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Ultrasound

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Ultrasound Ultrasound Presentation Transcript

  • The Role of Ultrasound in Obstetric and Gynaecology Max Brinsmead PhD FRANZCOG May 2006
  • Potential uses for ultrasound in obstetrics 1 :
    • Locate the pregnancy – exclude ectopic
    • Assess viability – assessment of threatened miscarriage
    • Determining gestation & dates
        • Crown rump length
    • Diagnosis of twins – the importance of zygosity
    • Assessment of other pelvic masses
        • e.g. fibroids, functional ovarian cysts & neoplasms
    • Screening for abnormalities first trimester
        • Nuchal fold measure, anencephaly etc.
    • Assisting CVS and amniocentesis
    • Diagnosis of molar pregnancy
  • Potential uses for ultrasound in obstetrics 2 :
    • Second trimester dating (+/- 10 days)
        • Biparietal diameter, head & abdominal circumference, femur length
    • Screening for abnormalities
        • e.g. spina bifida, cardiac, renal
    • Screening for placenta previa
    • Cervical length monitoring
        • >30 mm before 18w & >25 mm before 28 w = low risk of pre term delivery
    • Assessment of APH
    • Assessment of fetal growth
        • Asymmetrical and symmetrical
    • Evaluation of polyhydramnios and hydrops
  • Potential uses for ultrasound in obstetrics 3 :
    • Assessment of fetal welfare
        • Amniotic fluid index or deepest pool
        • Fetal breathing
        • Fetal movements and tone (the Biophysical Profile)
    • Doppler flow studies
        • In umbilical arteries
        • Fetal middle cerebral artery
        • Uterine arteries
    • Diagnosis and management of malpresentation
        • Breech and unstable or transverse lie
    • Directing intrauterine interventions
        • e.g. transfusion for hydrops, catheter for urethral stricture
    • Placental grading (of doubtful value)
    • Assessment of the postpartum uterus
  • Proven uses for ultrasound in pregnancy :
    • Dating the gestation
        • 30% of women cannot provide a LMP
        • Another 25% have a LMP that is >2w different from USS dates
        • When dates are known aneuploidy screening is accurate and errors of delivery are avoided, fewer inductions for post dates etc.
    • Identification of multiple pregnancy
        • Twins have a perinatal mortality that is 2-4x singletons
        • Monitoring for discordant growth with Doppler reduces risk
    • Identification of breech in the third trimester
        • ECV reduces the rate of Caesarean section
    • Few RCTs of routine ultrasound have shown any effect on overall perinatal mortality and morbidity
  • Unproven uses for ultrasound in pregnancy :
    • Screening for Aneuploidy
        • Cost effectiveness of universal screening debated
        • Ethical issues and patient choice involved
    • Screening for structural malformations
        • Sensitivity is 13 – 50% depending on expertise & equipment
        • And only half of these before 20 w gestation
        • False positives occur
    • Screening for IUGR in the 3 rd trimester
        • Sensitivity is 80-90%
        • But the positive predictive value of neonatal morbidity is only 25-50%
        • The rest have constitutional smallness
  • Harmful Effects of ultrasound in pregnancy :
    • It is not ionising radiation
    • However, thermal effects and cavitation can occur in tissues exposed to high power ultrasound
    • One RCT of repeated routine ultrasound with Dopplers in the 3 rd trimester found a small but significant decrease in birth weight in the exposed cohort
  • Potential uses for ultrasound in gynaecology 1 :
    • Assessment of adnexal pelvic masses
        • Compound B scan
        • Doppler vessel studies
    • Diagnosis of polycystic ovaries
    • Investigation of postmenopausal bleeding
        • Imaging and measure of endometrial thickness
    • Investigation of menorrhagia
        • Fibroids and adenomyosis
    • Monitoring of follicle number and growth for IVF
    • Egg recovery for IVF and ICSI
    • Evaluation of pelvic pain
        • A limited role
    • Screening for ovarian cancer
        • Too many false positives
  • Potential uses for ultrasound in gynaecology 2 :
    • IUCD and Implanon location
    • Treatment of ovarian cysts (aspiration) and ectopic pregnancy (methotrexate)
    • Saline hysterography for delineation of the uterine cavity
    • Tubal patency studies in infertility
    • Evaluation of primary amenorrhoea