Meckel Diverticulum

Etiology: Persistent remnant of omphalomesenteric (vitelline) duct which runs in umbilical cord connecting primitive midgut (terminal ileum) and extraembryonic sac that involutes by sixth week
Meckel scan:
— Shows simultaneous appearance of radiotracer in stomach and diverticulum as ~ 50% contain ectopic gastric mucosa
— Negative Meckel scan does not rule out Meckel diverticulum
Imaging US: Cystic lesion near distal ileum or in periumbilical location
Imaging CT: On antimesenteric border of small bowel
DDX: Acute appendicitis – Meckel diverticulitis can have similar appearance on ultrasound to acute appendicitis as an inflamed blind-ending tubular structure so best way to prove it is not appendicitis is to identify its origin from ileum or to see a normal appendix
Complications:
— Hemorrhage due to acid secretion or ulceration
— Can act as pathological lead point for ileocolic intussusception
Treatment: Surgical
Clinical:
— Can present with lower gastrointestinal bleed or small bowel obstruction
— Is most common congenital anomaly of gastrointestinal tract
— Rule of 2: in 2% of population and is 2 feet from ileocecal valve and 2% get complications and complications occur before 2 years old

Radiology Cases of Meckel Diverticulum

Meckel’s scan of Meckel's diverticulum — AP delayed image (left) from a Tc-99m pertechnetate scan (Meckel scan) shows a focal round concentration of radiotracer in the right lower quadrant superior and lateral to the midline bladder which is seen in the middle of the lower abdomen superior to the bladder on the lateral (right) delayed image.

CT of Meckel diverticulum — AP and lateral images from a Technetium-99m Meckel scan (above left) show no areas of abnormal uptake of radiotracer in the abodmen. Axial CT with contrast of the abdomen (above right) shows a small, round, primarily solid soft tissue mass just to the right of the midline between the loops of bowel that on coronal (below left) and sagittal (below right) images is seen to be tubular in appearance and connecting to the anterior abdominal wall near the umbilicus.

Radiology Cases of Meckel Diverticulum Causing Small Bowel Obstruction

CT of small bowel obstruction due to Meckel's diverticulum — AXR supine (upper left) and coronal CT with contrast of the abdomen (lower left) show multiple dilated loops of small bowel with thin walls throughout the abdomen. The lower axial CT (upper right) shows a small cystic structure in the midline with a thicker wall than the surrounding dilated bowel which is also seen on the midline sagittal CT (lower right) just beneath the umbilicus.

UGI of false positive malrotation with midgut volvulus — AXR upright (left) shows multiple dilated loops of small bowel with air fluid levels. Sagittal US of the abdomen (above right) shows multiple dilated loops of peristalsing small bowel, however an intussusception was not seen. AP image from an upper GI exam (below right) shows the duodenal-jejunal junction to be low in position and to be to the right of the spine.

US and radiograph and air enema of ileocolic intussusception caused by Meckel diverticulum — Transverse US of the right lower quadrant (above) shows a round structure with a hyperechoic center and a hypoechoic rim (target sign). AXR supine (below left) shows multiple dilated loops of air-filled small bowel. Final AP image from an air enema exam (below right) shows an air filled colon with a large oval soft tissue mass in the cecum.

Radiology Cases of Meckel Diverticulum Causing Small Bowel Volvulus and Closed Loop Obstruction Resulting in Small Bowel Ischemia

CT of Meckel diverticulum causing small bowel volvulus and a closed loop obstruction resulting in small bowel ischemia — Coronal (above left) CT with contrast of the abdomen shows in the center just above the bladder a C-shaped dilated small bowel loop with a thickened wall that is not enhancing. On the sagittal image (above right) the dilated, thickened and nonenhancing small bowel loop is seen anteriorly in the abdomen and superior to the bladder. On the axial image (below) the small bowel loop is in the center of the pelvis.

CT of Meckel diverticulum causing distal small obstruction due to small bowel volvulus around the Meckel diverticulum resulting in a closed loop obstruction and small bowel ischemia of the ileum and pneumatosis intestinalis from necrosis in the ileum — AXR AP (above left) shows multiple dilated loops of small bowel and a decomopressed colon. Coronal CT with contrast of the abdomen (above right) shows normal caliber and normal enhancement of the proximal jejunum loops in the left upper quadrant. The distal ileum loops in the right lower quadrant are dilated and do not enhance. There is pneumatosis intestinalis in the walls of the most lateral loop of ileum. Axial CT (below) again shows the pneumatosis in the walls of the most lateral loop of ileum on the right and again shows the difference in bowel wall enhancement between the normal jejunum on the left and the abnormal ileum on the right.

US of Meckel diverticulum — Transverse US of the abdomen (below) shows a non-peristalsing cystic lesion in the center of the image superiorly. Transverse US (above) shows a dilated loop of small bowel with an air-fluid level within it.

Surgery Cases of Meckel Diverticulum

Surgical image of Meckel diverticulum — Surgical image shows dilatation of almost the entire small bowel except for the decompressed terminal ileum in the left lower corner of the photograph. At this transition point, a diverticulum is noted on the anti-mesenteric border of the ileum.

Surgical image of Meckel's diverticulum — Surgical image shows shows multiple dilated loops of small bowel in the background with a sharp transition point seen in the center of the image in the terminal ileum where on its anti-mesenteric border a diverticulum is seen with an omphalomesenteric duct remnant coming off it. This remnant had been attached to the under surface of the umbilicus, serving as a fulcrum for a small bowel volvulus, resulting in a small bowel obstruction.

Surgical image of Meckel diverticulum causing closed loop bowel obstruction — Surgical image shows a closed loop small bowel obstruction caused by a small band of tissue (between the forceps) extending from small bowel to a purple in color Meckel diverticulum (center of image) arising from the antimesenteric border of the small bowel.

Surgical image of Meckel diverticulum causing ileocolic intussusception — Surgical image (above) shows an ileocolic intussusception which upon reduction is seen to be caused by a Meckel diverticulum (below in center of image with forceps pointing to it) on the antimesenteric border of the small bowel.

Surgical image of Meckel diverticulum causing closed loop small bowel obstruction — Surgical image shows a dark and necrotic appearing distal ileum and a dark and necrotic appearing Meckel diverticum on the antimesenteric border of the bowel with a prominent vitelline artery (upper right corner of image) and volvulus of the adjacent intestine around it.

Surgical image of Meckel diverticulum causing closed loop small bowel obstruction — Surgical image shows a dark and necrotic appearing distal ileum (left side of image) with a dark and necrotic Meckel diverticulum along the antimesenteric border of the bowel (upper image) causing an internal hernia and a closed loop small bowel obstruction with the necrotic distal ileum herniating through the band of the vitelline duct.

Gross Pathology Cases of Meckel Diverticulum

Gross pathology image of Meckel diverticulum — Gross pathological image shows a resected loop of necrotic distal ileum. The necrotic Meckel diverticulum is noted in the upper center of the image, arising from the antimesenteric border of the bowel.