Colonic Stent

Definition
Purpose
Demographics
Description
Diagnosis/Preparations
Aftercare
Normal results
Morbidity and mortality rates

Definition

A colonic stent is a tubular device made out of artificial materials that is positioned within the intestine in order to keep the intestine patent (open). A colonic stent is placed in order to relieve the symptoms of a bowel obstruction, which often occur when tumors are blocking the intestine. A stent is not a cure for the tumors, but it can provide relief of the unpleasant symptoms that accompany bowel obstruction, such as nausea and vomiting, intractable constipation, inability to pass gas, bloating, and abdominal pain.

Purpose

A colonic stent is used when a patient has an intestinal obstruction, meaning that there is something (often a tumor) blocking the intestine. During an intestinal obstruction, nothing can travel past the point of the obstruction. Therefore, the patient cannot pass gas or feces. If the patient continues to eat and/or drink while obstructed, he or she usually begins vomiting, since nothing he or she eats or drinks can proceed through the intestine. Other symptoms of intestinal obstruction include abdominal pain and uncomfortable bloating (abdominal swelling).

A colonic stent is often employed to relieve the symptoms of intestinal obstruction for either palliative purposes or as a bridge to surgery. “Palliative” treatments are things that are intended for symptom relief, but which do not hold the hope of cure. In the case of colon cancer, if the tumors are inoperable, a palliative procedure such as colonic stenting can allow the patient to experience a better quality of life, although it does not treat the actual underlying disease. In the case of a bridge procedure, colonic stenting can allow relief of symptoms until such time as surgery is deemed safe for the individual.

Demographics

Statistics on cancer of the large intestine (colon) are often linked with statistics on cancer of the rectum. Together, they are referred to as colorectal cancer. Colorectal cancer is the third most common cancer in the United States. Projections for 2008 suggest that 108,070 new cases of colon cancer alone will be diagnosed (about 14% of all cancer cases), with 53,760 cases striking men and 54,310 cases striking women. Colorectal cancer is an extremely serious form of cancer, and is responsible for about 14% of all cancer deaths annually. In 2008, the projection is that 49,960 people will die of colorectal cancer (24,260 men and 25,700 women). This means that colorectal cancer ranks third for causing cancer-related deaths in the United States.

About 90% of the time, colorectal cancer strikes people over the age of forty; most people receive the diagnosis while they are in their 50s or 60s. People with certain other conditions are more likely to develop colorectal cancer. This includes patients who have or have had breast, uterine, or ovarian cancer, ulcerative

KEY TERMS

Colon— The large intestine.

Colonoscope— The fiberoptic device used to view the inside of the large intestine, and through which a variety of procedures can be performed, including biopsies and colonic stent placement.

Colorectal— Pertaining to the large intestine and the rectum.

colitis, or Crohn’s disease. Additionally, a family history of either intestinal polyps or colorectal cancer increases an individual’s risk of colorectal cancer.

Description

Most colonic stents are placed in the intestine during the course of a colonoscopy. The same type of scope used for the diagnostic or screening exam is utilized. The stent is made of wire mesh, and is self-expanding.

While a regular screening colonoscopy can sometimes be performed in a clinic or doctor’s office, stent placement requires that the procedure take place in a hospital, so that the position of the stent can be confirmed through x rays. The procedure is usually performed by a specialist in intestinal disease, a gastroenterologist. The procedure is performed under either extensive sedation, given through an intravenous line, or with full general anesthesia.

The patient is placed on his or her side, with knees pulled up towards the chest. The colonoscope is thoroughly lubricated, then introduced into the anus. As the colonoscope progresses through the colon, the gastroenterologist will be watching carefully on a monitor, to see whether there are any other problems within the intestine. Mucus, blood, or feces that block the view may be suctioned out through the colonoscope. Air may be pumped into the intestine through the colonoscope, in order to open up the field for better viewing. During the course of the procedure, samples of the intestine (biopsies) may also be taken.

When the colonoscope reaches the level of the obstruction, the colonic stent is guided through the scope into the intestine. Once inside the intestine, the stent will expand itself into a wire-mesh tube. The colonoscope is then withdrawn through the anus, and the procedure is over.

Diagnosis/Preparations

As with any procedures involving the intestine, one of the most important ways to prepare involves cleaning the colon very thoroughly of any stool. Patients whose intestine is completely obstructed may require admittance to a hospital for this to be accomplished. Patients with only partial obstruction may be able to do this at home.

Patients who are allowed to eat solid food should assume a low-residue diet three days prior to the procedure. In general, a low-fiber/low-residue diet involves avoiding whole-grain and whole-wheat foods, processed meats, heavy, deep-fried foods, and foods in thick cream sauces.

The day before the procedure, the patient must follow a careful regimen of taking oral stool softeners, and then using a colon cleansing agent. This can be in a solution that is drunk, or in the form of multiple capsules that are taken with a great deal of water. In some cases, the patient may be required to receive one or more enemas, to make sure that all stool has been evacuated from the intestine.

The patient is usually required to stop eating all solid foods for the twenty-four hours prior to the procedure. They are usually allowed to drink clear fluids until about twelve hours prior to the procedure.

Patients who are using anticoagulant (blood thinning) medications, aspirin, or nonsteroidal anti-inflammatory drugs should discuss with their doctor whether these should be discontinued prior to the procedure, in order to decrease the risk of bleeding.

Aftercare

Patients who have had a colonic stent placed are usually kept in the hospital for a day or two after the procedure, in order to carefully monitor them. They will be slowly progressed to clear fluids, then full fluids, then a soft diet, and then a full diet.

Normal results

Successful placement of a colonic stent allows for the passage of both gas and stool through the intestine. Pain, bloating, and nausea are relieved, and the patient can resume eating and drinking normally. In patients awaiting surgery, a normal result allows the surgery to be scheduled nonemergently, thus decreasing the risk of colostomy as part of the surgical outcome. Success is achieved between 93 and 95% of the time in colonic stent placement.

Morbidity and mortality rates

Complications of colonic stent placement include dislodging of the stent from its original location (has occurred in about 10-12% of patients), passage of the stent in stool, obstruction of the stent’s lumen with impacted stool or expanding tumor, perforation (occurs in about 4% of patients) of the intestine, bleeding, abdominal pain, rectal spasms, embolism.

Resources

BOOKS

Abeloff, M. D., et al. Clinical Oncology, 3rd ed. Philadelphia: Elsevier, 2004.

Feldman, M., et al. Sleisenger & Fordtran’s Gastrointestinal and Liver Disease, 8th ed. St. Louis: Mosby, 2005.

PERIODICALS

Fregonese, D. “Ultraflex precision colonic stent placement as a bridge to surgery in patients with malignant colon obstruction.” Gastrointestinal Endoscopy 67 (2008): 68–73.

Repici, A. “WallFlex colonic stent placement for management of malignant colonic obstruction: a prospective study at two centers.” Gastrointestinal Endoscopy 67 (2008): 77–84.

Rosalyn Carson-DeWitt, MD