Ischemic Colitis

Question 1

Ischemic colitis (IC)

Answer 1

when the blood supply to colonocytes does not meet metabolic demands

Question 2

What is the most common cause of gastrointestinal (GI) ischemia.

Answer 2

Ischemic Colitis

Question 3

describe the injury Types and complications

Answer 3

• at the initial incident of decrease in blood flow phase and/ or after reperfusion.
• If the injury occurred only at the mucosa, it can be reversible.
• Transmural injury can present as a life-threatening condition that can lead to stricture formation, perforation, sepsis, and death.

Question 4

Which Sites are more prone to ischemia

Answer 4

• Griffith’s point, at the splenic flexure,
• Sudek’s point, at the rectosigmoid junction
• compromising 80% of IC cases.

Question 5

Risk Factors

Answer 5

• age > 60
• higher prevalence in women
• commonly occurs after aortic or cardiac surgeries.
• peripheral artery occlusive disease
• coronary artery disease
• heart failure
• chronic obstructive pulmonary disease
• inflammatory bowel disease (IBD).
• cigarette smokers, both current and former
• diuretics or digoxin and psychotropic medications within the past month

Question 6

high-risk, or “watershed,” areas ?

Answer 6

• regions in the colon between two major arteries
• Splenic flexure is the area between the SMA and the IMA arterial supply
• Rectosigmoid junction is the region between the IMA and the superior rectal artery supply.
• Rectosigmoid mostly supplied by the marginal artery; however, in 50% of the population, this artery is poorly developed.

Question 7

During aortic surgery, ensure what ?

Answer 7

• The left colon has adequate blood supply if the IMA is acutely sacrificed

Question 8

IC classified according to the mechanism of decreased blood flow to the colon

Answer 8

• Most commonly nonocclusive
  as in cases of shock, drugs, and colon obstruction
• Less commonly
  after a vascular insult, due to an arterial thrombosis, embolism, or even a venous occlusion

Question 9

special entity

Answer 9

> postoperative IC
after cardiac and vascular surgeries
intraoperative temporary cessation of blood flow to the colon.

For example, following abdominal aortic aneurysm repair or bypass, if the IMA was sacrificed or if there was prolonged cross clamp time

Question 10

Time to develop the injury

Answer 10

• Mucosal injury will develop in 20 minutes to 1 hour of decreased blood flow
• Transmural infarction occurs within 8 to 16 hours.
• Additional insult occurs when blood flow is reestablished

Question 11

Reperfusion injury causing more injury why ?

Answer 11

• Associated with the release of reactive oxygen species, which causes lipid peroxidation within cell membranes and leads to cell necrosis

Question 12

Classification

Answer 12

• mucosal vs. transmural
• mild, moderate, and severe

Severe> transmural infarcts of the colon wall
leads to peritonitis, sepsis, perforation, and death.

• Anatomic location or distribution: segmental colitis or sidedness.

Question 13

isolated right-sided colon ischemia (IRCI)

Answer 13

• Associated with poor outcomes
• 30-day mortality rate of 20.3%
• Higher frequency of severe cases requiring surgical intervention
• Associated with acute mesenteric ischemia.
• Associated more frequently in patients with coronary artery disease and chronic kidney disease on hemodialysis.

Question 14

Pancolitis and IRCI

Answer 14

• Seen frequently in patients with sepsis

Question 15

Presentation

Answer 15

> vague
diagnosis is often delayed
most common symptoms acute onset abdominal pain, hematochezia, and an urgent desire to defecate.

Question 16

Gangrenous colitis and fulminant colitis

Answer 16

• Gangrenous > increasing abdominal tenderness, guarding, rebound tenderness, rising temperature, and paralytic ileus.
• The sudden onset of a toxic colitis with signs of peritonitis and a rapidly progressive course > fulminant colitis, > rare variant of IC.

Question 17

Rectal bleeding is found more frequently in

Answer 17

non-IRCI

Question 18

important for patient survival in IRCI

Answer 18

• Timely diagnosis of IRCI

Question 19

Labs Inv

Answer 19

• Leukocytosis
• Elevated lactate, urea, and creatinine
• Metabolic acidosis and a base deficit in cases of severe ischemia, gangrene, and sepsis.
• Decreased hemoglobin levels, low serum albumin, and the presence of metabolic acidosis can be used to predict severity of IC.

Question 20

Imaging

Answer 20

> CT scan
abdominal x-ray

> Classic findings on an x-ray include thumbprinting, which indicates mucosal edema.
In cases of bowel perforation, an x-ray is a quick way to see free air under the diaphragm.

