Infants with Sacral Dimples: Clinical Outcomes and Usefulness of Ultrasonography

Purpose: Sacral dimples are common and occur in 1.8% to 7.2% of neonates. Most simple dimples are benign, and concerns have been raised about the routine use of spinal ultrasonography for all such cases. This study aimed to analyze the spinal ultrasound findings in neonates with sacral dimples and evaluate the clinical usefulness of this examination.Methods: We retrospectively reviewed the medical records of 588 infants who underwent spinal ultrasonography for sacral dimples at the National Health Insurance Service Ilsan Hospital between January 1, 2018, and January 1, 2024. Ultrasonography performed within 6 months of birth were included, and examinations were conducted by board-certified pediatric radiologists.Results: The infants in this study had a mean birth weight of 3,002±542 g and a mean gestational age of 37.3±2.0 weeks. Ultrasonography was performed at a mean age of 2 months. Of 588 infants, only two (0.3%) showed significant thickening (2.0 to 2.4 mm) of the filum terminale, and none demonstrated findings of a tethered cord.Conclusion: Most infants who underwent spinal ultrasonography for sacral dimples showed normal (94.8%) or benign (4.8%) findings. Pediatricians should carefully examine whether dimples are accompanied by other cutaneous markers suggestive of spinal dysraphism. As sacral dimples are commonly screened during national infant health check-ups, further large-scale studies are warranted to establish clear guidelines for the use of spinal ultrasonography in this population.