Conus medullaris migration during the third trimester: A retrospective study

Abstract

Objective To explore the migration process of the conus medullaris (CM) and propose a normal range of CM levels during the third trimester. Method We retrospectively collected the ultrasonographic and clinical data of 588 fetuses during the third trimester. We located the CM and assigned scores. One‐way analysis of variance and linear regression analyses were used to statistically analyze CM migration. Statistical significance was set at p < 0.05. Results The CM levels were statistically different among the different gestational weeks of the third trimester. The CM level showed a linear regression correlation with the gestational weeks. On an average, the CM migrated from the top third of the L2 vertebra to the L1/2 intervertebral disc level. Conclusion The CM continues to migrate, from the top third of the L2 vertebra to the L1/2 intervertebral disc level, during the third trimester. The term infant could have the CM at the normal adult level at birth. At the beginning of the third trimester, a CM located above the L2/3 intervertebral disc level could be normal; the CM location at the L3 vertebra level could be physiological and needs follow‐up; and a CM presenting below the L3 vertebra level might indicate tethered cord syndrome. The fetus with a CM significantly above the L1/2 intervertebral disc level may have caudal regression syndrome.

Comparison of prenatal ultrasonography and fetal MRI in diagnosing neural tube defects: A prospective observational study

“…Our previous studies have confirmed that both ultrasonography and MRI can be used to identify the fetal conus medullaris. 19,20 Meningocele and myelomeningocele belong to open dysraphic abnormalities, which is a prominent characteristic distinguishable from other diseases. Sacrococcygeal teratomas show conspicuous cystic or solid masses outside the spinal canal or inside the pelvis and abdomen.…”

Yenidoğan bebeklerde konus medullaris düzeyinin değerlendirilmesi

“…In a study involving 588 fetuses during the third trimester, Sun et al suggested that a CM level at L3 vertebra in the third trimester can be a physiological condition but should be followed. The authors also reported that a fetus with a CM level above L1/2 intervertebral disc can have caudal regression syndrome 9 . In an anatomical dissection study with postmortem 30 fetuses, spinal cord length and CM level were found to be associated with the gestational age of the fetuses.…”