Prenatally Diagnosed Vasa Previa: A Single-Institution Series of 96 Cases.

OBJECTIVE: To describe outcomes for a large cohort of women with prenatally diagnosed vasa previa, determine the percentage in patients without risk factors, and compare delivery timing and indications for singletons and twins. METHODS: This was a retrospective case series of women with prenatally diagnosed vasa previa delivered at a single tertiary center over 12 years. Potential participants were identified using hospital records and perinatal databases. Patients were included if vasa previa was confirmed at delivery and by pathologic examination. Maternal and newborn data were gathered from medical records. RESULTS: There were 77 singleton and 19 twin pregnancies with a prenatal diagnosis of vasa previa. There was one neonatal death from congenital heart disease. Perinatal management of recommended elective hospitalizations with corticosteroid administration and elective early delivery resulted in average gestational age for delivery in singletons at 34.7±1.6 weeks and 32.8±2.2 weeks for twins. Among the 77 singletons, delivery was elective in 48, as a result of contractions or labor in 21, bleeding in four, nonreassuring tracing in two, asymptomatic cervical shortening in one, and preeclampsia in one. Among 19 twins, delivery was elective in six and for contractions or labor in 13. Sixty-eight percent of twins compared with 37% of singletons had nonelective delivery (P<.05). Delivery occurred by 32 weeks of gestation in 6.4% of singletons and 26% of twins (P<.05) and by 34 weeks of gestation in 11% of singletons and 58% of twins (P<.001). Six neonates (5.2%) had major anomalies, all prenatally detected. Respiratory distress syndrome occurred in 57.1% of singletons and 65.7% of twins. Nineteen singletons (24.7%) had no risk factors for vasa previa. CONCLUSION: Planned preterm delivery for women with prenatally diagnosed vasa previa resulted in elective delivery for singletons in 62% and for twins 32%. Gestational age at birth on average was 34.7 weeks for singletons and 32.8 weeks of gestation for twins. Major anomalies were frequent as was respiratory distress syndrome. Elective delivery between 34 and 35 weeks of gestation for singletons is reasonable. As a result of the high rate of nonelective delivery in twins, delivery at 32-34 weeks of gestation may be risk-beneficial. The high rate of singletons without risk factors for vasa previa reinforces the recommendation to screen routinely for cord insertion site.

Nonstress testing at ≤ 32.0 weeks' gestation: a randomized trial comparing different assessment criteria.

OBJECTIVE: Comparison of time and outcomes of National Institutes of Child Health and Human Development defined fetal heart rate acceleration criteria at ≤ 32 weeks (≥ 10 beats/min, ≥ 10 seconds) compared with standard criteria (≥ 15 beats/min, ≥ 15 seconds). STUDY DESIGN: Singleton high-risk pregnancies that were referred for nonstress testing at ≤ 32 weeks' gestation were randomly assigned to 15 × 15 or 10 × 10 criteria. Data included nonstress test information, maternal data, and outcomes. RESULTS: One hundred forty-three women were randomly assigned to 15 × 15 (n = 71) or 10 × 10 (n = 72). The groups were similar in maternal and pregnancy characteristics. Median time to reactive nonstress testing was shorter in the 10 × 10 group (37.3 minutes) than the 15 × 15 group (41.3 minutes; P = .04). There were no serious adverse events. CONCLUSION: The time to attain a reactive nonstress testing at ≤ 32 weeks' gestation was 4 minutes shorter when the 10 × 10 criteria were used. There were no adverse events related to use of 10 × 10 nonstress testing criteria.

Antithrombotic therapy and pregnancy: consensus report and recommendations for prevention and treatment of venous thromboembolism and adverse pregnancy outcomes.

Venous thromboembolism and adverse pregnancy outcomes are potential complications of pregnancy. Numerous studies have evaluated both the risk factors for and the prevention and management of these outcomes in pregnant patients. This consensus group was convened to provide concise recommendations, based on the currently available literature, regarding the use of antithrombotic therapy in pregnant patients at risk for venous thromboembolic events and adverse pregnancy outcomes.

Management of thromboprophylaxis during pregnancy among specialists in maternal-fetal medicine.

