Disorders of the Gastrointestinal System, 2nd Edition
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Obstruction of the intestines causes GI secretions, gas, and swallowed air to accumulate near the location of the ob- struction. Peristalsis increases above and below the obstruction as the bowel tries to force its contents through the block- age. This damages intestinal mucosa and leads to distention and edema at and above the area of blockage. Distention interferes with venous blood flow and blocks normal absorption. Malabsorption causes the bowel to secrete water, sodi- um, and potassium, which collect in the lumen, thus worsening the distention and edema and further compromising blood flow (Smith et al., 2022). Bowel obstruction can lead to metabol- ic alkalosis and acidosis because of dehy- dration and loss of fluids and electrolytes. In developed countries, the leading cause of small bowel obstruction is adhesions. Malignancies, Crohn’s disease, and her - nias can cause obstructions (Bordeianou & Yeh, 2021). Large bowel obstruction is generally caused by malignancy or an in- flammatory process such as diverticulitis (Yeh & Bordeinabou, 2021). Mechanical obstruction may be caused by blockage from foreign objects (gall- stones, swallowed toys, illegal drug pack- ages, fruit pits), bowel wall compression, severe constipation, intussusception, or tumors. Nonmechanical obstruction may be caused by physiologic alterations such as the effects of medications such as opi- oids that slow peristalsis, thrombosis, or paralytic ileus (Bordeianou & Yeh, 2021). A paralytic ileus is a form of small bowel obstruction that can develop after surgery but can also have other etiologies. Para- lytic ileus causes a decrease or absence of intestinal motility, which creates blockage and backup of food through the GI tract. It usually resolves with bowel rest, gas-
tric decompression via nasogastric tube, and fluid and electrolyte repletion, but it can progress to require an ostomy or to a life-threatening obstruction in some cas- es (Cagir, 2021; Weledji, 2020). Postop- erative patients are typically restricted to only ice chips or nothing by mouth until a paralytic ileus can be ruled out by active bowel sounds in all four quadrants, flatus, or hunger without nausea. If treatment is prolonged, parenteral nutrition may be necessary (Cagir, 2021; Weledji, 2020). Signs and symptoms of intestinal ob- struction can begin with pain, nausea, and vomiting, and it may progress to shock, sepsis, and death if left untreated (Bordeianou & Yeh, 2021). These can vary depending on the location of the obstruc- tion and whether it is partial or complete. Signs and symptoms of small intestine obstruction include nausea, vomiting, constipation, abdominal distention, and colicky pain. Extreme thirst, malaise, and dry oral mucous membranes and tongue may develop. Bowel sounds are heard on auscultation. These may be loud and even heard without using a stethoscope. There is constant pain upon abdominal palpa- tion and rebound tenderness if strangula- tion of the bowel is present. Untreated ob- struction may cause hypovolemic shock. If the small bowel is completely obstruct- ed, extreme peristalsis may develop as the bowel attempts to move its contents through the obstruction. Bowel contents may be moved toward the mouth, and the vomitus will contain gastric juice, then bile, and eventually the contents of the ileum (Bordeianou & Yeh, 2021). In large intestinal obstruction, symp- toms progress more slowly because the large bowel can absorb fluid and distend well beyond its typical size. Initially, con- stipation may be the only sign; generally,
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