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Surgery of the Jejunum and Ileum
Surgery of the small bowel

The small bowel is where food is digested and absorbed into the blood. To sustain life, we need around 49 inches (100 cm) of small bowel. The small bowel is the largest hormone producing organ in the body. We ingest thousands of bacteria, viruses, and parasites every day and the small bowel quietly handles these without us knowing. Congenital anomalies, inflammation, obstruction, neoplasia (tumors), perforation, bleeding, and ischemia (lack of oxygen supply) are some of the reasons for small bowel surgery.

Anatomy

  • The demarcation between the duodenum (1st part of small bowel) and the jejunum (2nd part of small bowel) is the ligament of Treitz (see Surgery of the Duodenum) (Figure 1)
  • The length of the jejunum is 100 to 110 centimeters in length. It is greater around and has a thicker wall than the ileum
  • The ileum is 150 to 160 centimeters in length
  • The jejunum, ileum, and associated mesenteries (supporting and suspending structures) are attached to the back wall of the abdomen. They are completely covered with peritoneum (single layer of cells that line the surface of the abdomen and bowel)
  • The ileum joins the cecum (first part of the colon) in the right lower quadrant at the ileocecal valve near the appendix (Figure 1). The jejunum and ileum are mobile organs
Figure 1 - Anatomy of the digestive tract showing the relationship of the jejunum and ileum to the stomach, duodenum and colon. © C. McKee
  • The arterial blood supply of the entire small bowel except for the first portion of the duodenum is the superior mesenteric artery
  • The small bowel possesses an extensive lymphatic network that aids in the absorption of nutrients. It drains from the bowel wall into adjacent lymph vessels and lymph nodes and ultimately getting into larger lymphatics that finally empty into the left subclavian vein. The lymphatics of the small bowel play a major role in immune response (response to infection). The wall of the small bowel (Figure 2) is made up of four layers:
    1. The mucosa is the inner most layer and composed of small fingerlike projections (villi) covered with a single layer of cells (epithelium). Beneath the epithelium is thin layers of connective tissue (lamina propria) and muscle (muscularis mucosa)
    2. The submucosa is a thin strong layer containing connective tissue, vessels, nerves and lymphatics
    3. The muscularis propria is composed of smooth muscle that has a thicker circular inner layer and thin outer layer that runs lengthwise
    4. The serosa is the single cell thick outer layer similar to the peritoneum (visceral peritoneum)
Figure 2 - Cross-section of the wall of the small bowel showing the various layers. © C. McKee

Physiology

The functions of the small bowel are digestion, absorption, hormone production, and antibody production

  • Liver bile and pancreatic secretions and enzymes (proteins that improve the digestive process) are added to the bowel in the duodenum. These plus other enzymes from the bowel mucosa drive a complex process resulting in digestion and absorption of food
  • Fluid taken by mouth plus fluid produced in the bowel average 8 to 10 quarts (8-10 liters) per day. The small bowel will reabsorb all but about 1/2 quart per day. The villi provide a large surface area for absorption
  • The mucosa of the small bowel is the source of many hormones that help regulate digestion in the small bowel
  • The lamina propria is the home for many antibody producing cells that aid in control of disease

