As with any assessment, a thorough history and physical examination will help in delineating the problem. Most patients with colonic obstruction will present with abdominal distention, nausea, and vomiting. The duration of these symptoms can define the acuteness the process. Any associated pain implies urgency of the situation. Weight loss and melena would be concerning for a malignant process, as would a strong family history of cancer. Passing of flatus and stool differentiate between complete and partial obstruction. A history of previous cancer or current cancer would raise the concern for recurrence or disease progression. A previous history of abdominal surgery increases the likelihood of obstruction (adhesions) or incisional hernia. A complete assessment of the patient’s comorbidities and medications is essential to the overall care of the patient.

On physical examination, it is important to assess the patient’s vital signs for hemodynamic stability (instability witnessed in cases of dehydration, sepsis…). Patients with colonic obstruction often have abdominal distention and tympany. Dullness to percussion implies ascites as the cause of distention. Examine the abdomen for incisional scars and hernias. Be mindful of both internal hernias and adhesions as a cause of obstruction. The transverse and sigmoid colon have been reported to be incarcerated in hernias leading to obstruction. As always, a digital rectal examination is a key component of the physical examination.

Laboratory tests that are usually obtained include a complete blood count (CBC), basic metabolic panel, lactate level, and coagulation panel. Additional laboratory studies should be ordered as indicated. The CBC may point to an infectious process with a leukocytosis or a malignancy with anemia. The metabolic panel evaluates the patient’s electrolyte balance and renal function as well as the hydration status. A lactate level is frequently ordered in patients with abdominal pain to rule out an ischemic process. Coagulation studies and a type and screen are usually indicated if surgical intervention is entertained.

The first radiologic study commonly ordered is an acute abdominal series comprised of an upright chest radiograph, and an upright and flat abdominal radiograph. If free air is seen under the diaphragm (pneumoperitoneum), emergent surgical exploration is usually indicated. The presence of stool and/or air throughout the colon and rectum often (yet not always) points to a nonsurgical etiology. Occasionally, foreign bodies are seen on the radiographs. The classic radiographic presentation of sigmoid volvulus is described as a coffee bean, omega loop, or bent inner tube appearance (two dilated colonic limbs with the round loop in the right upper quadrant and the tip pointed to the left lower quadrant). A cecal volvulus appears as a dilated loop in the mid-abdomen, sometimes described as a “comma,” and often seen with dilated small bowel on the right of the abdomen on radiographic imaging. It is important to measure the cecal diameter in all cases of colonic obstruction as a diameter of 10–12 cm poses an increased risk of perforation and may require emergent decompression either endoscopically or surgically. Computed tomography of the abdomen and pelvis is often performed as a subsequent study. It provides significantly more data as to the underlying pathology. It has been reported to be highly accurate in diagnosing volvulus demonstrating a “swirl sign” of the twisted mesenteric pedicle.

Contrast enemas can be both diagnostic and therapeutic. Water-soluble contrast, such as gastrografin, can help evacuate the colon in patients with stool impaction. A double contrast enema with barium is helpful in cases when the colonoscopy in incomplete and localization of the stricture site is necessary for surgical planning. However, barium should be avoided in cases of high-grade or complete obstruction and in patients with perforation or potential perforation.

Endoscopy is also both diagnostic and therapeutic in certain types of colonic obstruction. It is invaluable in the diagnosis of malignant colonic obstructions. With self-expanding metallic stents, it can change an acute colonic obstruction with possible two-stage surgery to an elective one-stage resection. It has also been recommended to be the first decompressing therapy for volvulus. Colonoscopy is also helpful in diagnosing ischemic colitis as well as pseudo-membranous colitis.

Fluid resuscitation and electrolyte correction are the first line of treatment for patients with colonic obstruction. Nasogastric tube is indicated only in those with nausea and vomiting. A Foley catheter is required for close monitoring of the urine output, an indication of the patient’s volume status. The definitive management for differing pathologies will follow.