Reproductive: Congenital Fetal Flashcards
What are the most common congenital heart diseases associated with Down syndrome?
- AV canal defect
- Ventricular septal defect
What is the most common intraabdominal pathology associated with Down syndrome?
Duodenal atresia
Fetal ultrasound findings suspicious for Down syndrome
- Congenital heart disease
- Duodenal atresia
- Short femur length
- Echogenic bowel
- Choroid plexus cyst
- Nuchal translucency
- Nuchal fold thickening
- Echogenic focus in cardiac ventricle
What percentage of fetuses with Down syndrome will have congenital heart issues?
More than half
Which trisomy is most often associated with a choroid plexus cyst?
Trisomy 18
Note: Also seen in trisomy 21 (Down syndrome).
When is nuchal translucency measures?
First trimester (between weeks 9 and 12)
What is a normal nuchal translucency thickness?
3 mm or less (in the first trimester)
Note: If > 3 mm, think Downs syndrome.
What is being measured (**)?
Nuchal fold thickness
What is being measured?
Nuchal translucency (the anechoic area between the neck/occiput and the skin)
What is a normal nuchal fold thickness?
6 mm or less
Note: If > 6 mm, think Down syndrome or Turners.
How should the fetal head be positioned while measuring nuchal translucency?
In neutral position (nasal bone should be visualized with the head in the mid-sagittal position)
What maternal blood tests are run to screen for Down syndrome?
- Free beta-hCG
- PAPP-A (pregnancy associated plasma protein-A)
No other anatomic abnormalities
Think amniotic band syndrome (limb/finger amputation due to constriction from amniotic bands)
Think amniotic band syndrome
Note: Linear echogenicities entangling the fetus.
Missing fingers in an otherwise normal neonate…
Think amniotic band syndrome
Hydrops fetalis
A bad condition where there is fetal edema due to accumulation of fluid in the fetal tissues/organs
Common causes of hydros fetalis
- Rh sensitization from a prior pregnancy
- TORCH infections
- Turners
- Twin gestation
- Alpha thalassemia
Ultrasound diagnosis of hydrops fetalis
Two of the following:
- Pleural effusion
- Ascites
- Pericardial effusion
- Subcutaneous edema
Hydrops fetalis
Note: Pleural effusions and ascites.
Fetal ultrasound
Hydrops fetalis
Note: Pericardial (A) and pleural (B) effusions.
Hydrops fetalis
Note: Thickened placenta (C) and scalp edema (D).
Chiari II malformation
Caudal herniation of the cerebellar vermis, brainstem, and 4th ventricle due to low CSF pressure (CSF leaking out an open neural tube defect)
Think Chiari II malformation
Note: This is the “lemon head” appearance due to flattening of the bilateral frontal bones in the setting of insufficient CSF pressure to create the normal curvature. Once the brain grows large enough to push the frontal bones out during the third trimester, this appearance goes away and the skull appears normal.
Banana-shaped cerebellum, suggestive of a Chiari II malformation
Note: Left image shows banana cerebellum and right image shows normal bilobed cerebellum.
When are the banana and lemon signs visible on fetal ultrasound?
Lemon sign is only present during the second trimester (in the third trimester the brain grows large enough to push out the frontal bones and restore normal skull curvature)
The banana sign is present during the second and third trimesters
Which sign is more sensitive and specific for Chiari II malformations: lemon or banana?
Banana sign (appearance of cerebellar fusion) is more sensitive and specific
Note: On the test, the lemon sign will almost always indicate Chiari II, but in real like it can also be seen with Dandy-Walker, Absent corpus callous, ecephaloceles, etc.
What is the most common cause of non-communicating hydrocephalus in a neonate?
Aqueductal stenosis
Common causes of ventriculomegaly in a fetus/neonate
- Hydrocephalus (communicating and non-communicating)
- Cerebral atrophy
What is being measured by the double headed arrow?
Ventricular atrium diameter
What is a normal ventricular atrium diameter in a fetus?
10 mm or less
Note: Greater than 10 mm indicated ventriculomegaly.
“Dangling choroid plexus” which suggests ventriculomegaly if greater than 3 mm
Choroid plexus cyst
Choroid plexus cysts are associated with…
- Trisomy 18
- Trisomy 21
- Turner’s syndrome
- Klinefelter syndrome
Note: If isolated, this usually doesn’t mean anything, but you should look hard for other defects.
What is the most common fetal facial anomaly?
Facial clefts (e.g. cleft lip/palate)
Around 80% of pts with cleft lips have ______
Cerebral palsy
Facial clefts are associated with ______ approximately 30% of the time
Chromosomal anomalies
Cleft lip
Fetal ultrasound
Cleft palate
Cystic hygroma
Note: Complex cystic mass in the posterior neck.
Cystic hygromas are associated with…
- Turner’s syndrome
- Down syndrome
Cystic hygroma
Note: Complex cystic mass in the posterior neck.
What is the most common neural tube defect?
Anencephaly (total absence of the cranial vault and brain above the level of the orbits)
Anencephaly
Anencephaly
Note: Absence of cranium (arrow).
Congenital diaphragmatic hernias almost always occur on the…
Left (85%)
Note: The liver is protective on the right.
Congenital diaphragmatic hernia on the left
Congenital diaphragmatic hernia on the left
Congenital diaphragmatic hernia on the left
Why is congenital diaphragmatic hernia associated with a high mortality?
Pulmonary hypoplasia (due to compression of the lungs by the hernia)
Congenital diaphragmatic hernias are always associated with…
Intestinal malrotation
Fetal ultrasound
Echogenic intracaardiac focus (usually a calcified papillary muscle)
Note: This occurs in the normal general population (5%), but occurs more commonly in Down syndrome (12%) and trisomy 13 (so you should look closely for other abnormalities).
Fetal tachycardia
Heart rate > 180 bpm
Fetal bradycardia
Heart rate < 100 bpm
Think duodenal atresia
Note: This is the “double bubble sign” where the stomach and duodenum are distended.
How can you tell whether bowel is echogenic on fetal ultrasound?
Normal bowel should be isoechoic to liver, but echogenic bowel will be isoechoic to the iliac crest bone
Echogenic bowel is associated with…
- Cystic fibrosis
- Down syndrome (and other trisomies)
- Viral infections
- Bowel atresia
What is the most common tumor of the fetus/infant?
Sacrococcygeal teratoma
Think sacrococcygeal teratoma (most common tumor in the fetus)
What are the most common locations for a sacrococcygeal teratoma?
- External to pelvis (47%)
- Dumbell shaped with components both internal and external to pelvis (34%)
- Internal to pelvis (9%)
Are sacrococcygeal teratomas usually benign or malignant?
Benign (80%)
Note: Those presenting in older infants tend to have a higher malignant potential.
Complications of a sacrococcygeal teratoma
- Mass effect (GI issues, hip dislocation, incontinence due to nerve compression)
- High output cardiac failure
- Premature delivery
- Shoulder dystocia
- Tumor hemorrhage
Think autosomal recessive polycystic kidney disease
Note: Massively enlarged bilateral kidneys with oligohydramnios.
Fetal ultrasound
Think posterior urethral valve
Note: Distended bladder with appearance of diverticulum (distended proximal urethra). Look for bilateral hydronephrosis.
Measurement is below the 5th percentile
Short femur, suggestive of skeletal dysplasia (also seen in Down syndrome)
