Ultrasound findings

Oligohydramnios

1. decreased amniotic fluid

• Associated with renal problems, premature rupture of membranes (PROM), intrauterine growth restriction (IUGR), pulmonary hypoplasia

• Can cause elevated alpha-fetoprotein (AFP)

• Early detection = poor prognosis

Polyhydramnios

1. excess amniotic fluid

   • Associated with GI obstructions, intracranial problems (defective swallowing)

   • Common in pregnancies of obese and diabetic women 

   • 20% risk of a serious fetal anomaly

Hydrocephalus

fluid in the cerebral ventricles

Pleural effusion

fluid in the chest cavity

Ascites

fluid in the abdominal cavity

Pericardial effusion

fluid in or around the heart

Hydrops

excess fluid within two or more body cavities…75-90% mortality

• 90% are “non-immune” hydrops (if no indication of Rh incompatibility)

• Associated with heart defects, aneuploidy, infections

Amniotic Bands

• Rupture of the amnion, leading to free edges of the amnion adhering to the fetus and entrapping fetal parts  

• Causes a variety of asymmetrical malformations…amputations of limbs, abdominal wall defects, facial clefts 

• Usually sporadic (rare cases seen with connective tissue disorders, i.e. Ehlers-Danlos)

IUGR

• Fetal weight <10%ile for gestational age

• Affects 3-10% of all pregnancies

• 4-8 fold higher mortality… Significant morbidity in 50% of survivors

Macrosomia

• Fetal weight over the 90%ile for gestational age or >4500g at birth

  • Normal birth weight is 3000-3400g

• 1-2% of all deliveries

• Common in pregnancies of diabetic women

Single Umbilical Artery (Two Vessel Cord)

• The umbilical cord usually has three vessels (two arteries and one vein) 

• SUA occurs in 1-2% of all newborns 

• 20-30% will have other anomalies, 25% will have IUGR, and 50% will have low birth weight (LBW)

• If isolated, risk of aneuploidy is low (<1%)

Increased nuchal translucency

>3mm in 1^st trimester) 

     Increased nuchal fold (>6mm in the 2^nd trimester) 

• Increased thickness at the back of the fetal neck

• 40-60% risk of aneuploidy (trisomy 21 and Turner syndrome - most common)

• Also associated with other genetic syndromes (Noonan syndrome, 22q11 deletion) and cardiac abnormalities (therefore, recommend fetal echocardiogram)

Choroid plexus cysts

• Accumulation of cerebrospinal fluid in a choroid plexus

• Seen in 1-4% of all pregnancies; >95% disappear by 26 weeks

• ~1% risk of aneuploidy (mostly trisomy 18) - no difference in risk if CPCs are unilateral or bilateral, or if they disappear

• No indication of mental function (~30% of adults have CPCs at autopsy)

Ventriculomegaly / Hydrocephalus

• Ventriculomegaly (i.e. enlarged ventricles) is typically caused by hydrocephalus (excessive amount of cerebral-spinal fluid in the ventricles)

  • Ventriculomegaly can also be caused by brain destruction and maldevelopment

• Usually detectable by 17 weeks but may develop later

• Causes increased pressure on brain which may lead to some degree of learning disability

• Can be associated with aneuploidy, ONTDs, infections, etc.

• Some are X-linked (ex: L1CAM gene) and can recur in families

• May require early delivery or C-section if severe macrocephaly develops

Dandy-Walker malformation

• Defect of the cerebellar vermis, which leads to a posterior fossa cyst that connects to the 4^th ventricle

• Accounts for 4-10% of hydrocephalus cases

• 15-30% risk of aneuploidy

• Prognosis depends on presence of other anomalies (up to 70% have other anomalies)

Agenesis of the corpus callosum

• Complete or partial failure of the midline formation between the two cerebral hemispheres 

• Asymptomatic in some…Seizures, learning disabilities, or intellectual disabilities (ID) in others

