Second trimester ultrasonographic diagnosis of ileal atresia, histopathological findings consistent with cystic fibrosis and negative genetic tests

Abstract

Introduction: Echogenic bowel is diagnosed in 0.2% to 1.4% of second trimester ultrasonographic examinations. This finding occurs as a normal variant in the second trimester but also has been associated with several pathologic conditions that include cystic fibrosis (CF), chromosomal abnormalities and in utero infection with cytomegalovirus and toxoplasmosis. The diagnosis of fetal echogenic bowel in second trimester fetuses has significant implications for prenatal management. It is strongly associated with adverse pregnancy outcome with utero-placental insufficiency, particularly in cases in which the maternal serum alpha-fetoprotein concentration is elevated due to severe feto-maternal bleeding. Case Report: A 30 year old Ashkenazi woman was admitted at 22 weeks of gestation due to recurrent vaginal bleeding. During prenatal care an elevated Elevated maternal serum AFP (MSAFP) as well as hyperechogenic bowel were observed. Ultrasound at her admission showed fetal distended bowel with a lower abdominal mass appearance with hyperechogenic foci. Amniocentesis was performed, with normal fetal karyotype; Cytomegalovirus and cystic fibrosis (CF) testing. The mother was positive for CF, but both the husband and the fetus were negative. At the 24th week, she delivered a male fetus with abdominal distention. X-ray and abdominal ultrasound showed obstruction at the level of the terminal ileum. The newborn died 18 hours after delivery. A postmortem examination revealed no evidence of external malformations and atresia of the terminal ileum with total obstruction of the intestinal lumen; near the atretic portion changes consistent with meconium ileus were seen. Foci of mucous deposition on the intestinal surface and calcifications were observed, all features highly suggestive of CF. Our presentation discusses the prenatal ultrasonographic findings in non-duodenal bowel obstruction and histopathological findings in CF. This case is unique in the early detection of fetal bowel obstruction by ultrasound and the discrepancy between the histological and genetic results for CF. Conclusion: Echogenic bowel is associated with several serious conditions including CF that should be ruled out once the diagnosis of echogenic bowel is made, although it is subjective. These include fetal karyotype, infections, structural malformations, thalasemia, CF and placental damage. CF etiology is very important for genetic consultations for the next pregnancies and it should be diagnosed by examining the known mutations. However, a pathological examination of available bowel tissue can highly support the diagnosis.