Examination of fetal Sylvian fissure can and should be performed bilaterally during ultrasound screening

Neurosonographic Measurements of the Fetal Anterior Complex in Singleton Pregnancies

OBJECTIVE

To construct reference ranges of the fetal cerebral anterior complex, including ventricular index (VI), anterior horn of lateral ventricle width (AW), and cavum septi pellucidi (CSP) width, as a function of gestational age (GA), in Thai fetuses.

METHODS

Low-risk pregnancies were recruited to measure fetal anterior complex on axial transventricular and coronal transcaudate planes using transabdominal ultrasound. The downside and upside hemisphere were defined as cerebral hemisphere located distal and proximal to the transducer, respectively. The five variables, downside/upside VI, downside/upside AW and CSP width, were measured from each fetus. Best-fit models in predicting mean and standard deviation for each value as a function of GA were constructed, using regression analysis. Distributions of Z-scores of all values based on GA were created to evaluate the fitness of models. Intraclass correlation coefficients were used to assess inter-/intraobserver variability.

RESULTS

A total of 395 fetuses were measured for anterior complex. All parameters changed with GA with quadratic function. The models for predicting means and standard deviation of the five parameters as well as percentile charts were created. All models were proven well-fitted. The intra-/interobserver reliability coefficients of all values showed excellent agreement.

CONCLUSION

The reference ranges of the fetal anterior complex, including VI, AW, and CSP, in axial transventricular and coronal transcaudate planes have been established and available for clinical use.

Feasibility of extended ultrasound examination of the fetal brain between 24 and 37 weeks' gestation in low-risk pregnancies

OBJECTIVES

To assess the feasibility of identifying fetal brain structures and anatomic landmarks included in the anterior complex (AC) and posterior complex (PC), as well as the proximal hemisphere (PH).

METHODS

This was a prospective observational multicenter study of healthy pregnant women evaluated by ultrasound screening at 24 to 36 + 6 weeks' gestation. Six physicians performed transabdominal ultrasound, to obtain the planes required to visualize the AC, PC, and PH. Blind analysis by an expert and non-expert operator in fetal neurosonography was used to assess the structures included in each plane view.

RESULTS

In the population studied (n=366), structure detection rates for AC were over 95 %, with an agreement of 96 % when comparing expert and non-expert examiners. Visualization of the corpus callosum crossing the midline was detected in over 97 and 96 % of cases for the AC and PC, respectively, with an agreement of over 96 %. The PH plane, particularly through the posterior access via the mastoid fontanelle, enabled visualization of the proximal anatomical structures in almost 95 % of cases. Detection of the corpus callosum through the AC and PC, both proximal/distal germinal matrix (AC) and proximal Sylvian fissure through the anterior access (PH) in the 24-25 + 6, 26-31 + 6 and 32-36 + 6 weeks' gestation groups were successful in over 96 % of cases with high level of agreement.

CONCLUSIONS

Inclusion of AC, PC, and PH later in pregnancy proves feasible with a high level of agreement between both expert and non-expert operators.