What Is Terminal Ileum: Anatomy And Function

Written by Tricia Thompson
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Terminal Ileum Anatomy and Function

The terminal ileum is the final segment of the small intestine, located in the lower right side of the abdomen. It connects the small intestine to the beginning of the large intestine, known as the cecum. The ileum is about 3.5 meters long and is responsible for absorbing nutrients and electrolytes from the remaining food that was not absorbed by the jejunum, the middle segment of the small intestine.

The terminal ileum contains the ileocecal valve, which regulates the flow of digested food from the small intestine into the large intestine. This valve prevents the contents of the large intestine from flowing back into the small intestine. The terminal ileum also plays a crucial role in the immune system, as it contains Peyer’s patches, which are collections of lymphoid tissue that produce antibodies to fight infections. Inflammation of the terminal ileum, known as terminal ileitis, can cause symptoms such as abdominal pain, diarrhea, and weight loss.

Anatomy and Physiology of the Terminal Ileum

The terminal ileum is the final segment of the small bowel that connects to the cecum of the large intestine. It is located in the right lower quadrant of the abdomen, and its length varies from 15 to 30 cm. The ileum is a part of the small bowel and is located between the jejunum and the cecum.

Terminal Ileum Anatomy and Function

Structural Features

The terminal ileum has a similar structure to the rest of the small bowel. The mucosa is lined with columnar epithelial cells, which have microvilli that increase the surface area for absorption. The submucosa contains lymphoid tissue, which is known as Peyer’s patches. The serosa is the outermost layer of the ileum and is covered by mesothelium.

The ileum has circular folds, which increase the surface area for absorption. The circular folds are also known as plicae circulares. The lymphatic vessels of the ileum are known as lacteals. They absorb fats and lipid-soluble vitamins from the chyme.

Functional Role in Digestion and Absorption

The terminal ileum is responsible for the absorption of nutrients, including bile salts, vitamin B12, and water-soluble vitamins. The ileum absorbs the remaining nutrients that were not absorbed by the jejunum. The terminal ileum also absorbs electrolytes and water.

The smooth muscle of the terminal ileum contracts to move the chyme towards the ileocecal valve. The contraction of the smooth muscle is known as peristalsis. The chyme is a mixture of food, digestive enzymes, and stomach acid.

Ileocecal Valve and Transition to the Large Intestine

The ileocecal valve is a sphincter that separates the terminal ileum from the cecum of the large intestine. The ileocecal valve prevents the backflow of fecal matter into the small bowel. The ileocecal valve is composed of smooth muscle, which contracts to prevent the reflux of fecal matter.

The transition from the terminal ileum to the cecum is an important site for the absorption of water and electrolytes. The cecum is the first part of the large intestine, and it receives the chyme from the terminal ileum. The mesentery is a double layer of peritoneum that attaches the ileum to the posterior abdominal wall. The superior mesenteric artery supplies blood to the ileum.

In conclusion, the terminal ileum is an essential part of the digestive system that absorbs nutrients, electrolytes, and water. The ileocecal valve prevents the backflow of fecal matter into the small bowel and ensures the smooth transition of chyme to the large intestine.

Common Conditions Affecting the Terminal Ileum

The terminal ileum is the last portion of the small intestine that connects to the large intestine. It plays a crucial role in the absorption of nutrients and water. Several conditions can affect the terminal ileum, leading to inflammation, ulcers, and other complications.

Crohn’s Disease and Terminal Ileitis

Crohn’s disease is a type of inflammatory bowel disease (IBD) that can affect any part of the digestive tract, from the mouth to the anus. However, it most commonly affects the terminal ileum. When Crohn’s disease affects the terminal ileum, it is called terminal ileitis. The inflammation can cause abdominal pain, diarrhea, and other symptoms.

Infectious Diseases and Ileal Involvement

Several infectious diseases can cause inflammation of the terminal ileum. For example, tuberculosis can cause ileitis, leading to abdominal pain, diarrhea, and other symptoms. Other infectious diseases that can cause ileal involvement include bacterial infections, viral infections, and parasitic infections.