• Prognosis depends on presence of other findings (i.e. Dandy Walker, ONTDs, diaphragmatic hernia, heart defects)

• Seen in 80+ sporadic, genetic, and chromosomal syndromes

Holoprosencephaly

• Failure of the prosencephalon (forebrain) to cleave

• 3 types: a) lobar – least severe, but still have ID and seizures

b) semilobar – die within 1y

c) alobar – die in neonatal period

• 30-50% risk of aneuploidy (trisomy 13, trisomy 18, triploidy)

• Up to 70-80% have other anomalies, especially midline defects… single central incisor, hypotelorism, cyclops, cleft lip, absent nose

• Can be autosomal dominant (AD) - look for midline defects in parents

  • Less common cases of autosomal recessive (AR) or X-linked (XL) inheritance

Open neural tube defects (ONTDs)

• Anomalies involving the coverings of the nervous system 

• Occur when the neural tube does not close properly by the 4th week (24-26 days)

• Majority are multifactorial (95% of babies with ONTDs have no family history)

• Influenced by ethnicity:

  • More common in Hispanics and Caucasians

  • Less common in African American, Jewish, and Asian

• Associated with many syndromes (trisomy 13 or 18, Meckel-Gruber) and many teratogens (folate deficiency, maternal diabetes, some anticonvulsants, maternal hyperthermia)

• Population incidence (0.1-0.2%)

Spina bifida

• Failure of vertebral arches to fuse (can be seen by 15-18wk)

• On ultrasound, look for the following signs in the brain: lemon sign (caused by the meninges being pulled down) and banana sign (cerebellum looks like a banana instead of the normal bar-bell shape)

• >90% detection on U/S

• Severity depends on level of defect

Anencephaly

• Absence of forebrain and overlying skull/tissue (seen by 12-14wk)

• Always lethal 

Encephalocele

• Protrusion of intracranial contents through bony defect in skull (seen by 12-14wk)

• Prognosis OK if there is only fluid in the sac;

• Surgery may be needed if there is brain involved

Absent Nasal Bone

• Marker for Down syndrome and other chromosome abnormalities in the first trimester

• In 2003, Nicolaides reported on a large study where a nasal bone was detected in:

  • 97.3% of chromosomally normal fetuses, 33% of fetuses with Down syndrome, 33% of pregnancies with another chromosomal abnormality (overall detection rate: ~65%)

• Other studies have reported that the nasal bone was detected in 60-70% of babies with Down syndrome between 15-22wks.

• Very difficult to see sonographically…even experienced sonographers need ~80 practice cases before obtaining correct fetal image

Cleft Lip and Palate

• Failure of the frontal process and maxillary process to fuse (Incidence of 1:1000)

• Usually on the left or right; midline defects often represent an underlying brain malformation

• Embryology

  • Lip closure is complete by 5-6w; Palate closure occurs by 10w 

• Clefts can involve the soft palate alone or extend to hard palate

  • V-shaped cleft: primary defect

  • U-shaped cleft: tongue interferes with palatal closure (can be caused by small jaw)

• Etiology: most are multifactorial (3-5% RR)

  • 20% have an identifiable cause 

    • Teratogenic (alcohol, diabetes, anticonvulsants, hyperthermia)

    • Syndromic (400+ syndromes)

    • Chromosomal: 3.9%, higher if other anomalies

• ~60% are isolated, but there is an ↑ risk for other anomalies

• CL w/ or w/o CP (also abbrev. CL/P): more common in males, Asians, some Native Americans 

• CP alone: more common in females, no ethnic predilections

Cystic hygroma

• Fluid-filled pocket at the back of the neck (bigger than an increased nuchal fold)

  • Caused by swollen lymph glands

• Variable prognosis… risk of hydrops, fetal demise, or stillbirth (only 10% = normal outcome)

