N-Trivia

Posted: 03 Sep 2010 02:26 PM PDT

Colonoscopy uses a flexible fiber-optic video endoscope to permit visual examination of the lining of the large intestine. It's indicated for patients with history of constipation or diarrhea, persistent rectal bleeding, and lower abdominal pain when the results of proctosigmoidoscopy and a barium enema test are negative or inconclusive.

Purpose

To detect or evaluate inflammatory and ulcerative bowel disease.
To locate the origin of lower gastro intestinal bleeding.
To aid in the diagnosis of colonic strictures and benign or malignant
lesions.
To evaluate the colon postoperatively for recurrence of polyps and
malignant lesions.

Patient Procedure

Check the patient's medical history for allergies, medications, and information pertinent to the current complaint.
Tell the patient to maintain a clear liquid diet for 24 to 48 hours before the test and to take nothing by mouth after midnight the night before.
Instruct the patient regarding the appropriate bowel preparation.
Inform the patient that he'll receive an I.V. line and I.V. sedation before the procedure.
Tell the patient that the colonoscope is well lubricated to ease insertion and initially feels cool.
Explain that he may feel an urge to defecate when it's inserted and advanced.
Inform him that air may be introduced through the colonoscope to distend the intestinal wall and to facilitate viewing the lining and advancing the instrument.

Colonoscopy Procedure

The patient is assisted onto his left side with knees flexed.
Cover the patient with drape.
Baseline vital signs are obtained.
Vital signs and electrocardiogram are monitored during the procedure.
Continuous or periodic pulse oximetry is advisable.
The physician palpates the mucosa of the anus and rectum and inserts the lubricated colonoscope through the patient's anus into the sigmoid colon under direct vision.
A small amount of air is insufflated to locate the bowel lumen and then advance the scope through the rectum.
Abdominal palpation or fluoroscopy may be used to help guide the colonoscope through the large intestine.
Suction may be used to remove blood and secretions that obscure vision.
Biopsy forceps or a cytology brush may be passes through the colonoscope to obtain specimens for histologic or cytologic examination; an electro-cautery snare may be used to remove polyps.
Tissue specimens are immediately placed in a specimen bottle containing 10% formalin and cytology smears in a Coplin jar containing 95% ethyl alcohol.
Specimens are sent to the laboratory immediately.

Nursing Interventions for Colonoscopy

The patient is observed closely for signs of bowel perforation.
Check the patient's vital signs and document them accordingly.
Watch the patient closely for adverse effects of the sedative.
After recovery from the sedation, he may resume his usual diet unless the physician orders otherwise.
The patient may pass large amounts of flatus after insufflation.
After polyp removal, the stool may contain some blood. Report excessive bleeding immediately.
If a polyp is removed, but not retrieved, give enema and strain the stools to retrieve it.

Precautions

Although it's usually a safe procedure, beware that colonoscopy can cause perforation of the large intestine, excessive bleeding, and retroperitoneal emphysema.
This procedure is contraindicated in pregnant woman near term, the patient who has had a recent acute myocardial infarction or abdominal surgery, and one with ischemic bowel disease, acute diverticulitis, peritonitis, fulminant granulomatous colitis, perforated viscus, or fulminant ulcerative colitis. For these cases of for screening purposes, a virtual colonoscopy may be an option to help visualize polyps early before they become concerns.

Interpretations

Normal Results

Normally, the mucosa of the large intestine beyond the sigmoid colon appears light pink-orange and is marked by semilunar folds and deep tubular pits.
Blood vessels are visible beneath the intestinal mucosa, which glistens from mucus secretions.

Abnormal Results

Visual examination of the large intestine, coupled with histologic and cytologic test results, may indicate procrititis, granulomatous or ulcerative colitis, Crohn's disease, and malignant or benign lesions. Diverticular disease or the site of lower gastrointestinal bleeding can be detected through colonoscopy alone.

Interfering Factors

Fixation of the sigmoid colon due to inflammatory bowel disease, surgery, or radiation therapy that may hinder passage of the colonoscope. Blood from acute colonic hemorrhage that hinders visualization. Insufficient bowel preparation or barium retained in the intestine from previous diagnostic studies which makes accurate visual examination impossible.

Complications