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© 2025 Author(s) (or their employer(s)) 2025. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ Group. http://creativecommons.org/licenses/by-nc/4.0/ This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See:  http://creativecommons.org/licenses/by-nc/4.0/ . Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.

Abstract

Introduction

The cavum septi pellucidi (CSP) is a fluid-filled cavity box situated on the midline between the medial walls of the two lateral ventricles and placed above the fornix and below the corpus callosum. The formation of the CSP begins at 14 weeks and is completed around 17 weeks.

A regular CSP indirectly indicates the correct development of the corpus callosum and the midline of the fetal brain. Therefore, its evaluation is mandatory during routine obstetric scans. The available guidelines do not report specific recommendations on the morphology or biometry of the fetal CSP, thus leaving to the experience of the operator and, thus, to a subjective evaluation, the identification of potential anomalies.

Our aim is to construct methodologically robust reference charts for the CSP’s width, length and length-to-width ratio in relation to gestational age and fetal biparietal diameter.

Methods and analysis

The REC-FAST study (Reference Charts for the Fetal cAvum SepTi pellucidi) is a prospective monocentric cross-sectional study on consecutively enrolled pregnant women accessing our Obstetric Unit at the Foundation IRCCS San Gerardo dei Tintori, Monza, Italy, for fetal ultrasound evaluation.

Women will be eligible if carrying an uncomplicated singleton pregnancy between 190/7 and 366/7 weeks’ gestation with a certain pregnancy dating by first trimester ultrasound with crown-rump length measurement, and if aged between 18 and 45 years.

After signing the informed consent, the ultrasound scan will be performed and the CSP’s width and length will be measured by means of the inner-to-inner technique and its morphology recorded.

In order to achieve the statistical power required for properly constructing reference charts, we will divide our population into six groups according to the gestational age when the ultrasound scan will be performed (each group will cover a 3-week interval starting at 190/7 until 366/7 weeks). A minimum sample size of 80 will be reached for each gestational age group. Before charting, the data will be checked for consistency to identify any outliers. Where possible, outliers will be corrected by comparing with the original values (computation errors); otherwise, such data will be excluded. The fetal charts will be traced using the Cole and Green-Lambda, Median, and Sigmamethod (CG-LMS); in addition, the use of alternative modelling approaches, such as parametric models derived from the Extended Mechanistic Growth Function method, will be explored.

Ethics and dissemination

Ethical approval for this study was obtained by the Lombardy Ethics Committee n.3 (15 December 2023) prior to the commencement of the research. Written informed consent will be obtained from all participants. Women will be free to decline participation or to withdraw at any time.

Findings will be presented at scientific meetings and published in peer-reviewed scientific journals in the field of obstetrics and fetal medicine. Also, they will be disseminated to study participants through dedicated online and in-person meetings and to the public through reach-out activities involving families and healthcare specialists.

Details

Title
Reference charts for the fetal cavum septi pellucidi’s width, length and length-to-width ratio: protocol for a prospective monocentric cross-sectional study in Italy (the ‘REC-FAST’ study)
Author
Rovelli, Roberta 1 ; Verderio, Maria 1 ; Spada, Elena 2 ; Camponovo, Paola 3 ; Lanteri, Laura 1 ; Salmoiraghi, Elettra 3 ; Cozzolino, Sabrina 1 ; Vergani, Patrizia 4 ; Locatelli, Anna 3 ; Ornaghi, Sara 3   VIAFID ORCID Logo 

 Unit of Obstetrics, Foundation IRCCS San Gerardo dei Tintori, Monza, Italy 
 Laboratorio Carlo Corchia - LCC, Florence, Italy 
 Unit of Obstetrics, Foundation IRCCS San Gerardo dei Tintori, Monza, Italy; School of Medicine and Surgery, University of Milan-Bicocca, Monza, Italy 
 School of Medicine and Surgery, University of Milan-Bicocca, Monza, Italy 
First page
e098410
Section
Obstetrics and gynaecology
Publication year
2025
Publication date
2025
Publisher
BMJ Publishing Group LTD
e-ISSN
20446055
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
3224330354
Copyright
© 2025 Author(s) (or their employer(s)) 2025. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ Group. http://creativecommons.org/licenses/by-nc/4.0/ This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See:  http://creativecommons.org/licenses/by-nc/4.0/ . Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.