Common Surgical Problems of the Stomach and Small Intestine Tara Wofford

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Common Surgical Problems of the Stomach and Small
IntestineTara Wofford
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Links to Helpful Online Tutorials

• An Approach to Abdominal Plain Films
  http//www.learningradiology.com/lectures/gilectur
  es/plainabdomenflashpage.htm
• Abnormal Bowel Gas Patterns http//www.learningra
  diology.com/notes/ginotes/pictorialbowelgas.htm
• Recognizing SBO, LBO, and Paralytic Ileus
  http//www.learningradiology.com/medstudents/recog
  nizingseries/recogobstructflashpage.htm

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Objectives

• To become familiar with abdominal anatomy on a
  radiograph and CT image.
• To be able to identify the radiologic signs of
  pathology of the stomach and small intestine.
• To be able to evaluate the presence of common
  surgical problems in these organs.

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Anatomy of the Stomach

• The stomach has four parts (cardia, fundus, body,
  and pylorus) and two crurvatures.
• The gastric mucosa forms longitudinal folds
  called rugae.
• The stomach is bordered anteriorly by the
  diaphram, left lobe of the liver and ant. abd
  wall. Posteriorly it is bordered by the omental
  bursa and pancreas

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Barium X-Rays

• A barium swallow, also called an upper GI series,
  is an examination of the esophagus and stomach
  using barium to coat the walls of the upper
  digestive tract so that it may be examined under
  x-ray.
• Barium swallows are used to identify any
  abnormalities such as tumors, ulcers, hernias,
  pouches, strictures, and swallowing difficulties.

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High-Resolution CT scan of stomach

• Optimal luminal distension with barium, water, or
  gas is key for evaluating the gastric wall.
• Water-soluble oral contrast is used when
  perforation is suspected.

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Common Surgical Pathology of the Stomach

• Peptic Ulcers
• Tumors - Adenocarcinoma, Lymphoma
• Hiatal Hernia

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Peptic Ulcers

• Causes H. Pylori infection, hyperparathyroidism,
  steroid tx, uremia, stress, burns (curling),
  cerebral disease (cushing).
• Duodenal ulcers are also present in 5-42 of
  cases. The ratio of DUGU is 31.
• Most common location of benign ulcers is the
  lesser curvature area of body and antrum.
• Almost all lesions lt 1cm are benign.

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Radiologic Findings

• Ulcer crater barium collection on dependent
  surface penetrates beyond anticipated wall.
• Hamptons line 1mm thin straight line at neck of
  ulcer, represents undermined mucosa.
• Ulcer collar smooth, thick, lucent band at neck
  of ulcer, represents thicked wall.
• Ulcer mound tissue mass surrounding ulcer.

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Adenocarcinoma of the Stomach

• 24,000 new cases diagnosed each year.
• MF ratio is 21
• Risk factors H. Pylori infection, adenomatous
  polyps, chronic atrophic gastritis, pernicious
  anemia and partial gastrectomy.

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Radiologic Findings

• Conventional CT is not sensitive in early phases
  compared to HRCT.
• Early cases may appear as focal wall thickening
  with mucosal enhancement during the early
  arteriovenous contrast phase.
• Advanced cases appear as thickened, abnormally
  enhancing gastric wall, in localized or
  circumferential pattern,or as a polypoid mass.
  Ulceration may be apparent as well.

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Gastric Lymphoma

• The stomach is the most common site for GI
  lymphoma and is more commonly part of a
  generalized disease.
• 80 of cases are Non-Hodgkins.
• Perforation is a major complication occuring in
  9-47 of patients

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Radiologic Findings which differentiate Lymphoma
from Adenoarcinoma

• Gastric wall thickness is much greater in
  lymphoma, with a mean of 4cm.
• Adenopathy is more pronounced and lymph nodes
  larger.
• Mural thickening is more homogenous.

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Hiatal Hernia

• Caused by a weakness or tear in the
  phrenoesophageal membrane.
• There are two types
• Sliding hernia, in which the gastroesophageal
  junction is displaced above the diaphram
  (includes 99 of cases).
• Paraesophageal hernia, in which there is stomach
  herniating into chest but the GE junction is not
  effected.

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Radiologic Findings

• Extension of multiple gastric folds above the
  diaphram.
• Bulbous area of distal esophagus containing
  contrast.
• Schatzkis Ring - a filling defect that marks
  the position of esophagogastric junction and
  defines the presence of sliding hernia

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Anatomy of Small Intestine

• Includes duodenum, jejunum, and ileum.
• The mucosal wall is characterized by circular
  folds (plicae circulares).
• The duodenum has a c-shaped course around the
  pancreas and is partially retroperitoneal.
• Most of the jejunum lies in the LUQ and ileum
  mostly in RLQ.

