Overview of Small Bowel Resection
The removal of part of the small intestine, known as a small bowel resection, is a fairly common surgical procedure. The small intestine is pretty long, so taking out a piece doesn’t usually affect how well your digestive system works. If you’re going to have this operation, it’s good to know that your surgeon has been trained thoroughly on the procedure, even if they’re not a specialist in digestive system surgery.
This is a basic rundown of what the operation involves, why it might be needed, and what can result from it, including potential complications. It’s worth noting that every individual and every surgery is unique and outcomes can vary.
Anatomy and Physiology of Small Bowel Resection
The small intestine is made up of three parts, named after where they’re positioned: the nearest one is called the duodenum, followed by the jejunum in the middle, and then the ileum at the end. The duodenum, which extends from the entrance of the small intestine, is about the length of a ruler (25 to 30 cm). It receives its blood supply from two sources, the celiac axis and the superior mesenteric artery, which are like two large roads that bring food and oxygen (blood) to the duodenum.
The duodenum itself is divided into four parts. The first part, called the duodenal bulb, travels from the entrance of the small intestine in a rightward direction. The next part is titled the descending duodenum, which is located behind the other organs. This part contains two important tubes, named the ampulla of Vater and the duct of Santorini, which are close to the liver’s tubes and the pancreas, and any surgery here can be incredibly complex due to its location. The third part, the transverse duodenum, also resides behind the other organs. The fourth portion turns upward after it has passed under the nearby blood vessels.
The transition from the duodenum to second segment, the jejunum, is marked by the ligament of Treitz (a thin band of muscle and tissue). The jejunum, which is about the length of four rulers (100 cm), has circular muscular folds and long blood-supplying vessels. It’s the main site for absorbing nutrients, except for B12, bile acids, and folate which are absorbed in the ileum. Iron is another nutrient that’s not absorbed here; It’s absorbed mostly in the duodenum. Meanwhile, most water and salt is absorbed in the jejunum.
The ileum is the third and last part of the small intestine and it’s about five rulers long (150 cm). It’s marked by its shorter blood-supplying vessels. Its blood supply, along with the jejunum, comes from several branches which originate from the superior mesenteric artery. These branches create a network of blood vessels within the tissue holding the small intestine together, ensuring good blood flow throughout. There are no areas in a healthy small intestine that lack blood supply.
When a surgeon looks at the small intestine, they see it as being divided into three layers: the mucosa, which is the innermost layer; the muscularis, the middle layer; and the serosal layer on the outside. The mucosa, the innermost layer, is glossy, filled with blood vessels, and its tissue changes rapidly. Because it’s so delicate, it can’t hold sutures (medical stitches) very well. It also has a network of nerve cells. The muscularis layer, which is beneath the mucosa, contains separate circular and longitudinal muscles which help to mix and push the food along the intestine. Finally, the serosa is a shiny layer that separates the intestine from other organs. It attaches to the mesentery (the tissue that holds the small intestine to the gut). These layers are made of tough connective tissue that provides a strong surface for the surgeon to sew onto during a procedure.
Why do People Need Small Bowel Resection
A small bowel resection, which is a type of surgery that involves removing a part of the small intestine, is needed for a number of reasons. Let’s break down some of the main situations where it might be necessary:
1. Blockage that can’t be cleared by breaking up scar tissue. In certain cases, the small intestine can experience a blockage that can’t be resolved by breaking up the scar tissue that’s causing it.
2. Possible cancer: If a doctor suspects that a patient may have cancer in the small intestine, they may perform the surgery and aim to take out an extra 8-10 cm around the suspicious area to make sure all the cancerous tissue is removed.
3. Non-trauma-related perforation: If an adult patient has a hole in their small intestine and it is not due to an injury, the cause may be ulcers or cancer. The small bowel resection could be a better option than simply repairing the hole because it allows a pathologist to study the tissue in a lab and provide a diagnosis.
4. Trauma-induced perforation: For patients with holes in their small intestine caused by an injury, surgeons can repair the defect if it’s less than half of the small bowel loop. If the damage is greater than that, then the damaged portion of the intestine may need to be removed completely.
5. Ischemic necrosis: This is a condition where some tissue in the small intestine starts to die because it’s not getting enough blood. This can happen because of a blood clot, a blockage, or problems with blood flow. Treatment may involve taking out the affected piece of intestine. But even if doctors operate, there’s a high chance of complications, and more operations may be needed. This is because the underlying condition causing the poor blood flow might not be fixable, and the affected area might spread.
