Imaging of Bariatric Surgery

CT and upper GI radiography have complementary roles

Laparoscopic adjustable gastric banding (LAGB) procedure (a.k.a. "lap band")

• Less effective for sustained weight loss

• Complications: Less common and less varied

• May be too tight or too loose

• Band may erode into stomach or esophagus

Sleeve gastrectomy (gastric sleeve)

• 75% of stomach is removed by dividing stomach along its long axis

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    Complications: Less or comparable to LAGB, less than Roux-en-Y gastric bypass (RYGB)

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    Leak: Early complication seen in < 1%

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    Stricture in mid stomach (transient or persistent)

RYGB

• Gastrointestinal complications occur in ~ 10%

• Anastomotic stricture

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    Dilatation of gastric pouch, spherical shape, air-fluid-contrast material levels, delayed emptying

• Anastomotic leaks

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    Most commonly at gastrojejunal anastomosis

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    CT may demonstrate major and minor leaks; fluid collections not evident on upper GI series

• Marginal ulcers; rate of 0.5-1.4% after RYGB

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    Usually result of ischemia

• Small bowel obstruction

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    Most common etiology: Internal hernias (IH) and adhesions

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    IH: CT appearance depends on location

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    Clustering of small bowel loops; congestion, crowding, twisting of mesenteric vessels

• Obstruction of excluded stomach and biliopancreatic limb

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    Cannot be diagnosed with upper GI series; CT is key

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    May progress to perforation (often fatal)

Imaging techniques and findings used to evaluate possible complications of surgical procedures meant to induce weight loss

Morphology

• Laparoscopic adjustable gastric banding (LAGB) procedure

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    Silicone band with inflatable cuff is looped around fundus, 2-3 cm below gastroesophageal (GE) junction

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    Opening (stoma) is adjustable by accessing subcutaneous port connected to inflatable cuff

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      Fluid is injected into or removed from port to inflate or deflate cuff

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    Complications: Less common and less varied than in laparoscopic R oux-en- Y g astric b ypass (RYGB) procedure

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    May be too tight (→ nausea, dehydration, excessive weight loss) or too loose (→ insufficient restriction of food intake)

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    Twisting or displacement of band  (4-13% of patients)

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      Should lie at "phi" angle (between vertical line and horizontal axis of band) between 30-60°

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      May slip down and twist, partially obstructing gastric lumen through band

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      Signs of slip: Phi angle > 60°

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        Distended stomach above band with slow emptying (air-fluid levels)

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        O sign: On frontal image, gastric band is en face seen as O rather than seen in profile

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    May erode into stomach (1-14% of patients)

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      Partial erosion: May have nonspecific symptoms

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        Oral contrast coats intragastric band; may not extravasate beyond stomach

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      Complete erosion: May see intraperitoneal spill of contrast medium (CT or upper GI)

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    Leak from stomach may occur even without erosion of band into stomach (early complication)

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    May be less effective for sustained weight loss than other procedures

• Sleeve gastrectomy (gastric sleeve)

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    75% of stomach is removed by dividing stomach along its long axis

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      Removes greater curvature portion of fundus, body, and proximal antrum

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      Remaining stomach only holds volume of ~ 100 mL

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    Complications: Less or comparable to LAGB, less than RYGB

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      Leak: Early complication seen in < 1%

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        Usually along proximal end of staple line

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        Extends laterally from greater curvature

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      Stricture: Early or late complication

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        Focal narrowing in mid gastric pouch, at end of staple line

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        May be transient or require stent or revision

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      GE reflux (in 20% of patients)

• Laparoscopic RYGB

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    Surgeon divides stomach into small (~ 30-mL) gastric pouch (parts of cardia and fundus) and much larger excluded stomach

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    Excluded stomach empties into duodenum as usual, now referred to as biliopancreatic limb

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    Pouch is anastomosed to roux limb of jejunum (alimentary limb) that is 75-150 cm long

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      Roux limb is usually placed in antegastric and antecolic location

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    Roux (alimentary) and biliopancreatic limbs are joined side to side [jejunojejunal (J-J) anastomosis]

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    Normal postoperative upper GI study

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      Usually performed within 48 hours of surgery to exclude leak or obstruction

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      Esophagus and pouch should empty rapidly into roux limb

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      Blind end of roux limb should not be mistaken for leak or ulcer

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      Enteric contrast usually opacifies intestine to and beyond J-J anastomosis

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        Helps to exclude stricture at or near J-J anastomosis

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    Complications: More varied and common than with other bariatric procedures

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      Spasm or stricture at pouch-enteric anastomosis

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        Early (spasm) or late (stricture) complication

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        Recognized by dilated pouch with air-fluid level and slow emptying

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        Fairly common but may resolve or respond to balloon dilation

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    Leak: Usually at pouch-enteric anastomosis (up to 5% of cases)

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      Early (within 10 days) complication

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      Detected with upper GI or CT (complementary) by extravasation of water-soluble contrast medium

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      May be contained; look for opacification of surgical drain lumen

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      May extend into larger spaces, usually left subphrenic and around spleen

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    Marginal ulcer

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      Reported in 3-10% (more common after revision of prior gastric surgery)

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      May result from reflux of acid up roux limb or ischemic injury

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      Usually appears as fixed collection of barium with adjacent fold thickening

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      Near pouch-enteric anastomosis

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    Gastrogastric fistula

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      Opening of staple line meant to divide gastric pouch from excluded stomach

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      Evident by orally administered contrast material entering excluded stomach

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      May account for failure to lose expected weight, but this is relatively rare complication

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    Small bowel obstruction (affects 5-10% of RYGB patients)

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      Any site of obstruction may be due to adhesions or internal hernia (IH)

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      Think "ABC"

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      A = alimentary (roux) limb is dilated

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        Often down to near J-J anastomosis

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      B = biliopancreatic limb (excluded stomach, duodenum, and proximal jejunum)

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        This is closed loop obstruction and will not be detected by upper GI series (CT is essential)

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        Risk of perforation of stomach or duodenum; usually constitutes surgical emergency

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      C = common channel of bowel beyond J-J anastomosis

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    IHs are as common as adhesive obstructions in some reports

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      CT is more sensitive and specific than fluoroscopic barium studies for diagnosis of IH

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      CT signs of IH

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        Cluster of small bowel loops in abnormal location

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          Through defect in small bowel or transverse colon mesentery

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          Or between mesentery of roux limb and transverse colon (Peterson hernia)

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        Twisted, displaced, ± dilated mesenteric vessels

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        Displacement of J-J anastomotic staple line (from expected left mid abdomen to right side of abdomen usually)