Non-Infectious Inflammatory Conditions

Aside from Crohn’s disease, other non-infectious inflammatory conditions can affect the terminal ileum. For instance, eosinophilic enteritis is a rare inflammatory disorder that can cause inflammation of the small intestine, including the terminal ileum. Vasculitis, which is inflammation of blood vessels, can also affect the ileum, leading to abdominal pain, diarrhea, and other symptoms. Ischemia, or reduced blood flow to the intestines, can cause inflammation and damage to the terminal ileum, leading to abdominal pain and other symptoms.

In summary, the terminal ileum can be affected by various conditions, including inflammatory bowel disease, infectious diseases, and non-infectious inflammatory conditions. Symptoms can include abdominal pain, diarrhea, and other digestive problems. It is important to seek medical attention if you experience any of these symptoms to receive an accurate diagnosis and appropriate treatment.

Diagnostic and Imaging Techniques

Endoscopic Evaluation

Endoscopy is a diagnostic procedure used to visualize the terminal ileum endoscopically. Colonoscopy is the most common method of endoscopic evaluation of the terminal ileum. During colonoscopy, a long, flexible tube with a camera attached to its end is inserted through the anus and rectum and advanced through the colon to the ileocecal junction. The ileocecal valve is then crossed, and the terminal ileum is examined. The endoscopic evaluation of the terminal ileum is essential for the diagnosis of various inflammatory bowel diseases (IBD), such as Crohn’s disease, which preferentially involves the ileum. The endoscopic appearance of the terminal ileum in Crohn’s disease may reveal ulcers, strictures, nodules, or cobblestone mucosa.

Radiological Imaging

Radiological imaging is another method of evaluating the terminal ileum. CT scans and ultrasound are two commonly used radiological imaging techniques. CT scans are useful in identifying strictures, fistulas, abscesses, and other complications of Crohn’s disease. In contrast, ultrasound is particularly useful in the evaluation of the terminal ileum in pediatric patients, where it can be challenging to perform endoscopic evaluation. Ultrasound can identify bowel loops, the ileocecal junction, and the ascending colon and is useful in identifying complications such as strictures and abscesses.

In cases where endoscopic evaluation is inconclusive, biopsy of the terminal ileum may be necessary for the diagnosis of IBD. Biopsy specimens can be obtained endoscopically or radiologically. The biopsy specimens are then examined histologically for the presence of characteristic features of Crohn’s disease or other IBDs.

In conclusion, endoscopic evaluation and radiological imaging are the two primary methods of diagnostic evaluation of the terminal ileum. Endoscopy is the gold standard for evaluating the terminal ileum and is essential for the diagnosis of various IBDs. Radiological imaging is particularly useful in pediatric patients and can identify complications of Crohn’s disease. In cases where endoscopic evaluation is inconclusive, biopsy of the terminal ileum may be necessary for the diagnosis of IBD.

Treatment and Management Strategies

Terminal ileitis is a condition that can be managed with a combination of medical therapies and surgical interventions. The treatment approach depends on the underlying cause of the inflammation in the terminal ileum.

Medical Therapies

Medical therapies for terminal ileitis aim to reduce inflammation, relieve symptoms, and prevent complications. The most common medical therapies include:

  • Nonsteroidal anti-inflammatory drugs (NSAIDs): NSAIDs can be used to reduce inflammation and relieve pain associated with terminal ileitis. However, in some cases, NSAIDs can actually worsen the inflammation and lead to complications such as bowel obstruction.
  • Corticosteroids: Corticosteroids are used to reduce inflammation and relieve symptoms such as abdominal pain and diarrhea. However, long-term use of corticosteroids can lead to side effects such as weight gain, osteoporosis, and increased risk of infections.
  • Immunomodulators: Immunomodulators such as azathioprine, mercaptopurine, and methotrexate can be used to suppress the immune system and reduce inflammation in the terminal ileum. However, these drugs can also have serious side effects such as an increased risk of infections and cancer.
  • Biologic therapies: Biologic therapies such as infliximab and adalimumab can be used to target specific molecules involved in the inflammatory process. These drugs can be effective in reducing inflammation and improving symptoms, but they can also have serious side effects such as an increased risk of infections and cancer.

