Large-Bowel Obstruction Clinical Presentation

Obtain the patient's history of bowel movements, flatus, obstipation (ie, no gas or bowel movement), and symptoms. Attempt to distinguish complete bowel obstruction from partial obstruction, which is associated with passage of some gas or stool, and from ileus. 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 (eg, passage of melanotic bloody stools) strongly suggest carcinoma. When associated with weight loss, the likelihood of neoplastic obstruction increases.

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 vs partial obstruction vs ileus

Complete obstruction is characterized by the failure to pass either stools or flatus and the presence of an empty rectal vault upon rectal examination, unless the obstruction is in the rectum. Partial obstruction, in which the patient appears obstipated but continues to pass some gas or stools, is a less urgent condition.

Distinguishing colonic ileus from organic obstruction is important. Ileus may be suggested by abdominal pain as a dominant feature of the clinical presentation, by peritoneal signs, or by the presence of pronounced fever and leukocytosis.

Large-bowel obstruction 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 when fistulization of the sigmoid colon to the bladder occurs secondary to diverticulitis or cancer.

Colonic lesion development history

Right-sided 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.

LBO before perforation

Obstruction that dilates the colon causes vague, visceral abdominal cramps. Pain receptors sense distention or vigorous contraction. Peritonitis may ensue.

When giving a history of obstipation, patients may state that pants or belts are not fitting properly.

Large-bowel obstruction, or even constipation, may be accompanied by some degree of fever or leukocytosis. Similarly, based on peritoneal signs, distinguishing the tender gas-filled and stool-filled colon observed in organic obstruction from a tender abdomen due to peritonitis is difficult.

Intervention is necessary to prevent perforation.

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), or Ogilvie syndrome, are similar to large-bowel obstruction and usually develop over 3-7 days, or less commonly, over 24-48 hours. About 83% of patients complain of mild/moderate pain, which is typically diffuse and colicky in nature.

Nausea and vomiting are not predominate complaints, but fever may be present in the setting of colonic ischemia or perforation.

Although a complete physical examination is necessary, key elements of the physical examination should focus on 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 reveals 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 (following the Laplace law that states, in a long pliable tube, the site of largest diameter requires the least pressure to distend^[10] ; thus, in a distal large-bowel obstruction, with a competent ileocecal valve, the cecum is the most common site of perforation.^[10] ).

The presence of true involuntary guarding or peritoneal signs should raise the specter of another intra-abdominal process, such as an abscess. The practice of seeking rebound tenderness is misleading and potentially cruel. Many patients without peritoneal signs complain vigorously after an aggressive rebound maneuver. Seeking tenderness and pain by having the patient cough or by shaking the bed probably is more useful.

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.

Digital rectal examination and testing for occult blood

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.