Colonoscopy is an essential procedure that evaluates the colon mucosa for cancer, adenomas, and inflammation. The purpose of this paper is to outline the function of colonoscopy, the procedure followed when using colonoscopy, and the information generated. The paper will also outline the validity, reliability, sensitivity, and positive predictive values of colonoscopy.

Colonoscopy in Healthcare

Colonoscopy acts as a diagnostic, elective, and therapeutic tool within healthcare settings. It is executed using a colonoscope, a hand-held flexible tube-like tool with a high-definition camera at the tip (Saito et al., 2021). The colonoscope also constitutes accessory channels that help in the insertion and fluids to cleanse the colonic mucosa and the colonoscope lens. The camera project visual data on a screen that shows abnormalities and overgrowth of the colonic wall. The data also helps in evaluating, biopsy, and removal of mucosal lesions using the accessory channels.

Colonoscopy Purpose

Colonoscopy is indicated for various reasons. First, it is used for screening colonoscopies to assess for colorectal cancer in patients at high risks like those with a history of inflammatory bowel disease, hereditary polyposis, a family history of colorectal cancer at age <60 years, and surveillance after resection of colorectal cancer (Saito et al., 2021). Healthcare guidelines recommend starting the screening at age 45 and after every 10 years. As an elective procedure, colonoscopy evaluates symptoms like inexplicable changes in bowel habits, inflammatory colitis, GI bleeding, weight loss among the geriatrics, persistent abdominal pain, and iron deficiency anemia (Saito et al., 2021). Therapeutically, colonoscopy helps with excision and ablation of lesions, removal of foreign bodies, stenosis dilation, palliative management of known neoplasms, and handling of bleeding lesions.

Colonoscopy Performance

Generally, colonoscopy can be performed in an outpatient center or within a hospital. The process duration ranges between 30 and 60 minutes. It begins with the insertion of an IV needle in the arm for pain medicine, anesthesia, or sedatives. These help to numb pain during the procedure. Once sedated, the patient then lies on a table and the colonoscope is inserted into the colon through the anus. The scope inflates the large intestines with air for clarity as the camera sends a video image to a monitor (Saito et al., 2021). The scope is adjusted for clarity and better viewing. Once at the opening of the small intestines, the scope is withdrawn as the doctor inspects the lining of the large intestines again. The process looks for the presence of colon polyps and bowel cancer to address unexplained diarrhea, blood in the stool, and abdominal pain.

Reliability and Validity of Colonoscopy

Colonoscopy remains the gold standard for colon detection despite the emergence of new screening methods. It is safe and accurate since Mack et al. (2022) explain that it yields a 94% accuracy rate in both outpatient facilities and hospitals (Mack et al., 2022). Due to its high accuracy, experts recommend a baseline colonoscopy at age 50 and a repeat of the exam every 10 years. Colonoscopy is a reliable test because it reduces the risk of colorectal cancer by 72% and reduces mortality rates by 81% (Pilonis et al., 2020). With a high accuracy rate and higher positive outcomes, the procedure remains valid and reliable.

Colonoscopy reliability, sensitivity, and Positive Predictive Values

Colonoscopy is a sensitive test that correctly identifies patients with colon diseases. Kadari et al. (2022) affirm that it is more sensitive compared to barium enema x-rays and “virtual” colonoscopy in detecting colon polyps and cancer. The researchers calculated the sensitivity of the three imaging methods based on a per-patient, per-lesion, and per histology basis. According to the study, colonoscopy found 98% of lesions 10 millimeters or larger compared to only 48% for barium enema and 59% for virtual colonoscopy (Kadari et al., 2022). Further, for smaller six-to-nine millimeters lesions, colonoscopy identified 99% of the lesions compared to 35% for barium enema and 51% for virtual colonoscopy. For adenomas, colonoscopy detected 98% of 10 millimeters or larger adenomas compared to only 55% in barium enema and 64%f for CT colonography. Accurate detection of polyps is essential because it dramatically reduces the chances of developing colon cancer.


The tool sensitivity is further confirmed by Martín‐López et al. (2017) who estimated that the sensitivity and specificity per patient for polyp detection in asymptomatic patients is 92.5 percent and 73.2 percent for colonoscopy, but only 66.8 percent and 80.3% for CT colonoscopy. According to Issa and Noureddine (2017), colonoscopy finds and resects precancerous lesions and neoplasia across the whole large bowel. It is also a definitive examination when other screening tests are positive. The test is relatively safe because it results in less than 1/1000 perforation rate.

For the predictive values, Issa and Noureddine (2017) outline a study among 1179 patients where 889 underwent colonoscopy. The result indicates that 253 colorectal neoplasia cases were diagnosed including 219 polyps and 35 cancers. The number of advanced adenomas diagnosed was 209. The authors calculated the predictive values of the colonoscopy to be 3.9% for cancer, 12,9% for advanced adenoma, and 25% for adenoma overall. The results were a bit dismal compared to the positive predictive value of the average risk population selected by a positive fecal occult blood test (FOBT). Colonoscopy positive predictive rate after positive FOBT ranges from 7.5% to 10% for cancer, 15% to 27% for advanced adenoma and 32% and37% for adenoma (Issa & Noureddine, 2017). The study confirms that patients at risk of colon-related pathologies may benefit from fecal occult blood testing to select the best candidate for colonoscopy. Regardless, the optimal method remains the colonoscopy in all patients.


Colonoscopy remains a crucial tool when diagnosing colon-related pathologies. It evaluates the large intestines and the distal portion of the small intestines. The tool used consists of accessory channels, a camera, and fluid to cleanse the colonic mucosa. It helps in screening colonoscopies, for elective purposes, and therapeutic purposes like ablation of lesions and removal of foreign bodies among others. The procedure is executed in a hospital or an outpatient and it lasts for around thirty to sixty minutes. It is safe, accurate, well-tolerated, and has a higher sensitivity. The positive predictive values are slightly lower however it remains the most ideal choice when handling issues affecting the colon.










Issa, I. A., & Noureddine, M. (2017). Colorectal cancer screening: An updated review of the available options. World journal of gastroenterology, 23(28), 5086.

Kadari, M., Subhan, M., Parel, N. S., Krishna, P. V., Gupta, A., Uthayaseelan, K., … & Sunkara, N. A. B. S. (2022). CT Colonography and Colorectal Carcinoma: Current Trends and Emerging Developments. Cureus, 14(5).

Mack, M., Luzum, M., & Wesorick, D. H. (2022). Annals for Hospitalists-March 2022. Annals of Internal Medicine, 176(3), HO3.

Martín‐López, J. E., Beltrán‐Calvo, C., Rodríguez‐López, R., & Molina‐López, T. J. C. D. (2014). Comparison of the accuracy of CT colonography and colonoscopy in the diagnosis of colorectal cancer. Colorectal Disease, 16(3), O82-O89.

Pilonis, N. D., Bugajski, M., Wieszczy, P., Franczyk, R., Didkowska, J., Wojciechowska, U., … & Kaminski, M. F. (2020). Long-term colorectal cancer incidence and mortality after a single negative screening colonoscopy. Annals of internal medicine, 173(2), 81-91.

Saito, Y., Oka, S., Kawamura, T., Shimoda, R., Sekiguchi, M., Tamai, N., … & Inoue, H. (2021). Colonoscopy screening and surveillance guidelines. Digestive Endoscopy, 33(4), 486-519.

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