In bowel obstructive conditions, one finding can hide the other. In small bowel atresias for example, the first atresia may hide other atresias or an apple-peel syndrome. There is currently no reliable way on prenatal imaging, ultrasound or MRI, to predict multiple atresias . There has been discussion of whether or not the visibility/absence of the distal bowel, and the visibility/absence of a microcolon on imaging could be used as predictive factors. That said in cystic fibrosis, bowel atresia is not expected but rather meconium ileus: the lack of progression of the meconium due to its thickness. However, volvulus can also occur with secondary atresia.
On MRI, the meconium signal is unusual in cystic fibrosis. In normal conditions, the meconium is expected to feature marked T1 hyperintensity compared to the liver. In cases 1 and 2, the meconium shows mild hyperintensity, almost isointensity, compared to the liver. Our MRI findings are consistent with other prenatal MR findings in cystic fibrosis reported in the literature in which 4 fetuses with echogenic bowel on ultrasound are retrospectively analyzed: 2 with ileal atresia without cystic fibrosis, and 2 with meconial Ileus and cystic fibrosis . Regarding this peculiar MR characteristic of meconium, one theory speculates that what makes meconium hyperintense on T1 sequences, is the rich content in bile acids. In cystic fibrosis, the bile acids are less concentrated, hence less T1 signal intensity [3,4].
 Rubio EI, Blask AR, Badillo AT, et al. Prenatal magnetic resonance and ultrasonographic findings in small-bowel obstruction: imaging clues and postnatal outcomes. Pediatr Radiol. 2017 Apr;47(4):411-421. PMID: 28116474
 Carcopino X, Chaumoitre K, Shojai R, et al. Use of fetal magnetic resonance imaging in differentiating ileal atresia from meconium ileus. Ultrasound Obstet Gynecol, 28: 976-977. Publish date 11/2006. https://doi.org/10.1002/uog.3827
 Righetti C, Peroni DG, Pietrobelli A, et al. Proton nuclear magnetic resonance analysis of meconium composition in newborns. J Pediatr Gastroenterol Nutr. 2003 Apr;36(4):498-501. PMID: 12658044.
 Zizka J, Elias P, Hodik K, et al. Liver, meconium, haemorrhage: the value of T1-weighted images in fetal MRI. Pediatr Radiol. 2006 Aug;36(8):792-801. PMID: 16799788.