History
Obtain the patient's history of bowel movements, flatus, obstipation (ie, no gas or bowel movement), and associated symptoms. Attempt to distinguish complete bowel obstruction from partial obstruction, which is associated with passage of some gas or stool. Also inquire about the patient's current and past history in an attempt to determine the most likely cause.
Major complaints in patients with large-bowel obstruction (LBO) include abdominal distention, nausea, vomiting, and crampy abdominal pain. An abrupt onset of symptoms makes an acute obstructive event (eg, cecal or sigmoid volvulus) a more likely diagnosis. A history of chronic constipation, long-term cathartic use, and straining at stools implies diverticulitis or carcinoma.
Changes in the patient's caliber of stools strongly suggest carcinoma. When associated with weight loss, the likelihood of neoplastic obstruction increases.
When giving a history of obstipation, patients may state that pants or belts are not fitting properly.
A history of recurrent left-lower-quadrant abdominal pain over several years is more consistent with diverticulitis, a diverticular stricture, or similar problems.
A history of aortic surgery suggests the possibility of an ischemic stricture.
Complete obstruction vs partial obstruction vs ileus
Complete obstruction is characterized by the failure to pass either stool or flatus with an empty rectal vault (unless the obstruction is in the rectum). If the patient has a partial obstruction, the patient appears obstipated but continues to pass some gas or stools. Partial obstructions are a less urgent condition.
LBO from an anatomic abnormality leads to colonic distention, abdominal pain, anorexia, and, late in the course, feculent vomiting. Persistent vomiting may result in dehydration and electrolyte disturbances. Pneumaturia, mucinuria, or fecaluria may occur if fistulization of the sigmoid colon to the bladder occurs. This is most often seen in the setting of diverticulitis or cancer.
LBO is typically characterized by a slow onset of symptoms and may not cause vomiting despite a markedly distended bowel.
Paralytic ileus can be seen in the setting of peritonitis or traumatic injury. Bowel sounds are diminished, and abdominal cramping is less common.
Colonic lesion development history
Right-side colonic lesions can grow quite large before obstruction occurs because of the large capacity of the right colon and soft stool consistency. Sigmoid colon and rectal tumors cause colonic obstruction much earlier in their development, because the colon is narrower and the stool is harder in that area.
Obstruction secondary to intussusception
Patients may describe intermittent, crampy abdominal pain that is colicky and relieved by assuming fetal position. Weight loss and fatigue are common.
Obstruction secondary to ACPO
Symptoms of acute colonic pseudo-obstruction (ACPO; Ogilvie syndrome) are similar to those of LBO and usually develop over 3-7 days or, less commonly, over 24-48 hours. Abdominal distention is the earliest sign. Late symptoms are similar to those seen with LBO. Nausea and vomiting are not predominant complaints, but fever may be present in the setting of colonic ischemia or perforation.
Physical Examination
Although a complete physical examination is necessary, key elements of the physical examination should focus on a thorough examination of the abdomen, groin, and rectum.
Abdominal examination
Perform the examination in standard fashion, that is, inspection, auscultation, percussion, and palpation.
Abdominal distention may be significant in patients with a large-bowel obstruction (LBO). The bowel sounds may be normal early on but usually become quiet, and the abdomen is hyperresonant to percussion.
Palpation of the abdomen may reveal tenderness. Fever, severe tenderness, and abdominal rigidity are ominous signs that suggest peritonitis secondary to perforation. The cecum is the area most likely to perforate (according to the Laplace law stating that in a long pliable tube, the site of largest diameter requires the least pressure to distend [13] ; thus, in a distal LBO, with a competent ileocecal valve, the cecum is the most common site of perforation).
The presence of true involuntary guarding or peritoneal signs may be indicative of another intra-abdominal process, such as an abscess. Rebound tenderness is best elicited by having the patient cough or by shaking the bed.
Sigmoid diverticulitis and a perforated sigmoid secondary to carcinoma are clinically difficult to differentiate. Guaiac-positive stool may be seen with carcinoma or diverticulitis.
A rectal or lower sigmoidal mass may be palpated on rectal examination. An abdominal mass or fullness may be palpated if a tumor is present in the cecum.
Examination of inguinal and femoral regions
Evaluation of the inguinal and femoral regions should be an integral part of the examination in a patient with suspected large-bowel obstruction.
Incarcerated hernias represent a frequently missed cause of bowel obstruction. In particular, colonic obstruction is often caused by a left-sided inguinal hernia with the sigmoid colon incarcerated in the hernia. [14] Any old surgical scar should also be examined for the possibility of an incarcerated incisional hernia.
Digital rectal examination
Perform a digital rectal examination (DRE) to verify the patency of the anus in a neonate. The examination focuses on identifying rectal pathology that may be causing the obstruction and determining the contents of the rectal vault.
Hard stools suggest impaction; soft stools suggest obstipation. An empty vault suggests obstruction proximal to the level that the examining finger can reach.
Fecal occult blood testing (FOBT) should be performed. A positive result may suggest the possibility of a more proximal neoplasm.
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This chest radiograph demonstrates free air under the diaphragm, indicating bowel perforation in a patient with large-bowel obstruction. Radiograph courtesy of Charles J McCabe, MD†.
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Abdominal (kidney-ureter-bladder [KUB]) film of a patient with obstipation. Dilatation of the colon is associated with large-bowel obstruction. Radiograph courtesy of Charles J McCabe, MD†.
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Gastrografin study in a patient with obstipation reveals colonic obstruction at the rectosigmoid level. Radiograph courtesy of Charles J McCabe, MD†.
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Contrast study demonstrates colonic obstruction at the level of the splenic flexure, in this case due to carcinoma. Radiograph courtesy of Charles J McCabe, MD†.
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Abdominal (kidney-ureter-bladder [KUB]) radiograph depicting massive dilatation of the colon due to a cecal volvulus. Radiograph courtesy of Charles J McCabe, MD†.
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Contrast study of patient with cecal volvulus. The column of contrast ends in a "bird's beak" at the level of the volvulus. Radiograph courtesy of Charles J McCabe, MD†.
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Massive dilatation of the colon due to a sigmoid volvulus. Radiograph courtesy of Charles J McCabe, MD†.