OBJECTIVE: To evaluate practice patterns among maternal-fetal medicine physicians with regard to thromboprophylaxis in pregnancy. STUDY DESIGN: A Web-based survey was conducted among members of the Society for Maternal-Fetal Medicine (SMFM). The Web address for the survey and unique participant identification codes were mailed out to all SMFM members. Participants answered questions about their perceptions of risk factors for thrombosis in pregnancy as well as their use of thromboprophylaxis for cesarean section and for extended antepartum bed rest (>72 hours). RESULTS: A total of 157 physicians responded to the survey. Few respondents use routine thromboprophylaxis for patients at cesarean section (8%) or who are on antepartum bed rest (25%), but the majority would use prophylaxis for patients at cesarean (91%) or during antepartum bed rest (81%) if these patients were considered to be at high risk for thrombosis. There was, however, great variation in the conditions thought to be risk factors for thrombosis, the risk factors of great enough risk to warrant prophylaxis and the prophylactic regimens used. CONCLUSION: Routine thromboprophylaxis for cesarean section or extended antepartum bed rest is uncommon. Although more common, risk-based thromboprophylaxis lacks a clear consensus as to which factors warrant this strategy and which regimen should be used.

The use of unfractionated heparin and low molecular weight heparins in pregnancy.

Currently unfractionated heparin (UH) and low molecular weight heparins (LMWH) are the agents of choice for anticoagulation in pregnancy. LMWH have been used safely without monitoring in nonpregnant patients; however, because of documented changes in the pharmacokinetics of these agents in pregnancy, monitoring with anti-Xa levels is necessary in pregnancy to maintain target therapeutic ranges. Patients requiring only prophylaxis during pregnancy with either UH or LMWH might benefit from occasional assessment of anti-Xa levels to confirm that target prophylactic ranges are being achieved. Although LMWH may cause less osteoporosis than UH at therapeutic doses, the incidence of heparin-induced osteoporosis seems to be low when only prophylactic dosing is used and therefore LMWH do not seem to offer this advantage at low doses. Experience with newer agents such as pentasaccharide inhibitors and direct thrombin inhibitors are limited in pregnancy and it remains to be seen what role these agents will play in women who require anticoagulation in pregnancy.

Bone density changes in women who receive thromboprophylaxis in pregnancy.

OBJECTIVE: The purpose of this study was to compare unfractionated heparin therapy to the low molecular weight heparin, enoxaparin sodium, and their effects on bone mineral density over the course of pregnancy. STUDY DESIGN: Pregnant patients whose condition required thromboprophylaxis were recruited in this prospective randomized controlled trial and were assigned to receive either unfractionated heparin therapy or low molecular weight heparin therapy. Bone mineral density was measured by dual energy x-ray absorptiometry at the proximal femur on enrollment and again shortly after delivery. RESULTS: One hundred twenty women were enrolled, and 98 women completed the study. There was no difference in the change in bone mineral density at the femoral neck (P = .054) or total proximal femur (P = .584) between groups. Only 1 of 40 patients (2.5%) who received unfractionated heparin therapy and 1 of 49 patients (2.0%) who received low molecular weight heparin therapy (P = 1.0) experienced bone loss of > or = 10% at the femoral neck. CONCLUSION: In this study, the incidence of clinically significant bone loss (> or = 10%) in the femur in women who received thromboprophylaxis in pregnancy is approximately 2% to 2.5% and appears to be similar, regardless of whether the patient receives low molecular weight heparin therapy or unfractionated heparin therapy.

Cost-effectiveness of thromboprophylaxis with intermittent pneumatic compression at cesarean delivery.

OBJECTIVE: To evaluate the cost-effectiveness of thromboprophylaxis at cesarean delivery with intermittent pneumatic compression. METHODS: A decision tree model using Markov analysis was developed to compare two approaches to perioperative care at the time of cesarean delivery: 1) no use of perioperative thromboprophylaxis and 2) the use of intermittent pneumatic compression for thromboprophylaxis at the time of cesarean delivery. Postcesarean deep venous thrombosis was estimated to occur in 0.7% of patients (75% of whom were asymptomatic), and result in a 9% chance of postthrombotic syndrome. Mechanical prophylaxis was assumed to decrease the risk of deep venous thrombosis by 70% and to cost 120 dollars. Probability of morbidity and mortality of venous thromboembolism as well as anticoagulation and the costs and utilities for different health state were derived from published studies. Sensitivity analysis was performed over a wide range of variable estimates. RESULTS: Using the assumptions in our base case, routine thromboprophylaxis for cesarean delivery cost 39,545 dollars per quality-adjusted life year. One-way sensitivity analysis revealed that as long as the incidence of postcesarean deep venous thrombosis was at least 0.68%, intermittent pneumatic compression reduced the incidence of deep venous thrombosis by at least 50%, or the cost of intermittent pneumatic compression was less than 180 dollars, the cost-effectiveness of mechanical prophylaxis did not exceed 50,000 dollars per quality-adjusted life year. CONCLUSION: Mechanical thromboprophylaxis is estimated to be a cost-effective strategy under a wide range of circumstances.