• 40-60% risk of aneuploidy in 1^st trimester and 60-70% risk in 2^nd trimester 

• Commonly seen in Turner syndrome, Down syndrome, Noonan syndrome

Esophageal Atresia and Tracheoesophageal Fistula

• Esophageal Atresia: upper esophagus ends blindly and does not connect with the lower esophagus

• TE Fistula: communication between the trachea and esophagus

• These occur together 90% of the time

• Typically only detectable after 24wks when fetal swallowing begins to play a bigger role with amniotic fluid; look for small stomach and polyhydramnios on U/S

• 60% have other anomalies

• Usually sporadic… also associated with some teratogens and 40+ syndromes (Down syndrome 2-3%, VACTERL 10%, etc.)

• If isolated, 95% survival with repair

Diaphragmatic Hernia

• Herniation of intrabdominal contents into the thorax through an opening in the diaphragm

• Usually sporadic… but with risk of aneuploidy (i.e. trisomy 18) and rare cases of AD and XL 

• Seen in 30+ syndromes (i.e. Fryns) & with other anomalies 

• Overall survival is 65-75%, but much lower if polyhydramnios is present and dependent on symptoms at birth

• RR (recurrence risk) for siblings: 1-2%

Cardiac Abnormalities

• Most common structural birth defect (incidence = 1:125)

• Embryology:

  • Critical period for heart: 2-8 weeks

  • Five developmental mechanisms involved: RR may depend on specific mechanism

• ↑ risk for other anomalies: 10-40%... especially an increased nuchal translucency (early) or hydrops (later)

• Etiology: 

  • 90% multifactorial

  • 10-15% have an identifiable cause… often aneuploidy or 22q11deletion 

• For pregnancies at increased risk for cardiac abnormalities (due to family history, maternal diabetes, certain teratogen exposures, or other related ultrasound anomalies), the goal is to obtain clear views of the four chambers and outflow tracts during the fetal survey. If these views are not available, then a fetal echocardiogram (specialized ultrasound of the fetal heart performed by a pediatric cardiologist) is recommended.

Atrial Septal Defect (ASD) and Ventricular Septal Defect (VSD)

• Absence of part/all of the interatrial or interventricular septum, respectively

• Largest group of heart defects

• Often called a “hole in the heart”… most close on their own or are too small to need treatment

• Both are often multifactorial… but can be seen with 100+ syndromes and teratogens 

Coarctation of the Aorta

• Narrowing of the aorta

• Associated with Turner syndrome, 22q11 deletion, maternal diabetes, Vit. A

Ebstein’s Anomaly

• Malformation and displacement of the tricuspid valve – causes tricuspid regurgitation

• Usually sporadic; older reports linked it to Lithium exposure

Echogenic Intracardiac Focus (EIF)

• A bright spot in either ventricle (brighter than bone) – often a benign calcium deposit

• Seen in 3-5% of all pregnancies (more common in Asians); may be single or multiple; often disappear

• Not suggestive of a structural cardiac defect, but increases the risk of aneuploidy by 2X

Endocardial Cushion Defect (AV Canal Defect)

• Consists of an ASD, VSD, and abnormalities of the AV valves

• 60% have Down syndrome, 10% have heterotaxy syndrome (asplenia/polysplenia)

Hypoplastic Left-Heart Syndrome (HLHS)

• Hypoplasia of the left ventricle + atresia/stenosis of the mitral valves and aortic arch

• Usually sporadic… but can be seen with other anomalies, aneuploidy (up to 16%), etc.

