GI tract surgery Flashcards
Which of the following reasons as to why GI surgery would be performed are most likely to require emergency surgery?
A. Obstruction of GIT (complete)
B. Obstruction of GIT (partial)
C. Perforation of GIT
D. Strangulation of GIT vasculature
E. Structural/functional abnormality of GIT
F. Need biopsies for diagnosis
G. Need feeding tube
A. Obstruction of GIT (complete)
C. Perforation of GIT
D. Strangulation of GIT vasculature
Also volvulus or torsion
Dfdx for GIT obstruction
- Foreign body, neoplasia, intussusception, torsion/volvulus, anatomic anomaly, herniation, stricture, extramural compression
How can an obstruction lead to sepsis?
- Gas/fluid distension proximally
- Venous and lymphatic stasis in bowel wall
- Fluid moves into lumen and eventually across the serosa
- Bacteria/toxins move into circulation and across the serosa
- Ischemia/necrosis of the bowel wall may lead to perforation
Which ddx tend to have more acute onset and more severe signs?
- Complete obstruction compared to partial obstruction
- Orad obstruction compared to aborad obstruction
- Vascular compromise (as with strangulation or torsion) compared to just luminal obstruction
- FB obstruction as compared with neoplasia
What acid/base status can provide a clue that there is an obstruction proximal to the entry of bile into the GIT, and what is the pathophysiology?
- Vomit gastric secretions rich in K, Na, H, Cl
- Metabolic alkalosis
What acid/base status can provide a clue that there is an obstruction distal to the entry of bile into the GIT, and what is the pathophysiology?
- Vomit gastric and pancreatitis (HCO3) secretions
- Metabolic acidosis
Radiographic signs of obstruction (3)
a. Local intestinal distention, two populations of intestinal size
b. Stacked distended intestinal loops with hairpin turns
c. Small intestinal diameter >2x height of L5 body
WHat can lead to GIT perforation?
- Anything that damages bowel or its blood supply
- Causes include all causes of GIT obstruction, neoplasia, thrombosis, strangulation, ulceration, trauma, iatrogenic
What is the one specific circumstance when GIT perforation is NOT a surgical emergency?
- Small perforation in otherwise healthy tissue of the CERVICAL esophagus
Why is the cervical esophagus different than other sites in that a perforation there doesn’t warrant immediate surgery?
- That’s where we place esophagostomy tubes
What can happen with volvulus or torsion that warrants immediate surgery?
- Can cause obstruction of luminal organs
- In addition, whether an organ twists on itself or the mesentery of the organ twists, blood supply is compromised
Why are veins more susceptible to twisting with volvulus and torsion than arteries?
- They don’t have the muscular wall
What happens if blood can flow into an organ but not out?
- Organ gets congested, waste products cannot be removed
- new oxygenated blood can get in only to the point that the vasculature can expand to accommodate it (old blood is not flowing out to make room for new blood)
What can cause the rapid decline with volvulus/torsion?
- Tissue ischemia, shock (hypovolemic, circulatory, endotoxemic), multi-organ failure, and death
What happens with strangulation vs volvulus and torsion
- In strangulation, the vein and artery are both closed off
- In a volvulus or torsion, just the vein is closed off
Difference in clinical signs with strangulation
- Decline similarly to volvulus or torsion, but faster (peracute)
Other consequences of torsion or strangulation
- Vascular thrombosis
- Ileus
- Proliferation of bacteria with transmural migration and entry into circulation
What is reperfusion injury?
- Occurs if blood flow is re-established and can be fatal
What is the mechanism of reperfusion injury?
- Oxygen reacts with by-products of metabolism leading to free radicals
- Torsion/volvulus –> hypoxia nad poor perfusion –> anaerobic metabolism –> accumulate hypoxanthine and xanthine oxidase when oxygen is added –> reactive oxygen species like peroxide –> cell death
What is a consequence of reperfusion injury regarding how we remove certain organs?
- Organ is removed WITHOUT de-rotating if possible; doable for spleen or a liver lobe but not for the whole stomach or whole intestine
What by-products of metabolism does oxygen react with to form free radicals?
