A new method for evaluating short fetal corpus callosum

Sonographic diagnosis of short corpus callosum (SCC) is based on measurement of a short for gestational age antero-posterior length of the corpus callosum (CC) in the midsagittal plane. We suggest a new method for evaluating SCC without referring to biometry tables.

We measured the ratio between the CC length and the internal cranial occipitofrontal dimension (ICOFD) in the midsagittal plane in 399 normal fetuses at 20 + 6 to 35 + 3 weeks of gestation and in 31 fetuses with a diagnosis of a SCC and compared the mean ratio between two groups. The impact of cephalic biometric parameters, fetal presentation, and gender was assessed.

The ICOFD/CC length for normal pregnancies was constant throughout the pregnancy (2.35 ± 0.11). There was no correlation between the ICOFD/CC length and cephalic index, Biparietal Diameter (BPD), head circumference, fetal sex, or fetal presentation. The ratio of pregnancies with SCC was significantly higher: 3.20 ± 0.84 (P < .0001).

The ICOFD/CC length practically does not change throughout a normal pregnancy. The ratio was significantly higher in pregnancies with SCC. Measuring this ratio during fetal anatomical scan may enable rapid evaluation of the CC without the need to refer to biometry tables.