The usual presenting complain is pain and bloating. This pain is often mild and vague initially but is later described as cramps. They may also present with poor appetite, nausea and vomiting. Patients could also present with inability to pass faeces or flatus but this is not common in all patients. There is abdominal distension and the degree will depend in the level of the ileus. The abdomen will also be tympanic to percussion and there may be some degree of tenderness. A distinctive feature of ileus is the reduced or complete absence of bowel sounds on auscultation which is usually referred to as the silent abdomen [6].

• Acutely Ill Patient

  Films taken in the upright position (standing or sitting in acutely ill patients) or when lying on the side (the most sensitive view) may demonstrate free intraperitoneal air, which is evidence of GI perforation (Figure 6.1-16). [empendium.com]

• Vomiting

  However, side effects include postoperative nausea and vomiting, shivering, ileus, and urine retention and are specifically discussed here. [ncbi.nlm.nih.gov]

  […] obstruction of the bowel especially : functional obstruction of the gastrointestinal tract and especially the small intestine that is marked by the absence of peristalsis, is usually accompanied by abdominal pain, bloating, and sometimes nausea and vomiting [merriam-webster.com]

  There is persistent vomiting and abdominal distention. [medical-dictionary.thefreedictionary.com]

  Vomiting tends to be early in high-level obstruction. Faeculent vomiting is extremely unpleasant and is limited to low obstruction. Retrograde peristalsis results in faecal material being brought back. [patient.info]

• Nausea

  However, side effects include postoperative nausea and vomiting, shivering, ileus, and urine retention and are specifically discussed here. [ncbi.nlm.nih.gov]

  ˈi-lē-əs \ : obstruction of the bowel especially : functional obstruction of the gastrointestinal tract and especially the small intestine that is marked by the absence of peristalsis, is usually accompanied by abdominal pain, bloating, and sometimes nausea [merriam-webster.com]

  Symptoms are nausea, vomiting, and vague abdominal discomfort. Diagnosis is based on x-ray findings and clinical impression. Treatment is supportive, with nasogastric suction and IV fluids. [merckmanuals.com]

  Acupuncture has shown promise in both human and animal model studies to reduce post-operative nausea and vomiting and post-operative ileus. [clinicaltrials.gov]

• Constipation

  Risk factors for constipation in the ICU According to Nassar et al, (2009), constipation occurred in 69.9% of the patients who stayed for loger than 3 days in the ICU. [derangedphysiology.com]

  […] in patients aged 60 years and older clozapine is contraindicated in patients with paralytic ileus advise patients to report constipation immediately actively treat any constipation that occurs Gastrointestinal disorders Clozapine has been associated [gov.uk]

  Nonselective μ-opioid receptor antagonists reverse constipation and opioid-induced ileus but cross the blood-brain barrier and may reverse analgesia. [ncbi.nlm.nih.gov]

  Emerging pharmacologic therapies for constipation-predominant irritable bowel syndrome and chronic constipation. J Neurogastroenterol Motil. 20, 141-151. Galandiuk, S, Beyens, G, Ausma, J, and Vandeplassche, L (2008). [jnmjournal.org]

  Schizophrenia has an increased risk for megacolon and constipation whilst major depression is associated only with constipation but with none of the other colonic diseases. [patient.info]

• Abdominal Pain

  An 85-year-old man was brought to the Emergency Department due to vomiting, abdominal pain, and no stool passages for 2 days. His abdomen was markedly distended, and ileus pattern was observed in the plain film of abdomen. [ncbi.nlm.nih.gov]

  She was experiencing increasing abdominal pain and bloody diarrhea. Symptoms – Moderate abdominal pain, localized to the right lower quadrant, low-grade fever (37.9C). Physical – The abdomen was mildly distended. [undergradimaging.pressbooks.com]

  Snapshot A 47-year-old woman on the surgery floor complains of abdominal pain and bloating. She was admitted for appendicitis and underwent a laparoscopic appendectomy 2 days ago. [step2.medbullets.com]

• Abdominal Distension

  Symptoms and signs of ileus Primary features of postoperative or paralytic ileus include nausea and vomiting, inability to tolerate oral intake of food, abdominal distension, as well as the delayed passage of flatus and stool. [news-medical.net]

