Ultrasonography, Prenatal

Evidence-Based Prenatal Care: Part I. General Prenatal Care and Counseling Issues - Article

ABSTRACT: Effective prenatal care should integrate the best available evidence into a model of shared decision making. Pregnant women should be counseled about the risks of smoking and alcohol and drug use. Structured educational programs to promote breastfeeding are effective. Routine fetal heart auscultation, urinalysis, and assessment of maternal weight, blood pressure, and fundal height generally are recommended, although the evidence for these interventions is variable. Women should be offered ABO and Rh blood typing and screening for anemia during the first prenatal visit. Genetic counseling and testing should be offered to couples with a family history of genetic disorders, a previously affected fetus or child, or a history of recurrent miscarriage. All women should be offered prenatal serum marker screening for neural tube defects and aneuploidy. Women at increased risk for aneuploidy should be offered amniocentesis or chorionic villus sampling. Counseling about the limitations and risks of these tests, as well as their psychologic implications, is necessary. Folic acid supplementation beginning in the preconception period reduces the incidence of neural tube defects. There is limited evidence that routine use of other dietary supplements may improve outcomes for the mother and infant.

Late Pregnancy Bleeding - Article

ABSTRACT: Effective management of vaginal bleeding in late pregnancy requires recognition of potentially serious conditions, including placenta previa, placental abruption, and vasa previa. Placenta previa is commonly diagnosed on routine ultrasonography before 20 weeks' gestation, but in nearly 90 percent of patients it ultimately resolves. Women who have asymptomatic previa can continue normal activities, with repeat ultrasonographic evaluation at 28 weeks. Persistent previa in the third trimester mandates pelvic rest and hospitalization if significant bleeding occurs. Placental abruption is the most common cause of serious vaginal bleeding, occurring in 1 percent of pregnancies. Management of abruption may require rapid operative delivery to prevent neonatal morbidity and mortality. Vasa previa is rare but can result in fetal exsanguination with rupture of membranes. Significant vaginal bleeding from any cause is managed with rapid assessment of maternal and fetal status, fluid resuscitation, replacement of blood products when necessary, and an appropriately timed delivery.

Preterm Labor - Article

ABSTRACT: Preterm labor is the leading cause of perinatal morbidity and mortality in the United States. It is characterized by cervical effacement and/or dilatation and increased uterine irritability before 37 weeks of gestation. Women with a history of preterm labor are at greatest risk. Strategies for reducing the incidence of preterm labor and delivery have focused on educating both physicians and patients about the risks for preterm labor and methods of detecting preterm cervical dilatation. Methods used to predict preterm labor include weekly cervical assessment, transvaginal ultrasonography, detection of fetal fibronectin and home uterine activity monitoring. As yet, it is unclear if any of these strategies should be routinely employed. At present, management of preterm labor may include the use of tocolytic agents, corticosteroids and antibiotics.

Down Syndrome: Prenatal Risk Assessment and Diagnosis - Article

ABSTRACT: Down syndrome (trisomy 21) is the most commonly recognized genetic cause of mental retardation. The risk of trisomy 21 is directly related to maternal age. All forms of prenatal testing for Down syndrome must be voluntary. A nondirective approach should be used when presenting patients with options for prenatal screening and diagnostic testing. Patients who will be 35 years or older on their due date should be offered chorionic villus sampling or second-trimester amniocentesis. Women younger than 35 years should be offered maternal serum screening at 16 to 18 weeks of gestation. The maternal serum markers used to screen for trisomy 21 are alpha-fetoprotein, unconjugated estriol and human chorionic gonadotropin. The use of ultrasound to estimate gestational age improves the sensitivity and specificity of maternal serum screening.

Fetal Chromosomal Abnormalities: Antenatal Screening and Diagnosis - Article

ABSTRACT: Pregnant women of all ages should be offered screening and invasive diagnostic testing for chromosomal abnormalities before 20 weeks' gestation. New developments in screening methods have increased the number of options for patients. Diagnostic options include chorionic villus sampling in the first trimester and amniocentesis in the second trimester. Screening options in the first trimester include nuchal translucency testing in combination with measurement of pregnancy-associated plasma protein A and human chorionic gonadotropin. Nuchal translucency testing alone is not as effective. Screening options in the second trimester include serum screening using triple or quadruple screening, and ultrasonography. Patients may also choose a combination of first- and second-trimester screening in an integrated, stepwise sequential, or contingent sequential fashion. These options include an analysis of pregnancy-associated plasma protein A, with or without nuchal translucency testing, in combination with quadruple screening. An integrated test with nuchal translucency testing is the most effective method for women who present in the first trimester. If nuchal translucency testing is unavailable, the maternal serum-integrated test is safest and most effective. For women who do not present until the second trimester, the quadruple screen is recommended. Comprehensive counseling should be available to all pregnant women. Specific screening tests will depend on availability of the procedure and patient preference.

