Meconium ileus is most often seen in the first few days of life in neonates with cystic fibrosis, but can rarely occur in infants with a normal pancreas. In cystic fibrosis, the abnormal pancreatic secretions lead to inspissated meconium that produces intestinal obstruction. The dilated coils of ileum are opened here to reveal the inspissated green meconium (which may also be tarry or gritty), while the unopened colon at the upper left and the appendix at the lower left beyond the ileocecal valve are not dilated, and little or no meconium is passed per rectum. [Image contributed by Ted Pysher, MD, University of Utah]