Tetralogy of Fallot (TOF)

• 4 cardiac defects: VSD, pulmonary stenosis, right ventricular hypertrophy, over-riding aorta

• Usually sporadic…but can be seen with aneuploidy, 22q11 deletion (25%), CHARGE, Goldenhar, vitamin A, etc.; 15% have other anomalies

Gastroschisis

• Lateral walls of abdomen fail to close, which causes free-floating abdominal organs

• Often a vascular accident in the abdominal wall; usually on the right side; not membrane-covered

• <1% risk for aneuploidy and low RR

• More common in pregnancies of younger women 

• <5% have additional non-GI anomalies (most often heart defects)

• Virtually all cases are detected by AFP and U/S 

• Can cause swelling, edema, and/or necrosis, which may cause residual problems

• Surgery after birth (may be in stages) – variable prognosis but overall survival is 90%

Omphalocele

• Occurs when the intestines that have migrated into the umbilical cord fail to return to the abdomen; abdominal organs are covered by skin

• 25% risk of aneuploidy; 60% have other anomalies

• Also common in Beckwith-Weideman syndrome (large size, macroglossia, Wilm’s tumor), 8-10% of isolated cases

• Delivery: vaginal vs. C/S ?

• If isolated, RR for siblings 1-2%

• U/S detection is good (but AFP may not be positive)

Echogenic bowel

• Bright spots within the fetal bowel – operator dependent

• Seen in up to 2% of all 2^nd trimester ultrasounds

• 3% risk for each of the following: Down syndrome, cystic fibrosis, infection (CMV, toxo, or parvo), and GI abnormalities. Also an increased risk of adverse outcome (IUGR, IUFD, etc.)

  • Overall, 65% will have a normal outcome

• Can also be Meconium Ileus: intestinal obstruction caused by thickened meconium (a dark green fecal material that accumulates in the fetal intestines and is discharged at or near birth)

Duodenal atresia

• Failure of a section of the intestinal lumen to form

• “double-bubble” on U/S (pinching causes a back-up on each side)

• Usually sporadic, but 30-40% risk of Down syndrome (can also be seen in other syndromes)

• 50% have other anomalies

• May not show up until 2^nd or 3^rd trimester with severe polyhydramnios

• Postnatal: dehydration, abdominal distension, surgery

consequence of problem with kidneys

** The kidneys produce the amniotic fluid. Therefore, if there is a problem with the kidneys, there may be oligohydramnios (which can lead to lung hypoplasia). Unilateral problems are usually OK.

Hydronephrosis / Pyelectasis

• Dilation of the pelvis and calyces of the kidneys (excess fluid inside)

• Called “pyelectasis” if the dilation is minimal (usually a good prognosis)

• 20% have other anomalies (seen in Down syndrome and 70+ syndromes)

• Majority will resolve spontaneously; only 3-4% require surgery. If mild, <1% require surgery.

Polycystic kidneys

• Kidneys are enlarged, but the cysts are too small to be distinguished on U/S

• Infantile PKD (Autosomal Recessive) – often fatal when diagnosed in-utero

• Adult PKD (Autosomal Dominant) – may need to do renal U/S on parents

Renal agenesis

• Absence of one or both kidneys

• If bilateral, you will see “Potter’s facies,” limb deformities, and pulmonary hypoplasia (caused by absence of amniotic fluid)

• Usually sporadic… low risk of aneuploidy, but can be seen in 50+ syndromes and teratogens

PUV obstruction (posterior urethral valve)

• Urinary tract obstruction that causes hydronephrosis & keyhole bladder (males)

• 20% risk of aneuploidy

• Overall survival is 50%, but only 5% when oligohydramnios is present

important skeletal things to check for

** Important things to check for:  length, calcification, bowing, and fractures of bones; skull shape; 

digital abnormalities; measurements of chest and thorax

** Only 35-60% of skeletal dysplasias are diagnosed correctly in the prenatal period. However, the 

antenatal prediction of lethality is highly accurate (femur length:abdominal circumference ratio = <0.16 in lethal conditions)

Clubfoot

• Dorsiflexion and eversion of the foot with abnormalities in the musculature of the lower leg

• AKA: talipes equinovarus or calcaneovalgus, or metatarsus varus

• Only 30% detected by U/S btw 18-20wks (up to 60% by >25wks)

