1. Ultrasound of the Gastrointestinal Tract
Wendy Blount, DVM ~ Brian Huber, DVM, ABVP
June
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2. Indications for GI Ultrasound
Anorexia, weight loss, dehydration
Vomiting and/or Diarrhea
Abdominal pain (acute abdomen)
Highly regenerative or iron deficiency anemia
Patient deterioration 3-5 days after GI surgery
Evaluate for perforation or peritonitis which might require prompt surgical intervention
Patient inappetance after GI surgery
Distinguish ileus from complication requiring surgery
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3. Patient Preparation Fast for 12 hours Place in dorsal recumbency
Lateral recumbency for:
Compromised or deep chested patients
Left lateral recumbency for the duodenum, ileum, pylorus, and ascending colon
Right lateral recumbency for the stomach fundus and descending colon
Standing/sternal may be necessary for patients with large abdominal masses, dependent stomach/colon
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4. Transition Adjustments
Depth – more superficial for duodenum in the dog
Frequency – MHz
Use linear transducer if possible
Gain and Contrast – usually no change from liver & spleen
May need to decrease gain for small dogs and cats
TGC – top levers to the right
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5. Landmarks for GI Tract
Stomach – slide from duodenum to pylorus to fundus
Find liver-stomach-spleen view in L cranial abdomen
Stomach caudal to the liver
Duodenum – ventral to the right kidney (medial or lateral)
Parallel to the right body wall
Ileum/Jejunum – in the mid-abdomen and other places
Cat ileum can be distinguished based on bright submucosa
“wagon wheel” appearance on transverse
Colon – appears as a thin walled white dome throwing an acoustic shadow
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6. Landmarks for GI Tract
Stomach – slide from duodenum to pylorus to fundus
Find liver-stomach-spleen view in L cranial abdomen
Stomach caudal to the liver
Duodenum – ventral to the right kidney
Parallel to the right body wall
Ileum/Jejunum – in the mid-abdomen and other places
Cat ileum can be distinguished based on bright submucosa
“wagon wheel” appearance on transverse
Colon – appears as a thin walled white dome throwing an acoustic shadow
Fundus
Pylorus
Body
Transverse
Ascending
Cecum
Ileum
Duodenum
Descending Colon
(Jejunum)
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7. Landmarks for GI Tract
Stomach – slide from duodenum to pylorus to fundus
Find liver-stomach-spleen view in L cranial abdomen
Stomach caudal to the liver
Duodenum – ventral to the right kidney
Parallel to the right body wall
Ileum/Jejunum – in the mid-abdomen and other places
Cat ileum can be distinguished based on bright submucosa
“wagon wheel” appearance on transverse
Colon – appears as a thin walled white dome throwing an acoustic shadow
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8. Landmarks for GI Tract
Stomach – slide from duodenum to pylorus to fundus
Find liver-stomach-spleen view in L cranial abdomen
Stomach caudal to the liver
Duodenum – ventral to the right kidney
Parallel to the right body wall
Ileum/Jejunum – in the mid-abdomen and other places
Cat ileum can be distinguished based on bright submucosa
“wagon wheel” appearance on transverse
Colon – appears as a thin walled white dome throwing an acoustic shadow
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9. Image Views - Gut Long Axis Views (5-6) Short Axis Views (5-6)
1.-3. Stomach – fundus, body (transverse) and pylorus
4. Duodenum - sagittal
5. Ileum/Jejunum
(6.) (Abnormal Colon)
Short Axis Views (5-6)
1.-3. Stomach – fundus, body (sagittal) and pylorus
4. Duodenum - transverse
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10. Gut Layers From lumen to peritoneal cavity:
Lumen – normally a white line or ingesta < 1cm
Mucosa – black
Submucosa/Lamina Propria – white
Muscularis – black
Serosa – white
SI mucosa should be >1.6x thicker than muscularis
If muscularis > mucosa, muscularis is thickened
Stomach mucosal thickness = muscularis
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11. Gut Layers From lumen to peritoneal cavity:
Lumen – normally a white line or ingesta < 1cm
Mucosa – black
Submucosa/Lamina Propria – white
Muscularis – black
Serosa – white
SI mucosa should be >1.6x thicker than muscularis
If muscularis > mucosa, muscularis is thickened
Stomach mucosal thickness = muscularis
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12. Gut Layers Memory Aid: “The Sun is Bright Submucosa is white
Serosa is white
S#!t is white 
And it’s Dark and Midnight.”
