Bowel Dilation simply means that the baby’s intestines are measuring larger in some parts than others and can be a sign of complications.12 This can be caused by several factors, including bowel irritation which some doctors believe is caused by exposure to amniotic fluid, loss of blood flow to the intestines in utero, narrow spots in the intestines called “strictures”, or bowel atresia.13 Your doctor will typically begin measuring loops of bowel via ultrasound towards the end of the second trimester as part of a comprehensive fetal assessment.
Studies show that intra-abdominal bowel dilation measurements are indicative of intestinal atresias and longer NICU stays when measuring greater than 14mm.14Repeated studies demonstrate that measurements of extra-abdominal bowel dilation is not a good predictor of adverse outcomes15 and fetal health should be evaluated via ultrasound using the standard Biophysical Profile.16
13. http://fetus.ucsfmedicalcenter.org/bowel/
14. http://www.ncbi.nlm.nih.gov/pubmed/23893619