Ileocolic Intussusception

  • Etiology:
    — Idiopathic (90%) – due to hypertrophied Peyer’s patches after viral URI, is invagination / telescoping of terminal ileum (intussusceptum) through the ileocecal valve into colon (intussuscipiens) causing obstruction, intussusceptum includes mesenteric vessels and fat as well as bowel wall and compression of mesentery leads to compromise of venous drainage which over time can lead to arterial perfusion being reduced which can lead to subsequent bowel ischemia and infarction and necrosis
    — Pathologic (10%) – increasing prevalence of pathologic lead point with increasing age (> 3 years old) so always look for lead point with ultrasound, surgeon may still want reduction attempted if lead point is found in order to avoid emergency surgery, most common pathologic lead points – Meckel diverticulum / polyp / duplication cyst / lymphoma, less common pathologic lead points – bowel wall hemorrhage in Henoch-Schonlein Purpura / inspissated stool in cystic fibrosis
  • AXR: can show small bowel obstruction, Currarino’s sign of not seeing air in hepatic flexure of colon, usually unremarkable so normal AXR does not rule out intussusception
  • US: for diagnosis – target sign on transverse image / pseudokidney sign on sagittal image that is > 3 cm in transverse diameter, may see lymph nodes and fat and appendix along with small bowel in intussusceptum
  • Enema: coiled spring + filling defect caused by intussusceptum
  • DDX: small bowel-small bowel intussusception – should never see fat or lymph nodes in transient small bowel-small bowel intussusception
  • Treatment: pediatric surgery consult, IV fluids, rule out peritonitis + perforation which are contraindications to reduction, air enema for reduction done prone with tight buttock seal done according to Rule of 3’s: 3 attempts each lasting 3 minutes and with bag of contrast 3 feet off table (= not exceeding a pressure of 120 mm of Hg in air enema) with end point being massive reflux of contrast or air into terminal ileum, an 18 gauge needle should be readily available to treat pneumoperitoneum in case of perforation
  • Clinical: peak age is 6 months, 75% in patients less than 2 years, presents by passing blood / currant jelly stool and drawing legs up to abdomen, most common cause of obstruction in young children, air reduction is 80-90% successful with 0.5% perforation rate, 10% re-intussuscept within 24 hours post reduction

Radiology Cases of Ileocolic Intussusception

AXR of small bowel obstruction due to intussusception
AXR supine (left) shows decompressed loops of bowel (presumed jejunum) in the left upper quadrant and multiple dilated loops of bowel (presumed ileum) in the right lower quadrant. AXR upright (right) shows multiple air-fluid levels.
US of ileocolic intussusception
XR supine (upper left) shows a non-obstructive bowel gas pattern but suggests a soft tissue mass in the right lower quadrant. Transverse US of the right lower quadrant (upper middle) shows a soft tissue mass with a target sign measuring 3 cm in diameter while the longitudinal US (upper right) shows a pseudokidney sign. AP spot image from an air enema (bottom) shows a soft tissue mass being encountered in the cecum.
AXR of pneumoperitoneum
Supine AXR obtained during an intussusception reduction shows air outlining both the inner and outer walls of the small bowel (Rigler’s sign).

Clinical Cases of Ileocolic Intussusception

Clinical image of currant jelly stools in intussusception
Clinical image shows currant jelly stools.

Surgery Cases of Ileocolic Intussusception

Surgical image of ileocolic intussusception
Surgical image shows an ileocolic intussusception extending into the mid ascending colon with a dusky terminal ileum (to the right) intussuscepting into the cecum (to the left). Note that the appendix (in the middle of the image) is intussuscepted with the ileum. The intussusception was reduced without great difficulty manually. No lead point was seen.
Surgical image of ileocolic intussusception
Surgical image shows forceps in a 1.5 cm perforation in the mid point of the transverse colon. The ascending colon (on the right) is distended and is full of necrotic intussuscepted ileum up to the level of the hepatic flexure.