Mucosa is black
Muscularis is black
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13. Video Oncura Partners - Ultrasound of the GI Tract
Daniel Rodriguez Arroyo, DACVR
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14. Goals – GI Ultrasound Find and sample ascites in the acute abdomen
Is surgery indicated (fluid analysis chart) ?
More info in the ascites section (local or general)
Assess for perforation (more info in ascites section)
Assess for obstruction, foreign body or intussusception
Target lesions
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15. Goals – GI Ultrasound Find and sample ascites in the acute abdomen
Is surgery indicated (fluid analysis chart) ?
More info in the ascites section (local or general)
Assess for perforation (more info in ascites section)
Assess for obstruction, foreign body or intussusception
Target lesions
long axis intussusception
short axis intussusception
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16. Goals – GI Ultrasound Find and sample ascites in the acute abdomen
Is surgery indicated (fluid analysis chart) ?
More info in the ascites section (local or general)
Assess for perforation (more info in ascites section)
Assess for obstruction, foreign body or intussusception
Target lesions
Assess motility (count peristaltic waves for 3 minutes)
Normal stomach is 3-6 per minute
Normal intestine is 1-3 per minute
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17. Goals – GI Ultrasound pylorus & descending duodenum are thickest
Pay attention to localized pain as you scan
Redirect the probe to painful areas or abnormalities on palpation
Assess long and short axis of gut at the problem area
If you find a suspicious area, follow gut orad and aborad as far as is possible
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18. Goals – GI Ultrasound Find and sample ascites in the acute abdomen
Is surgery indicated (fluid analysis chart) ?
More info in the ascites section (local or general)
Assess for perforation (more info in ascites section)
Assess for obstruction, foreign body or intussusception
Target lesions
Assess motility (count peristaltic waves for 3 minutes)
Assess intestinal wall structure (layers)
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19. Tips – GI Ultrasound pylorus & descending duodenum are thickest
Pay attention to localized pain as you scan
Redirect the probe to painful areas or abnormalities on palpation
Assess long and short axis of gut at the problem area
If you find a suspicious area, follow gut orad and aborad as far as is possible
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20. Tips – GI Ultrasound pylorus & descending duodenum are thickest
Up to 5mm
stomach & SI – 3-5mm in dogs, 2-4mm in cats
Pay attention to localized pain as you scan
Redirect the probe to painful areas or abnormalities on palpation
Assess long and short axis of gut at the problem area
If you find a suspicious area, follow gut orad and aborad as far as is possible
Organ
Dogs
<20 kg
>20 kg
Cats
Stomach – body & fundus – rugal folds
3-5mm
3-4.5mm
Stomach – body & fundus – between rugae
3-4mm
1-3mm
Stomach – pylorus
4-5mm
2-4mm
Small intestine - duodenum
2-5mm
3-6mm mm
Small intestine – ileum mm
Small intestine – jejunum
Colon
2-3mm
1-2.5mm
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21. Tips – GI Ultrasound Evidence of obstruction
Jejunum lumen diameter > 1.5 cm
Especially when aborad(?) segments appear normal
May or may not be able to find the obstruction
Lumenal foreign body may show reflective interface or acoustic shadow
Linear foreign body may produce plication
Intussusception will produce target lesions
Wall mass will often disrupt the layers and cause thickness
Acute hypermotility will be followed by chronic ileus
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22. Tips – GI Ultrasound Evidence of obstruction
Jejunum lumen diameter > 1.5 cm
Especially when aborad(?) segments appear normal
May or may not be able to find the obstruction
Lumenal foreign body may show reflective interface or acoustic shadow
Linear foreign body may produce plication
Intussusception will produce target lesions
Wall mass will often disrupt the layers and cause thickness
Dilated loop of gut