6. Severe Inflammatory Bowel Disease (IBD): In cases where conservative treatments like medication and other types of surgery aren’t working, or the disease has caused a stricture (or blockage) that can’t be treated with a different procedure, a bowel resection might be necessary. However, because IBD makes the impacted area of the intestine inflamed, this makes complications more likely.
7. Enterocutaneous fistulas that can’t be treated conservatively: These conditions involve abnormal connections between the intestine and skin, that can’t be closed off with traditional measures, so sections of the small intestine may have to be removed.
8. Necrotizing enterocolitis with perforation: This is a serious condition mainly seen in premature babies, causing tissue in the colon or intestines to be damaged or die. If there’s a hole (perforation) in the intestine because of this condition, surgery may be necessary.
9. Troubling Meckel diverticulum or diverticular disease: These are conditions where pockets form in the lining of the digestive system, which can cause problems. Surgical removal may be possible if they cause noticeable symptoms.
When a Person Should Avoid Small Bowel Resection
There aren’t any hard-and-fast rules on who can’t undergo SBR (Small Bowel Resection), a surgery to remove a diseased part of your small intestine, for everyone. However, if a person is currently having a flare-up of IBD (Inflammatory Bowel Disease), it can be a bit risky. This is because the inflammation in the intestines can increase the chance of an anastomotic leak, which is a complication where the join between two parts of the intestine after the surgery can leak. A few other factors could also make the surgery a bit more risky, but these situations are rare, because this operation is typically only done when there aren’t any other treatments available to deal with the diseased part of the intestine.
Equipment used for Small Bowel Resection
A typical surgery tray has all the needed tools for an open Small Bowel Resection (SBR), which involves removing part of your small intestine. Certain retractors (devices used to hold back tissues or organs) mounted on the operation table, like the Omni-Flex or Bookwalter systems, are useful if the surgeon needs to examine your abdomen thoroughly during surgery.
For a laparoscopic SBR, a type of minimally invasive surgery, we prefer to use special tools called atraumatic graspers to handle your small intestine safely and avoid unnecessary injury to the intestinal lining. Devices like the Ligasure or Harmonic Scalpel, which use electric currents to cut or seal tissue, are necessary for carefully separating the small intestine from its supporting tissues.
Preparing for Small Bowel Resection
Small bowel resection, which is surgery to remove a part of your small intestine, can be carried out using open surgery or a less invasive approach called laparoscopic surgery. This decision depends on various factors like why the surgery is being done and when it’s planned.
When the surgery is scheduled ahead of time, patients are often advised to follow a low residue diet for a few days before surgery. This special diet includes foods that leave less waste in the digestive tract. Sometimes, a process known as a ‘mechanical bowel prep’ may be included, although this isn’t always the case.
However, many conditions that require a small bowel resection are emergency situations where there isn’t much time to prepare before the operation. In these cases, the focus is on providing support to critically ill patients.
Regardless of the circumstances, a few strategies are recommended to help reduce complications after the surgery. These include improving the patient’s nutrition, reducing the dose of any medications that lower the immune system, and draining any abscesses (pockets of pus) in the abdomen or pelvic area. These strategies are especially important for those with long-term conditions, like Crohn’s disease.
How is Small Bowel Resection performed
When doctors operate on the small intestine (also called the small bowel) it’s usually a pretty straightforward procedure, assuming the intestine is easy to move. But when they need to operate on a part of the small intestine called the duodenum, things can get quite complicated. This is because the duodenum is located behind the other organs in the abdomen (making it “retroperitoneal”) and is near important anatomical structures like the ampulla of Vater, the biliary tree, and the pancreas. In this case, they also must reconstruct the anatomy around it, which can be quite complex. Accordingly, specialized approaches are needed for different health conditions that affect the duodenum.