First Trimester Bleeding - Article

ABSTRACT: Vaginal bleeding in the first trimester occurs in about one fourth of pregnancies. About one half of those who bleed will miscarry. Guarded reassurance and watchful waiting are appropriate if fetal heart sounds are detected, if the patient is medically stable, and if there is no adnexal mass or clinical sign of intraperitoneal bleeding. Discriminatory criteria using transvaginal ultrasonography and beta subunit of human chorionic gonadotropin testing aid in distinguishing among the many conditions of first trimester bleeding. Possible causes of bleeding include subchorionic hemorrhage, embryonic demise, anembryonic pregnancy, incomplete abortion, ectopic pregnancy, and gestational trophoblastic disease. When beta subunit of human chorionic gonadotropin reaches levels of 1,500 to 2,000 mIU per mL (1,500 to 2,000 IU per L), a normal pregnancy should exhibit a gestational sac by transvaginal ultrasonography. When the gestational sac is greater than 10 mm in diameter, a yolk sac must be present. A live embryo must exhibit cardiac activity when the crown-rump length is greater than 5 mm. In a normal pregnancy, beta subunit of human chorionic gonadotropin levels increase by 80 percent every 48 hours. The absence of any normal discriminatory findings is consistent with early pregnancy failure, but does not distinguish between ectopic pregnancy and failed intrauterine pregnancy. The presence of an adnexal mass or free pelvic fluid represents ectopic pregnancy until proven otherwise. Medical management with misoprostol is highly effective for early intrauterine pregnancy failure with the exception of gestational trophoblastic disease, which must be surgically evacuated. Expectant treatment is effective for many patients with incomplete abortion. Medical management with methotrexate is highly effective for properly selected patients with ectopic pregnancy. Follow-up after early pregnancy loss should include attention to future pregnancy planning, contraception, and psychological aspects of care.

Preterm Labor - Article

ABSTRACT: Preventing preterm delivery remains one of the great challenges in modern medicine. Preterm birth rates continue to increase and accounted for 12.7 percent of all U.S. births in 2005. The etiology of preterm delivery is unclear, but is likely to be complex and influenced by genetics and environmental factors. Women with previous preterm birth are at increased risk of subsequent preterm delivery and may be candidates for treatment with antenatal progesterone. Fetal fibronectin testing and endovaginal ultrasonography for cervical length are useful for triage. For the patient in preterm labor, only antenatal corticosteroids and delivery in a facility with a level III neonatal intensive care unit have been shown to improve outcomes consistently. Tocolytic agents may delay delivery for up to 48 hours, enabling the administration of antenatal corticosteroids or maternal transfer. Routine use of antibiotics in preterm labor is not indicated except for group B streptococcus prophylaxis or treatment of chorioamnionitis.

Nonmedical Ultrasonography During Pregnancy - Curbside Consultation

Vaginal Bleeding at 16 Weeks - Photo Quiz

Update on Prenatal Care - Article

ABSTRACT: Many elements of routine prenatal care are based on tradition and lack a firm evidence base; however, some elements are supported by more rigorous studies. Correct dating of the pregnancy is critical to prevent unnecessary inductions and to allow for accurate treatment of preterm labor. Physicians should recommend folic acid supplementation to all women as early as possible, preferably before conception, to reduce the risk of neural tube defects. Administration of Rho(D) immune globulin markedly decreases the risk of alloimmunization in an RhD-negative woman carrying an RhD-positive fetus. Screening and treatment for iron deficiency anemia can reduce the risks of preterm labor, intrauterine growth retardation, and perinatal depression. Testing for aneuploidy and neural tube defects should be offered to all pregnant women with a discussion of the risks and benefits. Specific genetic testing should be based on the family histories of the patient and her partner. Physicians should recommend that pregnant women receive a vaccination for influenza, be screened for asymptomatic bacteriuria, and be tested for sexually transmitted infections. Testing for group B streptococcus should be performed between 35 and 37 weeks’ gestation. If test results are positive or the patient has a history of group B streptococcus bacteriuria during pregnancy, intrapartum antibiotic prophylaxis should be administered to reduce the risk of infection in the infant. Intramuscular or vaginal progesterone should be considered in women with a history of spontaneous preterm labor, preterm premature rupture of membranes, or shortened cervical length (less than 2.5 cm). Screening for diabetes should be offered using a universal or a risk-based approach. Women at risk of preeclampsia should be offered low-dose aspirin prophylaxis, as well as calcium supplementation if dietary calcium intake is low. Induction of labor may be considered between 41 and 42 weeks’ gestation.

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