A meta-analysis found that playing music improves tolerability to patients of the procedure.The first step is usually a digital rectal examination, to examine the tone of the sphincter and to determine if preparation has been adequate. The endoscope is then passed through the anus up the rectum, the colon (sigmoid, descending, transverse and ascending colon, the cecum), and ultimately the terminal ileum. The endoscope has a movable tip and multiple channels for instrumentation, air, suction and light. The bowel is occasionally insufflated with air to maximize visibility (a procedure that gives the patient the false sensation of needing to take a bowel movement). Biopsies are frequently taken for histology. Additionally in a procedure known as chromoendoscopy, a contrast-dye (such as indigo carmine) may be sprayed through the endoscope onto the bowel wall to help visualise any abnormalities in the mucosal morphology. A Cochrane review updated in 2016 found strong evidence that chromoscopy enhances the detection of cancerous tumours in the colon and rectum.In most experienced hands, the endoscope is advanced to the junction of where the colon and small bowel join up (cecum) in under 10 minutes in 95% of cases. Due to tight turns and redundancy in areas of the colon that are not "fixed", loops may form in which advancement of the endoscope creates a "bowing" effect that causes the tip to actually retract. These loops often result in discomfort due to stretching of the colon and its associated mesentery.
Structural closure in term babies occurs within 3 to 7 days. After it closes, the remnant is known as ligamentum venosum. If the ductus venosus fails to occlude after birth, it remains patent (open), and the individual is said to have a patent ductus venosus and thus an intrahepatic portosystemic shunt (PSS). This condition is hereditary in some dog breeds (e.g. Irish Wolfhound). The ductus venosus shows a delayed closure in preterm infants, with no significant correlation to the closure of the ductus arteriosus or the condition of the infant. Possibly, increased levels of dilating prostaglandins leads to a delayed occlusion of the vessel. == References ==