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Post-op ileus

Updated: May 27, 2021

Starting back at hospital within the UK straight after festival medicine and Nepal was a whirlwind, hospital inductions, new passwords and door code access. But luckily I was starting back on trauma and orthopaedics, a favourite of mine, seeing as vomit and faeces are usually minimal and the stench of melaena (black stools caused by a blood high up in the gastrointestinal tract) doesn’t hit you in the back of your throat. How wrong I was, within 2 days of being on the ward I’d caught vomit and had the pleasure of performing a rectal exam which turned out to release the patient’s bowel obstruction rather than act as a diagnostic test. I now know why you should always wear an apron when doing a PR exam.

So this week I thought I’d use that memory that will definitely stay with me forever, to look into pseudobstructions and ileus in post-operative patients. The gastrointestinal system moves contents through the lumen of the bowel through what’s known as peristalsis. A post-operative ileus is a slowing down or arrest of this peristalsis action of the gastrointestinal tract resulting in a functional obstruction. This is fairly common in surgical patient with many having some degree of physiological ileus. Although usually innocent, post-operative ileus could be a sign of a more serious pathology, such as a collection or anastomotic leak within the abdomen. Post-operative ileuses are more common when the surgical procedure involved the intestines in some way, whether this was handing of the intestines, intestinal resection or pelvic surgery. Also, contamination of the peritoneum within the abdomen with pus or faceces as well as use of opioid medication as pain relief can increase the risk.

A bowel obstruction can be detected clinically, where the patient fails to pass stool. More worryingly and a question that must be asked is whether the patient has passed flatus (farted) as this determines the extent of the obstruction. An uncomfortable feeling of bloating and vomiting is usually associated with ileus. When examining such as patient, there abdomen will be distended, and bowel sounds are absent in a functional obstruction, as peristalsis is not occurring. This is different from a mechanical obstruction where you would hear tinkling bowel sounds. Intra-abdominal leaks need to be excluded as a cause for obstruction, blood tests can help indicate if an infection is present (intra-abdominal collections or leaks) or if there is an electrolyte disturbance which can also cause a paralytic ileus. CT scans with oral contrast can be used to confirm diagnosis and rule out collections and leaks.

To help improve the ileus, mobilization is encouraged and reducing the amount of opiates used for pain relief also greatly helps. A Nasogastric tube can help relieve the pressure within the gastrointestinal tract when set on free drainage. Catheterizing the patient is important to measure accurately their fluid balance. Depending on the cause of the obstruction a flatus tube can be used. This is where a long soft tube is inserted into the patient rectum with assistance of a rigid/flexible sigmoidoscope. These flatus tubes can be left within the colon for up to 48 hours to help relieve the pressure.

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