Obstetric Ultrasound

1. See Also
   1. First Trimester Ultrasound
   2. Second Trimester Ultrasound (Fetal Survey)
2. Indications
   1. Determination of Gestational age
   2. Diagnosis
      1. Suspected Miscarriage or fetal demise
      2. Vaginal Bleeding
      3. Pelvic Pain
      4. Suspected Multiple Gestation
      5. Suspected hydatiform mole
      6. Suspected Ectopic Pregnancy
      7. Size-date discrepancy
      8. Uterine or pelvic mass or abnormality
      9. Congenital anomalies
      10. Fetal Presentation
   3. Antenatal Monitoring
      1. Biophysical Profile (BPP)
      2. Intrauterine Growth Retardation (IUGR)
      3. Fetal Macrosomia
   4. Adjunct to obstetrical procedures
      1. Chorionic Villus Sampling
      2. Amniocentesis
      3. Cephalic Version
   5. ACOG recommends Ultrasound at 18 weeks for all patients
      1. Confirm dates and Fetal Survey
3. Efficacy
   1. Radius Study evaluated screening Ultrasounds
      1. Evaluated low risk patients (n=15,151)
      2. Found no benefit
         1. No difference in perinatal mortality
         2. No difference in birthweight or preterm birth
      3. Did not evaluate high risk patients or other benefits
   2. Risks of screening Ultrasounds
      1. False Positives
         1. Anxiety
         2. Unnecessary intervention
      2. False Negatives
         1. False sense of reassurance
      3. Expensive: $200-$300
      4. Patients now want recreational U/S or for sexing
      5. Safety
         1. Thermal index (heat) should be 2 Celsius or less
            1. Increased risk with doppler Ultrasound
            2. Never use doppler Ultrasound in the first trimester of a viable pregnancy
         2. Mechanical index should be 4 or less
         3. Possible association with Speech Delay in children
            1. Does not appear to be significant risk
   3. Benefits of screening:
      1. Accurate Gestational age
      2. Earlier detection (first trimester) of fetal anomaly
      3. Enhanced prenatal bonding
4. References
   1. Paspulati (2004) Radiol Clin North Am 42(2):297-314 [PubMed]