Which GI conditions should be included in the differential diagnoses of cystic fibrosis (CF)?

Updated: Oct 22, 2019
  • Author: Girish D Sharma, MD, FCCP, FAAP; Chief Editor: Kenan Haver, MD  more...
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Answer

In meconium ileus, bowel dilatation is caused by a meconium obstruction but mimics similar findings in the following conditions:

  • Midgut volvulus

  • Congenital bands

  • Bowel atresia

  • Intestinal duplication

  • Internal hernia

  • Meconium plug syndrome

  • Hirschsprung disease

However, studies that show correlation between dilated fetal bowel and meconium ileus suggest that dilated fetal bowel warrants parental testing for CF and continued sonographic surveillance of the fetus.

In addition to the findings of increased abdominal echogenicity and bowel dilation, the inability to visualize the gallbladder on fetal ultrasonography is associated with CF. Combined with other sonographic features, nonvisualization of the gallbladder can help detect the disease prenatally. However, exercise caution in interpreting an absent gallbladder because the differential diagnosis includes biliary atresia, omphalocele, and diaphragmatic hernia.

Sonographic characteristics of fetal bowel obstruction are neither sensitive nor specific for meconium ileus. In general, a rate of sonographic detection for meconium ileus or meconium peritonitis can be up to 19%. Interpretation of these sonographic findings must consider the fetus' risk of CF. While ultrasonographic findings that suggest meconium ileus in a high-risk fetus indicate a high probability of CF, similar suspicious findings in a low-risk fetus warrant consideration of DNA testing or, at the very least, serial follow-up examinations.


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