Background: Anorectal malformation (ARM) is associated with occult spinal dysraphism (OSD). The guideline for screening for OSD in patients with ARM is still controversial.

Objective: 1) To evaluate the prevalence of OSD in each type of ARM and to elucidate which types of ARM should be screened for underlying OSD. 2) To compare the methods used in radiologic screening for OSD, such as plain lumbosacral X-ray, spinal ultrasound (U/S), and spinal magnetic resonance imaging (MRI).

Materials and Methods: The medical records of all patients with ARM treated at Siriraj Hospital between 2006 and 2016 were reviewed. Spinal dysraphism screening with lumbosacral X-ray, U/S, or MRI were performed depending on the surgeon’s request. Associated urinary tract anomalies were noted. Data of the surgical treatments, outcomes, and complications of treatments were collected.

Results: Among the 204 ARM patients treated, 150 patients were screened for OSD, involving 150 lumbosacral X-ray, 65 U/S, and 39 MRI. The prevalence of OSD (n=33) in all types of ARM was 16.2%. The higher types of ARM had higher prevalence of OSD, except for vestibular fistula (20.5%). The prevalence of OSD in cloaca malformation, rectobladder neck fistula, rectoprostatic urethral fistula, rectobulbar urethral fistula, and perineal fistula were 28.6%, 33.3%, 16.7%, 12.5%, and 9.8%, respectively. Lumbosacral X-ray had a sensitivity of 51.7% and was not a good screening method. Sixteen of 65 U/S revealed OSD (24.6%). Tethered cord and syringomyelia were noted in nine and seven, respectively. Spinal MRI (n=39) revealed 27 OSD (69.2%) comprising 16 tethered cords, 12 spinal lipoma, and 10 syringomyelia. ARM associated with KUB anomalies had a statistically significant correlation with OSD. In 33 OSD, 17 patients (51.1%) were operated on. Fourteen received untethering spinal cord, while five had intradural lipoma excised.

Conclusion: Patients with ARM had a high prevalence of OSD and should be screened for. U/S is the first-line method. MRI is strongly recommended in cloaca malformation, rectobladder neck fistula, rectoprostatic urethral fistula, vestibular fistula, and all ARM associated with KUB anomalies. Other types of ARM should be screened by MRI if feasible.

Keywords: Spinal dysraphism, Tethered cord, Anorectal malformation

DOI: doi.org/10.35755/jmedassocthai.2021.01.11521

Received 15 June 2020 | Revised 24 August 2020 | Accepted 25 August 2020