Prevalence:

• 1 in 200 births.
• More common in females than males: 3 to 1.

Ultrasound diagnosis:

• After 12 weeks’ gestation: the spine is distorted in the sagittal or coronal view resulting in scoliosis.
• The hemivertebra appears as a triangular bony structure, smaller than a regular vertebra, acting like a wedge against the adjacent normal vertebras.

Associated abnormalities:

• The incidence of chromosomal abnormalities is not increased.
• Associated syndromes are common: Jarcho-Levin (autosomal recessive; fused vertebrae, scoliosis, abnormal rib alignment) Klippel-Feil (autosomal recessive or dominant; fusion of cervical vertebrae), VACTERL association (sporadic; vertebral and ventricular septal defects, anal atresia, tracheoesophageal fistula, renal anomalies, radial dysplasia and single umbilical artery), OEIS complex (sporadic; omphalocele, exstrophy of the cloaca, imperforate anus, and spinal defects).
• Structural abnormalities, mainly musculoskeletal, genitourinary and cardiac are found in >70% of cases.

Investigations:

• Detailed ultrasound examination.
• 2D and 3D ultrasound examination of the spine to define the extent of the hemivertebra and exclude a lesion of the spinal cord.

Follow up:

• Ultrasound scans every 4-6 weeks to monitor the evolution of scoliosis.

Delivery:

• Standard obstetric care and delivery.

Prognosis:

• Isolated: good. In 75% of cases there is no or slow progression of scoliosis, but in 25% there is rapid progression at 2-3 years of age.
• Associated with other structural defects: poor with increased risk of perinatal death.

Recurrence:

• Single vertebra, isolated: no increased risk.
• Multiple vertebras isolated: 5-10%.
• Part of an autosomal recessive condition: 25%.