Caudal Regression Sequence, 12+6 wks
Department of Genetics, Polish Mother's Memorial Hospital, Lodz, Poland; 2 - Medical Genetics Department - Institute of Mother and Child, Warsaw, Poland
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Answer
Ultrasound Findings (12+6 weeks):
Trunk shortening relative to limbs, with overall disproportion. CRL eqivalent to 12+4 wks, BPD corresponding to 12+6 wks
Juxtaposed iliac bones, abnormally close together in the axial plane.
Sacrum was not not visualized; the lower spine ended abruptly and had irregular caudal tapering, suggesting agenesis (Tortori-Donati et al., 2011).
The anus was visualized in the transverse plane and there was no dilation of the rectum or distal colon, which would likely be apparent at this gestational age in the case of anal atresia (Sepulveda et al., 2002).
non-visualization of nasal bones echo
Lateral neck cyst.
These findings are highly suggestive of caudal regression syndrome (CRS), a rare congenital disorder characterized by developmental failure of the caudal part of the spine and associated structures. CRS encompasses a broad spectrum of severity, ranging from isolated sacral agenesis to complete lumbosacral agenesis with lower limb anomalies and genitourinary or gastrointestinal involvement (Duhamel, 1961; Barkovich, 2018).
Discussion and Differential Diagnosis:
At this gestational age, CRS can be suspected by detailed evaluation of:
Truncal - head and limb disproportion
Early sacral non-visualization
Pelvic bone orientation anf juxtaposition
Associated findings such as imperforate anus, lower limb abnormalities, or bladder anomalies (not seen in this case)
Unossified nasal ridge and lateral neck cyst are not typically associated with CRS and probably represent incidental co-findings.
a-CGH microarray obtained by CVS rendered normal result
📚 Selected References
Tortori-Donati P, et al. Neuroradiology of the Spine. Springer, 2011. (Caudal regression overview)
Duhamel B. From caudal regression to sirenomelia. Teratology. 1961;4(4):277–88.
Sepulveda W, et al. Prenatal sonographic diagnosis of caudal regression syndrome in the first trimester. J Ultrasound Med. 2002;21(8):885–9.
Barkovich AJ. Pediatric Neuroimaging. 6th ed. Lippincott Williams & Wilkins; 2018.
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