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Obstetric Ultrasound

Obstetric Ultrasound. Felipe Moretti, MD Griff Jones, MD, FRCS Assistant Professor – Uottawa Maternal Fetal Medicine Division.

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Obstetric Ultrasound

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  1. Obstetric Ultrasound Felipe Moretti, MD Griff Jones, MD, FRCS Assistant Professor – Uottawa Maternal Fetal Medicine Division

  2. “About 4% of all pregnancies are complicated by one or more major fetal malformations, 2% by a fetal genetic disorder, 1% by miscarriage after the first trimester, and another 1% result in infant death in the first year of life”. • Obstetrical and Gynecological Survey, 2008.

  3. What is Prenatal Diagnosis? Aneuploidy Downs’ Syndrome Anomalies Spina bifida / NTD Fetal diseaseIso-immunisation (Rh) Infection Cardiac arrythmias

  4. Obstetric Ultrasound First Trimester scan Second trimester Third trimester

  5. Obstetric Ultrasound First Trimester scan Determine Gestational age Viability Number of embryos or fetus Intrauterine pregnancy

  6. First Trimester scan Determine Gestational age: CRL (Crump Rump Length)

  7. Normal Early Pregnancy Fetal cardiac activity present

  8. Viability

  9. Viability

  10. First Trimester scan Number of embryos or fetus

  11. Intrauterine pregnancy or Ectopic pregnancy

  12. First Trimester scan IPS ( Integrated Prenatal Screen): Combine test with Maternal blood work and Ultrasound Blood work and US at 11-13+6 days: pregnancy associate plasma protein-A (PAAP-A) and free-hCG plus NT Blood work at 15-19 weeks: AFP, estriol and inhibin.

  13. Fetal Structural Anomalies • Anatomy review done at 18 - 20 weeks • Striking a balance • Adequate visualisation of fetal structures • Allow adequate time for further investigation • Leave parents the option of not continuing the pregnancy • Studies have shown a higher detection rate at 20+ weeks

  14. NuchalTranslucencia

  15. NT

  16. IPS result

  17. Second trimesterMorphology scan at 18-20 weeks

  18. Difficulties in Imaging Obesity

  19. Fetal Position • Apposing structures • Shadowing • Orientation • TV scanning • Heart • Head • Engagement

  20. Amniotic Fluid Volume

  21. Congenital Cardiac Anomalies • Detection rate remains poor • 25-50% • Technically difficult • Complex anatomy • Movement • Function changes at birth

  22. Small & Rapidly Moving Target

  23. Level 2 Ultrasound for Maternal Valproate Exposure “Normal” genetic sonogram “Normal” extended anatomy review Baby discovered to have Downs’ Syndrome at birth

  24. Prenatal ultrasound is not a perfect science Risks are modified Nothing is 100%

  25. Normal Fetal Spine

  26. What is wrong with this spine?

  27. Abnormal Lower Spine

  28. What if you can’t see the spine?

  29. Other ways to make the diagnosis

  30. Ventriculomegaly

  31. What else Ultrasound can help us in the 2nd and 3rd trimester? Placenta Location; Anterior/Posterior/Fundal/Lateral Previa or non-previa Presentation; Cephalic Breech Transverse

  32. How is the Baby Doing?Fetal Well Being

  33. Fetal Growth • There is a higher morbidity and mortality in babies that are small for gestational age • Unfortunately, most babies weighing <10th centile are “normally” grown and a significant number of IUGR babies have birthweights >10th centile

  34. Fetal Measurement 2nd and 3rd trimester Fetal Head: BPD and HC Fetal Abdomen: AC Femur Length Estimate Fetal Weigth (EFW)

  35. EFW: 10 to 90% centile

  36. Variability in Weight Estimates • Technical / image quality • Caliper placement • Numerous mathematical models • Log weight = 3-1.7492+0.0166(BPD + 0.0046*AC – 0.00002646*AC*BPD) • All tend to be poor at weight extremes • Aim for +/- 10% in 90% estimates

  37. Ultrasound Assessment of Fetal Behaviour • Significant Canadian contribution to the field • Followed on from the introduction of real-time ultrasound • Led to the development of the Biophysical Profile (BPP)

  38. Fetal Breathing • Occurs 30% of time at term • Clusters lasting 20+ minutes every 60-90 minutes • Apnea episodes lasting up to 2 hours occasionally seen

  39. Fetal Movement • Fetus moves 10% of time at term • Average of 31 movements per hour • No movement occasionally occurs for up to 75 minutes

  40. Fetal Tone • One episode of extension and return to flexion in 30 min • More recent modification to reflect fine motor activity • Hand opening / closing • Mouth opening / closing

  41. Component Criteria to score “2” 1.Breathing movements At least one episode continuing more than 30 seconds. Hiccoughs / hiccups count. 2.Body Movements At least three body or limb movements. 3. Tone An episode of active extension with return to flexion or opening and closing. 4. Amniotic fluid volume At least one cord and limb free fluid pocket which is 2 cm by 2 cm in two measurements at right angles. Biophysical Profile

  42. Oligohydramnios • Three pathologies to consider • Renal tract anomaly • Rupture of membranes – • especially if very preterm • Renal hypoperfusion • Compensatory mechanism to maintain blood flow to heart and brain • Analagous to oliguria in sick adults • Seen in IUGR

  43. Oligohydramnios and Perinatal Mortality

  44. Amniotic Fluid Assessment • One measure • 2 x 2 pocket • Single deepest pool • Four quadrants • AFI • Subjective impression

  45. Doppler

  46. Umbilical Artery Doppler

  47. Abnormal Umbilical Artery Dopplers Normal Absent EDF 4x PNM Reversed EDF 11x PNM

  48. Antepartum Haemorrhage • Abruption • By the time an abruption can be seen on ultrasound, there will often be haemodynamic effects on mother or fetus • Praevia • TV ultrasound is diagnostic method of choice

  49. The principle role of ultrasound in antepartum haemorrhage is to exclude placenta praevia

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