bowel iscehmia

1. Bowel Ischemia
Dr. Abdullah Al Huwaiyshil
R1 – Urology resident
King Fahad Hospital Hofuf

2. Outline
• Types
• Anatomy
• Pathophysiology
• Acute Mesenteric Ischemia
• Mesenteric Vein Thrombosis
• Focal Segmental Ischemia
• Colon Ischemia
• Chronic Mesenteric Ischemia

3. Types
TYPE FREQUENCY (%)
Colon ischemia 75
Acute mesenteric ischemia 25
Focal segmental ischemia <5
Chronic mesenteric ischemia <5

4. Anatomy – Celiac Axis
• Supplies stomach, duodenum,
pancreas, and liver
• Three branches: left gastric,
common hepatic, splenic
• Common hepatic:
gastroduodenal, right
gastroepiploic, anterior
superior pancreaticoduodenal
• Splenic: pancreatic and left
gastroepiploic

5. Anatomy – Superior Mesenteric Artery
(SMA)
• Anterior and posterior inferior
pancreaticoduodenal
• Middle colic
• Right colic
• Ileocolic

6. Anatomy – Inferior Mesenteric Artery
(IMA)
• Left colic
• Sigmoid branches
• Superior rectal
• Supply distal transverse to
proximal rectum
• Distal rectum: internal iliac

7. Pathophysiology
• Bowel can tolerate 75% reduction of blood flow
and oxygen consumption for 12 hours
• Collaterals open immediately
• After hours, vasoconstriction reduces collateral
flow
• Hypoxia, reperfusion injury
▫ Microvascular injury

8. Acute Mesenteric Ischemia
CAUSE FREQUENCY (%)
SMA embolus 50
Nonocclusive mesenteric ischemia 25
SMA thrombosis 10
Mesenteric venous thrombosis 10
Focal segmental ischemia 5

9. Clinical Features
• Acute abdominal pain
• Rapid and forceful bowel evacuation
• Pain out of proportion to exam
• Unexplained abdominal distention (sign of
infarction) or GI bleeding
• Physical findings worsen with progressive loss of
bowel viability
• Infarction: 70-90% mortality

10. Diagnosis
• Labs
▫ 75% have WBC > 15
▫ 50% have metabolic acidosis
• Plain films
▫ Poorly sensitive (30%) and nonspecific
▫ Formless loops of small intestine
▫ Ileus, thumbprinting, pneumatosis
▫ Portal or mesenteric vascular gas
• CT
▫ Colon dilatation
▫ Bowel wall thickening
▫ Lack of enhancement of arterial vasculature
▫ Ascites
• CT angiography
▫ Better evaluation of vessels
• Selective mesenteric angiography
▫ Gold standard
• Prompt laparotomy if angiography not available

14. Portal Gas

15. Treatment
• General
▫ Resuscitation, Broad-spectrum antibiotics
• Superior Mesenteric Artery Embolus
▫ Cardiac origin
▫ Major: proximal to ileocolic
 Intra-arterial papaverine
 Surgical revascularization
▫ Minor and no peritoneal signs
 Intra-arterial papaverine (or thrombolytics)
 Anticoagulation

16. SMA Embolus
Pre and post treatment

17. Treatment
• Nonocclusive Mesenteric Ischemia
▫ Vasoconstriction from preceding cardiovascular
event
▫ Angiography
 Narrowing of SMA branch origins
 Irregularities in intestinal branches
 Spasm of arcades
 Impaired filling of intramural vessels
▫ SMA infusion of papaverine for 24 hours
▫ Surgery if peritoneal signs are present

18. Treatment
• Acute Superior Mesenteric Artery Thrombosis
▫ Severe atherosclerotic narrowing
▫ Often superimposed on chronic mesenteric
ischemia
▫ Demonstrated on aortography
▫ Management same as SMA embolism

19. Mesenteric Vein Thrombosis
• Age: mid-60s to 70s
• 20% mortality
• Manifest as colon ischemia, acute mesenteric
ischemia, or focal segmental ischemia
• Causes
▫ Arterial hypertension
▫ Neoplasms
▫ Coagulation disorders
▫ Estrogen

20. Mesenteric Vein Thrombosis
• Acute
▫ Pain out of proportion to exam, n/v
▫ Lower GI bleeding suggests infarction
• Diagnosis
▫ CT is study of choice (finds >90%)
▫ Mesenteric arteriography
 Slow or absent filling of mesenteric veins
 Failure of arterial arcades to empty
 Prolonged blush in involved segment
• Treatment
▫ Incidental: up to six months of anticoagulation (AC)
▫ Peritonitis: surgery, papaverine, post-op heparin
▫ No peritoneal signs: heparin followed by 3-6 mos AC

21. Mesenteric Vein Thrombosis
• Subacute
▫ Abdominal pain for weeks to months but no
infarction
• Chronic
▫ Asymptomatic
▫ May develop GI bleeding from varices
▫ Treatment: control bleeding

