A diagnostic colonoscopy is a medical procedure used to examine the entire length of the large intestine, which includes the colon and the rectum. This examination is performed using a colonoscope, a long, flexible tube equipped with a tiny camera and a light source. The purpose is to visually inspect the inner lining of the bowel, identify abnormalities, and often, treat them in the same session. Understanding this procedure and its preparation can significantly reduce anxiety and help ensure the most accurate results.
Defining the Diagnostic Colonoscopy
A colonoscopy is a diagnostic tool that allows a physician to look for signs of disease within the gastrointestinal tract. This procedure is distinct from a screening colonoscopy, which is performed on patients without symptoms to search for early signs of cancer. A diagnostic procedure is ordered when a patient is already experiencing specific symptoms or has had an abnormal result from another test.
Common reasons for a diagnostic colonoscopy include unexplained rectal bleeding, chronic diarrhea, persistent abdominal pain, or iron-deficiency anemia. It is also frequently used as a follow-up to an abnormal non-invasive test, such as a positive stool-based test or an abnormal CT scan.
The procedure allows for therapeutic interventions. The scope has channels that permit the passage of specialized instruments to remove suspicious growths, known as polyps, through a process called polypectomy. It also enables the collection of tissue samples, or biopsies, from the colon lining to test for inflammation, infection, or cancer. A primary goal is to identify and address issues like inflammatory bowel disease, diverticulosis, or the source of internal bleeding.
Essential Preparation Steps
The preparation phase, often called the bowel prep, is the most crucial step for a successful diagnostic colonoscopy. The colon must be completely empty of all stool residue so the physician can clearly see the entire mucosal lining. A poorly prepared colon can hide small polyps or other abnormalities, necessitating a repeat procedure sooner than expected.
Preparation typically begins several days before the procedure with dietary modifications, including moving to a low-fiber diet. This means avoiding high-residue foods like nuts, seeds, whole grains, and raw fruits and vegetables for three to seven days prior. Acceptable foods generally include white bread, white rice, eggs, lean meats, and peeled potatoes.
The day before the colonoscopy, solid food is eliminated entirely, and the patient must transition to a clear liquid diet. Examples include water, apple juice, plain gelatin, and clear broth. It is important to avoid liquids with red, blue, or purple dyes, as these colors can be mistaken for blood inside the colon during the examination.
The final stage of preparation involves consuming a prescribed laxative solution, usually administered using a split-dose regimen. The first half of the solution is typically taken the evening before the procedure, and the second half is consumed the morning of the colonoscopy. This split-dose timing results in superior bowel cleansing compared to taking the entire dose the day before.
The second dose of the prep should be completed approximately four hours before the scheduled procedure time. This timing ensures the colon is at its cleanest state when the examination begins. Patients must also discuss all current medications with their physician, particularly blood thinners and diabetes medications, as these often require temporary adjustment or cessation before the procedure.
The Procedure and Immediate Aftermath
Upon arrival at the facility, the patient is prepared for the procedure in a pre-operative area where an intravenous line is placed. Most diagnostic colonoscopies are performed with moderate or deep sedation, often using an agent like Propofol. This allows the patient to sleep comfortably through the examination. This ensures the patient is relaxed and experiences no discomfort, with many having little to no memory of the actual procedure.
The patient is continuously monitored by an anesthesia professional, tracking heart rate, blood pressure, and oxygen levels throughout the examination. The procedure itself usually takes between 30 and 60 minutes, though the total time at the facility is longer due to preparation and recovery.
During the colonoscopy, the physician carefully guides the flexible scope through the rectum and into the colon, advancing it to the junction with the small intestine. To create a clear viewing space, the colon is gently inflated with air or carbon dioxide, which can sometimes cause a temporary feeling of pressure or cramping. If polyps or abnormal tissue are found, instruments are passed through the scope to remove them or take biopsies.
Immediately following the procedure, the patient is moved to a recovery area to allow the sedative to wear off. The most common immediate sensation is bloating or gas. Passing this residual gas is encouraged and helps alleviate the discomfort quickly.
Due to the lingering effects of the sedation, patients are prohibited from driving, operating heavy machinery, or making important decisions for the remainder of the day. A designated driver is required to take the patient home and should be present to assist for the first 24 hours.
Understanding Your Results and Post-Procedure Care
The physician will typically provide preliminary findings immediately after the patient is alert in the recovery room. This initial discussion covers any polyps removed, areas of inflammation noted, or other visual observations made during the examination. This provides reassurance and an early indication of the results.
If polyps were removed or biopsies were taken, those tissue samples are sent to a pathology laboratory for detailed analysis. The full pathology report, which provides a definitive diagnosis, usually takes between one and two weeks. The patient will then be contacted by the physician’s office to review these final results and discuss any necessary follow-up treatment or surveillance plan.
Post-procedure care involves gradually reintroducing a normal diet, starting with light, easily digestible foods. It is important to drink plenty of fluids to rehydrate the body. Patients may experience mild abdominal cramping, gas, or light spotting of blood in the stool, particularly if polyps were removed, which generally resolves within 24 hours.
Patients are given specific instructions on when to contact the medical team. This is necessary if they experience severe or worsening abdominal pain, significant rectal bleeding, or a fever. A follow-up appointment is then scheduled based on the diagnostic findings, which may involve another procedure in the future for surveillance or further treatment.