Twilight sedation is, however, inherently safer than general anesthesia; it also allows the patients to follow simple commands and even to watch the procedure on a closed-circuit monitor. Tens of millions of adults annually need to have colonoscopies, and yet many dont because of concerns about the procedure.Colonoscopy can be carried out without any sedation and without problems with pain, which is practised in several institutions in many countries with the patients agreement. This allows the patient to shift the body position to help the doctor carry out the procedure and significantly reduces recovery time and side-effects. There is some discomfort when the colon is distended with air, but this is not usually particularly painful, and it passes relatively quickly. Unsedated patients can be released from the hospital on their own without any feelings of nausea, able to continue with normal activities, and without the need for an escort as recommended after sedation. Ultrasound
Duodenography and colonography are performed like a standard abdominal examination using B-mode and color flow Doppler ultrasonography using a low frequency transducer — for example a 2.5 MHz — and a high frequency transducer, for example a 7.5 MHz probe. Detailed examination of duodenal walls and folds, colonic walls and haustra was performed using a 7.5 MHz probe. Deeply located abdominal structures were examined using 2.5 MHz probe. All ultrasound examinations are performed after overnight fasting (for at least 16 hours) using standard scanning procedure. Subjects are examined with and without water contrast.
(Personal communication to the Joint Commission on Ambulatory Care, May 1983)

Etymology
The terms colonoscopy or coloscopy are derived from the ancient Greek noun κόλον, same as English colon, and the verb σκοπεῖν, look (in)to, examine. The term colonoscopy is however ill-constructed, as this form supposes that the first part of the compound consists of a possible root κολων- or κολον-, with the connecting vowel -o, instead of the root κόλ- of κόλον. A compound such as κολωνοειδής, like a hill, (with the additional -on-) is derived from the ancient Greek word κολώνη or κολωνός, hill. Similarly, colonoscopy (with the additional -on-) can literally be translated as examination of the hill, instead of the examination of the colon. In English, multiple words exist that are derived from κόλον, such as colectomy, colocentesis, colopathy, and colostomy among many others, that actually lack the incorrect additional -on-. A few compound words such as colonopathy have doublets with -on- inserted. See also
References
Further reading
Gupta S, Lieberman D, Anderson JC, Burke CA, Dominitz JA, Kaltenbach T,  et al. (March 2020). "Recommendations for Follow-Up After Colonoscopy and Polypectomy: A Consensus Update by the US Multi-Society Task Force on Colorectal Cancer". Gastroenterology. 158 (4): 1131–1153.e5. doi:10.1053/j.gastro.2019.10.026. PMC 7672705. PMID 32044092. Gupta S, Lieberman D, Anderson JC, Burke CA, Dominitz JA, Kaltenbach T,  et al. (March 2020). "Recommendations for Follow-Up After Colonoscopy and Polypectomy: A Consensus Update by the US Multi-Society Task Force on Colorectal Cancer". Am J Gastroenterol. 115 (3): 415–434. doi:10.14309/ajg.0000000000000544. PMC 7393611. PMID 32039982. External links

Colonoscopy.