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Assessing the Abdominal Radiograph

• Gas pattern stomach- always a small amount,
  small int. will have 2-3 gas filled loops (lt
  2.5cm in diameter), and rectum- usually has a
  small amount.
• Air-fluid levels stomach- always present, small
  int. may have 2-3 levels, usually never in
  rectum.
• Also look for soft-tissue masses and
  calcifications.

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Small vs Large Intestine

• Small intestine located centrally, has circular
  folds that extend across the lumen, and has a
  maximum diameter of 2-2.5 cm.
• Large Intestine located peripherally and has
  haustral markings that do not cross the lumen

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Abdominal Anatomy on CT

• Identify Stomach, small and large intestine,
  liver, spleen, and descending aorta.

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Vascular Supply to the Small Intestine

• The duodenum is supplied by both the celiac trunk
  (proximal to bile duct) and the SMA (distal to
  the entry of the bile duct).
• The jejunum and ileum are supplied by the SMA via
  15-18 branches which form arterial arcades that
  give rise to the vasa recta.

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Common Surgical Problems of the Small Intestine

• Small Bowel Obstruction
• Crohns Disease
• Acute Mesenteric Ischemia
• Intussusception
• Gall-Stone Ileus
• Tumors - Adenocarcinoma, Lymphoma
• Pneumoperitoneum
• Superior Mesenteric Artery Syndrome

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Small Bowel Obstruction

• Pathophysiology bowel proximal to obstruction
  dilates with swallowed air and secretions and
  there is hyperparastalsis. Ischemia can occur
  from vascular compromise of effected loops.
• Most common etiologies adhesions from prior
  surgery, hernia, intussesception, gallstone
  ileus, volvulus, and tumors.
• Clinical symptoms abdominal pain, distention,
  N/V/D, hyperactive bowel sounds.
• Surgery is indicated with s/s of ischemia,
  peritonitis, or when refractory to conservative
  tx.

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Radiographic Findings

• Proximal loops dilated gt2.5-3cm
• Multiple air-fluid levels
• Absence or small amount of gas in colon.

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Associated CT Findings

• Dilated, fluid filled loops of small bowel
  proximal to obstruction and collapse of distal
  bowel.
• Signs of ischemia include thickening of bowel
  wall, stranding of adjacent to small bowel
  mesesentary or pneumatosis intestinalis.

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Crohns Disease

• Characterized by non-caseating granulomas with
  transmural inflammation, which can effect any
  part of the GI tract.
• Clinically patients frequently have recurrent
  diarrhea, occult blood loss, anemia, abd pain,
  and low-grade fever.
• Small intestine is involved 80 of the time,
  particularly the terminal ileum.

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Radiographic findings

• Skip lesions - separated by normal areas of
  bowel.
• Squaring of folds, indicating lymphedema.
• Apthous ulcers - small nodular filling defects
  which appear as a mound of edema with central
  ulceration.
• String-sign - marked narrowing of terminal ileum
  usually from edema, spasm and fibrosis. Proximal
  dilatation is common.

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Associated CT Findings

• Bowel wall thickening with skip lesions.
• Proliferation of mesenteric fat and
  lymphadenopathy.
• Inflammatory stranding.

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Ddx in Crohns Dz

• Ulcerative Colitis - the entire colon is
  frequently involved with the terminal ileum
  spared.
• Diverticulitis - diverticula are present, mucosa
  is intact, and terminial ileum less involved.
• TB - cecum is more effected than terminal ilem.
• Lymphoma - tumor masses are visualized.

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Acute Mesenteric Ischemia

• Defined as interruption of blood supply to small
  or large intestine. (Associated with 70-90
  mortality overall)
• Causes embolism (SMA most common), arterial
  thrombus, venous thrombus, and diffuse mesenteric
  vasoconstriction due to low cardiac output.
• Common clinical symptoms severe abd pain out of
  proportion to exam, usually poorly localized,
  N/V/D, and GI bleeding.
• Surgical options thrombectomy/ embolectomy,
  arterial bypass, and resection of necrotic bowel.

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Radiographic Findings

• X-ray is abnormal in 20-60.
• Thumbprinting - (nonspecific) indicates wall
  edema and hemhorrage in the this setting.
• Pneumatosis, portal vein gas, pneumoperitoneum -
  indicates infarcted bowel.

Pneumoperitoneum
Pneumatosis
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Possible CT Findings

• Bowel wall thickening indicating edema or
  hemorrhage.
• Lack of enhancement in wall indicated infarction.
• Pneumatosis, portal vein gas, pneumoperitoneum.
• Intraluminal thrombus in involved vessel.

