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OB/GYN Board Exam - Ultrasound1

Chapters 14 & 15
STUDY
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Esophageal Atresia
Discontinuity of the esophagus.
What is Esophageal Atresia accompanied by 90% of the time?
Distal tracheo-esophageal fistula
Congenital malformations associated with esophageal atresia:
cardiovascular, gastrointestinal, gastrourinary, muskuloskeletal anomalies
Meconium (mixture of:)
Bile, swallowed vernix, desquamated cells, and fetal hair
When is the colon most obvious?
3rd trimester
Peristalsis can be seen by:
Late 2nd trimester
Sonographic findings of esophageal atresia:
small or absent stomach, inability to demonstrate stomach on serial exams, polyhydramnios
Duodenal Atresia
The first part of the small bowel (duodenum) hasn't developed properly.
Anomalies associated with duodenal atresia:
Karyotype, or anomalies present at birth. Most commonly cardiac or vertebral. Trisomy 21.
Sonographic findings of duodenal atresia:
"double bubble" sign, polyhydramnios
"Double Bubble" sign
dilated stomach and dilated proximal duodenum
Duodenal atresia may not become apparent until:
24 weeks gestation
Intestinal Atresia
Narrowing, absence, or obstruction of the intestine. (w/ subsequent distention of bowel loops)
Intestinal Atresia - The small bowel internal diameter is:
>7mm
Intestinal Atresia - Sono - PAC PIM
P - polyhydramnios
A - ascites
C - calcifications

P - perforation,
I - increased peristalsis,
M - multiple fluid filled bowel.
Meconium Peritonitis
Rupture of the bowel prior to birth. (perforation in utero)
Results in fetal stool (meconium) escaping into the peritoneum.
Leads to peritonitis. (sterile chemical peritonitis)
Etiology of Meconium Peritonitis:
Cystic Fibrosis (35-40%)
Because of thick, sticky meconium
Meconium Peritonitis can occur after:
Fetal bowel obstruction.
Fetal bowel obstruction can be caused by:
Intestinal atresia, volvulus, or meconium ileus.
Meconium Peritonitis - sono - CAMP
C - calcifications in fetal abdomen
A - ascites
M - meconium pseudocyst
P - polyhydramnios.
Hyperechoic Bowel
The echogenicity is increased and is similar to or greater than the adjacent bone.
Hyperechoic Bowel cant be identified until:
2nd trimester
Hyperechoic Bowel is located in:
Lower fetal abdomen and pelvis
Hyperechoic Bowel characteristics:
Focal or diffuse, doesn't shadow
What should be used to determine Hyperechoic Bowel?
Lower frequency.
Etiologies of Hyperechoic Bowel: STINC
S - swallowed intra-abdominal blood (rare)
T - trisomy 21
I - infection - CMV (cytomegalovirus)
N - normal variant
C - cystic fibrosis
What plane can you see the upper lip and nares?
Oblique coronal plane
What plane can you see the eyes?
True coronal or trans
What is associated with an absent or hypoplastic nasal bone?
Trisomy 21
Trisomy 21 is associated with a NF of:
>6mm (between 15 and 21 weeks)
Hypotelorism
Decreased intraorbital distance
Hypertelorism
Increased intraorbital distance
Hypotelorism associated with:
Holoprosencephaly, and other symptoms
Hypertelorism associated with:
Anterior cephalocele, and other symptoms
What is the most common congenital facial anomaly?
Cleft lip / Palate
Cleft lip/palate percentages:
25% cleft lip only
50% cleft lip and palate
25% cleft palate only
Asymmetric clefts can be associated with:
Amniotic band syndrome
Cleft lip/palate - sono - PB SAM
P - polyhydramnios
B - Best seen in coronal section

S - shouldn't be mistaken for philtrum
A - Anechoic cleft extending from nostril to lip
M - may see tongue moving in cleft
Median Cleft Lip
Midline malformation without cleft palate
Median cleft lip embryonic development is related to:
Differentiation of the forebrain
Median cleft lip associated with:
Holoprosencephaly, other ML defects of the face
Median cleft lip - sono:
Similar to cleft lip/palate
Search for other facial anomalies (face predicts the brain)
Micrognathia
Abnormally small jaw
Micrognathis associated with:
Trisomy 18
Frontal Bossing
A prominent forehead due to absent nasal bridge
Frontal Bossing associated with:
Skeletal Dysplasia
Epignathus
Pharyngeal teratoma which protrudes from the fetal mouth.

Rare
Epignathus associated with:
Polyhydramnios (b/c ineffective fetal swallowing)
Epignathus - sono:
Large complex cystic and solid mass
May hyperextend the neck
Cystic Teratoma
Complex cystic or solid mass near the fetal neck

Can occur anywhere on or around the neck
Cystic Teratoma may be mistaken for:
Cystic Hygroma
Nuchal Thickening
Increased soft tissue thickness at the posterior aspect of the neck.
Nuchal Thickening associated with:
Trisomy 21, and other chromosomal anomalies
When looking for nuchal thickening, what else do you see in the oblique axial plane?
Cavum Septum Pellucidum
3rd Ventricle
Cerebellum
Cisterna Magna
Nuchal Thickening - Abnormal Measurement:
>6mm (15-21 weeks)

Fetal head must NOT be hyperextended
Cystic Hygroma
Single or multiple cystic areas surround the neck.
Benign.
Cystic Hygroma associated with: FAT TAP
F - fetal Hydrops (Large ones)
A - ascites
T - trisomy 21

T - turner's syndrome
A - anasarca
P - pleural effusion
The orgin of a cystic hygroma is:
Lymphatic system
Cystic Hygroma may mimic:
Cervical Teratoma
Encephalocele
Cervical Meningomyelocele
Cystic Hygroma - sono:
Thin walled
Multiseptated mass
Nuchal ligament may be seen extending posterior.
What can be a cause of Polyhydramnios?
Inability for the fetus to swallow. (Fetus normally swallows amniotic fluid)

Anything causing more fetal urine output (Fetal urine is a major source of amniotic fluid)

Most things associated with GI anomalies (Trisomy 18 & 21)