Pathology

  • Congenital diverticula (outpouchings) may occur anywhere in the small bowel and become inflamed (diverticulitis) thus requiring surgery. Meckel's diverticulum (occurs in1-3 % of the population, (Figure 3) arises about 2 feet from the ileocecal valve and contains all bowel wall layers. It frequently contains stomach or pancreatic tissue and is a site for bleeding or inflammation
Figure 3 - Illustration of a Meckel's diverticulum of the small bowel. © C. McKee
  • Crohn's disease is a chronic disease that causes an inflammation and may involve any part of the digestive tract from the mouth to the anus. It is the most common surgical disease of the small bowel
    • It is a granulomatous (nodular) inflammatory process most often involving the end of the ileum. Deep ulcers, thick scarring and shortening of the bowel are present (Figures 4)
    • The cause is uncertain and bacterial infection and autoimmune reaction are possible causes
    • The disease may be isolated to a single segment of bowel or it may skip around with several segments involved
    • Bowel obstruction, bleeding and perforation are late complications of the disease
    • Crohn's patients have a higher incidence of small bowel cancer
Figure 4 - Illustration of the inside wll of the small bowel in Crohn's disease. © C. McKee
  • Infection of the small bowel with typhoid or tuberculosis may very occasionally require surgery
    • Benign growths of the mucosa may be adenomatous (arising from the cells lining the intestine) or hamartomatous (overgrowth of the normal structures) polyps
    • The polyps will be variable in size and symptoms. Symptoms will frequently be due to bleeding or obstruction of the bowel
    • Benign tumors can arise from the supporting tissues: fat, fibrous tissue, vessels, lymphatic tissue, nerve and smooth muscle
  • Cancer of the small bowel
    • Adenocarcinoma (mucosal or epithelial cancers) is the most common malignancy of the small bowel. Adenocarcinomas of the small bowel decrease in frequency the farther down the bowel
    • Cancer of all the supporting structures occur in the small bowel
    • Lymphomas occur most often in the terminal ileum
    • Carcinoid tumors are usually malignant and arise from argentaffin cells most often in the ileum. This tumor secretes 5-hydroxyindoleacetic acid (a breakdown product of serotonin, a chemical that affects nerve function)
  • Small bowel obstructions
    • Obstructions are mechanical much like the kinking of a garden hose. This is similar to kinking a garden hose. Water continues to flow until that critical point is reached where flow stops. Obstruction may be partial, complete or intermittent. The major concern with obstructions is that the blood supply to the obstructed bowel may be lost
    • Hernias cause obstruction when a portion of the bowel is stuck in a narrow opening. The marrow opening may be within the abdominal cavity or in the abdominal wall
    • Intussusception (the bowel telescopes into itself) or volvulus (twisting of bowel) can cause obstruction. Polyps or enlarged lymphoid tissue will frequently be the leading edge for intussusception, which presents as an obstruction or bleeding. Peristalsis (muscular contractions) carries the leading edge downstream causing it to telescope into the next segment
    • Benign or malignant tumors can cause obstructions
    • Adhesions result from previous surgery or inflammation. Any process that causes irritation of the outer bowel sets the stage for adhesion formation such as blood in the abdomen
  • Chronic intestinal ischemia results from occlusion or severe stenosis (narrowing) of the major arteries to the bowel. Most of these changes are due to atherosclerosis (due to a plaque of fatty deposits) at the origin of the arteries. Following meals these patients will usually experience abdominal pain because the gut needs more oxygen delivery for digestion and absorption
  • Acute occlusive intestinal ischemia is usually caused by acute occlusion (blockage) of the superior mesenteric artery (major artery to the bowel) by an embolus (clot from another site)
    1. These clots frequently come from the heart; enter the origin of the vessel and breakup into smaller clots. The occlusions are frequently beyond the origin of the vessel
    2. Acute occlusive ischemia can also be caused by a sudden blockage at the origin of the artery due to narrowing. Significant narrowing is present before the sudden occlusion
    3. Acute blockage presents with severe persistent abdominal pain with pain out of proportion to the examination
    • Urgent treatment is required or the bowel will quickly become gangrenous
    • Resection of most of the small bowel is often necessary with a very high death rate
  • Acute venous thrombosis of large bowel veins may cause intestinal ischemia of acute or chronic nature. These people frequently have undiagnosed clotting disease, cancer, blood disorders or infection
  • Non-occlusive mesenteric ischemia may occur in people who do not have artery or vein occlusions
    1. This may be due to severe and prolonged intestinal vasoconstriction (narrowing of the blood vessel feeding the tissue) or a situation usually seen in the intensive care setting where low blood pressure or total decrease in blood flow is taking place due to non intestinal causes
    2. Arteritis (inflammation of blood vessels) or collagen diseases may compromise blood flow to the intestine
    3. Drugs like Digoxin, Ergotrates (migraine headache medications), and vasopressors (drug for raising blood pressure) have been implicated

