Toxic Megacolon Flashcards
(38 cards)
most commonly seen as a complication of
- inflammatory bowel disease (IBD)
more commonly ulcerative colitis (UC) - Clostridium difficile– associated (pseudomembranous) disease (CDAD).
- In cases of IBD, toxic megacolon results as a progression from fulminant colitis.
fulminant colitis
- severe inflammation of the colon with associated systemic toxicity with or without colonic dilatation.
in UC, fulminant colitis is diagnosed by the presence of
- bloody diarrhea more than 10 times
- heart rate higher than 90 beats/ min
- temperature above 37.5 ° C
- requirement of blood transfusion
- erythrocyte sedimentation rate (ESR) more than 30 mm/ hr
- with the presence of abdominal distension and tenderness on clinical examination, and dilated colon on x-ray.
CDAD
CDAD severity, fulminant colitis is diagnosed by the presence of a
- heart rate above 120 beats/ min
- leukocytosis with more than 30% bands
- severe oliguria
- requirement of mechanical ventilator and vasopressors.
Toxic megacolon
- segmental or total colonic distension of 6 cm or more in the presence of acute colitis with systemic toxicity.
- Radiologically, it typically exhibits dilatation of the proximal colon with thickened inflamed distal colon and associated pneumatosis.
- Unlike colonic obstruction, in which cecal dilation with perforation is a concern, the transverse colon is the most common area of dilatation in toxic megacolon.
Causes of Toxic Megacolon
Any inflammatory condition of the colon
-IBD, infectious causes including pseudomembranous colitis caused by C. difficile or other bacteria, such as Salmonella, Shigella, Campylobacter, or Entamoeba, and ischemic colitis
Chemotherapy Colonoscopy Barium enema Drugs that slow colonic motility (narcotics, antidiarrheal drugs, anticholinergic drugs)
pathogenesis of the toxic dilatation
- Severe mucosal inflammation becomes transmural,
extends into the smooth muscle layer > loss of motor tone and paralysis. - Severely inflamed smooth muscle produces nitric oxide, which is released into the colonic wall and further inhibits smooth muscle tone and causes dysmotility and atony.
- Causes dilatation of the colon proximal to the colonic segment that is severely inflamed.
- The toxic systemic response results from bacterial translocation and subsequent bacteremia.
other factors that can affect colon motility
hypokalemia
hypomagnesemia
opiates
anticholinergic or antimotility agents
antidepressants
barium enemas
colonoscopy
may affect adversely colonic motility and exacerbate colon Dilatation
Diagnosis of Toxic mega Colon
Based in Clinical and Radiological findings
diagnosis must be suspected in patients who have
diarrhea
abdominal distension
and signs of systemic toxicity.
patient’s history
- Symptoms of severe colitis :
severe diarrhea (usually bloody)
abdominal pain
fever, chills, and tachycardia.
Hx of previous diagnosis of IBD
medical therapy
recent use of antibiotics
other medications such as steroid, antimotility, and chemotherapeutic agents
It is not uncommon that peritoneal signs maybe masked by
high dose steroid treatment typically used in IBD patients with fulminant colitis.
Clinical criteria for the diagnosis of toxic megacolon
- The Presence of three of the following for the clinical diagnosis:
1- fever higher than 101.5 ° F (38.6 ° C)
2- heart rate higher than 120 beats/ min
3- white blood cell count above 10.5 (× 109/ L)
4- anemia. - Should have one of the following criteria:
1- dehydration
2- mental changes
3- electrolyte disturbances
4- or hypotension. - Abdominal x-ray confirming the diagnosis of toxic megacolon > proximal colonic distention
Dilatation of the ascending and transverse colon that varies from ( 6 cm up to 15 cm )
What Radiological Sign may indicate for pending perforation ?
Transverse colon is dilated past 8 cm
Other radiologic features include
- Presence of air fluid levels
- Loss of normal haustral pattern in the colon
- Thickening and edema of colonic wall
- Small bowel and gastric distension
CT findings indicative of severe colitis
- colonic wall thickening
- submucosal edema
- pericolic stranding
- thickened haustra
Laboratory tests are not specific, but include
- leukocytosis
- anemia
- elevated ESR
- serum C-reactive protein
- electrolyte abnormalities with hypokalemia, hypomagnesemia, and hypoalbuminemia
- Stool sample for culture, sensitivity, and C. difficile toxin assay
- blood culture
what is the two-stage test approach, and why used ?
- Stool culture is highly sensitive but it does not differentiate between the presence of Clostridium bacteria and active infection.
- Initial screening with glutamate dehydrogenase assay followed by confirmation of a positive test with cell cytotoxicity assay.
In Patient not known to have IBD , What to do next ?
- Limited endoscopy, proctoscopy, or sigmoidoscopy may be considered to determine the cause of toxic megacolon
pseudomembranes > CDAD
presence of inclusion bodies in the biopsies > (CMV) colitis
How to Perform scope ?
- extreme caution
- without bowel preparation
- minimal air insufflation
- the endoscope should be advanced only as far as necessary to make a diagnosis.
- Complete colonoscopy should not be performed because of the high risk of perforation.
Medical Therapy
- NO NGT
- Frequent Position to redistribute the Air
- Bowel Rest
- IV Fluids
- Correct electrolyte, Dehydration and Anemia
- DC Meds That affect Motility
- Start DVT Prophylaxis
- Start Gastric Ulcer Prophylaxis
- Start Abx
- DC any agent that cause C.Diff
- Frequent Clinical assesemnt
- Physical exam
- Serial Blood Counts and electrolytes
- Abdominal Xrays
Management algorithm for toxic megacolon.
see
Management of Patients with Inflammatory Bowel Disease
- High-dose intravenous steroid (hydrocortisone 100 mg every 6 hours) > Immediately to prevent progression to Toxic mega Colon
If no response to Steroids ?
- cyclosporine and antitumor necrosis factor-alpha (TNF-α) are immunosuppressant medications used in severe cases of UC.
- Both medications are initiated if there is no response to high-dose intravenous steroids within 3 days.
Which Drug Can reduce the need for Emergent Surgery
Some data suggests >
cyclosporin may have an initial effect in 80% of patients with severe fulminant colitis bordering on toxic megacolon and therefore may reduce the need for emergent surgery.
