Ultrasound-Based Analysis of Fetal Conus Medullaris Anomalies: A Comprehensive Study on Prenatal Diagnosis and Postnatal Outcomes

Background

To explore prenatal characteristics and the long-term prognosis in fetal conus medullaris (CM) location anomalies.

Methods

This was a retrospective observational study of all fetuses diagnosed with CM location anomalies using ultrasound between November 2016 and June 2022 at our institution. Clinical data, including general information, prenatal CM location changes, associated malformations, genetic information, and pregnancy outcomes, were collected and analyzed.

Results

In total, 210 fetuses were selected and allocated to the simple group (with isolated CM location anomalies) or the anomaly group (with other congenital anomalies). Among the anomaly group, the most frequently involved congenital anomalies were related to the spine, heart, and limbs. The probability of chromosomal abnormalities was 4.1% in the simple group and 12.5% in the abnormal group, and the live birth rates were 94.6% and 22.1%, respectively. Prenatal tracking revealed that CM ascended above L3 in 89.2% and 19.1% in the two groups, respectively. Receiver operating characteristic curve analysis indicated that a CM located below L4 was the diagnostic cutoff for predicting lumbosacral anomalies. During the one- to five-year follow-up, except for three cases with adverse outcomes, all live-born children from both groups had good growth and development with no evident symptoms of tethered cord syndrome.

Conclusions

The prenatal CM location is closely related to lumbosacral anomalies. Fetuses with CM located above L4 and without other congenital anomalies or with only minor anomalies other than lumbosacral anomalies generally have a favorable prognosis. However, caution is warranted when examining lumbosacral anomalies when the CM is located below L4.