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    2019-12-26, Pseudo-Obstruction of Large Bowel and Toxic Megacolon. DR - Hozaifah R2

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    Huthaifa M Ali
    Toxic megacolon is a serious complication that can occur in inflammatory bowel disease and infectious colitis where the colon becomes severely dilated. The mechanisms are not fully understood but likely involve chemical mediators such as nitric oxide and interleukins. Nitric oxide works to dilate blood vessels while interleukins help regulate the immune system. Diagnosis is based on colon dilation of over 6cm seen on imaging along with loss of haustral markings and potential perforation. Treatment focuses on managing the underlying condition, correcting biochemical abnormalities, and surgical intervention if needed to decompress the colon.

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    2019-12-26, Pseudo-Obstruction of Large Bowel and Toxic Megacolon. DR - Hozaifah R2

    Uploaded by

    Huthaifa M Ali
    12 views6 pages
    Toxic megacolon is a serious complication that can occur in inflammatory bowel disease and infectious colitis where the colon becomes severely dilated. The mechanisms are not fully understood but likely involve chemical mediators such as nitric oxide and interleukins. Nitric oxide works to dilate blood vessels while interleukins help regulate the immune system. Diagnosis is based on colon dilation of over 6cm seen on imaging along with loss of haustral markings and potential perforation. Treatment focuses on managing the underlying condition, correcting biochemical abnormalities, and surgical intervention if needed to decompress the colon.

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    Megacolon

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    2019-12-26, Pseudo-obstruction of Large Bowel and Toxic Megacolon. Dr.hozaifah R2

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    Toxic megacolon is a serious complication that can occur in inflammatory bowel disease and infectious colitis where the colon becomes severely dilated. The mechanisms are not fully understood but likely involve chemical mediators such as nitric oxide and interleukins. Nitric oxide works to dilate blood vessels while interleukins help regulate the immune system. Diagnosis is based on colon dilation of over 6cm seen on imaging along with loss of haustral markings and potential perforation. Treatment focuses on managing the underlying condition, correcting biochemical abnormalities, and surgical intervention if needed to decompress the colon.

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    © All Rights Reserved
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    12 views6 pages

    2019-12-26, Pseudo-Obstruction of Large Bowel and Toxic Megacolon. DR - Hozaifah R2

    Uploaded by

    Huthaifa M Ali
    Toxic megacolon is a serious complication that can occur in inflammatory bowel disease and infectious colitis where the colon becomes severely dilated. The mechanisms are not fully understood but likely involve chemical mediators such as nitric oxide and interleukins. Nitric oxide works to dilate blood vessels while interleukins help regulate the immune system. Diagnosis is based on colon dilation of over 6cm seen on imaging along with loss of haustral markings and potential perforation. Treatment focuses on managing the underlying condition, correcting biochemical abnormalities, and surgical intervention if needed to decompress the colon.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    of 6

    Toxic megacolon is a complication that can be seen in both types of inflammatory bowel disease, and less

    commonly in infectious colitis, as well as in some other types of colitis.

    Terminology
    Toxic colitis is preferred by many now as the colon is not always dilated.

    Pathology
    The mechanisms involved in the development of toxic megacolon are not entirely clear, although chemical mediators such as
    nitric oxide and interleukins are thought to play a pivotal role in its pathogenesis.

    Nitric oxide is a gas that is inhaled. It works by relaxing smooth muscle to widen (dilate) blood vessels, especially in
    the lungs. Nitric oxide is used together with a breathing machine (ventilator) to treat respiratory failure in premature
    babies.

    Interleukins (ILs) are a group of cytokines (secreted proteins and signal molecules) The human genome encodes more than 50
    interleukins and related proteins.

    The function of the immune system depends in a large part on interleukins, The majority of interleukins are synthesized by helper
    CD4 T lymphocytes. They promote the development and differentiation of T and B lymphocytes, and hematopoietic cells.

    Radiographic features
    ֍ The colon dilated to at least 6 cm.
    ֍ Loss of haustral markings
    ֍ Thumbprinting from mucosal edema may be present.
    ֍ Pneumoperitoneum if dilatation has progressed to cause perforation.

    Practical points
    Barium studies and colonoscopy should be avoided, due to the risk of perforation.
    Colonic pseudo-obstruction (also known as Ogilvie syndrome) is a potentially fatal condition leading to
    an acute colonic distention without an underlying mechanical obstruction.

    ֍ Usually elderly unwell patients.


    ֍ Mostly seen in people over 60 years of age
    ֍ Male predilection.

    ➢ Patients usually present with constipation, nausea, vomiting and abdominal distension.
    ➢ Pseudo-obstruction can present with a sudden painless enlargement of the proximal colon
    accompanied by distension.
    ➢ Bowel sounds are normal or high-pitched, but should not be absent.
    ➢ Despite the absence of mechanical obstruction, patients can nonetheless go on to bowel
    necrosis and perforation (especially if dilatation is severe).

    Pseudo-obstruction is related to decreased parasympathetic activity.

    Risk factors include:

     Trauma
     Burns
     Recent surgery
     Medications
    o Opioids
    o Phenothiazines
    o Clozapine
     Respiratory failure
     Electrolyte disturbances
     Diabetes mellitus
    Findings will be identical to a mechanical large bowel obstruction.

    A single contrast/water-soluble enema demonstrates the absence of any mechanical obstruction.

    Dilatation of the large bowel with no abrupt transition point or mechanically obstructing lesion.

    ✓ Correction of the underlying disorder and correction of any biochemical abnormalities.


    ✓ Medical treatment include:
    Anticholinesterases like neostigmine
    Antibiotics like erythromycin.
    ✓ In severe cases, surgical or fluoroscopy-assisted cecostomy is necessary, or even occasionally a
    percutaneous endoscopic colostomy (PEC).

    Cecal perforation: decompression (with a rectal tube) is usually undertaken if the caliber is more than 9-
    12 cm.
    Anteroposterior supine abdominal radiographs obtained after cardiac surgery in a 55-year-old man with
    abdominal distension

    Radiograph shows marked distension of the entire colon despite rectal tube (arrow) in place.

    Radiograph after administration of water-soluble enema demonstrates patent colon without evidence
    of obstruction. The pseudo-obstruction resolved with colonic decompression tube placement.
    https://radiopaedia.org/cases/toxic-megacolon-2

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