- Hypoxanthine and xanthine oxidase
Are most GI tumors malignant or benign?
malignant
What is the most common type of GI tumor in dogs?
- Adenocarcinoma
What is the most common type of GI tumor in cats?
Lymphoma or lymphosarcoma
Common sites for metastasis for GI tumors
- Lymph nodes, liver, and lungs
Prognosis for benign GI tumors
- Benign can be cured if resectable
Prognosis for malignant GI tumors
- many months to 1-2 years if resectable, poor if mets
Surgical plan for GI tumors
- Resect tumor with 4-8 cm or more of grossly normal GIT (or biopsy is no resectable)
- Biopsy local lymph nodes
What is the amount of jejunum that can be removed w.o getting short bowel syndrome?
Look it up
Local node examples
- Portal/hepatic nodes
- Pancreaticoduodenal nodes
- Mesenteric nodes
- Splenic nodes
- Gastric nodes
What is a Bilroth procedure?
- Involves removing the pylorus (i.e. pylorectomy) and various amount of stomach and duodenum on either side
-
What are some possible consequences to consider with a Bilroth procedure?
- They sometimes disrupt the common bile duct, which must then be re-routed by anastosmosing a hole made in the gallbladder and to a hole made in a piece of intestine that will reach up to the gallbladder
Etiology of pyloric stenosis
- Congenital
Etiology of pyloric hypertrophy
- Acquired
Age of dogs with pyloric stenosis
- Young > old
Age of dogs with pyloric hypertrophy
- middle aged to older
Breed that gets pyloric stenosis
- Brachycephalic dogs
- Siamese cats
Breeds that get Pyloric hypertrophy
- Small breed dogs
Contrast studies seen with benign pyloric outflow obstruction?
- Delayed emptying
- Thickened pyloric canal
- Filling defect at the pylorus
- Thickening can be seeno n ultrasound as well
What does definitive diagnosis of either pyloric stenosis or pyloric hypertrophy require?
- Full thickness biopsy
- Cannot make definitive diagnosis with imaging or from a mucosal biopsy as obtained from endsoscopy
Prognosis for pyloric stenosis or pyloric hypertrophy
- Good to excellent outcome in 85% with appropriate surgical treatment
What type of bacteria are normal inhabitants in the oral cavity?
- Gram positive, anaerobes
- Peridontitis can lead to increased gram negative species
What type of bacteria are normal inhabitants in the esophagus?
- Gram positives and anaerobes
What type of bacteria are normal inhabitants in the stomach?
- Insignificant
What type of bacteria are normal inhabitants in the small intestine?
- Gram positive transitioning to gram negative anaerobes as you go more aborad
What type of bacteria are normal inhabitants in the colon/rectum?
- Gram negative and anaerobes
What should you do before incising into the GI lumen?
- Complete non-contaminating procedures if prioritization allows
- Designate a region of the table for contaminated instruments
- Pack off the section of bowel to be incised with several layers of moist laparotomy pads
- Take steps to prevent spillage (e.g. stay sutures to elevate the stomach; Doyens on esophagus or intestine
How many clicks for Doyens?
- One click only!
In VTH, where do we place all instruments used after the bowel is opened?
- On a huck towel on the front of the instrument table
- When ready to convert to clean, we can roll up tehse instruments in the towel and easily pass them off to a non-sterile assistant
To perform an -otomy: incise full-thickness into a non-vascular portion of the tissue
- Describe the location of the non-vascular areas you will use to perform a gastrotomy
- Between the greater and lesser curvatures
To perform an -otomy: incise full-thickness into a non-vascular portion of the tissue
- Describe the location of the non-vascular areas you will use to perform an enterotomy in the duodenum
- Look it up
To perform an -otomy: incise full-thickness into a non-vascular portion of the tissue
- Describe the location of the non-vascular areas you will use to perform an enterotomy in the jejunum
- Look it up, but I think it’s the antimesenteric side
To perform an -otomy: incise full-thickness into a non-vascular portion of the tissue
- Describe the location of the non-vascular areas you will use to perform an enterotomy in the ileum
- Look it up