Colonoscopy is the endoscopic examination of the large colon and the distal part of the small intestine with a CCD camera or a fiber optic camera on a flexible tube passed through the anus for the visual diagnosis of polyps or ulcerations and for biopsy or removal of suspected lesions. It is possible to remove polyps smaller than one millimeter by Colonoscopy. Gastrointestinal hemorrhage, sudden changes in bowel habits, suspected Cancer are usual indications for Colonoscopy. Colonoscopy can be used to diagnose Colon Cancer and Inflammatory Bowel Syndrome. In contrast to Sigmoidoscopy that allows the view of only the final two feet of the colon, Colonoscopy allows the examination of the entire colon. According to the new American guidelines, Colonoscopy is the preferred method for screening asymptomatic people for Colorectal Cancer (CRC). A study to perform a meta-analysis of the prospective cohorts using total Colonoscopy for screening an asymptomatic population for CRC has shown that Colonoscopy is feasible and a suitable method for screening for CRC in asymptomatic people (Niv et.al, 2008).
Interventions During Preparation
For the Colonoscopy to be performed effectively, the colon should be free of any solid matter. Hence, the patient is put on a low fibre or clear-fluid only diet for one to three days before the procedure. The day before the Colonoscopy, whole bowel irrigation is performed using a solution of polyethylene glycol and electrolytes. Alternatively, the patient is administered a laxative preparation such as Bisacodyl, Phospho Soda, Sodium Picosulfate, Sodium Phosphate or Magnesium Citrate. Inadequate preparation of the bowel for Colonoscopy can result in both missed pathological lesions and cancelled procedures (Ness et.al, 2001). Bowel preparation appears to be also a key deterrent for early detection of Colorectal Cancer during Screening Colonoscopy. Adequate hydration is important before, during and after bowel preparation regardless of the bowel preparation administered (Dykes and Cash, 2008). A recent study to compare the efficacy and patient acceptance of an oral high dose of senna to conventional polyethylene glycol-electrolyte lavage solution (PEG-ES) in adults undergoing elective Colonoscopy has shown that the quality of colon cleansing, overall tolerance of the preparation and compliance are significantly better with senna with lower nausea and vomiting (Radaelli et.al, 2005). The use of the less-invasive oral sodium phosphate low-volume colon-cleansing preparation is recommended for colonic cleansing in children in terms of tolerance, discomfort, and administration. Nurses should ensure an adequate oral fluid intake during the preparation time and avoid its use in patients with renal insufficiency (Da Silva et.al, 1997). It is better to avoid aspirin and ibuprofen combinations at least ten days prior to the procedure to avoid the risk of bleeding if a Polypectomy is to be performed. A blood test is usually done before the procedure (Decker and Joe, 2007).
Interventions During Procedure
Although Colonoscopy can be performed in unsedated state, intravenous sedation with midazolam or fentanyl is recommended during the procedure. A study to evaluate the safety of propofol sedation administered by intermittent intravenous bolus titration by trained Practice Nurses in a cohort of outpatients of an ambulatory practice for Colonoscopy has shown that the cecum can be reached in 99 % of such Colonoscopies and propofol can be administered safely for ambulatory Colonoscopy by Trained Practice Nurses. After an initial rectal examination to assess the sphincter tone, the endoscope is passed via the anus towards the rectum, colon and the terminal ileum. A nurse's knowledge of oxygen saturation and the timing of nursing interventions have a relationship for positive patient outcomes in Colonoscopic procedures (Hinzmann et.al, 1992). Colonic loop formation can prolong Colonoscopy, increase patient discomfort and preclude complete examination (Sorbi et.al, 2001). During screening, a closer visual inspection is done by withdrawal of the endoscope over the course of 20 to 25 minutes. Suspicious lesions should be cauterized, treated with laser light or cut with an electric wire for biopsy or complete removal Polypectomy.
Although Colonoscopy has a low risk of complications, serious complications like Gastrointestinal Perforation, Bleeding and Splenic Rupture are sometimes life threatening. The patient may experience hemorrhagic shock several hours after a diagnostic Colonoscopy and requires an emergency Splenectomy or experience symptomatic anemia several days after a diagnostic Colonoscopy to be treated by Angiographic Embolization (Holubar et.al, 2007). It is better to use a Pediatric Colonoscope instead of the standard Colonoscope in female and some male adult patients with a fixed, angulated colon (Okamoto et.al, 2005). Flatulence and minor wind pain is common during or after the procedure. Nurse's knowledge and skills in managing pain during Colonoscopy procedures is vital. The majority of nurses have been shown to use non-pharmacological methods of managing pain and have practice-based knowledge of pain management during the Colonoscopy procedure (Ylinen et.al, 2007).
Invendoscope is a new Colonoscope consisting of an endoscopic sheath with an inverted sleeve, instrument channel and an electrohydraulic deflecting tip steered by a hand-held device and propelled by a motorized drive unit. Recent evaluation of the instrument has demonstrated 82% cecum reach and an absence of pain in 92% of cases (Rösch et.al, 2008). Virtual Colonoscopy is based on 2D and 3D imagery reconstructed from computed tomography (CT) scans or from nuclear magnetic resonance (MR) scans. Although, Virtual Colonoscopy does not allow for therapeutic maneuvers such as polyp/tumor removal or biopsy nor visualization of lesions smaller than 5 millimeters, Virtual Colonoscopy provides valuable information on both proximal and extracolonic pathology (White et.al, 2008). CathCam is a flexible guide wire-directed thin diagnostic Colonoscope designed to overcome the limitations of conventional Colonoscopes (Ravens et.al, 2006). Sightline ColonoSight System designed for a disposable, power-assisted, non-fiber-optic Colonoscopy has disposable components protecting the reusable parts from contact with colonic contents and eliminating the need for disinfection between procedures. Further it has an air-pressure-powered engine that assists in Colonoscope advancement and a light emitting diode (LED) illumination eliminating the need for fiber optics and an external light source (Shike et.al, 2008). Double-balloon endoscopy is a new technique for antegrade or retrograde examination of the small intestine, with a flexible scope and a sliding overtube with a balloon at the distal end (Pasha et.al, 2007). A Colonoscope thinner than the pediatric Colonoscope, 9.8 mm in diameter, has been evaluated recently and has been shown to outperform the Pediatric Colonoscope in cases with stricture or severe angulation (Okamoto et.al, 2005).
A novel Computer-Assisted Colonoscope that utilizes a fully articulated, computer-controlled insertion tube has been evaluated recently that encodes the position and angle of the scope's tip into a computer algorithm. This Colonoscope has been shown to reduce discomfort during Colonoscopy related to looping, which displaces the colon from its native configuration and stretches attachments to the mesentery. An increasing interest in Natural Orifice Surgery (NOS) and the lumen of the appendix being connected to the cecum, a minimally invasive method for removing the appendix by Colonoscopy has been evaluated recently. Various prototypes have been evaluated by inserting them into the appendiceal orifice to its luminal tip, with the intent to invert the appendix in a controlled fashion into the lumen of the Cecum (Silberhumer et.al, 2008).
Colonoscopy is the preferred method for screening asymptomatic patients for Colorectal Cancer and Inflammatory Bowel Syndrome. Nurse care is vital during the preparation and procedure for the Colonoscopy to be performed effectively.
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Charles L. Berman
Liz Di Bernardo