Bowel Obstruction
Kenneth D. Hatch
GENERAL PRINCIPLES
Definition
Obstruction of the bowel is divided into two categories: adynamic ileus and mechanical obstruction.
After laparotomy, the small bowel normally undergoes paralytic ileus for 6 to 12 hours, the stomach for 24 to 48 hours, and the large bowel for 2 to 4 days.
Adynamic ileus is suspected when the patient has absent bowel sounds and abdominal distention persisting beyond the expected 2 to 4 days. When the patient becomes nauseous and has vomiting, she may have adynamic ileus. An abdominal radiograph series will disclose scattered air throughout the intestine with some dilation of the small bowel and air-fluid levels (Fig. 29.1).
Mechanical obstruction can occur in both the small and large bowels. Small bowel obstruction (SBO) comprises about 75% of the bowel obstructions on a gynecologic oncology service. An abdominal radiograph will reveal the typical “stair-step” pattern of loops of the small bowel. A CT scan will reveal the area of transition where the obstruction is located (Fig. 29.2).
Large bowel obstruction is most often due to recurrent gynecologic cancers obstructing the pelvic colon (Fig. 29.3). When the cecum is dilated greater than 12 cm, the obstruction has been greater than 4 days, and there is direct tenderness over the cecum, emergent diversion will be necessary to prevent rupture.
Differential Diagnosis
Nongynecologic cancers such as colorectal, pancreatic, gastric, and metastatic breast cancer may present with bowel obstruction, ascites, and pelvic mass.
Inflammatory conditions such as diverticulitis, tuboovarian abscess, and inflammatory bowel disease should be considered.
Nonoperative Management
Treatment of postoperative ileus is conservative. Ample IV fluid replacement and correction of electrolytes are begun. Reduce or eliminate narcotic pain medications. If the patient has vomiting, a nasogastric (NG) tube should be placed to reduce the risk of aspiration.
SBO is suspected if the patient is still distended, not passing flatus, and requiring an NG tube 8 to 10 days postoperatively. The patient may transition from an ileus to an obstruction when the “soft” postoperative adhesions begin to contract and create an obstructive kink in the bowel.
An upper GI soluble contrast study is highly accurate in differentiating a lingering ileus from an SBO. In addition, it may have some therapeutic value, as the hypertonic contrast pulls additional fluid onto the lumen of the bowel.
Ceresoli et al. published meta-analysis papers reporting the use of water-soluble contrast in postoperative patients with adhesive SBO and found it reduced the need for surgery, the length of stay, and the time to resolution of the obstruction compared with conservative support.
Scotté published a randomized prospective trial of water-soluble contrast versus saline in a population of patients with adhesive SBO and who were not postoperative patients. He reported that the water-soluble contrast did not decrease
the rate of operative intervention (26% vs. 21% in the saline group), the hospital stay, or the morbidity.
Figure 29.1. Radiographic image of ileus with scattered loops of air-filled small bowel.
Figure 29.2. Small bowel obstruction. Radiograph showing gas-filled loops of small bowel. The arrow in the CT shows the transition point.
For postoperative patients, the conservative therapy will be successful in 90% of the patients with SBO.
For non-postoperative patients, conservative therapy will succeed in 20% to 80% of patients. The wide range of success depends on the etiology of the obstruction, with cancer-related obstruction being the highest.
Figure 29.3. CT of large bowel obstruction from ovarian cancer. The colostomy performed on this patient is shown in the video (Video 29.1
).
Large bowel obstructions rarely occur postoperatively. The patients will most often present with severe abdominal cramping pain. An abdominal radiograph will be diagnostic. Conservative treatment is rarely effective.
IMAGING AND OTHER DIAGNOSTICS
The initial study should be the abdominal radiograph. If the pattern is that of a postoperative ileus, then continue the conservative treatment until 8 to 10 days postoperatively, then perform the contrast study. Water soluble is preferred instead of barium by most clinicians. Barium does not absorb fluids and does not stimulate peristalsis. It may pass into the large bowel and then become impacted. If a perforation occurs, the ensuing barium peritonitis may be morbid.
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