Echogenic bowel in fetuses with homozygous alpha-thalassemia-1 in the first and second trimesters.

Abstract

Fetal echogenic bowel has been observed in fetuses with meconium peritonitis, cystic fibrosis, aneuploidy, congenital viral infection and intrauterine growth restriction. The pathogenesis of echogenic bowel is unknown, but it may be attributed to bowel ischemia. Fetuses affected by homozygous alpha-thalassemia-1 are severely anemic and hypoxic. We investigated the incidence of echogenic bowel in these hypoxic fetuses in the first and second trimesters. Prospective observational study. Women referred for the prenatal diagnosis of homozygous alpha-thalassemia-1 before 24 weeks' gestation. All subjects had one or more abdominal and/or vaginal ultrasound examination between 12 and 24 weeks' gestation. Echogenic bowel was diagnosed if the bowel appeared either isoechogenic or more echogenic than the bone. Between March 1997 and July 1998, 126 pregnancies were studied. Thirty-six fetuses were confirmed to be affected by homozygous alpha-thalassemia-1, and 11 of them (31%, 95% CI 16-48%) had echogenic bowel. These observations were made before the invasive test results were available. None of the fetuses unaffected by homozygous alpha-thalassemia-1 had echogenic bowel. There is a strong association between homozygous alpha-thalassemia-1 and echogenic bowel. The pathogenesis is unknown. Speculations include bowel hypoperistalsis or bowel wall edema due to severe anemia and hypoxia.