Many Faces of Bowel Obstruction

Prof. Raju SharmaAll India Institute of Medical Sciences, New

Delhi

Bowel Obstruction Wide variety of causes Non-specific clinical manifestations: pain, vomiting,

distension, decreased passage of stool & flatus Pain out of proportion to exam. findings s/o strangulation Imaging plays a vital role Time is critical Reliance on imaging has steadily increased Qs: Sx or not? Expectations are very high!

IMAGING MODALITIES

Plain radiograph (supine/erect) Ultrasonography- children, pregnant women Computed Tomography- modality of choice CT Enterography in low grade obstruction Magnetic Resonance Imaging – seldom used

Computed Tomography

Modality of choice Global perspective of entire abdomen Uninhibited by bowel gas & fat Transition point, cause, vascular compromise MDCT: thin collimation, MPRs Oral contrast: not useful in emergent situation I.V contrast mandatory unless CI CT Angiography: bowel ischemia Radiation concern: ASIR, low dose protocols

Bowel Obstruction

Accounts for 20% of acute abdominal surgical condition Small bowel obstruction 4 to 5x more common than large Common causes: adhesions, hernia, volvulus,

inflammatory strictures, neoplasms, intussusception, ischemic

Intraluminal/ Intramural/ Extrinsic Acute/Subacute/Chronic Simple/Strangulated Complete/Incomplete Open/Closed loop

Plain Radiographs

Supine, erect, chest radiographs Utility of erect radiograph? If severely ill- lateral decubitus abdominal radiograph Moderate sensitivity 40-80% Dilated loops > 3cm Air fluid levels: >2.5 cm, at disparate levels Transition point is important D/D: Paralytic ileus

Plain Radiographs

Mechanical Obstruction

Paralytic IleusPseudo-

obstruction

Small BowelProximal/

DistalLarge Bowel Acute/Subacute

Partial/CompleteSimple/

StrangulatedOpen/Closed loop

Ischemia/ Perforation

Etiology

CT

Causes of Small Bowel Obstruction

External hernias Adhesions Malrotation, bands Internal hernias Peritoneal Carcinomatosis Gall stone ileus Parasites Foreign body

Ulcero-constrictive lesions Intussusception Tumors

Carcinoma Carcinoid

Radiation Ischemia

Extrinsic

Intra-luminal

Intrinsic

Small Bowel Obstruction Large Bowel Obstruction

Large Bowel Obstruction

• Cecum has the widest diameter – develops the maximum tension in the wall

• Risk of perforation ↑ when diameter > 9 cm

Pneumoperitoneum

• CT has sensitivity of 81-94% & specificity of 96% for high grade obstruction

• Dilated bowel with transition point

• Small bowel faeces sign close to transition point

• Evaluate for hernia, volvulus, ischemia

Closed Loop Obstruction

2 points along the course of bowel are obstructed at single location

More than one transition zone Affected loops are markedly dilated

(>4cm) with fluid Fusiform tapering at point of twist Stretched mesenteric vessels

converging to a point Vascular supply may get

compromised: prompt surgery

MRI

Signs of Vascular Compromise

Clinical signs like fever, tachycardia, acidosis are not reliable

Meta-analysis found CT sensitivity of 83% and specificity 92%

Bowel wall edema or hemorrhage Altered bowel wall enhancement: ↑ enhancement then ↓ Mesenteric fluid & stranding Vascular engorgement Pneumatosis, free intraperitoneal air, portal venous gas Certain causes have higher likelihood of vascular

compromise: closed loop, volvulus, hernia, obstructing mass

Bowel Ischemia

58 yr male with acute pain abdomen

Mesenteric Venous Ischemia

Usually a diagnosis of exclusion, kinking or tethering of loops

Form in 90% abdominal surgeries but only 5% complicated by SBO

Highest incidence after colo-rectal surgery 1% of patients develop obstruction in immediate post-op

period -90% of are due to adhesions Signs for predicting need for surgery:

Free intra-peritoneal fluid Mesenteric fat stranding High grade obstruction Absent small bowel feces sign

Adhesive Obstruction

Adhesive Obstruction

Ileo-Cecal Tuberculosis

Inflammatory Stricture

Duodenal Tuberculosis

• 2% of GI TB• 3rd part most common• Ulcerative type or hyperplastic• Healing with fibrosis may lead to

duodenal obstruction

Crohn’s Disease

Chronic Fibro-stenotic Disease

Hernia Causing Obstruction Internal/ External Inguinal (80%)/ Femoral (5%)/ Obturator/ Ventral/

Spigelian Hernial sites should be included on plain radiographs Inferior epigastric artery is landmark to differentiate

indirect/ direct IH Femoral hernia is seen anteromedial to femoral vein, more

common in women, more prone to strangulation Obturator hernia: more common in elderly women,

between the pectineus and obturator externus

Obstructed Right Inguinal Hernia

80 yr lady: Obturator hernia

Intussusception

70 yr old male patient with vomiting & abdominal distension

Small Bowel Obstruction due to Intussusception Caused by GIST

Intussusception Causing Obstruction & Ischemic Bowel

Adenocarcinoma

• Duodenal/ Jejunal location• Annular/ Polypoidal/ Asymm. wall thickening• Obstruction is common

25 year male with recurrent pain abdomen

Midgut Volvulus

Sclerosing Encapsulating Peritonitis

Ascariasis

Gall Stone Ileus: Riggler Triad

Post-Gad

Mesenteric Lymphangioma causing SBO due to Volvulus

Mesenteric lymphangioma causing volvulus

Causes of Large Bowel Obstruction

Sigmoid volvulus Cecal Volvulus Tumors: 55% Diverticulitis: 12%

Intussusception Tuberculosis Ischemic strictures Stercoral colitis/ulcer

10%

Large Bowel Obstruction

Volvulus

Caecal Sigmoid

70 year old man with constipation and vomiting

Adenocarcinoma Sigmoid Colon

Diverticulitis

• Bowel wall thickening, peri-colonic inflammation, diverticulosis

• Inflamed diverticuli may be hyperdense on CT

• Sigmoid colon: most often involved

• Hinchey’s classification• Perforated malignancy may

mimic perforated diverticulitis

Sigmoid Perforation

Conclusion Confirm bowel obstruction Small bowel or large bowel Likely etiology Is strangulation / perforation present Increasing shift towards conservative management in

uncomplicated SBO If CT features point towards vascular compromise –

urgent surgery In conjunction with clinical signs guide management Early diagnosis is critical

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