performed in 713 (11%) gravidas who met the inclusion criteria. Vaginal delivery was attempted in 588 (82%) and 517 (88%) achieved vaginal birth. Older women (14 versus 1 versus 8%, p = 0.04), of higher parity (63 versus 35 versus 17%, p = 0.0001), requiring preterm delivery (14 versus 8 versus 4%) were more likely to have an elective repeat cesarean than a successful or failed trial of labor. Pregnancies requiring oxytocin (90 versus 53%, p = 0.02), receiving epidural analgesia (62 versus 49%, p = 0.05), developing chorioamnionitis (20 versus 4%, p < 0.0001) were more likely to fail a trial of labor. Four uterine ruptures occurred and only one patient was receiving oxytocin. There were no differences in umbilical artery blood acidemia among elective repeat cesarean sections and successful or failed trial of labor.(ABSTRACT TRUNCATED AT 250 WORDS)

Uterine arcuate artery Doppler and decidual microvascular pathology in pregnancies complicated by type I diabetes mellitus.

The objective was to correlate Doppler indices from the uterine arcuate arteries with an analysis of the decidual vascular histology in patients with type I diabetes. Pulsed wave Doppler was used to sample the uterine arcuate artery system beneath the placenta within 8 days of delivery in 47 patients with type I diabetes mellitus. A placental pathologist, without knowledge of either clinical outcome or Doppler information, classified the histological appearance of the decidual arteries as normal, type A (hyalinization, mural thickening), or type B (fibrinoid necrosis, atherosis, thrombosis). Patients were then grouped according to the histology of the decidual arteries. An analysis of variance (ANOVA) of the systolic/diastolic (S/D) ratios (log. S/D) showed significant variation (p < 0.025). A multiple range comparison test showed that patients with normal or only mildly abnormal (type A) vessels had similar values, whereas those with severe vasculopathy (type B) had significantly higher S/D ratios (p < 0.05). The study confirmed a relationship between arcuate artery Doppler indices and downstream decidual vascular pathology.

The pharmacokinetics of oxytocin as they apply to labor induction.

OBJECTIVE: Our purpose was to determine the relationship among plasma oxytocin levels, metabolic clearance rate of oxytocin, and uterine activity in gravid women undergoing labor induction. STUDY DESIGN: Ten women receiving oxytocin for labor induction and agreeing to participate had blood sampled before initiation of oxytocin and at different levels of uterine pressure. Samples were analyzed with 200 microliter extracts from 1 ml of plasma with an oxytocin radioimmunoassay. The intraassay coefficient of variation was < 3%. Sensitivity of the assay was 1.5 pg/ml. Pharmacokinetic parameters including plasma levels and metabolic clearance rates were calculated. Data were analyzed with the paired t test and linear and logistic regression. RESULTS: Mean oxytocin levels and metabolic clearance rates were 26.6 pg/ml and 7.97 ml/min. There was no correlation between changes in oxytocin level and metabolic clearance rate. Increases in infusion rates were correlated with increases in oxytocin levels (r = 0.71, p < 0.001). Cervical dilatation and uterine contraction pressures did not correlate with oxytocin levels. CONCLUSION: Peripheral plasma levels of oxytocin may not accurately reflect uterine activity or progress in labor. Plasma levels of oxytocin may merely reflect the rate of oxytocin infusion.