Bowel Obstruction Clinical Features

Bowel Obstruction

• Small bowel obstruction causes periumbilical pain and cramp with paroxysms of pain occurring every four or five minutes.
• Focal and constant pain may indicate peritoneal irritation related to complications (ischemia, bowel necrosis).
• Proximal small bowel obstruction can cause severe nausea and vomiting.
• Large bowel obstruction presentation depends on the location and etiology of the obstruction.
• Tumor (Colonic adenocarcinoma) is the most common cause of large bowel obstruction, followed by adhesive disease and volvulus.

Clinical Features

• Dehydration is a hallmark feature of bowel obstruction, characterized by tachycardia, orthostatic hypotension, and reduced urine output.
• Fever may be associated with infection or complications of obstruction.
• Hematochezia can be a sign of tumor, ischemia, or inflammatory mucosal injury, or intussusception.
• Abdominal inspection reveals distention, surgical scars, and abdominal wall hernia.

Diagnosis

• History and examination confirm the diagnosis, with plain radiography and CT of the abdomen being the most practical and useful diagnostic tools.
• Plain radiographs are used to quickly confirm a diagnosis, while CT of the abdomen characterizes the nature, severity, and potential etiologies of the obstruction.

Pathophysiology

• Luminal obstruction leads to progressive dilation of the intestine proximal to the blockage, while distal to the blockage the bowel decompresses as luminal contents pass.
• Swallowed air and gas from bacterial fermentation can accumulate, adding to bowel distention.
• The bowel wall becomes edematous, normal absorptive function is lost, and fluid is sequestered into the bowel lumen.

Risk Factors

• Prior abdominal or pelvic surgery
• Abdominal wall or groin hernia
• Intestinal inflammation
• History of or increased risk for neoplasm
• Prior abdominal or pelvic irradiation
• History of foreign body ingestion

Clinical Presentation

• Abrupt sudden onset of abdominal pain, nausea, vomiting, and abdominal distention
• Intermittent, acute symptoms that resolve only to recur again
• Some patients with chronic, partial obstruction may develop superimposed symptoms and signs of acute bowel obstruction

Symptoms

• Abdominal pain in 70-92% of patients
• Vomiting in 77-82% of patients
• Absence of passage of flatus in 90% or stool in 81% of patients

Differential Diagnosis

• Nausea and vomiting may be a manifestation of many disorders
• Bowel obstruction is uncommon relative to all possible causes of nausea and vomiting and abdominal pain
• Pain often precedes vomiting when associated with an acute surgical etiology

Adynamic (Paralytic) Ileus

• Causes include post-operative complications, peritonitis, trauma, intestinal ischemia, and medications
• Exacerbated by electrolyte disorders, particularly hypokalemia
• Initial return of bowel function and oral intake, followed by nausea, vomiting, abdominal pain, and distention, indicates mechanical bowel obstruction

Intestinal Pseudo-Obstruction

• A chronic condition characterized by symptoms of recurrent abdominal distention associated with nausea, vomiting, and diarrhea
• The colon is generally affected more than the small intestine
• No mechanical cause can be demonstrated, and the patient frequently has a history of several previous operations for bowel obstruction during which no cause for obstruction could be found.