22. Focal Segmental Ischemia
• Involves small bowel
• Causes
▫ Atheromatous emboli
▫ Strangulated hernias
▫ Immune complex disorders
▫ Trauma
▫ Segmental venous thrombosis
▫ Radiation therapy
▫ Oral contraceptives
• Usually adequate collaterals to prevent infarction
• Presentation: enteritis, stricture, acute abdomen
▫ Chronic can resemble Crohn's

23. Focal Segmental Ischemia
• Radiologic studies
▫ Smooth tapered stricture
▫ Abrupt change to normal distally
▫ Dilated proximally
• Treatment: resection

24. Colon Ischemia
TYPE FREQUENCY (%)*
Reversible colopathy and transient colitis >50
Transient colitis 10
Chronic ulcerating colitis 20
Stricture 10
Gangrene 15
Fulminant universal colitis <5

25. Colon Ischemia
• Most common form of intestinal ischemia
▫ 7.2 cases per 100,000 person-years
• Female predilection
• Most > 60 years old
• Young pt: vasculitis, coagulation disorders,
cocaine, medications
• Right colon ischemia
▫ May have small intestinal ischemia

26. Medications
• Penicillins
• Alkaloid and taxanes
• Constipation-Inducing Agents
• Pseudoephedrine
• Diuretics
• Oral contraceptive pills
• Amphetamines (R sided)
• Cocaine (L sided)
• Kayexelate
• Magnesium citrate
• Sodium phosphate
• Bisacodyl
• Glycerin enemas
• NSAIDs
• Sumatriptan
• Alosetron

27. Pathology
• Mild: mucosal and submucosal hemorrhage and
edema
• More severe: ulcerations, crypt abscesses,
pseudopolyps, pseudomembranes, iron-laden
macrophages, submucosal fibrosis (stricture)
• Most severe: transmural infarction

28. Clinical Features
• Sudden cramping
• Mild left lower quadrant pain
• Urgent desire to defecate
• Hematochezia within 24 hours
• Location:
▫ Sigmoid 23%
▫ Descending-to-sigmoid 11%
▫ Cecum-to-hepatic flexure 8% (worse prognosis)
▫ Descending 8%
▫ Pancolonic 7%

29. Diagnosis
• CT scan
• If nonspecific, colonoscopy within 48 hours
• Colon single-stripe sign
▫ Line of erythema with erosion or ulceration along
the longitudinal axis of the colon
▫ Milder course

30. Colonoscopy

34. Treatment
• NPO, IVF, antibiotics
• EKG, Holter, echo
• Colonic infarction
▫ Laparotomy and resection
▫ Serosa can be misleading
• Segmental Ulcerating Colitis
▫ Recurrent fevers and sepsis
▫ Continuing or recurrent bloody diarrhea
▫ Persistent or chronic diarrhea with protein-losing
colopathy
▫ Treat by resection

35. Treatment
• Ischemic Stricture
▫ Dilation or resection
• Universal Fulminant Colitis
▫ Colectomy with ileostomy
• Isolated Ischemia of the Right Colon
▫ Check CTA for concurrent AMI
• Carcinoma/Obstructive Lesions (<5%)
▫ Lesion distal, increased intracolonic pressure proximal
• Irritable Bowel Syndrome
▫ Colon ischemia 3.4 to 3.9x more common
▫ ?Hypersensitivity of the colonic vasculature
• Complicating Aortic Surgery
▫ Up to 7% of surgeries (60% for ruptured aneurysm)
▫ Colonoscopy within 2-3 days if high risk
 Ex: ruptured aneurysm, prolonged cross-clamping time, post-op diarrhea

36. Chronic Mesenteric Ischemia
• “Intestinal angina”
• Mesenteric atherosclerosis
• Pain from small bowel ischemia
▫ Blood stolen to meet increased gastric demand
from food

37. Clinical Features
• Gradual cramping discomfort within 30 minutes
of eating, resolves over hours
• Fear of eating, weight loss
• Nonhealing antral ulcers without H. pylori
• 1/3 to ½: cardiac, cerebral, peripheral vascular
disease
• Exam
▫ Abdomen soft and nontender
▫ Bruit common but nonspecific

38. Diagnosis
• Gastric tonometry exercise testing (GET)
▫ NG tube and arterial line
▫ Patient on PPI
▫ Obtain gastric juice and arterial blood fasting, during,
after exercise
▫ Measure gastric-arterial PCO2 gradients
▫ Increase after exercise indicates ischemia
• Combine with duplex U/S
• Angiography
▫ Should show occlusion of ≥2 splanchnic arteries
▫ Does not make diagnosis in itself

39. Treatment
• Revascularization
▫ Need occlusive involvement of ≥2 major arteries
▫ Surgical if healthy
▫ Otherwise percutaneous +/- stent

40. References
Uptodate

41. •Thank you ..