Question 21

CT Features

Answer 21

• can exclude other causes
  suggest a location and source of ischemia
  and identify complications
• bowel wall thickening
• thumbprinting
• pericolonic stranding with or without ascites
• After reperfusion, > submucosal edema or hemorrhage
• Emboli or thrombi causing complete arterial occlusion > thin, unenhancing colonic wall due to complete lack of reperfusion.
• colonic pneumatosis and portomesenteric venous gas can be used to predict the presence of transmural colonic infarction
• Free Air, Bowel Perf

Question 22

When to use splanchnic angiography

Answer 22

Patient with heralding sign of acute mesenteric ischemia (e.g., IRCI, severe pain without bleeding, and atrial fibrillation) and the multiphasic CT is negative for vascular occlusive disease.

Question 23

Gold standard for confirming diagnosis

Answer 23

• Endoscopy > IC identified and biopsied
• Performed within 48 h of presentation

Question 24

Features on Scope

Answer 24

• segmental erythema
• edema
• mucosal ulceration
• submucosal hemorrhagic nodules
• and involvement of watershed areas
• pseudomembranes related to mucosal sloughing
• colonic single stripe sign, a single linear ulcer running longitudinally along the antimesenteric colonic
• After 48 hours > sloughing occurs, the purple submucosal hemorrhages dissipate, and ulcerations develop.
• In more severe ischemia with transmural infarction, the mucosa may appear gray-green or even black

Question 25

On histologic examination

Answer 25

- mucosa with necrosis and sloughing of the surface epithelium - loss of epithelium in the superficial aspects of the crypts (with or without ghosts of crypts) - mucin depletion - reactive changes in the residual crypt epithelium - nuclear hyperchromasia - increased mitoses - paucity or complete absence of acute inflammatory cells - hyalinosis in the lamina propria

Question 26

Mild to Mod Disease Tx

Answer 26

- supportive care - bowel rest - intravenous fluids - optimizing cardiac output - avoiding medications like vasopressors - correction of electrolytes - nasogastric tube decompression for ileus. - intravenous antibiotics > treat bacterial translocation > both aerobic and anaerobic pathogens > recommended 2 weeks.

Question 27

When to Consider Surgical Intervention

Answer 27

Hr > 100 SBP < 90 Hgb < 12 hyponatremia < 136 LDH > 450 blood urea nitrogen > 28 mg/ dL A pancolonic distribution of disease and IRCI also portend a poor outcome.

Question 28

Surgical intervention should be considered in the presence of IC accompanied by

Answer 28

hypotension tachycardia abdominal pain without rectal bleeding > IRCI and pancolonic IC presence of gangrene.

Question 29

acute setting, operative indications include

Answer 29

peritonitis on examination massive bleeding fulminant colitis portal venous gas or pneumatosis on imaging with clinical picture of IC worsening clinical condition

Question 30

General principle of surgery

Answer 30

- Remove all segments of the colon that are grossly ischemic - midline laparotomy or diagnostic laparoscopy - it can be difficult to determine the extent of resection as the serosa > preoperative CT scan > Endoscopic evaluation Intraoperatively > Doppler ultrasonography > endoscopy > photoplethysmography to assess mucosal viability or colonic blood flow. - concern for ongoing ischemia > leave the fascia open and bowel in discontinuity > intensive care unit for continued resuscitation > second-look laparotomy and closure in 12 to 48 hours

Question 31

The decision to construct an anastomosis versus an ostomy

Answer 31

> main concern is anastomotic leak or nonhealing anastomosis > A primary anastomosis can be done safely in uncomplicated isolated right colon ischemia > For left-sided IC > opinion advocates for an end colostomy and rectal stump (Hartmann procedure) > reversed later after 6– 8 weeks postsurgery > In selected cases, it may be reasonable even with left-sided disease to perform a primary anastomosis with or without a protective diverting loop ileostomy.

Question 32

complications Post Op

Answer 32

pneumonia urinary tract infections atrial fibrillation postoperative myocardial infarction acute renal failure Hemodialysis

Question 33

Independent risk factors of mortality after emergent colectomy for IC

Answer 33

- elderly age - poor functional status - multiple comorbidities - ejection fraction < 20% - preoperative septic shock - preoperative blood transfusions - preoperative acute renal failure - delay from hospital admission to surgery - Postoperative death is associated with the peak preoperative lactate level (if above 2.5 mmol/ L) - amount of intraoperative blood loss - pre- and intraoperative catecholamine administration, - subtotal or total colectomy - need for dialysis postoperatively - (ASA) class 4.

Question 34

Operative intervention for sequelae of IC

Answer 34

- symptomatic colonic strictures - ostomy reversal. - facial dehiscence - wound complications.

Question 35

Stricture Post IC

Answer 35

- colonoscopy - contrast enema : > helpful to describe the length and location of the stricture. If clinically significant > obstruction or severe abdominal pain > elective resection and primary anastomosis. Alternatively > balloon dilation, and stenting.