  There is abdominal distension and the degree will depend in the level of the ileus. The abdomen will also be tympanic to percussion and there may be some degree of tenderness. [symptoma.com]

  distension; and the absence of flatus. [ncbi.nlm.nih.gov]

  This patient with spina bifida presented with abdominal distension. This radiograph shows dilatation of the entire colon, which measures almost 11 cm. There are no dilated small bowel loops. [svuhradiology.ie]

• Quadriplegia

  Volvulus, impaction of the intestine, constipation and megacolon are all more common in patients with presenile dementia and Alzheimer's disease, Parkinson's disease, multiple sclerosis and quadriplegia. [patient.info]

• Phenylketonuria

  A 7-y-old girl with phenylketonuria and long-term constipation was admitted to the emergency department with symptoms of seizure, vomiting and abdominal distention. Laboratory results revealed hypocalcemia and hyperphosphatemia. [ncbi.nlm.nih.gov]

• Plain abdominal X-ray is an important investigation in ileus. It is done with the patient in the supine and erect positions and it will show copious gaseous dilatation of the small intestine and colon. 
• Enteroclysis is an X-ray of the small intestine using liquid contrast and studying how it moves. It is expected that the contrast medium should reach the cecum within 4 hours if the patient has paralytic ileus. If it remains motionless for more than 4 hours, then mechanical obstruction is more likely.
• Ultrasound scans are also useful in the evaluation of this condition and can accurately exclude the condition in approximately 89% of patients.
• CT scan may be employed if a high index of suspicion remains despite normal X-ray findings.
• Laboratory investigations that could be done include complete blood count, erythrocyte sedimentation rate, and blood culture to evaluate for infections. Serum electrolytes, urea and creatinine as well as blood glucose studies should be done to check for metabolic imbalance [7]. 

• Bowel Distention

  Paralytic ileus typically presents with abdominal distention and minimal pain, which intensifies with increasing distention. Bowel sounds are generally minimal or absent. [patientcareonline.com]

  Small Bowel Distention Causes An Ileus may be caused any of the following conditions: Abdominal surgery. Joint or spine surgery. Injury or trauma. Infections, such as: Abdominal infections: peritonitis, appendicitis, diverticulitis and Pneumonia. [stomawise.co.uk]

  Fluid sequestration in the small bowel increases bowel distention, a vicious circle ensues. [mysurgery.de]

  Definition Ileus is a type of bowel obstruction. It happens when wavelike contractions stop. This is called peristalsis. Peristalsis pushes material along the digestive pathway. Small Bowel Distention Copyright © Nucleus Medical Media, Inc. [winchesterhospital.org]

  These include, the fixed anatomy, gas distribution, degree of bowel distention, air fluid levels, and arrangement of the bowel loops. [hawaii.edu]

• The management of this condition depends greatly on the surgical procedure performed and also on the nature of the disease. Management of this condition aims to resolve the underlying medical conditions, correct electrolyte imbalance and regulate acid base irregularities. 
• Most cases that occur postoperatively will resolve with supportive therapy and watchful waiting. Patients should be placed on intravenous infusion and a fluid chart kept to monitor intake and output. In patient who are vomiting and who have abdominal distension, a nasogastric tube may be passed to help relieve symptoms. Drugs that cause ileus like opiates should be discontinued. Non-steroidal anti-inflammatory drugs (NSAIDs) should be used instead for pain management and it also has the additional advantage of reducing local inflammation. The drugs of choice is Celobix (COX 2 selective agent) as it eliminates the unwanted effect of platelet dysfunction seen with non-selective NSAIDs [8].
• Oral feeding should be delayed until the ileus resolves clinically. It has been advocated that chewing gum helps to promote recovery from ileus postoperatively [9]. 
• Surgery may be required if the is a complication like perforation but this is rarely the case.

The prognosis is generally good as most cases of postoperative ileus resolve within 72 hours. Very rarely is there complication. The risk of a future occurrence is however increased in a patient who has had ileus [5].

The cause of ileus is still uncertain but there have been strongly linked associated risk factors. The main identified risk factor is major gastrointestinal surgery and the postoperative state is the most popular setting for development of ileus and it is an expected complication. Other contributing factors are electrolyte imbalance, hypothyrpidism, metabolic acidosis e.g. diabetic ketoacidosis, drugs like antimuscarinics and opiates, spinal cord injury above the fifth thoracic vertebrae, chest infections, cardiopulmonary failure like myocardial infarction, sepsis, intraabdominal inflammation and peritonitis, as well as biliary and renal colic [2].

