Craniosynostosis is premature fusion of one or more cranial sutures, producing a characteristic head shape and (in some syndromes) midface/orbital abnormalities.
Prenatal recognition is most often triggered by abnormal skull shape on the axial head view and/or abnormal head biometry trends, and can be supported by
3D/4D evaluation of sutures when available.[1][2]
Best “screen” window: 18–24 w
Often clearer on follow-up: 24–32 w
High suspicion: cloverleaf / severe turricephaly
General ultrasound approach
- Confirm head shape in multiple planes (axial BPD/HC plane + coronal + mid-sagittal profile). Document asymmetry and frontal contour.
- Trend head indices (HC, BPD, OFD, cephalic index) if suspicion is mild/subtle; progressive deviation may be the earliest clue in single-suture synostosis.[3][4]
- Target the sutures with 3D/4D (if available) to look for absent suture gap / ridging and to explain an “unusual” skull contour.[2]
- Look beyond the skull: orbits (proptosis/shallow orbits), midface hypoplasia, hands/feet (syndactyly, broad thumbs/toes), ventriculomegaly/hydrocephalus, airway/choanal issues, and other anomalies.[1]
- Escalate evaluation if suspected: detailed anatomy + consider fetal MRI for cranial sutures/brain and palate in selected cases.[1]
Single-suture patterns (high-yield recognition)
| Pattern (suture) |
Classic head shape clue |
Ultrasound findings / tips |
Notes / genetics |
| Metopic synostosis (metopic) |
Trigonocephaly: triangular/“keel” forehead, frontal narrowing; may have apparent hypotelorism |
Narrow/pointed frontal contour on axial/coronal views; assess interorbital distance and forehead shape.
3D surface rendering can help demonstrate forehead contour.
|
Often sporadic; can be syndromic in some settings.
(Many centers use imaging + genetics selectively based on associated anomalies.)[5][6]
|
| Unicoronal synostosis (one coronal) |
Anterior plagiocephaly: asymmetric forehead/orbit; “harlequin” orbit postnatally |
Asymmetric frontal contour; orbital asymmetry; facial asymmetry. Evaluate ears, orbits, and midface.
Consider whether this is isolated vs a coronal-synostosis syndrome.
|
Can be isolated or syndromic (e.g., Muenke, Saethre-Chotzen).[7][8]
|
| Sagittal synostosis (sagittal) |
Scaphocephaly: long, narrow skull (dolichocephaly) |
Progressive reduction in cephalic index across the second half of pregnancy is a practical clue;
consider targeted 3D evaluation of sutures when CI trends down.[3][4]
|
Often isolated/sporadic; evaluate for associated anomalies if any red flags. |
Syndromic craniosynostosis (Apert, Crouzon, Pfeiffer, Muenke, Saethre-Chotzen)
The goal at ultrasound is often not to “name” the syndrome immediately, but to recognize the pattern (coronal/multisuture + midface/orbits + limb findings)
and trigger an appropriate diagnostic pathway (targeted gene/panel testing, fetal MRI, multidisciplinary counseling).
| Condition |
Key prenatal ultrasound clues |
Genetics (typical) |
Distinguishing notes |
| Apert syndrome |
- Coronal (often bicoronal) ± multisuture craniosynostosis → brachy/turribrachycephaly; abnormal frontal contour
- Symmetric syndactyly (“mitten” hands; fused central digits), sometimes easier with 3D
- Midface retrusion; possible cleft palate; polyhydramnios may occur
|
FGFR2, autosomal dominant; many cases de novo.[9]
|
“Hands + skull” combination is the classic prenatal trigger.[10]
|
| Crouzon syndrome |
- Craniosynostosis (often coronal/multisuture) with brachycephaly/turricephaly
- Proptosis/shallow orbits may be appreciable; midface hypoplasia
- Usually no hand/foot anomalies (helps separate from Apert/Pfeiffer)
|
Most commonly FGFR2, autosomal dominant (variable expressivity).[11]
|
Familial cases may be suspected on subtle brachycephaly + proptosis on 2D, aided by 3D surface rendering.[12]
|
| Pfeiffer syndrome |
- Multisuture craniosynostosis; severe forms may show cloverleaf skull
- Midface hypoplasia; proptosis
- Broad, medially/radially deviated thumbs and great toes; variable syndactyly
|
FGFR2 and FGFR1, autosomal dominant; many severe cases are de novo.[13]
|
“Cloverleaf skull + broad thumbs/toes” is a classic high-suspicion prenatal pattern.[14]
|
| Muenke syndrome |
- Coronal craniosynostosis (uni- or bilateral) → anterior plagiocephaly or brachycephaly
- Mild hand/foot abnormalities may be present (often subtle on prenatal imaging)
|
FGFR3 p.Pro250Arg (P250R), autosomal dominant.[7][15]
|
Often milder/variable; consider when coronal synostosis is identified and the rest of anatomy is near-normal.
|
| Saethre-Chotzen syndrome |
- Coronal synostosis (often) → anterior plagiocephaly/brachycephaly; facial asymmetry
- Ptosis/low frontal hairline and small external ear anomalies may be present (variable)
- Mild limb findings can occur (e.g., partial syndactyly)
|
TWIST1, autosomal dominant (haploinsufficiency).[8]
|
Prenatal recognition has been reported in familial/high-risk pregnancies using skull-shape cues and 3D rendering.[16]
|
Practical reminders for the differential
- Coronal / multisuture + hand syndactyly → think Apert (FGFR2) bucket.[9]
- Coronal / multisuture + proptosis, no limb anomalies → think Crouzon (FGFR2) bucket.[11]
- Cloverleaf skull ± broad thumbs/toes → think Pfeiffer (FGFR2/FGFR1) bucket.[13]
- Unicoronal / mild phenotype → consider Muenke (FGFR3 P250R) and Saethre-Chotzen (TWIST1).[7][8]
- Isolated skull-shape change (metopic/sagittal) → focus on pattern, trends, and associated anomalies; add 3D suture evaluation if available.[1][2]
Genetic testing note (quick, practical)
When craniosynostosis is suspected on ultrasound, many centers consider: chromosomal microarray when multiple anomalies are present,
and targeted craniosynostosis gene testing (e.g., FGFR2/FGFR3/FGFR1/TWIST1) or a broader panel/exome depending on the pattern and family history.
(Local practice varies; coordinate with genetics.)
