Medical Archive

Introduction

Sonography in obstetrics

Technology and safety

Gestational age assessment

• Fetal biometry
  • BPD (biparietal diameter)
  • HC (head circumference)
  • AC (abdominal circumference)
  • FL (femur length)
• The estimated fetal weight (EFW) can also be determined from these measurements and varies in accuracy by ±15%.

Gestational Age	Parameter(s)	Threshold to Revise
<9 wks	CRL	>5 d
9 to <14 wks	CRL	>7 d
14 to <16 wks	BPD, HC, AC, FL	>7 d
16 to <22 wks	BPD, HC, AC, FL	>10 d
22 to <28 wks	BPD, HC, AC, FL	>14 d
?28 weeks	BPD, HC, AC, FL	>21 d

First-trimester sonography

Second- and third-trimester sonography

Normal and abnormal fetal anatomy

Brain and spine

Face and neck

• Nuchal translucency (NT, ??? ???)
  • GA 11-14?? ??, 3mm ??
  • ???? chorionic villous sampling(CVS) + quadruple test

Thorax

Abdominal wall

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Gastrointestinal tract

Kidneys and urinary tract

Skeletal abnormalities

Three- and four-dimensional sonography

Doppler

Umbilical artery

Ductus arteriosus

Uterine artery

Middle cerebral artery

Ductus venosus

Magnetic resonance imaging