The radiological investigations relevant to chronic IBD are described briefly with emphasis placed on compression techniques in small bowel studies. A classification for reporting small bowel Crohn's disease is proposed, where the disease is staged as early, advanced or complicated, and the extent of involvement measured directly from the film. The terminal ileum may be normal in 20% of children with proximal Crohn's disease, so that ileoscopy should not be used to exclude small bowel disease. Radiological assessment of the small bowel is important in management. Surgical referral was based on the radiological changes in 6% of patients, and in 24% the presence of extensive uncomplicated small bowel Crohn's disease led to treatment with elemental diet. The use of some specialized examinations, such as the instant and ileostomy enema, are discussed.

While Crohn's disease and ulcerative colitis are both conditions characterized by intestinal inflammation, with some overlap in their clinical and histological features, they are essentially different in pathogenesis. Crohn's disease appears to be primarily a condition of chronic T-lymphocyte activation, with tissue damage induced by secondary macrophage activation. What activates the T-cells is unknown. In this chapter we look at the evidence for and against cell-wall deficient mycobacteria species, viral infection of vascular endothelium and luminal contents as potential mechanisms of chronic activation. In ulcerative colitis, by contrast, there is no strong evidence for T-cell activation, and humoral mechanisms predominate. While the finding of atypical anti-neutrophil cytoplasmic antibodies (P-ANCAs) may be useful in screening, the only novel pathogenetic discovery is the co-localization of a 40 kD colonic autoantibody with immunoglobulins and complement on the apical enterocyte surface. Despite the fundamental differences in initiating mechanisms, the two conditions have many 'downstream' inflammatory processes in common. We discuss the evidence for local production of cytokines, arachidonic acid metabolites and reactive oxygen and nitrogen radicals, highlighting the potential adverse consequences for intestinal vascular integrity.

Infections of the esophagus are unusual in the general population and strongly imply immunodeficiency, although immunocompetent individuals are not exempt. HIV infection is predominant among risk factors for infectious esophagitis. For all immunocompromised patients, the most frequently identified esophageal pathogens are Candida, CMV, and HSV. Peculiar to HIV-infected patients are idiopathic esophageal ulcers as well as unusual bacteria and parasites. Patterns of presentation differ with each infecting organism, and clinical features should be used as a guide in achieving a correct diagnosis. For example, a patient with AIDS presenting with esophageal symptoms and thrush, along with abdominal pain, nausea, vomiting, and fever, is unlikely to resolve all symptoms with empiric antifungal therapy alone. Parsimony of diagnosis does not hold among immunodeficient patients in whom concurrent infections are common. Accurate and timely diagnoses are essential as effective treatments are available for particular etiologies. Finally, among immunocompromised patients, all esophageal symptoms are not necessarily due to an infection, and possible diagnoses of pill esophagitis, acid-peptic injury, or structural and functional abnormalities should not be overlooked.

The surgical world is experiencing a revolution brought about by the proliferation of minimally invasive techniques. These developments have had most impact on abdominal surgery and chest surgery, but there are ramifications affecting other fields as well. One feature of this change is the increasing dependence of surgeons on technology. Developments in video imaging, ultrasound and robotics are required to make complex endoscopic procedures surgeon-friendly, just as the minimally invasive approach has made surgery more patient-friendly. In the future, integration of stereo imaging systems, computers, microrobots and robotic manipulators will result in technically sophisticated but ergonomic operating systems that will allow surgeons to perform endoscopically almost any type of surgery that can be done today.

Endoscopic retrograde cholangiopancreatography (ERCP) is clearly a useful adjunct in the management of patients undergoing laparoscopic cholecystectomy who have common bile duct stones. Whether endoscopic sphincterotomy plus laparoscopic cholecystectomy is superior to traditional open cholecystectomy and bile duct exploration is a question which remains to be answered by prospective, randomized trials. The immense popularity of laparoscopic cholecystectomy may prohibit such a study in the USA. In expert hands, endoscopic stone extraction is usually successful, so ERCP can be deferred until after cholecystectomy unless there is serious suspicion of a duct stone preoperatively. Actual clinical practice will depend, however, on the skill of the surgeon, the skill of the endoscopist, and the commitment to removing the gallbladder laparoscopically. It would seem prudent for surgeons to continue to direct their energy toward conquering the common bile duct via the laparoscope, and leave ERCP and stone extraction in the realm of the endoscopist who has been extensively trained in this difficult technique. Proficiency at ERCP, sphincterotomy and stone extraction requires considerable training, and the procedure should not be attempted by individuals who have performed fewer than 100 ERCPs and 25 individually supervised sphincterotomies, according to the ASGE Standards of Training, 1992. As experience with video endoscopic surgery increases and technology improves, it will become possible to remove most duct stones at the time of cholecystectomy, thus obviating the need for endoscopic sphincterotomy. In addition, ERCP should be regarded as the treatment of choice for postoperative cystic duct stump leaks. Studies have shown that any type of biliary decompression, i.e. sphincterotomy, stents or nasobiliary catheters, will be successful. The authors recommend that, in the absence of duct stones, stenting or nasobiliary catheters be used as they are less invasive. Bile duct leaks may also be managed endoscopically, but success depends on the individual characteristics of the duct injury. The decision to manage late onset strictures endoscopically should be individualized, and consideration of local endoscopic expertise, operative risk, interval between surgery and stricture, and the patient's wishes should be made.

