Ultrasound Findings Flashcards
Measurement for dating pregnancy in first trimester
crown-rump length
Measurement for dating pregnancy in second trimester
composite gestational age measurement
Elements of the composite gestational age
- biparietal diameter
- circumference of the head
- abdominal circumference
- femur length
Indications for a targeted ultrasound examination (feel free to add more)
- Suspicious findings on a Level I scan
- History of prior congenital anomaly
- Insulin dependent diabetes or other medical problem that increases the risk of anomaly.
- History of seizure disorder, particularly if being treated with medications known to increase the risk of anomaly.
- Teratogen exposure
- Abnormal serum screen (AFP)
- Suspected chromosome abnormality
- IUGR
- Fetal arrhythmia
- Oligohydramnios, Polyhydramnios, Anhydramnios
- Advanced maternal age
- Medication Exposure/Drug Use
Soft markers on ultrasound
- echogenic bowel
- echogenic intracardiac focus
- hydronephrosis
- short humerus, short femur
gestational age when nuchal translucency can be measured
11-14 weeks
Cutoff for increased NT:
measurement greater than the 95th percentile (usually >3mm or >3.5mm
Increased NT causes:
- cardiac failure or severe CHDs
- venus congestion of head/neck
- delayed/abnormal development of the lymphatic system
- altered composition of subcutaneous connective tissue
Increased NT differential:
- chromosome abnormalities (T21>T13/18>Turner>triploidy)
- isolated cardiac/renal/genitourinary tract defect
- genetic syndrome (noonan)
- normal fetus.
% of fetuses with increased NT that have a chromosomal abnormality
20-60% …so just a lot
(some) genetic syndromes associated with increased NT
Noonan, Multiple pterygium syndrome, 22q, Joubert, Meckel-Gruber, SLOS, SMA type 1, Zelleweger, Turner, T21, et al
Prognosis of isolated increased NT
50-85% normal outcome (with normal karyotype)
Difference between increased NT and cystic hygroma
No scientific consensus
Options for first trimester cystic hygroma
- diagnostic testing
- serum screening (but will be positive is NT is >99 percentile)
- detailed fetal anatomy scan (18-20weeks)
- fetal echo (18-22 weeks)
% cystic hygroma associated with aneuploidy
~60% (mostly Turner, DS, T18, Noonan), higher risk when seen in 2nd trimester than 1st
percentage of karyotypically normal cystic hygroma (normal outcome)
10% normal outcome
Absent nasal bone differentials
T21 (absent in 68%), T18 (55%), T13 (35%), Turner (10%)
Cleft lip +/- Cleft palate incidence, M:F ratio, recurrence risk
1 in 700 newborns
2:1 M:F ratio
recurrence risk 3-5%
CL +/- CP differentials
Aneuploidy
Micro del/dup (22q11.2)
Isolated defect
Choroid plexus cyst prognosis
99% normal, 1% risk of aneuploidy (T18)
Hydronephrosis incidence
2-3% of fetuses, isolated 84% of the time
isolated echogenic bowel prognosis
60-85% normal healthy infants
echogenic bowel differentials
GI malformations, CF, viral infection (CMV, tovxo, parvo), T21 or other chromosome abnormality
Isolated intracardiac echogenic focus prognosis
isolated ICEF is most often normal variation
Hydrops: definition and prognosis
excess fluid in 2+ body cavities
75-90% mortality (d/t heart defects, aneuploidy, infections)
Two vessel cord (single umbilical artery) prognosis
20-30% have other anomalies
25% have IUGR
50% have LBW
low risk of aneuploidy if isolated
Dandy-Walker malformation prognosis
- 15-30% risk of aneuploidy, up to 70% have other anomalies
- anchor sign on U/S
Rhabdomyoma prognosis
50-85% tuberous sclerosis
Duodenal atresia
30% risk of T21
lethal femur lenth:abdominal circumference ratio
<0.16
Campomelic dysplasia US findings
shortened limbs, bell shaped chest, micrognathia, CP, club feet
Thanatophoric dysplasia US findings
bowed long bones, shortened upper bones, telephone-receiver shaped femurs, short ribs, cloverleaf skull, polyhydramnios
Molar tooth sign indicates what syndrome?
Joubert syndrome
Lemon and banana sign indicate:
open neural tube defects
holoprosencephaly
30% risk of aneuploidy (13)
hydrocephalus
risk of aneuploidy, NTDs, infections
EA/TEF
- detectable after 24 weeks (swallowing)
- small stomach & polyhydramnios
- T21, VACTERL
- 60% of TEF have other anomalies
ASD/VSD
- usually sporadic
- 10-15% aneuploidy
Coarctation of Aorta
- Turner (mostly)
- 22q, maternal diabetes
Tetralogy of Fallot
- usually sporadic
- 22q, CHARGE, Goldenhaar, Alagille
- 18% have other anomalies
Rhabdomyoma
- 50-80% have tuberous sclerosis
Ebstein’s Anomaly
- tricuspid valve displacement
- usually sporadic
- enlarged right atrium
- lithium teratogen!
HLHS
- small left ventricle, atresia of mitral valve/aordic arch
- 16% have aneuploidy
AV canal defect
- 60% have T21
- 10% have aspenia/polysplenia
Gastroschesis
- <1% risk of aneuploidy
- young mom’s who smoke club
Omphalocele
- 30-50% risk aneuploidy
- T13, T18, Beckwith-Wiedeman
- 60% other anomalies
Diaphragmatic Hernia
- 10-25% risk aneuploidy (T18)
- recurrence risk 1-2%
- Fryns syndrome
- Cornelia de Lange syndrome
Hydronephrosis/pyelectasis
- 20% other anomalies
Polycystic kidneys
- bilateral enlarged echogenic kidneys & oligohydramnios
- infant = autosomal recessive, adult = autosomal dominant
Renal agenesis
- Potter sequence
- usually sporadic
Club foot
- 30-40% have identifiable cause
Achondroplasia
- shortened long bones
- macrocephaly
- 80% de novo (FGFR3)
Triploidy
- cleft lip/palate
- hydrocephalus
- limb abnormality
- oligohydramnios
- renal abnormalities