Surgical Interventions

Surgical interventions for terminal ileitis are usually reserved for cases where medical therapies have failed or complications such as bowel obstruction have developed. The most common surgical interventions include:

  • Strictureplasty: Strictureplasty is a surgical procedure that involves widening the narrowed portion of the terminal ileum. This procedure is often used in cases where there is a small bowel obstruction.
  • Resection: Resection is a surgical procedure that involves removing the inflamed portion of the terminal ileum. This procedure is often used in cases where there is transmural inflammation or complications such as anemia and weight loss.

Conclusion

The treatment and management of terminal ileitis require a multidisciplinary approach that involves a combination of medical therapies and surgical interventions. The choice of treatment depends on the underlying cause of the inflammation and the severity of the symptoms. It is important to work closely with a healthcare provider to develop an individualized treatment plan that takes into consideration the potential benefits and risks of each treatment option.

Frequently Asked Questions

1. How is a colonoscopy performed on the terminal ileum?

A colonoscopy is a procedure that allows a doctor to examine the inside of the colon and rectum. It is usually done to investigate symptoms such as abdominal pain, rectal bleeding, or changes in bowel movements. During a colonoscopy, a long, flexible tube with a camera on the end is inserted into the rectum and guided through the colon. To reach the terminal ileum, the tube is advanced through the ileocecal valve, which separates the small intestine from the large intestine. The doctor can then examine the terminal ileum for any abnormalities.

2. What do normal terminal ileum colonoscopy images look like?

Normal terminal ileum colonoscopy images show a pink, smooth mucosal surface with no visible lesions or ulcers. The ileocecal valve, which separates the small intestine from the large intestine, is also visible. The terminal ileum is the last part of the small intestine and is located near the lower right side of the abdomen. It is normal for the terminal ileum to have some lymphoid follicles, which are small, round structures that help the body fight infection.

3. What are the potential causes and treatments for cancer in the terminal ileum?

Cancer of the terminal ileum is rare, but it can occur. The most common type of cancer in the terminal ileum is carcinoid tumor, which arises from the hormone-producing cells in the intestine. Other types of cancer that can occur in the terminal ileum include adenocarcinoma and lymphoma. Treatment options depend on the type and stage of cancer, but may include surgery, chemotherapy, and radiation therapy.

4. What is the function of the terminal ileum in the digestive system?

The terminal ileum is the last part of the small intestine and plays an important role in the digestive system. It absorbs vitamin B12, bile salts, and other nutrients that were not absorbed in the upper part of the small intestine. It also helps regulate the flow of material into the large intestine through the ileocecal valve.

5. Is it possible to surgically remove the terminal ileum, and what are the implications?

In some cases, it may be necessary to surgically remove the terminal ileum. This can occur as a result of conditions such as Crohn’s disease, cancer, or obstruction. Removal of the terminal ileum can affect the absorption of vitamin B12 and bile salts, which can lead to deficiencies. It can also affect the regulation of material into the large intestine, which can lead to diarrhea or constipation. However, most people can adjust to these changes with dietary modifications and medication.

5. How can one identify and describe pain associated with the terminal ileum?

Pain associated with the terminal ileum can be described as crampy, intermittent, and located in the lower right side of the abdomen. It may be accompanied by diarrhea, constipation, or bloating. Pain in the terminal ileum can be caused by a variety of conditions, including Crohn’s disease, inflammation, infection, or obstruction. If you experience persistent or severe pain in the lower right side of the abdomen, it is important to seek medical attention.

Written by

Tricia Thompson

Tricia Thompson, MD, is a board-certified physician with over 15 years of experience practicing general medicine. She completed her medical training at Johns Hopkins School of Medicine, where she graduated top of her class. Dr. Thompson runs a private practice in Seattle, WA, where she specializes in providing comprehensive care for patients of all ages. With a dedication to continuing education, Dr. Thompson regularly attends medical conferences and reads peer-reviewed journals to stay up-to-date on the latest advancements in treatments and technologies. She is a member of the American College of Physicians and is affiliated with multiple respected hospitals and medical centers.

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