What are the radiological signs and management of small bowel obstruction, Crohn's disease, pseudomembranous colitis, and pneumoperitoneum?

Radiological Signs aur Management: Small Bowel Obstruction, Crohn's Disease, Pseudomembranous Colitis, aur Pneumoperitoneum

Small Bowel Obstruction (SBO)

Radiological Signs

CT abdomen and pelvis with IV contrast sabse preferred initial imaging hai SBO ke liye, with >90% diagnostic accuracy for detecting obstruction, cause identify karne, aur complications evaluate karne ke liye. 1, 2

Key CT findings include:

• Dilated small bowel loops (>3 cm) with air-fluid levels upstream of transition point 3, 2
• Clear transition point from dilated to decompressed bowel 2
• "Small bowel feces sign" aur "beak sign" at transition point 2
• Multiplanar reformations significantly improve accuracy in locating transition points 2

Plain radiography findings (sensitivity 74-84%, specificity 50-72%): 3

• Dilated intestinal loops with air-fluid levels 3
• Relative or complete absence of gas in colon (obstruction vs ileus differentiate karne ke liye) 3
• Left lateral decubitus view essential hai bedridden patients mein pneumoperitoneum detect karne ke liye 3

Ultrasound alternative hai (sensitivity 91%, specificity 84%) jab CT available nahi ho 3, 2

Management Approach

Initial conservative management with nasogastric decompression aur IV fluids recommended hai partial obstruction ke liye. 2

Immediate surgery ke indications: 1

• Signs of strangulation, perforation, ya ischemia 1
• Free peritoneal perforation with pneumoperitoneum aur free fluid 1
• Hemodynamic instability with persistent obstruction 1
• Complete obstruction jo medical therapy se respond nahi karta 1

CT signs of ischemia requiring urgent intervention: 1, 2

• Abnormal bowel wall enhancement 1, 2
• Intramural hyperdensity 1, 2
• Bowel wall thickening 1
• Mesenteric edema 1
• Pneumatosis 1, 2

Surgical approach: 1

• Laparoscopic approach recommended hai hemodynamically stable patients mein if appropriate expertise exists 1
• Open surgical approach for hemodynamically unstable patients 1

Critical pitfall to avoid: Oral contrast administration in high-grade obstruction can delay diagnosis, increase patient discomfort, aur aspiration ka risk badha sakta hai. 1, 2

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Crohn's Disease

Radiological Signs

MRE (Magnetic Resonance Enterography) aur CTE (CT Enterography) preferred imaging modalities hain, with MRE generally preferred over CT to limit radiation exposure, especially in young patients. 4

Active inflammatory Crohn's disease ke imaging findings: 4

Wall thickening (measured in distended bowel loops): 4

• Mild: 3-5 mm 4
• Moderate: 5-9 mm 4
• Severe: ≥10 mm 4

Characteristic features: 4

• Asymmetric wall thickening aur hyperenhancement along mesenteric border 4
• Intramural edema (hyperintense signal on fat-saturated T2-weighted MRI) 4
• Ulcerations (small focal breaks in bowel wall - marker of severe inflammation) 4
• Pseudosacculations (broad-based outpouchings along anti-mesenteric border) 4
• Diminished motility 4

Stricture definition: Luminal narrowing in area of Crohn's disease WITH unequivocal upstream dilation. 4

Stricture classification by upstream dilation: 4

• Mild upstream dilation: 3-4 cm 4
• Moderate to severe upstream dilation: >4 cm 4

MRE vs Ultrasound comparison (METRIC trial): 4

• MRE sensitivity: 97% for small bowel disease 4
• US sensitivity: 92% for small bowel disease 4
• MRE had higher sensitivity (80% vs 70%) aur specificity (95% vs 81%) for small bowel disease presence and location 4
• US had superior sensitivity for colonic disease in newly diagnosed patients (67% vs 47%) 4

Pediatric considerations: 4

• US abdomen suitable alternative hai younger children mein jo otherwise sedation require karenge for MRE/CTE 4
• Plain radiography limited role hai, but useful for detecting perforation or obstruction in severely ill children 4