It has been illustrated that a convergence of new technologies, including advanced laparoscopic techniques, flexible video endoscopy, coaxial balloon dilators and biliary lithotripsy, has allowed the modern laparoscopic surgeon to address a pressing issue: how to deal with choledocholithiasis. A variety of techniques and methods have been described; each has their advocates, philosophical advantages and potential drawbacks. The definitive decision as to which technique is the best awaits the results of future prospective studies. Until then, the three techniques outlined will allow the majority of surgeons to extend the advantages of minimally invasive surgery to patients with choledocholithiasis. There is no doubt that this is desirable. These procedures, however, are not without their failure rate and complications, and they remain technically demanding. Increased education and training of surgeons is needed and further improvement of existing technology is demanded. This includes improved fibreoptic choledochoscopes with better optics, more flexibility and larger working channels; better stone baskets and better mechanical graspers, and safer and more effective stone lithotriptors. Other questions remain unanswered, such as the relative and absolute contraindications to performing laparoscopic common duct explorations. Can patients with multiple common duct stones or very small ducts be safely handled using these methods? Is there a size of common duct stone that is safe to leave behind, and are there safe antegrade methods of treating distal duct stenosis? The new interest in avoiding the placement of T-tubes for common duct drainage also needs close scrutiny. All these questions need well-constructed studies to answer them; but in the meantime, laparoscopic common duct exploration is undoubtedly here to stay, and this new approach to an old problem is inducing biliary surgeons to question many traditionally held dicta, which can in the long run only be in the patients' best interest.

The rapid adoption of laparoscopic cholecystectomy by the world of general surgery is remarkable. The experience of the first five years has done much to promote the safety and efficacy of this important procedure. As experience continues to accumulate, there will be more data to establish the contraindications, the proper role of cholangiography and the best means of avoiding complications. Improved tools and technical aids will also improve surgeons' ability to safely perform this procedure for their patients.

The technology that has permitted the rapid advance of minimal access surgery has now made it feasible to perform laparoscopically assisted colon resections safely. As the instrumentation improves, specimen removal problems are solved, surgeons' sewing skills improve, and other anastomotic methods are devised, an increasing amount of colonic surgery will be done using laparoscopy. It is clear that the techniques now in use are evolving, and will be substantially different a few years hence. Previously accepted surgical principles may continue to be challenged by new techniques, which must be evaluated under strict protocol before being widely accepted. These operations should be performed by surgeons who are able to achieve the same level of radical operation that they would achieve through a laparotomy. Special training in advanced laparoscopic techniques including microsurgical suturing is a distinct advantage in performing these operations successfully. It may be best for surgeons to start with palliative procedures or operations for benign diseases of the colon, to avoid the risk of jeopardizing an operation for cancer.

Laparoscopic appendicectomy for acute appendicitis has been promulgated in many European countries during the 1980s. The introduction of the microchip camera and visual assistance on a monitor has increased the appeal of laparoscopic appendiceal resection. It carries a unique appeal in that the extent of inflammation and the presence of other pathological conditions are readily identified. This approach does not prevent the surgeon proceeding to open surgery if appropriate, and will aid in defining the site of incision. Prospective analyses (McAnena et al, 1992; Attwood et al, 1992) have shown that this approach shortens hospital stay, decreases wound infection rates and provides excellent cosmetic results. It also hastens return to full activity. It requires experience and, as with cholecystectomy, the option of converting to an open procedure should not be considered a failure of the approach. Details of approaches to the inflamed appendix are described. Caution in the use of diathermy is needed (particularly at the base of the appendix), as it may cause necrosis of the caecum or dissolution of the ties at the appendix base. Control of the appendicular artery by clip ligation is preferable to diathermy. The training of surgical residents will be enhanced rather than diminished if, under close, experienced supervision, they are taught to perform appendicectomy laparoscopically, as the essentials of anatomic dissection of the appendix are perhaps better appreciated on a video screen than at open surgery through a small incision.

