large intestine .pdf

Large intestine Mariam Mohamed Ali  The large intestine (also known as the large bowel) is a 1.5 meter muscular tube that extends from the cecum to the rectum.  The large bowel is divided into the following parts: cecum appendix ascending colon right colic flexure transv...

Large intestine Mariam Mohamed Ali  The large intestine (also known as the large bowel) is a 1.5 meter muscular tube that extends from the cecum to the rectum.  The large bowel is divided into the following parts: cecum appendix ascending colon right colic flexure transverse colon left colic flexure descending colon sigmoid colon rectum  NB: some people use the term colon as a synonym for the large intestine/bowel, however anatomically, the colon does not include the rectum, and therefore colon and large intestine are not synonymous. Cecal volvulus Cecal volvulus describes torsion of the cecum around its mesentery which often results in obstruction. If unrecognised, it can result in bowel perforation and fecal peritonitis. On abdominal radiographs, there is marked distension of a loop of large bowel with its long axis extending from the right lower quadrant to the epigastrium or left upper quadrant. The general caliber for the cecum is < 9 cm.  3-6-9 rule (bowel): The 3-6-9 rule is a simple aide-memoire describing the normal bowel caliber: small bowel: 6 mm) appendix without periappendiceal inflammation periappendiceal inflammation fat stranding extraluminal fluid inflammatory mass) abscess  Intussusception: Intussusception occurs when one segment of bowel is pulled into itself or a neighboring loop of the bowel by peristalsis. It is an important cause of an acute abdomen in children.When occurring in the adult population, intussusception is usually caused by a focal lesion acting as a lead point.  Fluoroscopy A contrast enema remains the gold standard, demonstrating the intussusception as an occluding mass prolapsing into the lumen, giving the "coiled spring” appearance (barium in the lumen of the intussusceptum and in the intraluminal space). The main absolute contraindication for an enema is perforation, which needs to be treated surgically.  Ultrasound: Ultrasound signs include: target sign (also known as the doughnut sign) pseudokidney sign  CT CT has become the modality of choice for assessment of acute abdomen in adults, and thus most frequently images intussusception. Best known is the so-called bowel-within- bowel configuration, in which the layers of the bowel are duplicated forming concentric rings (CT equivalent of the ultrasonographic target sign).