Management Approach

Crohn's-related SBO management: 1

Medical management for active inflammation causing obstruction: 1

• Corticosteroids for acute inflammation (ineffective for maintenance) 1
• Azathioprine 1.5-2.5 mg/kg/day ya mercaptopurine 0.75-1.5 mg/kg/day 1
• Infliximab may be considered for refractory cases 1

Conservative management ka prognosis: 5

• Agar initial obstruction episode reverse ho jaye with small-bowel tube aur IV ACTH, subsequent maintenance therapy resection eliminate ya postpone kar sakti hai 5
• 8 months useful cutoff criterion hai recurrence likelihood ke liye 5
• Agar recurrence 8 months ke andar hota hai, surgery ultimately required in 6 of 7 patients 5
• Patients jo first 8 months without obstruction weather karte hain, unka prognosis better hai 5

Surgical indications: 1

• Complete obstruction failing medical therapy 1
• Signs of ischemia, strangulation, or perforation 1
• Hemodynamic instability 1

Post-operative care: 1

• Nutritional support essential hai before and after surgery for diffuse small bowel disease 1
• Smoking cessation critical hai for maintaining remission 1
• Post-operative maintenance therapy with azathioprine/mercaptopurine should be considered to prevent recurrence 1

Critical pitfall: Failing to distinguish between inflammatory versus fibrotic strictures - inflammatory strictures may respond to medical therapy while fibrotic strictures require intervention. 1

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Pseudomembranous Colitis

Radiological Signs

Plain radiography findings: 6

• Polypoid mucosal thickening 6
• "Thumbprinting" (wide transverse bands associated with haustral fold thickening) 6
• Gaseous distention of colon 6
• Toxic megacolon with distention aur occasionally pneumoperitoneum in severe cases involving perforation 6

Contrast enema findings (contraindicated in severe PMC due to perforation danger): 6

• Small nodular filling defects representing mucosal plaques in mild cases 6
• Larger plaques coalescing to form irregular bowel wall margin in extensive involvement 6
• Mural thickening aur wide haustral folds caused by intramural edema 6

CT findings (preferred imaging modality): 6

• Wall thickening 6
• Low-attenuation mural thickening corresponding to mucosal and submucosal edema 6
• "Accordion sign" (alternating areas of thickened haustra and contrast-filled lumen creating accordion-like appearance) 6
• "Target sign" or "double halo sign" 6
• Pericolonic stranding 6
• Ascites 6

Management Approach

CT imaging allows early diagnosis and treatment, preventing progression to more serious pathologic conditions. 6

Contrast enema contraindicated hai in patients with severe PMC due to danger of perforation. 6

Surgical intervention indicated hai if toxic megacolon with perforation develops (pneumoperitoneum on imaging). 6

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Pneumoperitoneum

Radiological Signs

Left lateral decubitus radiograph essential hai bedridden patients mein pneumoperitoneum detect karne ke liye, in addition to supine radiograph. 3

Plain radiography findings: 3

• Free air between abdominal wall and liver on left lateral decubitus view 3
• Upright radiograph bhi useful hai if patient can stand 4

CT findings (most sensitive): 7

• Small bowel perforation mein extraluminal air often small or absent hai in most cases (in contrast to gastroduodenal perforation) 7
• Direct signs: extraluminal air 7
• Indirect signs: peritoneal fluid, bowel wall thickening, mesenteric stranding 7

Management Approach

Free peritoneal perforation with radiological signs of pneumoperitoneum aur free fluid is indication for immediate surgery. 1

Left lateral decubitus radiograph should be performed in addition to supine radiograph to adequately evaluate for pneumoperitoneum and air-fluid levels in patients who cannot stand. 3

CT provides more comprehensive information about site and cause of perforation compared to plain radiography. 3, 7

Causes of small bowel perforation include: 7

• Crohn disease 7
• Ischemic or bacterial enteritis 7
• Diverticulitis 7
• Bowel obstruction 7
• Volvulus 7
• Intussusception 7
• Trauma 7
• Ingested foreign bodies 7