Minor Surgery - Best treatment › Endoscopic procedures
Introduction
Endoscopic techniques have been evolving rapidly since the introduction of the cystoscope during the last quarter of the 19th century. Urology, followed by pulmonology and thoracic surgery (which used thoracoscopy and bronchoscopy), were the first disciplines that took advantage of the possibility of having access to the human body’s tracts and cavities. The early devices were rigid endoscopes, with varied directions of view (the most common are 0°, 30° or 70°), and viewing angles (usually of 60-70°).
With the advent of the fibre-optic and subsequently endoscopic technology, the practice of medicine and surgery has advanced as it relates to the gastrointestinal tract, upper respiratory tract and bronchial tree as well as the genitourinary system. Endoscopy of these tracts has also transformed the surgical practice of gastroenterology, thoracic surgery, otorhinolaryngology, gynaecology, and urology (e.g. bronchoscopes can be used to remove foreign bodies from the airway; other endoscopes can aid in the removal of sinus or nasal tumours; approximately 70% of all urological procedures can now be undertaken endoscopically) (Wrightson WR (ed), 2006) , (Coptcoat M, 1989) . Vascular surgeons are also turning to endoscopic procedures, using stents instead of bypass grafts when possible.
Fibre-optic technology has enabled to develop a flexible endoscope. The obvious advantage of a flexible endoscope is its ability to follow natural paths and reach sites that previously were inaccessible. All endoscopes are sized in terms of their calibre, according to the “French” (F) scale; the F size represents the outer circumference expressed in millimetres (Wrightson WR (ed), 2006) . The original endoscopes were fibre-optic. In this technology, very small (as little as 10 µ) fibre-optic fibres were assembled into bundles. Each fibre of a high refractive index had an outer coating of glass of a lower refractive index. Coherent bundles were used to visualize an image. Now most endoscopes use a non-coaxial optic fibre system to carry light to the tip of the endoscope, and a solid-state chip camera mounted at the instrument’s tip (Fig. 2B, 3A). The main advantage of the modern endoscopes is that they do not need the fragile fibre-optic fibre bundle to transmit the image (the coaxial optic fibres were prone to damage and consequent loss of picture quality). In addition, as the output is via a monitor rather than an eyepiece, the other members of the endoscopy team see the image. This is useful when taking biopsies or performing interventional techniques, and also facilitates teaching and training.
Fig. 1. Endoscopy suite: endoscopy mobile workplace (modular system) (A); video-image processing system (B); electrosurgical unit for cutting and coagulation (C)
Fig. 2. Flexible endoscopy: endoscopes used to examine the upper GI tract (A-C)
Fig.3.Distal end assembly of an endoscope (A) and endoscopic devices (B), including brushes and forceps for taking biopsies, and various graspers.
Legend for (A): 1 – light guide lens, 2 – image guide lens, 3 – openings of twin working channels for advanced procedures, 4 – snare or oval loop, 5 – forceps or scissors (in varying shapes, sizes and grips, e.g. for biopsy, grasping, etc.), 6 – air/water nozzle
Endoscopy now includes both diagnostic and therapeutic techniques. In gastroenterology, it allows to examine the upper and lower gastrointestinal (GI) tract, providing a cost-effective means of cancer surveillance, monitoring of GI pathologies, and enhancing minimally invasive therapeutic options (Wrightson WR (ed), 2006) . Its value in these fields is well established. Direct examination of the mucosal surface is much more informative than two-dimensional scans and X-rays (American Society for Gastrointestinal Endoscopy, 2000) . However, GI endoscopy should always be integrated into the overall clinical evaluation of the patient, and endoscopic findings integrated into patient care. Further technical improvements and innovations may even extend potential endoscopic applications in therapy.
Proper cleaning and processing of endoscopes is paramount in preventing nosocomial infection caused by both patient-borne and environmental pathogens.
