SBO vs Ileus/ partial SBO KUB

Heidi Ramos, PGY-2

Oakwood Hospital Radiology

Normal

• Normal Gas in Bowel – Always in stomach

– Two or three loops small bowel (<2.5cm)

– Almost always in rectum/ sigmoid (<6cm) (c<9cm)

• Normal Air Fluid Levels – Always in stomach

– Two or three in small bowel

– Never in colon

Small Bowel Obstruction

• X-ray findings:

– Bowel proximal to point of obstruction dilates – Swallowed air and continuous secreted fluid/ mucus

• Dilated sb >2.5 to 3 cm

• Air-fluid levels (think step ladder from left to right )

• Vomiting will release some proximal dilatation

– Bowel distal to point of obstruction collapses – Empties over time until collapse

• Absence/ paucity of gas in distal colon

Small Bowel Obstruction

• CT findings:

– Proximal

• Dilated, air/fluid filled loops

– Distal

• Collapsed bowel

– “Small Bowel Feces Sign”

• Air mixes with stagnant food bolus

Small Bowel Obstruction vs Ileus/ partial Small Bowel Obstruction

SBO Ileus

Etiology Prior surgery (weeks to yrs) Recent (hrs) post op

Pain Colicky Not a prominent feature

Abdominal distension Frequently prominent +/-

Bowel sounds Usually increased Usually absent

Small bowel dilatation Present Present

Large bowel dilatation Absent Present

Ileus/ partial SBO

• Localized ileus

– Sentinel loop (s)

• One/two persistently dilated loops

• Gas in sigmoid/ rectum

• Generalized adynamic ileus

– Persistently dilated small and large bowel loops

– Post op inpatient (not an ER/ outpatient)

• Small bowel obstruction

– SB 5cm

– No distal gas

– Evidence of prior sx (sutures)

Small Bowel Obstruction

Paralytic/ Diffuse Ileus

• Post op Ileus – Evidence of surgical wound

– Air in distal colon

– Evidence of recent surgery

Small Bowel Ileus

• Focal Ileus

• Sentinel loop

– Patient with known acute pancreatitis

Obstruction (partial)

• Large Bowel Obstruction – Colon dilated to distal

descending

– Soft tissue density likely colon mass causing partial obstruction

– Not complete obstruction (air still in rectum)

Large Bowel Obstruction

• Sigmoid volvulus LBO

– “Coffee bean”

– Fixed point in left iliac fossa

– Bird’s Beak on BE

Large Bowel Obstruction

• Cecal volvulus LBO

– Massively dilated cecum

• Displaces small bowel

• SB now in RLQ (valvulae conniventes)

Bowel Inflammation

• Mucosal edema

– Distance between loops of bowel increased

– Haustral folds are very thick

• “thumbprinting”

Ulcerative Colitis vs. C. diff Pseudomembranous Colitis

• Toxic Megacolon – Dilated colon + Mucosal

Edema + Mucosal islands

Obstruction

• SBO

– SB dilated:

• Yes

– LB dilated:

• No

– Rectal air:

• No

– Other clues:

• Evidence sx

Gallstone Ileus

• SBO

– SB dilated:

• Yes

– LB dilated:

• No

– Rectal air:

• No

– Other clues:

• Round calcific density in RLQ/ TI

Rigler’s triad: Biliary gas SBO Gallstone

Obstruction

• SBO – SB dilated:

• Yes

– LB dilated: • No

– Rectal air: • No

– Other clues: • Air-fluid levels

– Too many/ stepladder

Small Bowel Obstruction

• Spot the transition point.

Focal Ileus

• Ileus – SB dilated:

• Yes, focal loop

– LB dilated: • No

– Rectal air: • Yes

– Other clues: • RLQ tenderness

– Acute appendicitis

Paralytic ileus

• SBO

– SB dilated:

• Yes

– LB dilated:

• Yes

– Rectal air:

• Yes

– Other clues:

• Inpatient / Recent Postop

F/u studies recovery time: Small intestine: 0-24h Stomach: 24-48h Colon: 48-72h

Large Bowel Obstruction

• Sigmoid volvulus: – Bird’s beak on BE

• Abrupt cut off

Large Bowel Obstruction

• LBO:

– Obstructing intraluminal mass

– “Apple Core” on plain film and BE

Obstructive Uropathy

• Uterine fibroid

– Degenerating (ca)

– Ureteral stent demonstrates not calcified bladder wall

• Tricked you: – This one’s GU

not GI!

Small Bowel Obstruction

• Spot the transition point.

Gastric Volvulus

• Last thing we think to volvuse

– Yes, if we use it in Radiology then it’s a word.

• Organoaxial makes a C shape.

• Mesoaxial twist to an 8 shape.

Gastric volvulus

• Presentation:

– Triad of Borchardt

• Severe sudden epigastric pain

• Intractable retching without vomiting

• Inability to pass NG tube

Gastric Volvulus

• Herniation of bowel into chest cavity.

• Note: two gastric air bubbles

• Need f/u Upper GI fluoroscopy study vs. CT ab/pelv WITH contrast to exclude other differentials such large abscess or esophageal diverticulum.