The Screening Ultrasound Exam

The following is a list of the topics and images that are in the book "Your High-Risk Pregnancy", available at the Apple App Store. I've included some of them in this outline to show you the breadth and depth of the book.

All screening exams include measurements of the baby. If no previous measurements have been done early in pregnancy, then the gestational age can be presumed as the number of days elapsed since the FIRST day of the LAST menstrual period, and ultrasound measurements used to confirm that date. Fetal measurements for assessment of gestational age and fetal growth include

Biparietal diameter (image)

Head circumference (image)

Abdominal Circumference (image)

Femur length (image)

Abnormalities in femur length or the length of other extremities can suggest skeletal dysplasias such as dwarfism.

Next, a survey of fetal anatomy is done to detect possible abnormalities. The following organs are examined:

Skull

• (Brachycephaly - a round head)
• (Dolichocephaly - an oval head)
• Lemon sign (meningocele)
• Microcephaly (head size markedly smaller than expected)
• Encephalocele

Spine

Myelomeningocele (aka spina bifida or neural tube defect)

Neck

• Cystic hygroma - cyst on back of neck associated with chromosomal abnormalities
• Masses on the front of the neck

Brain

• Holoprosencephaly - malformation of the brain
• Lateral ventricles

• Hydrocephalus
• Aqueductal stenosis
• Choroid plexus cysts
• Posterior fossa:
  • Normal 2nd trimester
  • Normal term fetus
  • Cerebellar diameter
  • Cerebellar vermis
  • Absent vermis: Dandy-Walker cyst
  • Cisterna Magna
• Third ventricle
  • Enlarged with aqueductal stenosis

Face (normal chin, nose, forehead)

Orbits (eye sockets)

• Binocular, interocular and ocular diameters (measurements of the size and distance between the eyes)

Lips Nose Chin

• Micrognathia (small chin associated with some anomalies)
• Cleft lip and/or palate

Chest

• Fetal cardiac anatomy
• Fetal cardiac physiology
• Fetal cardiac arrhythmias
• Lung masses
• Pulmonary sequestration
• Congenital cystic adenomatoid malformation (CCAM)
• Diaphragmatic hernia (bowel in left chest)
• Pleural effusion

Abdomen / Pelvis

• Stomach bubble should be present; if absent, suspect:
• Esophageal atresia
• Tracheoesophageal fistula
• If stomach distended or "double bubble" seen:
  • Jejunal atresia
  • Duodenal atresia
• 3-vessel cord
  • Normal - 2 arteries, 1 vein
  • Single umbilical artery is a sign to look for other anomalies
• Intact abdominal wall
  • Gastroschisis
  • Omphalocele
• Renal pelvis measurement should be <10mm
• Ureteropelvic junction obstruction
• Hydronephrosis
• Urine should be seen in bladder
  • Overdistention: posterior urethral valve in males
  • Absent urine in bladder: renal agenesis
• Bowel
  • Dilated: atresia
  • Echogenic: cystic fibrosis, chromosomal anomaly, fetal infection

Extremities

• Angulation of feet
• Radius bone present in forearms

Spine

• Curvature
• Intact skin and lamina