A relatively new diagnostic tool that may be used in conjunction with GI endoscopy is endoscopic ultrasonography (EUS). In this technique a high frequency ultrasound transducer is incorporated into the tip of the endoscope or a catheter endoscopic US probe is passed through the biopsy channel of a standard endoscope into the GI lumen. This probe sends high frequency sound waves that bounce off the GI wall. A computer creates an image of the GI wall by translating the pattern of echoes generated by the reflected sound waves. This provides high resolution US images of five layers of the GI wall (correlating with its histology, with a total thickness of 34 mm) and adjacent structures (e.g. in the mediastinum, upper abdomen and perirectum) (American Society for Gastrointestinal Endoscopy, 2000) , (Van Dam J, Wong RCK, 2004) . EUS is especially beneficial because it can provide valuable information on depth of tumour invasion. Moreover, various instruments can be passed under ultrasonographic guidance to obtain tissue samples or perform endoscopic therapy.
The two major advances in gastrointestinal endoscopy that have been made in recent years are:
- Capsule endoscopy (CE) - a diagnostic procedure during which the patient swallows a miniature video capsule that allows visualization of the gastrointestinal (GI) tract that traditional diagnostic methods (i.e. conventional upper endoscopy or colonoscopy) cannot adequately visualize.
The system is based on a single-use wireless capsular endoscope, which is ingested by the patient, and then moves automatically in a tubular, compliant and slippery environment of the GI tract (Fig. 4). This capsule is actually an active robotic device that contains advanced micro-electro-mechanical systems (MEMS), including miniature colour video cameras with flash, batteries, transmitter and an antenna to transmit the acquired images. During a typical eight-hour test, it transmits approximately 50,000 images from the digestive system to the portable data recorder as the capsule passes through the patient’s GI system until it is excreted in a natural way (Not known) . The images can be downloaded from the data recorder for review and diagnosis.
Fig. 4. Capsular endoscope: side view (A) and front view (B), showing six light-emitting diodes (LEDs) and camera lens
CE showed to be a convenient, safe and sensitive method comparable with traditional GI endoscopy. CE of the oesophagus permits diagnosis and evaluation of oesophageal diseases (e.g., gastro-oesophageal reflux disease [GERD], oesophagitis, Barrett's oesophagus, oesophageal ulcer, oesophageal varices) while avoiding the invasiveness of conventional upper GI endoscopy. But at the present time, the capsule camera is primarily used to visualize the small intestine. Whereas the upper GI tract and the colon can be very adequately visualized with scopes, the small intestine is very long and very convoluted. No available scope is able to traverse the entire length of the small intestine. CE is useful for examination of its mucosa, e.g. in patients with suspected small bowel bleeding. It is also intended as a tool for the detection of other abnormalities of the small bowel in adults and children from 10 years of age and up (Not known) . The main disadvantage of this method, however, is lack of possibility to perform biopsies of the ‘suspicious’ mucosal areas.
- Virtual colonoscopy (VC) [also known as ‘CT colonography’] – it represents a noninvasive test for the examination of the colonic lumen that involves the generation of both 2-dimensional and 3-dimensional views of the colon and rectum using data derived from the standard spiral CT.
During this examination, images of the entire thorax, the abdomen and the pelvis are captured in one brief procedure as patients alternated between the supine and the prone positions. Then they are rendered in two dimensions for diagnosis of lesions inside and outside the colon, and in three dimensions, allowing surgeons to better plan their approach. VC is not restricted by the adhesions that sometimes develop in the colon following resection, which a colonoscope cannot penetrate.
his imaging modality may supplant the classic barium enema and has also been explored as an alternative to conventional (optical) endoscopic colonoscopy, in particular as an alternative screening tool for colorectal cancer (Kochman ML, Levin B, 2004) . It should be stressed, however, that the gastroenterology societies and the published colorectal cancer screening guidelines do not include VC as a standard modality. At this point in time, the gold standard for colorectal cancer screening is still endoscopic colonoscopy.
On the other hand, virtual colonoscopy can be used to diagnose colon polyps before they develop into colorectal cancer. It can detect most large colorectal polyps and masses but is less sensitive for detecting smaller polyps (Not known, 2005) . It can also accurately detect flat lesions in the colon (Pickhardt PJ, Nugent PA, Choi JR, Schindler WR, 2004) .
Moreover, although VC appears to be a promising imaging technique, does not require sedation and requires less time for completion, the same bowel-cleansing preparation as conventional colonoscopy is necessary as well as gas insufflation of the intestine, which may be associated with some patient discomfort (Kochman ML, Levin B, 2004) .