Approximately 50% of people who undergo major abdominal surgery will develop ileus postoperatively. It is seen in all age groups although it is becoming more common in the elderly, probably due to increased surgical procedures now being performed in this age group. It has no sex preferences and affects individuals of all races [3].

The exact pathway by which ileus occurs is still unclear. It has been hypothesised that it might be mediated through activation of inhibitory spinal reflex arcs. 3 separate reflexes are involved, the long, short and ultrashort reflex. The long reflexes which involve the spinal cord is the most significant. Nerve cutting techniques have been seen to either diminish or prevent the development of ileus.
Usually, the response to surgical stress leads to systemic generation of endocrine and inflammatory mediators that then promote the development of ileus. Abdominal surgeries causes increased number of monocytes, macrophages, dendritic cells, natural killer cells, T cells and mast cells. Macrophages and mast cells are the key players in the inflammatory cascade. Other mediators are nitric oxide, calcitonin gene-related peptide, substance P and vasoactive inhibitory peptide and these serve as inhibitory neurotransmitters in the nervous system of the bowel [4].

Not much is available in terms of prevention of this condition. It occurs as a result of surgery, medical conditions and injuries which makes it difficult to control [10].

Ileus initially referred to any form of intestinal obstruction including mechanical obstruction. It is however now limited to intestinal obstruction resulting from failure of peristalsis. It is a very common post-operative complication in abdominal surgery [1].

• Definition: Ileus is a type of obstruction of the intestine that is not due to a mechanical cause i.e. blockage. Is arises when the normal movement of food and faecal matter in the intestines stop. It can be seen in any age group.
• Cause: More than half of the cases usually occur after surgery. Other causes may include, infections of the abdomen or chest, heart attack, certain types of drugs, injury to the intestine, imbalance of electrolytes like potassium and a previous history of ileus.
• Symptoms: The most common symptom is pain, this is initially vague but may become like cramps. There is also abdominal swelling, hiccups, nausea and vomiting and most patients will not be able to pass gas or stool.
• Diagnosis: Plain X-rays are usually enough to make a diagnosis of ileus. But ultrasound, CT scan and contrast X-rays also have their application. Blood tests will also be done to check for infections as well as underlying factors like electrolyte imbalance or diabetes.
• Treatment: The treatment is most often conservative as most postoperative cases resolve within 72 hours. Fluid is given intravenously, feeding is withheld and if necessary, stomach and small bowel is drained with a nasogastric tube. When drug treatment is instituted, it is to correct the underlying conditions.

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2. Lyer S, Saunders WB, Stemkowski S. Economic burden of postoperative ileus associated with colectomy in the United States. J Manage Care Pharm. 2009;15:485
3. Ramirez JA, McIntosh AG, Strehlow R, et al. Definition, incidence, risk factors, and prevention of paralytic ileus following radical cystectomy: a systematic review. Eur Urol 2013; 64:588.
4. Livingston EH, Passaro EP Jr. Postoperative ileus. Dig Dis Sci 1990; 35:121.
5. Boeckxstaens GE, de Jonge WJ. Neuroimmune mechanisms in postoperative ileus. Gut 2009; 58:1300.
6. Behm B, Stollman N. Postoperative ileus: etiologies and interventions. Clin Gastroenterol Hepatol. Mar 2003;1(2):71-80
7. Barquist E, Bonaz B, Martinez V, et al. Neuronal pathways involved in abdominal surgery-induced gastric ileus in rats. Am J Physiol 1996; 270:R888.
8. Luckey A, Livingston E, Taché Y. Mechanisms and treatment of postoperative ileus. Arch Surg 2003; 138:206.
9. Asao T, Kuwano H, Nakamura J, et al. Gum chewing enhances early recovery from postoperative ileus after laparoscopic colectomy. J Am Coll Surg 2002; 195:30.
10. Yeh YC, Klinger EV, Reddy P. Pharmacologic options to prevent postoperative ileus. Ann Pharmacother. Sep 2009;43(9):1474-85