Presentation on theme: "Obstetric Ultrasound Felipe Moretti, MD Griff Jones, MD, FRCS Assistant Professor – Uottawa Maternal Fetal Medicine Division."— Presentation transcript:
Obstetric Ultrasound Felipe Moretti, MD Griff Jones, MD, FRCS Assistant Professor – Uottawa Maternal Fetal Medicine Division
“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.
What is Prenatal Diagnosis? AneuploidyDowns’ Syndrome AnomaliesSpina bifida / NTD Fetal diseaseIso-immunisation (Rh) Infection Cardiac arrythmias
Obstetric Ultrasound First Trimester scan Second trimester Third trimester
Obstetric Ultrasound First Trimester scan Determine Gestational age Viability Number of embryos or fetus Intrauterine pregnancy
Normal Early Pregnancy Empty uterus Positive HCG Gestation sac Plus or minus yolk sac Gestation Sac Fetal pole No fetal cardiac activity seen Gestation Sac Fetal pole Fetal cardiac activity present
First Trimester scan Number of embryos or fetus
Intrauterine pregnancy or Ectopic pregnancy
First Trimester scan IPS ( Integrated Prenatal Screen): Combine test with Maternal blood work and Ultrasound Blood work and US at days: pregnancy associate plasma protein-A (PAAP-A) and free-hCG plus NT Blood work at weeks: AFP, estriol and inhibin.
Fetal Structural Anomalies Anatomy review done at 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
Second trimester Morphology scan at weeks Body SystemDetection Rates Abdominal Wall95% CNS80% Renal60% Skeletal30% Cardiac20% to 50%
Difficulties in Imaging Obesity
Fetal Position Apposing structures Shadowing Orientation – TV scanning – Heart – Head Engagement
Amniotic Fluid Volume
Congenital Cardiac Anomalies Detection rate remains poor – 25-50% Technically difficult – Complex anatomy – Movement Function changes at birth
Small & Rapidly Moving Target
Level 2 Ultrasound for Maternal Valproate Exposure “Normal” genetic sonogram “Normal” extended anatomy review Baby discovered to have Downs’ Syndrome at birth
Prenatal ultrasound is not a perfect science Risks are modified Nothing is 100%
Normal Fetal Spine
What is wrong with this spine?
Abnormal Lower Spine
What if you can’t see the spine?
Other ways to make the diagnosis
What else Ultrasound can help us in the 2 nd and 3 rd trimester? Placenta Location; Anterior/Posterior/Fundal/Lateral Previa or non-previa Presentation; Cephalic Breech Transverse
How is the Baby Doing? Fetal Well Being
Fetal Growth There is a higher morbidity and mortality in babies that are small for gestational age Unfortunately, most babies weighing 10 th centile
Fetal Measurement 2 nd and 3 rd trimester Fetal Head: BPD and HC Fetal Abdomen: AC Femur Length Estimate Fetal Weigth (EFW)
EFW: 10 to 90% centile
Variability in Weight Estimates Technical / image quality Caliper placement Numerous mathematical models – Log weight = (BPD *AC – *AC*BPD) All tend to be poor at weight extremes Aim for +/- 10% in 90% estimates
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)
Fetal Breathing Occurs 30% of time at term Clusters lasting 20+ minutes every minutes Apnea episodes lasting up to 2 hours occasionally seen
Fetal Movement Fetus moves 10% of time at term Average of 31 movements per hour No movement occasionally occurs for up to 75 minutes
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
Biophysical Profile ComponentCriteria to score “2” 1.Breathing movements At least one episode continuing more than 30 seconds. Hiccoughs / hiccups count. 2.Body MovementsAt least three body or limb movements. 3. ToneAn 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.
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
Oligohydramnios and Perinatal Mortality
Amniotic Fluid Assessment One measure – 2 x 2 pocket – Single deepest pool Four quadrants – AFI Subjective impression
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
The principle role of ultrasound in antepartum haemorrhage is to exclude placenta praevia