For example, to tackle tumors in the duodenum (even the ones that don’t cause symptoms and are discovered by chance during an upper gastrointestinal endoscopy), doctors have to carefully evaluate their malignant potential i.e., their likelihood to turn into cancer. These tumors should be removed if they tend to become cancerous as they pose a risk to the patient. Small tumors (those under 1 cm in diameter) can be removed by a procedure called endoscopic polypectomy, which can be performed without traditional surgery. However, if the tumor is larger (over 2 cm), doctors might need to remove it surgically. In these cases, they may need to do a procedure called transduodenal polypectomy or a segmental duodenal resection, depending on where the tumor is located in the duodenum. Some particularly tricky tumors are those near the ampulla of Vater; these are usually removed by a surgical procedure that involves removing the head of the pancreas, the first part of the small intestine, gallbladder, and bile duct, called a pancreaticoduodenectomy or a Whipple’s procedure. In some cases, however, if the tumors are between 1-2 cm, endoscopic polypectomy is preferred, especially if they haven’t grown beyond the lining of the intestine.
Once a doctor has removed a tumor from the small intestine using a common endoscopic procedure, they’ll usually need to keep a close eye on the place where the tumor was to catch any reappearance promptly. If a recurring adenoma appears within the second part of the duodenum, a pancreaticoduodenectomy might be recommended.
Before cutting out any part of the small intestine, it should be thoroughly checked. If doing an open surgery, the part to be cut out should be lifted out of the body and placed on a towel to minimize the risk of contamination from the contents of the intestine. This removal process is planned based on how the surgeons intend to reconnect the ends of the intestine: whether they plan to do it manually with sutures or using a stapler. For stapled reconnection, cuts are made towards the wall of the intestine, avoiding any large blood vessels. A specific type of stapler called gastrointestinal anastomosis stapler (GIA) is then put across the bowel and then fired to cut and seal the intestine. The diseased segment is then separated from the surrounding tissue using a tool that cuts through tissue by heat (electrocautery), while blood vessels are tied up with sutures. Afterwards, a common channel is made between the two ends of the intestine, and the incisions are closed up. The safety stitches in the corners, and the closure of the surgical defect in the supporting tissue of the bowel is an important final step in the procedure.
Another way to join the two intestines ends is by manually sewing them together using sutures. This takes longer but is preferred by many surgeons. The process includes making suitable defects, clamping and ligating the tissue, and placing the non-crushing clamps across the bowel. Once the diseased part is cut off and removed, the cut ends of the small bowel are aligned, and sutures are placed in the corners. The surgery is typically done in an end-to-end fashion. In some cases, there might be a size difference between the two segments, like when one segment is more swollen than the other or when fixing the connection between the small and the large intestine (ileocecal anastomosis). Several techniques are employed to join the two segments together, and the operative time could be longer in some cases.
If the doctor prefers to use one layer of sutures to close the wound, the progress is parallel except for the use of additional stitches (Lembert stitches). This is faster compared to a double layer. However, it’s up to the doctor to decide which method to use based on their clinical judgment. A single layer of stitches is often used in patients with naturally narrow intestines, such infants. A double layer of stitches is often used because a single layer might risk blocking the intestines if the lumen or the passageway in the intestine is small. It’s challenging to compare these two techniques because of all the factors like the type of suture, surgeon experience, patient’s specific condition, and other health issues that can affect the overall outcome.
When removing tumors, the surgeon will generally have to remove more tissue (8-10 cm) along with the associated supportive tissue and lymph nodes. However, in benign processes, doctors only have to make a small cut and not disturb the blood supply.
Possible Complications of Small Bowel Resection
After a surgery, there can sometimes be infections on the top layer of the wound. These infections are pretty common, especially when the surgical site gets contaminated to some extent. Letting the wound heal on its own, without stitches, can help reduce the risk of these infections. It also helps avoid the development of abscesses (which are collections of pus) and decreases the chance of the wound splitting open.
Breaking down of the union of two sections of the bowels after a Small Bowel Resection (SBR), a type of surgery where a part of the small intestine is removed, is a common but serious complication. Depending on many factors, it happens in 1% to 24% cases. Doctors try to reduce this risk by making sure there’s a good blood flow to the surgical site and putting as little strain on it as possible. Getting proper care before and after surgery and eating a balanced, nutritious diet can counter any related problems.
Unlike some surgeries on the large intestine, SBR doesn’t allow bypassing the normal flow of our digestive waste to protect the surgical site. If there’s a breakdown of the surgical union, it can lead to leakage of bowel contents, causing abscesses, inflammation of the abdomen, and potentially severe infections. This could also lead to the wound splitting open.
A fistula, which is an abnormal connection between two parts of the bowel or between the bowel and the skin, is another complication that can occur after the surgery. They can appear as a result of leaking at the surgical site and sometimes as a reason for another SBR. Fistulas inside the abdomen impair the small intestine’s ability to absorb nutrients, which can potentially add to any existing nutritional problems.