• M:F = 2:1; More common in Pacific Islanders

• 30-40% have identifiable cause

  • Spina bifida, neuromuscular disease, aneuploidy, oligohydramnios, intrauterine constraint; associated with 200+ syndromes

• If isolated and idiopathic, then presumably multifactorial (3-5%RR)

Achondroplasia

• Most common non-lethal skeletal dysplasia; rhizomelic limb-shortening and macrocephaly

• AD with 80% due to de-novo mutations

Campomelic dysplasia

• Bowed/shortened lower limbs, bell-shaped chest, flat face, micrognathia, cleft palate, club feet

• AD, de-novo mutations in the SOX9 gene on 17q

• Preponderance of females on U/S because 46,XY males can have ambiguous genitalia

• Usually lethal

Osteogenesis Imperfecta (types I-VIII)

• Most in-utero cases are type II

  • Multiple fractures, bell-shaped chest, all bones are extremely short

  • AD, usually lethal

Thanatophoric Dysplasia

• Most common lethal short-limbed skeletal dysplasia

• Small chest and thorax, all long bones are bowed, but only the upper bones are short, telephone-receiver shaped femurs, short ribs, cloverleaf skull, and severe polyhydramnios

• Usually AD, de-novo mutations in the FGFR3 gene on 4p

common Down syndrome findings

1. increased nuchal translucency (>3mm in 1^st trimester) or nuchal fold (>6mm in 2^nd trimester)

2. heart defects (esp. endocardial cushion defects / VSD and ASD)

3. duodenal atresia (“double-bubble”)

4. short humerus/femur 

5. choroid plexus cysts

6. renal pyelectasis

7. fifth-finger clinodactyly

8. echogenic bowel

9. echogenic intracardiac foci

10. sandle-gap toe

11. increased iliac angle

12. single umbilical artery

13. mild ventriculomegaly

14. pleural effusion or hydrops

** amniotic fluid, placenta, and fetal growth are usually normal

** ~50-60% of pregnancies with Down syndrome will have at least one U/S finding

common trisomy 18 findings

1. limb anomalies (clenched hands, overlapping 4^th digits, rocker-bottom feet or clubfeet)

2. micrognathia, cleft lip and palate

3. heart defects (VSD, TOF, transposition, coarctation of the aorta)

4. omphalocele

5. diaphragmatic hernia

6. neural tube defects

7. choroid plexus cysts

8. single umbilical artery

9. cystic hygroma

10. IUGR

11. amniotic fluid abnormalities (mostly polyhydramnios)

** ~80% of pregnancies with trisomy 18 will have at least one U/S finding.

common trisomy 13 findings

 (think about mid-line defects!)

1. CNS anomalies (holoprosencephaly, enlarged cisterna magna, cystic hygroma)

2. central cleft lip and palate

3. close-set eyes (hypotelorism… cyclops)

4. nasal abnormalities (single nostril… proboscis)

5. hand and feet abnormalities (polydactyly, clubfeet and rocker-bottom feet)

6. heart defects (hypoplastic left heart, VSD)

7. cystic kidneys 

8. omphalocele

9. neural tube defects

10. amniotic fluid abnormalities (both polyhydramnios and oligohydramnios)

** ~90% of pregnancies with trisomy 13 will have at least one U/S finding.

common triploidy findings

(extra set of chromosomes: 60% = 2 sperm fertilizing 1 egg, 40% = fertilization of a diploid egg)

1. IUGR

2. CNS anomalies (hydrocephalus)

3. limb abnormalities (clubfoot, syndactyly)

4. heart defects

5. renal anomalies (hydronephrosis)

6. facial clefts

7. oligohydramnios

8. abnormal placenta

common Turner syndrome findings

(only females)

1. cystic hygroma

2. ascites / pleural effusion

3. heart defects (coarctation of the aorta)

4. renal anomalies (agenesis, horseshoe kidney) and oligohydramnios