7 Small Bowel
Small Bowel Obstruction
Overview
Most commonly due to adhesions (70%) or incarceration of bowel within a hernia
Other etiologies include small bowel tumor, volvulus, intussusception, and strictures
Obstruction may be partial or complete
Signs and Symptoms
Colicky periumbilical pain that may be relieved with bilious emesis
Abdominal distention, tenderness, and occasional high-pitched bowel sounds
Severe tenderness at the site of incarcerated hernia with possible overlying skin changes
Patients with complete bowel obstruction will have absence of flatus or bowel movement, patients with partial bowel obstruction will present with abdominal distention with decreased passage of flatus
Diagnosis
Abdominal x-rays will show multiple air–fluid levels with distended loops of small bowel
CT scan with IV contrast may be obtained to assess for a transition point
Treatment/Management
NPO for bowel rest, IV fluids, NG decompression; correct any underlying electrolyte abnormalities
Attempt to perform bedside reduction of any incarcerated hernia
Patients with diffuse peritonitis or complete bowel obstruction should warrant surgical exploration
Patients with partial bowel obstruction who do not improve with conservative management will require exploration and adhesiolysis with possible bowel resection
Patients without signs of incarcerated hernia and who have no previous abdominal surgeries should also be surgically explored
RADIOLOGY
Plain film findings (Fig. 7.1)
• Dilated small bowel loops with air fluid levels
CT findings (Fig. 7.1)
• Fluid-filled, dilated small bowel loops
• Closed-loop obstruction manifests as a C-shaped configuration of dilated bowel loops with mesenteric vessels converging toward the point of torsion
• Strangulation is characterized by bowel wall thickening, little or no contrast enhancement of the bowel wall, engorgement of mesenteric vasculature, and mesenteric edema
• Small bowel loops are dilated proximal to the obstruction, and decompressed distal to the obstruction
FIGURE 7.1 A–H
FIGURE 7.1 A
FIGURE 7.1 B
FIGURE 7.1 C
FIGURE 7.1 D
FIGURE 7.1 E
FIGURE 7.1 F
FIGURE 7.1 G
FIGURE 7.1 H
Ileus
Overview
Lack of peristalsis or bowel function without a structural obstruction
Most commonly secondary to abdominal surgery
Other causes are electrolyte abnormalities, intra-abdominal abscess, systemic infection, hypothyroidism, or other medications such as anticholinergics
Signs and Symptoms
Abdominal distension without flatus or bowel movements
Bilious or feculent emesis
Generalized abdominal distension associated with discomfort without diffuse peritonitis
Diagnosis
Same as small bowel obstruction
Treatment/Management
Same as small bowel obstruction
May consider initiation of total parenteral nutrition (TPN) for patients who have prolonged ileus with underlying malnutrition
RADIOLOGY
Plain film findings (Fig. 7.2)
• Distended small bowel loops with air fluid levels
• May be indistinguishable from SBO
• Distal air in the rectum may help differentiate ileus from SBO
FIGURE 7.2 A,B
FIGURE 7.2 A
FIGURE 7.2 B
Small Bowel Enterocutaneous Fistula
Overview
A fistula is defined as an abnormal connection between two epithelized organs
Small bowel enterocutaneous fistula is usually caused by unrecognized iatrogenic injury to the bowel, anastomotic leak, inflammatory bowel disease, or malignancy
Signs and Symptoms
Fever, leukocytosis, ileus, abdominal tenderness followed by drainage of enteric contents via the wound or skin
Factors that prevent fistula closure—(FRIEND)
• Foreign body
• Radiation
• Inflammation/infection
• Epithelialization of the tract
• Neoplasm
• Distal obstruction
Diagnosis
CT scan with enteric contrast will help identify any undrained abscess. It might help identify the origin of the fistula
Fistulogram or sinogram consists of contrast injection into the cutaneous end of the fistula to evaluate the tract and origin of the fistula
Treatment/Management
Usually treatment consists of making patient NPO, parenteral nutrition, possible octreotide to decrease the output from the fistula for easier wound management
Definitive treatment is surgery if spontaneous closure does not occur within 4 to 5 weeks’ time
RADIOLOGY
Plain film findings
• Contrast injection through the fistula can diagnose the tract between the skin and the small bowel lumen
CT findings (Fig. 7.3)
• CT can be performed in addition to a fistulogram to distinguish fluid collections from bowel loops, and also to guide percutaneous drainage of any abscesses
• A fistula between the small bowel and skin can sometimes be directly seen on CT
• Fat stranding and abscess formation may be seen around the fistula tract
FIGURE 7.3 A–C
A. Stomach
B. Descending colon
C. Portal vein
D. Liver
E. Mesenteric vessels
F. Psoas muscle
G. IVC
H. Common iliac artery
I. Small bowel loops
J. Vertebra
K. Kidney
FIGURE 7.3 A
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