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Intussusception

• Most common cause of bowel obstruction in kids
  but much less common in adults.
• In adults there is usually an associated cause
  such as a mass, polyp, or adhesions.
• There are three types enteroenteric, ileocolic,
  and colocolic.
• CT characteristics include a target-shaped mass
  enveloped with a thick outter rim of soft tissue
  representing edematous bowel wall.

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Gallstone Ileus

• Occurs when a gallstone erodes into GI tract and
  causes obstruction.
• Dilated loops of small intestine are seen, with
  air in the biliary tree and gallbladder.
• The stone is usually located in the terminal
  ileum but can be anywhere along small intestine.

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Adenocarcinoma of the Small Intestine

• Most often this lesion arises in the proximal
  jejunum.
• Risk factors hx of Crohns, sprue,
  Peutz-Jeghers, and duodenal/jejunal bypass surg,
  among others.
• Common types are infiltrative (bowel obstruction)
  and ulcerative (bleeding).
• On CT the tumor appears as eccentric focal mass
  or circumferential bowel wall thickening in a
  short segment.

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Lymphoma of the Small Intestine

• Occurs most often in the ileum where there is
  more lymph tissue.
• Risk factors immunocompromised or suppressed
  state, celiac sprue, and CLL.
• Small intestine is the second most common site in
  the GI tract for lymphoma.

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CT Findings

• The typical patterns are aneurysmal,
  constrictive, nodular, and ulcerative.
• There is frequently asymmetric wall thickening
  (gt2cm), aneurysmal dilatation, polyploidal mass,
  abdominal lymphadenopathy.
• Tissue density in the thickened bowel is
  relatively homogenous.

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Pneumoperitoneum

• Defined as free air in abdominal cavity.
• Causes
• disruption of a hollow viscus from trauma,
  iatrogenic perforation, or GI tract disease.
• Extension from chest.
• Via female GU tract.
• Through peritoneal surface via a procedure.
• Intraperitoneal source, such as abscess rupture
  or gas-forming microbes.

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Key Radiologic findings

• Riglers sign or double-wall sign, which
  appears as air on both sides of bowel wall
  (usually indicating gt 1000 ml of free air).
• RUQ is the best place to look for small air
  collections. These appear as lucency over liver.
• With a larger gas collection the patient may have
  abdominal distension and lack a gastric air-fluid
  level.

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Superior Mesenteric Artery Syndrome

• Compression of the third (transverse) portion of
  duodenum against the aorta by the SMA.
• This results in chronic or intermittent acute
  complete or partial obstruction.

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Quiz Time!!
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42 y.o. woman presents with abd pain, distension,
and nausea. What is the most likely problem?

• A. Mesenteric Ischemia
• B. Small Bowel Lymphoma
• C. Small Bowel Obstruction

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42 y.o. woman presents with abd pain, distension,
and nausea. What is the most likely problem?

• C. Small Bowel Obstruction

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65 y.o. man c/o rapid onset of diffuse abd pain
combined with vomiting, diarrhea, and blood in
the stool. What is the likely problem?

• A. Perforated Gastric Ulcer
• B. Acute Mesenteric Ischemia
• C. Small Bowel Obstruction.

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65 y.o. man c/o rapid onset of diffuse abd pain
combined with vomiting, diarrhea, and blood in
the stool. What is the likely problem?

• B. Acute Mesenteric Ischemia

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32 y.o. woman with recurrent moderate epigastric
pain, hematemesis, and anorexia. What is the
likely problem?

• A. Gastric Ulcer
• B. Gastric Adenocarcinoma
• C. Gastric Lymphoma

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32 y.o. woman with recurrent moderate epigastric
pain, hematemesis, and anorexia. What is the
likely problem?

• A. Gastric Ulcer

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42 y.o. man with recurrent crampy abd pain
combined with weight loss, diarrhea, and fever.
What is the likely cause?

• A. Small Bowel obstruction
• B. Acute Mesenteric Ischemia
• C. Crohns disease

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42 y.o. man with recurrent crampy abd pain
combined with weight loss, diarrhea, and fever.
What is the likely cause?

• C. Crohns disease

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References

• Haaga, Lanzieri, and Gilkeson. CT and MR Imaging
  of the Whole Body. 4th ed. Mosby 2003.
• Strang and Dogra. Body CT Secrets. Mosby Elsevier
  2007.
• Moore and Dalley. Clinically Oriented Anatomy.
  4th ed. Lippincott Williams and Wilkins1999.
• www.meddean.luc.edu/Lumen/Meded/Radio/curriculum/G
  I/GI_atlas_list1.htm
• rad.usuhs.mil/medpix/medpix_home.html
• www.learningradiology.com
• www.brighamrad.harvard.edu/education/online/tcd/tc
  d.html