Abnormal Foot
Janice L. B. Byrne, MD
DIFFERENTIAL DIAGNOSIS
Common
-
Clubfoot
-
Rockerbottom Foot
-
Sandal Gap Foot
-
Edema of Feet and Extremities
Less Common
-
Amniotic Band Syndrome
-
Ectrodactyly
-
Abnormal Toes
-
Terminal Transverse Limb Defect
Rare but Important
-
Sirenomelia
-
Amelia, Micromelia
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
-
Is the anomaly an isolated finding?
-
Are there multiple anomalies?
-
Bilateral vs. unilateral
-
Are hands similarly affected?
-
Is the finding associated with abnormal or lack of fetal movement?
-
Lack of movement within the amniotic cavity?
-
Does the fetus appear “stuck” to the placenta?
-
Helpful Clues for Common Diagnoses
-
Clubfoot
-
Plane of imaging important
-
Coronal view: Ankles should be straight
-
Lateral view: Bones of foot and tibia/fibula should not be seen in same plane
-
“Footprint” view: Clubfoot associated with abnormal shape/shortening
-
-
Bilateral vs. unilateral
-
Limitations to diagnosis
-
Gestational age: Clubfoot difficult to diagnose past 2nd trimester
-
Oligohydramnios
-
Crowding in multiple gestation
-
Footling breech position limits visualization of feet
-
-
-
Rockerbottom Foot
-
Prominent heel associated with rounded bottom of foot
-
Best seen in lateral view
-
May be associated with dorsiflexed great toe, short hallux
-
Look carefully for other anomalies associated with trisomy 18
-
Persistently clenched hands or overlapping digits
-
-
-
Sandal Gap Foot
-
Gap between great toe and 2nd toe
-
May be normal finding with fetal “flare” of toes while moving feet
-
Look for persistence of gap even when fetus at rest
-
Most often seen in normal fetuses but is a minor marker in trisomy 21
-
-
Edema of Feet and Extremities
-
Pattern of edema important for establishing differential diagnosis
-
Edema of extremities vs. body edema
-
Unilateral edema concerning for obstructive phenomenon such as amniotic bands or tumor
-
Helpful Clues for Less Common Diagnoses
-
Amniotic Band Syndrome
-
Amputations of digits or feet/hands
-
Usually asymmetrical
-
Associated disruptions of face, calvarium, body wall
-
Constriction rings of extremities
-
Adherence to placenta in severe cases
-
Extremity edema distal to constriction band is common
-
-
Ectrodactyly
-
Split hand-split foot malformation
-
Fusion of digits with deep median cleft (“lobster claw”)
-
-
May be unilateral or bilateral
-
May involve upper, lower, or both
-
Variable appearance between extremities
-
-
Abnormal Toes
-
Polydactyly
-
Often difficult to diagnose, especially in early gestation
-
Foot usually appears wider than normal
-
Look at hands for extra fingers
-
Post-axial more common than pre-axial except in diabetic embryopathy
-
-
Syndactyly
-
Usually not diagnosed prenatally
-
May be associated with abnormal shape of foot
-
-
Oligodactyly
-
Foot appears narrow
-
Often associated with abnormality of tibia or fibula
-
Abnormal position of foot common
-
-
-
Terminal Transverse Limb Defect
-
Varying degree of limb deficiency
-
May be seen with congenital varicella infection
-
Helpful Clues for Rare Diagnoses
-
Sirenomelia
-
Legs may appear “stuck” together
-
Single femur or fewer than 4 lower extremity long bones valuable clues
-
Foot/feet may be absent, single, or a complex fusion of structures
-
Usually associated with bilateral renal agenesis
-
May be difficult to visualize due to oligohydramnios
-
-
Amelia, Micromelia
-
Extremities may be absent (amelia) vs. severely shortened (micromelia)
-
May be limited to upper or lower extremities
-
Digits may be present
-
Symmetrical micromelia associated with severe skeletal dysplasias
-
Other Essential Information
-
If multiple anomalies, consider aneuploidy syndromes
-
Trisomy 18
-
Rockerbottom feet classic finding
-
Hands with overlapping digits
-
Multiple other anomalies including cardiac, orofacial, extremity
-
Severe growth restriction the rule by late 2nd trimester
-
-
Trisomy 21
-
Extremity findings are often subtle “soft marker” findings
-
Extremity anomalies: “Sandal gap” foot & clinodactyly, short humeri & femora
-
Pattern of edema in hydrops rarely involves hands and feet
-
Increased nuchal thickening in 2nd trimester
-
Flat mid-face with hypoplastic nasal bone common
-
May see tongue thrusting behavior in 3rd trimester
-
-
Turner syndrome
-
Pattern of edema characteristic
-
Edema of the dorsum of hands & feet
-
Anasarca common
-
Often with large cystic hygroma
-
Female gender
-
-
-
Fetus with multiple anomalies: Transfer of care to a tertiary care center
Alternative Differential Approaches
-
Clubfoot with abnormal calvarium shape: Neural tube defect
-
Severe foot and extremity edema with cystic hygroma: Turner syndrome
-
Rockerbottom feet with other anomalies and growth restriction: Trisomy 18
Image Gallery