Small bowel procedures such as placement of feeding jejunostomy, diagnosis of small bowel ischaemia and obstruction, bowel resection and lysis of adhesions can all be performed laparoscopically. Diagnostic laparoscopy can be performed with low complication rates, and can help avoid unnecessary laparotomy. The open method of trocar placement is preferred in patients with adhesions or distended bowel due to obstruction or ileus. Feeding jejunostomy can be placed by laparoscopically assisted methods, pulling the jejunum out or completely laparoscopically. The latter requires fixation of the jejunum to the abdominal wall by transabdominal sutures or T-fasteners. The T-fastener technique for feeding jejunostomy is simple to perform, safe and effective. Small bowel ischaemia can be difficult to diagnose laparoscopically. Fluorescein and ultrasound Doppler examination of the small bowel may be as useful as in laparotomy, but there is little clinical experience with these techniques. Laparoscopically assisted small bowel resection involves intraperitoneal division of the mesenteric vessels and exteriorization of the small bowel through a small abdominal incision, followed by resection and anastomosis. The causes of small bowel obstruction can be diagnosed laparoscopically, and adhesions can be lysed under laparoscopic guidance. The laparoscopic approach is replacing laparotomy for many small bowel procedures. Improvements in instruments and experience in laparoscopic procedures will continue to make these procedures easier and safer to perform.

Laparoscopic adaptation of highly selective vagotomy procedures associated with no mortality, low morbidity and no reports of diarrhoea and dumping syndrome has been reported. Although experience to date with these procedures is limited, they hold the promise of being a viable alternative for patients refractory to medical therapy or for those non-complaint with long-term maintenance pharmacologic treatment. Simple closure of an acute perforated ulcer has also been accomplished laparoscopically. In performing laparoscopic surgical procedures for duodenal ulcer disease, the relief of symptoms appears similar to that reported following comparable open procedures but with the advantages of diminished postoperative pain and disability. Moreover, the use of angled endoscopes and the magnification afforded by laparoscopy greatly facilitate the identification and transection of small vagal fibres adjacent to the oesophagus.

This chapter reviews the physiology of the pneumoperitoneum, focusing specifically on the traditional CO2 method and new alternatives which may ultimately replace it. A continued emphasis of providing for a safe, effective and physiologically benign intra-abdominal exposure will be mandatory if laparoscopic procedures of increased complexity and longer duration are to be applied to patients who are old or very young, and ill.

The evaluation of chronic constipation with or without encopresis must begin with a careful history. The intervals between bowel movements and the size and consistency of stools deposited into the toilet should be noted. Encopresis may be manifested as dirtying the underwear. The physical examination should include a rectal and neurological examination. No specific organic cause can be found in the majority of children. One or several anorectal physiological abnormalities have been found by us and others in 95% of children with idiopathic constipation. These abnormalities include impaired rectal and sigmoid sensation and decreased rectal contractility during rectal distention. The external anal sphincter and pelvic floor muscles may be abnormally contracted during straining for defecation, and the child may be unable to defecate a rectal balloon. Most patients will benefit from a program designed to clear stools, to prevent further impaction, and promote regular bowel habits. Fifty percent of patients will be cured after 1 year and 65%-70% after 2 years.

Pancreatic arteriovenous malformation is a rare condition that may cause gastrointestinal bleeding. A 66-year-old man with large arteriovenous malformation at the pancreatobiliary region is described. The patient had recurrent episodes of hemobilia after cholecystectomy performed for the treatment of cholelithiasis. Enlargement of the arteriovenous malformation was documented by angiography performed before and after the cholecystectomy. Bleeding from the biliary tract was successfully controlled by transarterial embolization. Cholecystectomy may have caused a hemodynamic change at the pancreatobiliary region, leading to the enlargement of the lesion and hemobilia.

The last half century has witnessed the birth, infancy, and early adolescence of a new field, intestinal immunology, with an explosion of knowledge about the role of the intestinal immune system in normal intestinal physiology and disease. This field is still in its rapid growth phase. A major spin-off of such growth will be the development of new approaches for the diagnosis and treatment of disease. For example, studies of oral tolerance have led to new insights into possible mechanisms of autoimmunity and ultimately could lead to new treatments for autoimmune disease. The discovery that Peyer's patches are a major inductive site for initiation of the mucosal immune response, and IgA responses in particular, and that antigen enters these sites via the M cell, forms one current basis for the development of new mucosal vaccines and vaccine delivery systems. Studies of immunogenetics are leading to new insights into the molecular basis of diseases such as celiac disease, IBD, and hepatic disorders. Studies of cytokines and the role they play in acute and chronic inflammation are leading to new approaches for the treatment of intestinal inflammatory diseases. The field of intestinal immunology is now well on its way through the turbulent "teenage" years. It is true maturation over the next several decades will test and witness the evolution and validity of concepts formed over the past 50 years. Certainly, tremendous growth and change will come with the increasing application of molecular tools, and the enthusiasm and the fresh insights brought by the next generation of young investigators, as they begin to further unravel the intricacies of the intestinal immune system and its role in health and disease.