History and Physical

  • The patient's history can give helpful information:
    1. Pain onset, location, type, progression or changing pattern
    2. History of anorexia (lack of desire to eat), nausea, vomiting, abdominal distention, failure to pass stool normally, diarrhea, blood in stool are all important
    3. History of trauma, bowel disease or abdominal operations
    4. A good menstrual history is important
  • Pain. Abdominal pain may be described as vague, diffuse, non localizing, heavy, burning, sharp, stabbing, crampy, intermittent, constant, localizing, and associated with sweating, nausea and vomiting. An understanding of abdominal pain is necessary to manage the patient with abdominal pain
    1. Visceral pain (pain within the thoracic or abdominal cavities) is poorly defined and localized. Visceral nerves are extremely sensitive to stretching or distention sensations and typically refer discomfort to a zone around the belly button
    2. Somatic (body wall) pain is well defined and localizes to the site of irritation and may be sharp, stabbing or cutting type of pain. As bowel inflammation progresses, the inflammation begin to irritate the lining of the abdominal wall and give rise to localizing body wall pain
  • Signs of peritoneal irritation are tenderness, guarding, rigidity, rebound (pain on release of pressure over an irritated site) and presence or absence of bowel sounds
  • Abdominal distention, abdominal masses, abdominal wall masses or defects, and presence of abdominal fluid are noted
  • Rectal exams are done routinely and pelvic examination when indicated
  • Chemical testing of stool for blood should is performed
  • Within a few minutes a decision can be made as to whether a patient should be rushed to the operating room
    1. If the situation doesn't warrant urgent operation then additional examinations; laboratory studies; X-ray, MRI or CAT testing; giving of intravenous (IV) fluids, pain control, possibly antibiotics and nasogastric decompression (removal of excess bowel fluids through a tube passed through the nose into the stomach
    2. Not all patients who exhibit signs of peritoneal irritation will require surgery. Frequent repeat examinations of the abdomen may be the most helpful step

Tests

  • Laboratory studies may include complete blood count; urinalysis and creatinine test (kidney function); blood sugar; amylase and lipase (for pancreatic disease); bilirubin and serum asparate aminotransferase (liver function), electrolytes (amount of salt in the blood) and pregnancy test
  • Radiological testing will include a chest X-ray and an X-ray of the abdomen with the patient flat and upright. These films will provide information about the amount of gas in the bowel, where the gas is (very helpful as regards bowel obstruction), possible mass effect, abnormal calcifications, presence of fluid, possible organ enlargement and haziness of retroperitoneal (back wall of the abdomen) structures
  • Ultrasound examination will provide information about the liver, gall bladder, common bile duct, spleen, pancreas, kidneys, aorta, ovaries, tubes, uterus, abnormal fluid or abscess collections
  • Computerized axial tomography (CAT scan) gives information about solid organs (such as liver and spleen), inflammatory processes, bowel wall thickening, blood vessels, amount of fluid or gas in the intestinal tract or outside the intestinal tract. It may identify the point of obstruction and may show abdominal wall defects. The CAT study will be performed after the patient drinks radio opaque (shows up on X-ray) material and is given radio-opaque dye intravenously
  • Endoscopy of the stomach and duodenum (flexible fiber optic lighted scope) may be necessary in evaluating upper abdominal pain
  • Arteriography (injection of dye into blood vessels) will be performed if there is consideration of acute intestinal ischemia. It may also detect bleeding points and can be used to stop bleeding
  • Barium contrast studies will usually be performed for chronic disorders of the bowel (Figure 5)
    1. The study includes the esophagus, stomach and upper small bowel with or without a study of the lower small bowel. The study requires the patient to drink radio opaque material and air may be instilled into the bowel to provide more contrast
    2. This same technique can be done with a barium enema study of the colon and terminal ileum
Figure 5 - Barium contrast X-ray showing a narrowed segment with Crohn's disease (arrowheads). Courtesy S. Sadiq
  • Flexible fiberoptic scopes may be used to examine the small bowel as well as examine the end of ileum by way of the colon. Some of these scopes will have small channels for tiny ultrasounds to study the bowel wall and adjacent organs (e.g. pancreas) or hold small instruments for biopsy (taking of tissue for analysis)
    1. Radioactive isotopes tagged to red blood cells are used to identify occult bowel bleeding and may detect abnormal stomach tissue in a Meckel's diverticulum that has bled.
    2. Doppler ultrasound can evaluate the blood vessels

