Clinics in gastroenterology最新文献

The advent of the video endoscope is the most profound change in the design of gastrointestinal endoscopes since the introduction of the optical fibre bundle. As a television system, it is more expensive than existing systems but surpasses them in quality in my opinion. However, the CCD endoscope will not survive only as a special system for television. Although all the currently available and prototype instruments are acceptable for most aspects of diagnostic endoscopy, there is debate as to whether or not the CCD endoscope will replace the fibrescope. I think that this is a distinct possibility, but in order for the video endoscope to supplant the fibrescope it must not only equal it in all respects but must also surpass it in some significant way. This potential superiority hinges on the inherent versatility of the method by which the video endoscope obtains an endoscopic image. This leads readily to any number of methods of electronic and computerized storage, recall, comparison and transmission of endoscopic data, capabilities that can be used to advantage in many areas. In research that utilizes endoscopic methods it will prove invaluable; properly interfaced with other technological developments it can greatly increase the efficiency of an endoscopy unit. Remarkable as these possibilities may be, however, it is the prospect of computerized and electronic manipulation of the endoscopic images that most threatens the position of the fibrescope. If emerging CCD technology provides useful methods of diagnosis that go beyond simple observation in the visible light spectrum, then the argument will be decided in favour of the video endoscope. What form this will take, and when it will come to pass, remain to be seen.

The realm of endoscopy has gone from that of diagnosis to that of diagnosis and therapy. Therapeutic endoscopy is a rapidly advancing frontier in the field of gastroenterology. Its use in securing haemostasis has recently flourished. Considerable progress has been made. Various experimental techniques have been tried and found lacking, while others, such as laser photocoagulation, electrohydrocoagulation and endoscopic sclerotherapy, are proving to be very useful.

The mortality for upper gastrointestinal bleeding has remained high for decades, despite recent advances in medicine. This may be related to the shift in the population toward the older age group. Recent advances in endoscopic haemostasis seem to be showing promise in improving survival rates. This is a result of improved recognition of risk factors, including the stigmata of recent haemorrhage, of early surgical intervention in the elderly, and of the ability to reliably secure haemostasis endoscopically.

This chapter gives an account of the various techniques of endoscopic haemostasis and explains the numerous controversies through the discussion of selected experimental and clinical trials.

The adenomatous colonic polyp, a neoplastic lesion, is the precursor of most if not all carcinomas of the colon and rectum. Confirmatory evidence is derived from epidemiological, histological and clinical data demonstrating a close parallelism between adenomas and cancer of the colon. Based on current knowledge, all colonic polyps should be removed to prevent the development of colonic cancer. However, since the risk of malignancy within an adenoma is related to its size, histology and the degree of dysplasia, practical considerations dictate that all polyps 1 cm in diameter or larger should be removed upon their detection by barium enema or colonoscopy since such adenomas are the ones most likely to contain malignancy.

The endoscopic removal of colon polyps can be efficiently and safely accomplished when established principles of colonoscopy and electrosurgery are followed. This technique requires the proper equipment, a skilled endoscopy assistant, and an experienced endoscopist with the ability to adeptly perform colonoscopy, an understanding of the basic concepts of electrocautery and knowledge of the various structural configurations of colonic polyps. Colonoscopic polypectomy will avoid the need for surgical resection in most instances.

Management of the malignant colonic polyp remains controversial. The patient with a sessile or pseudo-pedunculated polyp containing invasive cancer should undergo colonic resection. Surgery is not necessary for the majority of patients whose pedunculated adenomas contain invasive cancer, unless the malignancy is poorly differentiated, the cancer invades lymphatics or vascular channels, or tumour is seen at or near the resection margin.

Surveillance colonoscopy after endoscopic polypectomy should be performed in most instances within one year to look for recurrent tumour, missed polyps or a metachronous adenoma. Subsequently, colonoscopy should be performed every two years in patients with multiple index polyps, and every three years after removal of a single index adenoma.

In recurrent pyogenic cholangitis (RPC), there is primary bacterial cholangitis resulting in the formation of strictures and stones in the intrahepatic as well as the extrahepatic bile ducts. Endoscopic retrograde cholangiopancreatography (ERCP) is a very useful investigation in the study of RPC. The location of stones and strictures and the morphology of the bile ducts are well delineated. Moreover, cholangitic liver abscesses and biliary-enteric fistulas, which are frequently encountered in RPC, are demonstrated. ERCP can also be used to differentiate RPC from ascariasis, clonorchiasis, hepatocellular carcinoma and cholangiocarcinoma, which sometimes have quite similar clinical pictures and can be confused with RPC. ERCP should be performed in every patient with RPC in order to plan surgical treatment.

Endoscopic papillotomy (EPT) is indicated in RPC patients with residual common bile duct stones or papillary stenosis, and as primary treatment in selected high-risk patients. More studies are necessary to establish additional indications for EPT.

Endoscopic measurements of flow and pressure in blood vessels of the gastrointestinal tract are very young techniques which have been described in the last three years. Laser doppler flowmetry provides measurement of blood flow in humans; the results are thought to reflect mucosal blood flow, at least in the stomach. Provided that the first encouraging results can be confirmed by further studies, the technique should open up new possibilities for endoscopic research.

Endoscopic application of the doppler ultrasonic probe can be used to detect blood flow in the paravaterian region and in oesophageal varices. The clinical value of the detection of small arteries at the site of endoscopic papillotomy may be useful in the prevention of post-papillotomy bleeding. Since this complication rarely occurs, the clinical value of the doppler is likely to be limited in this field.

Investigation of the flow pattern in oesophageal varices is a very interesting subject. The results, however, are not easy to understand. Further studies and the comparison of the pressure profile with the flow profile of the varix should provide better insight into portal hypertension pathophysiology. Due to its clinical importance, further interesting studies and results should ensue from this field. To date, most studies have involved measuring the pressure in oesophageal varices. Both the application of the pneumatic pressure gauge and the puncture technique are easy to perform. The simultaneous application of the two techniques (Staritz and Gertsch, 1985) revealed the advantages and disadvantages of the procedures. The invasive puncture provides exact and reproducible measurement of the IOVP in smaller varices (grade II) and the tracings are easy to read, whereas the pneumatic pressure gauge can only be attached to large varices (grade III and IV), and artefacts caused by respiration, patient's movements, oesophageal peristalsis and deviation of the pressure gauge from the variceal column affect the practicability of the procedure. The results simultaneously obtained by the two methods were only in accordance in some of the patients. The present form of the pressure gauge therefore needs improvement. Further investigations will elucidate whether the exact, reproducible, but invasive puncture technique can be replaced by less invasive pressure devices.

Finally it should be pointed out that all endoscopic methods suffer from the common flaw that it is not yet clarified whether or not endoscopy affects flow and/or pressure in gastrointestinal vessels. Therefore, further studies should be carried out to establish the reliability of these methods.