Like all surgeries within the abdomen, SBRs may lead to the development of adhesions, which are bands of scar tissue that can cause different parts of the body to stick together, potentially causing blockages in the future.
For our bodies to absorb fat-soluble vitamins, they need to be broken down with the help of enzymes from our pancreas and bile from our liver. However, in people with Short Bowel Syndrome (SBS, which is a condition often resulting from SBR), the food passes through their intestines too quickly. This leaves less time for these vitamins to be properly broken down and incorporated into particles called micelles, which are required for absorption. As a consequence, people with SBS may experience deficiencies in fat-soluble vitamins.
What Else Should I Know About Small Bowel Resection?
When a large amount of the small intestine is removed, it might result in short bowel syndrome (SBS). SBS is a health condition that is due to insufficient small intestine length to absorb nutrients properly, leading to malnutrition. This could happen because the food moves too quickly through the short small intestine, preventing essential nutrients from being absorbed effectively. People with SBS might experience weight loss, diarrhea, fatty stool, electrolyte imbalance, and deficiencies in fat-soluble vitamins.
SBS is a serious condition; a third of patients could potentially pass away during the same time they are diagnosed. Moreover, one in three patients with SBS could pass away within the first year after diagnosis due to malnutrition and other related health issues which are a result of treating the disease.
The aim of treating SBS is to provide patients with a normal, healthy life and meet their nutritional needs from the food they eat. Patients that have to depend on receiving nourishment directly into their veins over long periods is burdensome in terms of cost and lifestyle. It can also lead to other health issues such as liver disease, and an increase in risk for complications related to the infusion device that’s placed in a patient’s vein.
While our small intestine does improve absorption once it has healed, the length of the remaining small intestine is the most important factor that determines how well a person with SBS will fare. It’s important to note that the small intestine’s ability to absorb isn’t usually affected until more than half of it is gone. If an adult has 180 cm or more of their small intestine remaining, chances are they could manage without long-term vein feeding. But if they have less than 60 cm of small intestine, they would likely need to rely on vein feeding indefinitely. Along with the length of the small intestine, other factors also affect how well the remaining small intestine can absorb nutrients. For example, the presence of the ileocecal valve and terminal ileum, the last part of the small intestine, significantly increases the chances of being able to eat normally.
Babies and children are at a higher risk of developing SBS due to a premature birth condition called necrotizing enterocolitis and birth defects that cause the small intestine to twist unexpectedly or fix improperly in the abdomen. For children, if they have more than 60 cm of the small intestine, they will likely be able to eat normally. However, the chances of survival and whether they can be maintained on regular food alone cannot be accurately predicted based only on the total bowel length. This is because the total bowel length varies with the age of the child. Among children with SBS, around 70% survive. The risk of death and dependency on vein feeding increases drastically when the length of the predictive bowel based on the child’s age drops to 10%.
The treatment strategies for SBS include preventing weight loss and deficiencies, managing the underlying cause without causing further loss of the small intestine, and to stop the progression of the disease. During the early stages of SBS diagnosis, many patients are critically ill and losing weight rapidly. Thus, they would need to rely on vein feeding to meet their nutritional needs. However, once the patient’s intestinal function has recovered, oral feeding is advised even if they’re likely to develop SBS. This is because the act of eating stimulates the cells of the small intestine to adjust to the changes. Certain drugs like loperamide and opiates can help slow down gut function, thus increasing the time the food stays in the intestine, promoting better absorption. Other important goals include controlling diarrhea and reducing gastrointestinal secretions to maximize the absorption of nutrients.
Surgery for people with SBS is rarely used in adults and reserved for patients who cannot maintain their nutritional needs with regular food. Children, on the other hand, are more likely candidates for surgery but are also more likely to thrive on eating normally. If surgery is needed, the main goal should be to preserve the remaining small intestine. About half the patients with SBS may have to undergo additional abdominal surgeries for various intestinal problems after the diagnosis.
In some cases, children might develop obstructions, causing an enlargement of the bowel and overgrowth of bacteria. These obstructions should be treated surgically. If a child’s bowel is highly dilated, a surgical procedure to increase the length of the small intestine may be effective. In some situations, reversing small segments of the intestine or placing grafts from the large intestine for a short segment have shown some anecdotal positive outcomes.