Indication for Surgery

  • Obstruction of the small bowel for any reason warrants surgery
  • Perforation requires urgent surgery to eliminate continued spillage of bowel contents into the abdominal cavity causing peritonitis (inflammation of the peritoneum)
  • Inflammation of diverticula or Meckel's diverticulitis with or without bleeding may require surgery
  • Bleeding will require surgery when it is excessive and cannot be controlled non-surgically. Surgery is usually indicated when the individual has received 5-6 units of packed red blood cells and bleeding continues
  • Intractability (persistent disease) becomes an indication when medical therapy is unable to control the disease. The most frequent example is Crohn's disease. Patients who require frequent hospital admission for incomplete small bowel obstructions may need surgery
  • Tumor or inflammatory mass may warrant surgery. Jejunal and ileal small bowel tumors are rare with carcinoid being the most common. Any malignant tumor of the small bowel is resected (removal of the tissue), if possible
  • Resections are often necessary with vascular compromise whether it is arterial or venous in origin

Contraindications for Surgery

  • Contraindications to small bowel surgery are determined by the patient's overall health and other diseases. If the patient's condition is marginal and the likelihood of surviving an operation is not good, surgery should be withheld or postponed
  • Unfortunately, many of the indications for surgery cannot be postponed since the possibility of a strangulated (loss of blood supply) small bowel obstruction or major vascular event will result in the patient's death if not corrected immediately

Surgical Procedures

  • Patients requiring surgery need special attention to fluid and electrolyte balance. Get the patient's condition back to near normal lessens the risk of surgery
  • Small bowel surgery is usually performed under general anesthesia with the patient supine (on the back)
  • A nasogastric tube is inserted through the nose into the stomach for drainage
  • A catheter is placed in the urinary bladder to monitor urinary output
  • Central venous catheters and/or an arterial catheter may be placed
  • Midline (up and down) or transverse (from side to side) incisions may be used
  • Different types of drains may be left in the abdominal cavity and brought out through the abdominal wall. The amount of drainage determines removal
  • Temporary feeding tubes may be placed in the stomach or small bowel
  • Benign or malignant (cancerous) tumors of the jejunum or ileum are treated with wide resection of the bowel and adjacent mesentery with anastomosis (suturing the two ends of the bowel together (Figure 6)
    1. The amount of small bowel to be resected is determined and two special clamps placed on the bowel at each of these points
    2. The bowel is cut between the clamps 3. The vessels in the attached mesentery are clamped, cut and tied
    3. The resected bowel is removed
    4. The two ends of the bowel are then brought together and sutured or stapled together
    5. The abdomen is closed with sutures
    6. Bringing a loop of small bowel out through the abdominal wall (enterostomy) is seldom necessary. It is necessary when there is concern about the anastomosis healing or adequacy of blood supply
Figure 6a - Tumor of small bowel is removed by clamping the bowel on both sides of the tumor as seen on the right. The bowel is cut through as seen on the left and the cut extended through the mesentery. © C. McKeeFigure 6b - After removal of the bowel with tumor, the cut ends of the small bowel are sutured together. © C. McKee
  • An intussusception may be reduced by pulling the telescoped bowel back to remove the obstruction or the intussusception may require resection
  • Diverticula, Meckel's diverticulum, inflammatory bowel disease (Crohn's disease), ischemic bowel, and non malignant perforations are treated with resection and anastomosis
  • Identified points of small bowel bleeding that are persistent require resection and anastomosis
  • Small bowel obstruction secondary to adhesions is ideally treated with lysis (cutting) of the adhesions and straightening out of the bowel. Not infrequently, single or multiple small bowel resections with anastomosis will be necessary
  • Chronic ischemia of the bowel is treated with endarterectomy (cleaning out of the plaque), bypass grafting (place a graft around the occlusion), or reimplantation (divide the vessel and reattach to another site)
  • Acute intestinal ischemia due to embolic occlusion requires urgent embolectomy (removal of clot) and anticoagulation
  • Massive bowel resections are frequently required at the time of the embolectomy. Mortality approaches 70% for this condition
  • Acute occlusive intestinal ischemia due to thrombosis of the superior mesenteric artery requires possible endarterectomy with thrombectomy (removal of clot and plaque) and patch graft, bypass or reimplantation (removal of the diseased segment and suture back into the aorta, major artery of the body)
  • Occasionally intra-arterial (into the artery) infusions of thrombolytic (clot busting) medications and vasodilators (blood vessel dilator) will be added to the surgery
  • Acute non-occlusive intestinal ischemia requires treatment of the underlying disease and discontinuing the drugs causing the problem. Infusion of intra arterial vasodilators may be done. Venous thrombosis will infrequently require thrombectomy (removal of clot) or bowel resection. These patients require life long anticoagulation unless the precipitating cause has been eliminated