gastrointestinal mass
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23. Tips – GI Ultrasound Rugal folds tell you it is the stomach
Differentiate colon from SI:
Thinner wall (may not see layers)
Lack of motility
+ acoustic shadow (white dome)
For the most thorough interrogation of the GI tract, “mow the lawn” in 2 directions
Slide in rows, in 2 orthogonal directions
Rotate the probe in 2 orthogonal directions
Use spleen as an acoustic window for better detail
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24. Pitfalls – GI Ultrasound
Thorough interrogation of entire GI tract may not be possible
Gas can interfere
GI tract is mobile, so it’s impossible to follow from one end to the other
And orientation can be from any angle
Brachycephalics can be difficult due to aerophagia
Deep chested dogs can be difficult because so much is under the costal arch (especially if liver is small)
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25. Pitfalls – GI Ultrasound
Do not mistake “corrugation” for “plication”
Corrugation is abnormal spastic peristalsis
Caused by irritation/inflammation
Not associated with obstruction
Plication is caused by linear foreign body and indicates surgery ASAP – “ribbon candy” sign
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26. Pitfalls – GI Ultrasound
Do not mistake “corrugation” for “plication”
Corrugation is abnormal spastic peristalsis
Caused by irritation/inflammation
Not associated with obstruction
Plication is caused by linear foreign body and indicates surgery ASAP
corrugation
plication
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27. Pitfalls – GI Ultrasound
Do not mistake “corrugation” for “plication”
Corrugation is abnormal spastic peristalsis
Caused by irritation/inflammation
Not associated with obstruction
Plication is caused by linear foreign body and indicates surgery ASAP
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28. Pitfalls – GI Ultrasound
Do not mistake “corrugation” for “plication”
Corrugation is abnormal spastic peristalsis
Caused by irritation/inflammation
Not associated with obstruction
Plication is caused by linear foreign body and indicates surgery ASAP
Do not mistake duodenal papilla for a mass
Can see it with high resolution ultrasound
Duodenal papilla
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29. Pitfalls – GI Ultrasound
Do not mistake “corrugation” for “plication”
Corrugation is abnormal spastic peristalsis
Caused by irritation/inflammation
Not associated with obstruction
Plication is caused by linear foreign body and indicates surgery ASAP
Do not mistake duodenal papilla for a mass
Can see it with high resolution ultrasound
Do not mistake Peyer’s Patches for masses
Mucosal indentations on the antimesenteric border
Peyer’s patches
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30. Pitfalls – GI Ultrasound
If your not sure if the gut you are looking at is abnormal, compare to gut in other locations
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31. Summary PowerPoint – Ultrasound of the Gastrointestinal Tract
.pdf of PowerPoint – Ultrasound of the Gastrointestinal Tract
Gastrointestinal Ultrasound TIPs Sheet
Fluid Analysis Diagnostic Chart
Article: Pseudo-obstruction in the Dog
Animated Powerpoint – Scanning the Gut
Video: Scanning the Gut

32. Acknowledgments Soren Boysen & Jennifer Gambino
Chapter 7: Focused or COAST3 – Gastrointestinal and Pancreas Focused Ultrasound Techniques for the Small Animal Practitioner Editor Greg Lisciandro
John Mattoon, Danelle Auld, Thomas Nyland
Chapter 4: Abdominal Ultrasound Scanning Techniques Small Animal Diagnostic Ultrasound Editors Nyland and Mattoon – 3rd Edition 2014

33. John P. Graham, MVB, MSc, DVR, MRCVS
Acknowledgments
Dominique G Pennick
Chapter 11: Gastrointestinal Small Animal Diagnostic Ultrasound Editors Nyland and Mattoon – 3rd Edition 2014
John P. Graham, MVB, MSc, DVR, MRCVS
Diplomate, ECVDI, Diplomate, ACVR Diagnostic Imaging in Dogs and Cats Nestle Purina – Clinical Handbook Series

34. Martha Moon Larson, DVM & David S Biller, DVM
Acknowledgments
Martha Moon Larson, DVM & David S Biller, DVM
Chapter 11: Gastrointestinal Ultrasound of the Gastrointestinal Tract Editors Nyland and Mattoon – 3rd Edition 2014