The duodenum is the C-shaped segment of small bowel located between the stomach and jejunum, into which the bile duct and pancreatic ducts empty via the ampulla of Vater, the sphincter of Oddi and the papilla. The duodenum is intimately attached to the head of the pancreas.
Tumours of the duodenum are rare and include:
Adenomas of the duodenum can cause symptoms of pain, vomiting and anaemia due to acute or chronic bleeding. Furthermore, they have the potential to develop into adenocarcinoma so they should be removed. In some cases, they can be removed endoscopically by snaring or endomucosal resection through a gastroscope. Still, if this is deemed too risky, they would be resected surgically after incising the duodenum and then repairing the duodenum. Some adenomas found in the duodenum arise in the ampulla of Vater. If, after meticulous evaluation, they are considered to have no evidence of malignancy, they can be removed by way of a transduodenal sphincteroplasty and ampullectomy with re-anastomosis of the common bile duct and main pancreatic duct to the medial wall of the duodenum. This is a very delicate and complex operation, and the excised adenoma and surrounding mucosa must be checked by the pathologist intra-operatively to ensure there is no carcinoma present.
Adenocarcinomas of the duodenum that are resectable are treated in the same way as resectable cancers of the ampulla and the head of the pancreas -by pancreatoduodenectomy, with or without a distal gastrectomy, depending on how close it extends to the junction of stomach and duodenum at the pylorus.
Duodenal gastrinomas develop below the mucosa and may be very small, so it may be possible to remove them by opening the duodenum and locally excising the tumour. It is essential to check for multiple submucosal tumours, as well as regional lymph nodes in the so-called gastrinoma triangle in the vicinity of the gallbladder, bile duct, porta hepatis and around the head of the pancreas. Intra-operative ultrasound and magnification can improve the chances of not missing any nodal metastases or additional tumours.
Small GISTS may be amenable to local excision of the tumour and adjacent standard duodenal wall. Still, if they are large or invading nearby organs, such as the kidney or colon, resection may have to involve pancreatoduodenectomy and en bloc multivisceral resections. Usually, for such large and invasive tumours, it would be wise to treat the patient with Imatinib for about six months before proceeding to surgery. This neoadjuvant treatment with Imatinib may reduce the size and extent of invasion to allow a less mutilating resection.
Small bowel resections are done to treat a variety of different types of problems that may cause obstructions or perforations of the small intestine or bleeding into the lumen of the bowel. Resection of short segments of the small intestine has minimal effect on the quality of life, but very extensive small bowel resections can cause chronic diarrhoea and malabsorption.
Tumours of the small intestine are rare, with the most common being neuroendocrine tumours (eNETS or "carcinoid" tumours), lymphomas and gastrointestinal stromal tumours (GISTs). Like GISTs of the stomach, intestinal GISTs rarely metastasise to lymph nodes, but they may spread to the peritoneum and liver.
Small intestinal neuroendocrine tumours (carcinoids) commonly secrete a hormone called serotonin. The hormone, serotonin, can evoke a severe desmoplastic response, which manifests as severe fibrosis in the adjacent mesentery. This can obstruct the bowel and obstruct the blood supply to the intestine. In many cases the primary tumour is small and, yet, there are sizeable mesenteric lymph node and liver metastases, as well as widespread small metastases in the peritoneum and omentum. In a significant number of patients, there are multiple primary tumours in the small bowel.
Surgery for small intestinal neuroendocrine tumours may be done as an emergency after the patient presents with small bowel obstruction or as planned surgery after investigations are done to investigate subacute symptoms. In those cases where a pre-op diagnosis is made, the patient should be thoroughly investigated before surgery with laboratory investigations including serum Chromogranin A and a 24-hour urinary five hydroxy indole acetic acid (5-HIAA) assay, imaging of the liver with a Primovist-enhanced MRI scan and a 68 Ga DOTA PET-CT scan to check for other metastatic disease and cardiac assessment to exclude carcinoid heart disease - sub-endothelial fibrosis causing tricuspid and pulmonary valve incompetence. If there is carcinoid heart disease, it may be necessary for the cardiac surgeon to replace the tricuspid and pulmonary valves, before it would be safe to deal with the abdominal tumours.
Surgery small intestinal NETs involves:
Large bowel resections are done most commonly to treat adenocarcinomas of the colon, which is a very common type of cancer. Other reasons for doing colonic resections are to remove large benign polyps that cannot be removed at colonoscopy, for complications of diverticulitis such as perforation, strictures or fistulas between the colon and other adjacent organs, injuries, inflammatory bowel disease, volvulus (severe twisting) of the sigmoid colon or caecum or, very occasionally, for very severe slow transit constipation.
Before a large bowel resection, bowel preparation is needed to clear as much faecal matter as possible. On the day before the bowel resection, the patient must consume a low-residue diet and take strong purgative medication.
For a laparoscopic bowel resection, small incisions are made in the abdomen and ports (5-15mm diameter tubes with air taps and air-tight valves) are inserted through these into the abdominal cavity. The surgeon then introduces carbon dioxide gas into the abdomen and then inserts a narrow telescope (laparoscope) into the abdomen. The laparoscope is connected to a video camera (at CBMH we have a very sophisticated Storz 3D system), which projects images of the intra-abdominal organs onto a monitor in the operating room. The vascular pedicles to the segments of the bowel to be resected are isolated, clipped and divided. Then the mesentery and bowel are dissected free of adjacent structures to mobilise the segment of the bowel to be removed. The bowel is then divided and closed with a stapling device. One of the laparoscopic port wounds is enlarged, or a separate suprapubic incision is made to remove the diseased bowel that has been resected. The bowel proximal and distal to the resected bowel are then anastomosed (joined), either with sutures or with a circular stapling device.
In some cases, it is necessary to exteriorise the bowel through an opening in the abdominal wall sutured to the skin – ileostomy or colostomy. A specially designed bag is placed over the colostomy or ileostomy to collect the effluent. Sometimes stomas are temporary, to allow the anastomosis further downstream to heal safely and the stoma will be closed at a second surgery about twelve weeks later. Occasionally it is necessary if it is not possible to construct an anastomosis, to construct a permanent stoma. A specialist nurse called a stomal therapist assists the patient to manage the stoma and adapt to life with a stoma.
In days following surgery, the bowel will not contract normally, so oral food intake is not permitted, and the stomach and intestine are decompressed by a tube placed via the nose into the stomach. As bowel peristalsis resumes, the patient will be allowed to drink fluids and then progress to soft food and later typical food if there are no complications.