Complications

  • Small bowel
    1. Bleeding, leak at a suture line (fistula), infection or abscess
    2. Loss of blood supply to the bowel
    3. Bowel obstruction
    4. Short gut syndrome - extensive resection with questionable length of bowel left to sustain nutrition
    5. Development of blood clots in abdomen
    6. Evisceration - wound breakdown with protruding intestine
    7. Hernias developing at the incision site
    8. Malabsorption - failure to adequately absorb certain vitamins and bile salts if there is excessive resection of the end portion of the ileum
  • Stomach - stress induced bleeding, collections of excessive blood or intestinal contents in the stomach
  • Pulmonary - aspiration of bowel content into lungs, atelectasis (failure to expand portions of lungs), pneumonia
  • Urinary - bladder infections, bleeding because of catheters
  • Extremities - insidious development of blood clots in leg veins
  • Nasopharynx - sinus infections, ulceration of nasopharynx, bleeding (all due to presence of a nasogastric tube)
  • Diarrhea - determined by length of bowel resection

Postoperative Care

  • Vital signs - blood pressure, temperature, heart rate, and respiratory rate are taken every 1 - 4 hours for the first 24 hours and tapered gradually
  • A catheter is placed in the urinary bladder to measure urine output, which is monitored frequently
  • A nasogastric tube is placed in the stomach through the nose and irrigated every 4-6 hours and placed on suction for 3-4 days. The tube is usually removed by the 3rd or 4th day. Once removed the diet progresses from liquids to soft food to a regular diet
  • IV fluids are given as necessary for 3-4 days or until the patient is drinking adequately
  • For control of pain, IV or intramuscular (in the muscle) medications are given for 2-3 days and then given by mouth when the patient can eat
  • Antibiotics are given for 24 hours IV if the bowel resection was clean or longer if the surgery was contaminated
  • Anticoagulants (blood thinners) are usually given subcutaneous (under the skin) every 8-12 hours until the patient actively walking
  • IV or oral medications may be given to prevent stomach stress bleeding
  • Deep breathing and walking are encouraged early and often
  • Laboratory studies may be ordered as necessary
  • Discharge is usually in 6 - 7 days after surgery

Post Discharge Instructions

  • The patient sees the surgeon in the office 5-10 days post discharge
  • No heavy lifting or straining for 6-8 weeks and no driving for 7-10 days
  • The patient can usually return to work in 4-8 weeks after surgery. The surgeon should be visited before returning to work
  • Crohn's disease patients and malignant conditions should be followed indefinitely