How Can We Improve the Implementation of New Endoscopic Techniques? Concerning Colonic Stenting

Dear Sir,

Endoscopy is a fertile field that frequently offers further new diagnostic and/or therapeutic procedures. Nowadays these procedures are very demanding, and compete with other nonendoscopic techniques; thus, their performance in clinical practice must be optimal, and provide outcomes which compare well with those of nonendoscopic approaches [1] [2]. Furthermore, in the endoscopic community there is great interest in how we can achieve better implementation of any new endoscopic techniques, so that papers such as the ”Expert approach“ series are welcome. In the practice of endoscopy, we need to find technical solutions and strategies from expert experience in order to improve the outcomes of endoscopic practice. I have read with great interest the paper by Baron and co-authors and I wish to make some comments [3]. This paper deals with the expert approach to the placement of expandable metal stents for malignant colorectal obstruction.

In clinical practice we encounter two types of patients with neoplastic colon stricture needing colonic stenting: the first are patients with chronic neoplasia with subocclusive episodes for whom surgical palliation is not suitable; the others are patients admitted to the emergency room because of acute colonic occlusion, usually without a previous diagnosis of colonic tumor and needing an urgent colonic decompression [4]. The condition of the patient, the timing of the procedure, and the degree of difficulty of the procedure are very different when stents are placed in patients with acute or chronic presentations of colon stricture, even though the endoscopic techniques may be similar.

Todd Baron and co-authors state that it might be useful to obtain a retrograde radiographic contrast study to assess the size of the stenosis, and to exclude the presence of any synchronous stenosis that could negate the advantage of stenting a single site of obstruction. However, in clinical practice it is not safe to seek an enema image, such as those shown in Figure 2 of the paper, in a patient with acute occlusion, because of the risk of explosion, microperforation and bacteremia, as the authors themselves note. Moreover, though a radiological enema study may be done in a patient with chronic neoplasia needing definitive palliation, performance of the same radiological study should be avoided in a patient with an acute presentation. At very least the investigation of stenosis is more safely achieved after successful catheterization with an endoscopic retrograde cholangiopancreatography (ERCP) catheter opacifying the proximal colon tract during the endoscopic procedure of stenting. Surprisingly, the utility of computed tomography (CT) is not discussed by the authors. The CT study is a valuable tool in the evaluation of a patient admitted to the emergency room because of acute colon occlusion: it can help us in the diagnosis of the site and etiology of the colon stenosis, and raise suspicion about the neoplastic nature of an acute colon occlusion, which can be later confirmed by endoscopic evalution during the stenting procedure.

There are two main indications for colon stenting: definitive palliation and presurgical decompression. Baron and co-authors consider the first type at length, with regard to those patients with a subocclusive stenosis who need a palliative stenting because they are not fit for surgery, but pay little attention to the other type of patient, i. e. those with acute neoplastic occlusion. In the first case, positioning of the stent is very easy for any endoscopist who knows about metal stent placement, and the information provided by the authors is very exhaustive. The main problem with regard to the definitive palliation procedure, however, is not technical but the correctness of the indication for and timing of the stenting. From a technical point of view, Baron and co-authors suggest the use of a balloon or any mechanical dilation, or also of laser therapy, if the scope cannot be passed through the stenosis, in order to ensure complete endoscopic assessment of the stenosis. I do not agree that any form of dilatation should be used or that the entire lesion ought be studied endoscopically prior to stenting, because these procedures can be associated with a greater risk of complications, such as perforation or dislocation of the stent, and are not necessary for the correct placement of a metal self-expandable stent. Dilation might be necessary only when it is impossible to pass the metal stent through the stricture, but this is a rare occurrence with neoplastic strictures of the colon because they are generally soft, and not hard.

By contrast, in the case of presurgical decompression, when the indication is very clear, that is, acute occlusion of the colon, there are many technical difficulties. The patients themselves are very different from those with chronic neoplasia needing definitive palliation. The patients are critically ill, often unaware that they have a neoplastic disease, and have an acute problem which needs to be solved urgently. In the day to day practice is very important, for organizational reasons; the timing of the procedure; and information about those factors upon which we base the timing of this urgent procedure, such as cecal or ileal dilatation found upon radiological study, or any other clinical or laboratory parameters that can indicate an impending colon perforation. From a technical point of view, we need more information on how we can optimize our success rate in the case of difficult colon stenosis and on what precautions are needed to lessen the risk of perforation during the procedure. Success rates close to 100 %, as reported by the authors, are expected in the case of lesions which are not completely obstructing; in this situation expert advice is less important. In the case of a completely obstructing lesion, or when it is difficult to cross the stenosis, because, for instance, it is severely angulated or fixed, the experience and the suggestions of experts may be very useful. Unfortunately the paper lacks this sort of information. The authors suggest the use of a completely hydrophilic guide wire, but is such a guide wire the ideal choice where there is a soft villous tumor or would it be better to use a guide wire where only the tip is hydrophilic? In addition, do the authors always try to pass through a soft stricture with a guide wire, or do they also use a ball-type catheter?

Finally, as the authors stated, two types of metal stent are employed in colonic stenting: the ”through the scope” (TTS) type and the ”over the guide wire” type. While TTS stenting may show no technical difficulties after the stricture has been passed with a guide wire, the ”over the guide wire” type may present some technical difficulties in going across the stent above the guide wire up to the stenosis, if the stenosis is not very distal and if the sigma is angulated. Could Baron and co-authors give us some technical suggestions?

The stenting of colonic neoplastic strictures has gained much popularity in recent years, both in the endoscopic community and in patient and surgeon expectations. Unfortunately this procedure is not widely performed, due to technical difficulties and the unavailability of endoscopists who are expert in the placement of metal stents. While the definitive palliation procedure, which is the easier of the two, may be performed in tertiary endoscopic centers to give the best possible outcome, this cannot be the case for the relief of acute obstruction, the more difficult procedure, because it is an urgent endoscopic treatment; thus the latter procedure needs better performance in the wider endoscopic community. Therefore, papers such as this one by Baron and co-authors, are a welcome means of improving this technical approach in the endoscopic community, refining the techniques of all endoscopists who are concerned with this disease.

References

• 1 Mosca S. What sort of endoscopist for the endoscopy of the future?.  Endoscopy. 2002;  34 742
• 2 Siegel J, Cohen S A, Kasmin F E. Experience and volume: the ingredients for successful therapeutic endoscopic outcome especially ERCP in postgastrectomy patients.  Am J Gastroenterol. 2000;  95 2133-2134
• 3 Baron T H, Rey J F, Spinelli P. The expert approach: expandable metal stent placement for malignant colorectal obstruction.  Endoscopy. 2002;  34 823-830
• 4 Mosca S, Festa P, Simeoli C. et al . Acute colon obstruction at splenic flexure: effective presurgical decompression with an Ultraflex biliary stent.  J Gastroenterol Hepatol. 2003 in press;