Growth of the colon and rectum throughout gestation: evaluation with fetal MRI

Study of Correlation between Fetal Bowel Dilation and Congenital Gastrointestinal Malformation

BACKGROUND

Ultrasound serves as a valuable tool for the early detection of fetal bowel dilatation, yet the correlation between fetal bowel dilatation and gastrointestinal malformations remains to be further investigated. This study aims to explore the relationship by conducting a follow-up and analysis of fetuses with bowel dilation.

METHODS

A retrospective analysis was conducted on 113 fetuses with bowel dilatation at our center from July 2014 to December 2019. The location and degree of bowel dilatation were analyzed. ROC curves were constructed based on the diameter of the bowel and its ratio to fetal gestational age.

RESULTS

In total, 40 of 41 cases (97.6%) with upper gastrointestinal dilatation (double-bubble sign) and 46 of 72 cases (63.9%) with lower gastrointestinal dilatation were diagnosed with gastrointestinal malformations postnatally. The AUC of the dilatation diameter was 0.854 with a cutoff value of 18.05 mm in patients with lower gastrointestinal dilatation. The ratio of the diameter to gestational age (D/GA) showed a higher AUC of 0.906 with a cutoff value of 0.4931.

CONCLUSIONS

The presence of the double-bubble sign in fetuses indicates a close association with duodenal obstruction. The risk of gastrointestinal malformations increases when the bowel diameter exceeds 18.05 mm, particularly when the D/GA surpasses 0.4931.

Biometric analysis of the foetal meconium pattern using T1 weighted 2D gradient echo MRI

Objectives:

Foetal MRI is used to assess abnormalities after ultrasonography. Bowel anomalies are a significant cause of neonatal morbidity, however there are little data concerning its normal appearance on antenatal MRI. This study aims to investigate the pattern of meconium accumulation throughout gestation using its hyperintense appearance on T₁ weighted scans and add to the current published data.

Methods:

This was a retrospective cohort study in a tertiary referral clinical MRI centre. Foetal body MRI scans of varying gestational ages were obtained dating between October 2011 and March 2018. The bowel was visualised on T₁ weighted images. The length of the meconium and the width of the meconium at the rectum, sigmoid colon, splenic flexure and hepatic flexure was measured. Presence or absence of meconium in the small bowel was noted. Inter- and intrarater reliability was assessed.

Results:

181 foetal body scans were reviewed. 52 were excluded and 129 analysed. Visualisation of the meconium in the large bowel became increasingly proximal with later gestations, and small bowel visualisation was greater at earlier gestations. There was statistically significant strong (r = 0.6–0.8) or very strong (r = 0.8–1.0) positive correlation of length and width with increasing gestation. Interrater reliability was moderate to excellent (r = 0.4–1.0).

Conclusion:

This study provides new information regarding the pattern of meconium accumulation throughout gestation. With care, the results can be used in clinical practice to aid diagnosis of bowel pathology.

Advances in knowledge:

The findings of this study provide further information concerning the normal accumulation of foetal meconium on MR imaging, an area where current research is limited.