Measuring distance between the fetal bladder neck and rectal end using prenatal MRI
10.3760/cma.j.cn113903-20240625-00456
- VernacularTitle:MRI测量胎儿膀胱颈-直肠末端距离
- Author:
Yaxian CAO
1
;
Shuyi LIU
1
;
Zhen CHEN
1
;
Rui WANG
1
;
Li HUANG
1
;
Xiaochun ZHANG
1
Author Information
1. 广州医科大学附属妇女儿童医疗中心放射科，广州 510000
- Publication Type:Journal Article
- Keywords:
Fetal development;
Distance between bladder neck and distal rectum;
Congenital anorectal malformations;
MRI
- From:
Chinese Journal of Perinatal Medicine
2025;28(5):403-407
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To measure the distance between the fetal bladder neck and the rectal end using prenatal MRI and analyze the developmental patterns of this distance and the gender differences in the second and third trimesters of pregnancy.Methods:This retrospective cohort study involved fetuses born at Guangzhou Women and Children's Medical Center, Guangzhou Medical University after regular prenatal examinations from January 2019 to December 2022 and confirmed to have typical anorectal structures after birth. These fetuses had undergone prenatal MRI examinations for reasons other than abdominal issues. The morphology of the fetuses' colons, rectums, and bladders was observed, and the vertical distance between the bladder neck and the rectal end was measured on sagittal T1weighted imaging. Differences in the distance between male and female fetuses were analyzed. The fetuses were divided into five groups based on their gestational age at the time of MRI examination (23-24 weeks, >24-26 weeks, >26-28 weeks, >28- 30 weeks, and >30-32 weeks), and the changes in the distance with gestational age were analyzed. Statistical analysis was performed using t-test, Kruskal-Wallis test, and Spearman correlation analysis. Pairwise comparisons among multiple groups were conducted using the Bonferroni method. Results:(1) A total of 142 fetuses were included in this study, all of which were singletons, with 73 males (51.4%) and 69 females (48.6%). The gestational age at the MRI examination was 28 weeks (26-30 weeks). (2) All fetuses had meconium filling the entire rectum and colon, with the rectal end located 0.570-2.610 cm below the bladder neck. (3) The distance between the bladder neck and the rectal end was shorter in male fetuses than in female fetuses [(1.140±0.261) vs. (1.519±0.405) cm, t=－6.58, P<0.001]. (4) In female fetuses, four pairs of groups showed statistically significant differences in the distance (23-24 weeks group vs. >26-28 weeks, >28- 30 weeks, and >30-32 weeks groups, and >24-26 weeks group vs. >30-32 weeks group). However, only two groups of male fetuses (23-24 weeks group vs. >28-30 weeks group) had statistically significant differences in the distance (all P<0.005). (5) The distance was moderately correlated with gestational age in male fetuses ( r=0.42, P<0.001), but they were strongly correlated in female fetuses ( r=0.66, P<0.001). Conclusions:The distance between the bladder neck and the rectal end in fetuses shows certain developmental patterns and gender differences in pregnancy's second and third trimesters. The correlation between the value and gestational age is stronger in female fetuses.
