Ileus is a functional, non-mechanical inhibition of coordinated gastrointestinal activity that frequently occurs after abdominal surgery. The pathogenesis of this condition is multifactorial, with disturbances in inflammatory, neurologic, immunologic, electrolyte, and receptor-mediated functioning.
The occurrence of this condition has consequences for both patients and hospitals alike. Ileus slows patient recovery, thereby prolonging hospital stay, and is associated with an increased number of diverse complications, which are primarily thrombotic or infectious in nature. In addition, prolonged hospital stays often have a negative psychological impact on a patient, creating an additional barrier for adequate postoperative recovery.
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Symptoms and signs
The primary features of postoperative or paralytic ileus include nausea, vomiting, inability to tolerate oral intake of food, abdominal distension, as well as the delayed passage of flatus and stool. The wall of the gut can become congested and edematous in this condition, and a significant amount of fluid can be secreted into the bowel lumen. This can in turn cause dehydration and significant electrolyte imbalance.
Upon physical examination, the patient can be severely dehydrated, which results in hypotension, tachycardia, and the loss of skin turgor. Additionally, the distended abdomen is often tympanic. Unlike mechanical obstruction, where peristalsis may be visible and bowel sounds increased, in postoperative and paralytic ileus, both of these signs are absent. The rectal examination will also typically shows an empty rectum.
Types of ileus
The terminology used to describe postoperative ileus falls into two distinct classifications. Postoperative ileus is defined as the obligatory period of gastrointestinal dysfunction that occurs instantly after surgery, with resolution signaled by the passage of stool or flatus, as well as an improved tolerance of oral intake.
Comparatively, prolonged postoperative ileus should have at least two of the following six signs:
- Inability to tolerate oral intake 24 hours after surgery
- Absence of flatus 24 hours after surgery
- Abdominal distension
- Radiologic evidence of bowel distension without mechanical obstruction
Initial examinations of ileus should encompass full blood count and other laboratory tests. The hemoglobin and hematocrit may be raised due to hemoconcentration, which is often a consequence of dehydration. In addition, the white blood cell (WBC) count is sometimes elevated. Electrolyte disturbances are often found, depending on the severity of the condition; therefore, raised urea and creatinine indicate renal impairment.
An abdominal X-ray indicative of ileus will show copious gas dilatation of large and small bowels. An erect chest film is necessary in order to exclude perforation, which can be identified as free air beneath a raised hemidiaphragm. In patients with risk factors for gastroparesis, a gastric emptying study is sometimes considered.
In postoperative patients, a computerized tomography (CT) scan is performed if the presumed ileus has not resolved within one week, or the clinical condition of the patient is getting worse. Such imaging of the abdomen may be performed with intravenous and oral water-soluble contrast. In the immediate postoperative period, a CT scan with an oral contrast represents a method of choice in distinguishing prolonged ileus from mechanical obstruction.