The document discusses the potential uses of ultrasound in obstetrics and gynecology. In obstetrics, ultrasound can be used to locate the pregnancy, determine gestation dates, screen for fetal abnormalities, monitor fetal growth and welfare, assess placental function, and assist with procedures. Proven uses include dating pregnancies and identifying multiple pregnancies. Unproven uses include widespread screening for anomalies or growth issues. The document also outlines uses of ultrasound in gynecology such as evaluating pelvic masses, fibroids, and endometrial thickness.

1. The Role of Ultrasound in Obstetric and Gynaecology Max Brinsmead PhD FRANZCOG May 2006

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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