A bowel resection is surgery to remove a damaged or diseased section of the intestine. It’s one of the most common abdominal surgeries, performed to treat conditions ranging from colorectal cancer to severe inflammatory bowel disease. The procedure can involve the small intestine, the large intestine (colon and rectum), or both, and the specific name changes depending on which segment is removed.
Why a Bowel Resection Is Needed
The most common reasons for bowel resection include colon cancer, diverticulitis, gastrointestinal bleeding, bowel obstruction, and severe inflammatory bowel disease such as Crohn’s disease or ulcerative colitis. In cancer cases, the goal is to remove the tumor along with a margin of healthy tissue and nearby lymph nodes. For conditions like diverticulitis, surgery removes a section of colon that has developed infected pouches and is at risk of rupturing or has already done so.
Some resections are planned weeks in advance (elective), while others happen on an emergency basis, such as when a bowel obstruction cuts off blood supply to the tissue. Elective procedures carry significantly lower risk, with mortality rates around 1 to 1.5%, a number that has been steadily declining over the past decade.
Types of Bowel Resection
The name of the surgery corresponds to the part of the intestine being removed. A small bowel resection (or segmental resection) removes a portion of the small intestine. On the large intestine side, the options are more specific:
- Right hemicolectomy: removes the first part of the colon, including the appendix and the bend near the liver
- Transverse colectomy: removes the middle section of the colon
- Left hemicolectomy: removes the descending colon and part of the sigmoid colon
- Sigmoid colectomy: removes the sigmoid colon, the S-shaped section just before the rectum
- Low anterior resection: removes the sigmoid colon and part of the rectum
- Abdominoperineal resection: removes the rectum, anus, and surrounding muscles
A total colectomy removes the entire colon. Which type you need depends entirely on where the disease is located and how much tissue is affected.
Open Surgery vs. Laparoscopic Surgery
Bowel resection can be done through a single large incision (open surgery) or through several small incisions using a camera and specialized instruments (laparoscopic surgery). Some procedures use a hand-assisted approach, where one incision is large enough for the surgeon’s hand while the rest of the work is guided by camera. Robotic-assisted versions of laparoscopic surgery are also increasingly available.
Laparoscopic surgery takes longer in the operating room, but the recovery advantages are well documented. Patients experience less pain afterward, need fewer pain medications, and regain bowel function faster. In clinical trials, the gut started working again about 36 hours after laparoscopic colon surgery compared to 55 hours after open surgery. First bowel movements came roughly a full day sooner. Hospital stays are consistently shorter with laparoscopic approaches, and patients report better physical and social functioning in the weeks that follow. Not every patient is a candidate for laparoscopic surgery, particularly if the disease is extensive or there are dense abdominal adhesions from prior operations.
What Happens During the Procedure
After the diseased section of bowel is removed, the surgeon needs to restore the path for digested food to travel through. In most cases, the two remaining ends of the intestine are reconnected, a step called an anastomosis. This reconnection allows the digestive system to function normally without any external devices.
Sometimes a direct reconnection isn’t safe. If the remaining bowel is inflamed, the blood supply is poor, or the patient is critically ill, the surgeon may create a stoma instead. This is an opening in the abdominal wall where the intestine is brought to the surface, and waste collects in an external pouch. A stoma can be temporary, allowing the bowel to heal before a second surgery reconnects it, or permanent if the rectum and anus have been removed. Surgeons tend to reserve stomas for sicker patients or more complex situations.
Risks and Complications
The most serious complication specific to bowel resection is an anastomotic leak, where the reconnection site fails to heal properly and intestinal contents spill into the abdominal cavity. Leak rates range from about 3% to as high as 30% depending on the location of the surgery, with rectal reconnections carrying higher risk than colon reconnections. A leak typically requires a return to the operating room and can significantly extend the hospital stay.
Surgical site infections occur in roughly 13% of cases, including both superficial skin infections and deeper infections within the abdomen. Other potential complications include bleeding, blood clots, and injury to surrounding organs. Overall mortality for elective colon resection sits between 1% and 2% at most hospitals.
Preparing for Surgery
For planned procedures, preparation typically begins the day before surgery. Most surgeons prescribe a combination of an oral laxative solution to clean out the colon and oral antibiotics to reduce the bacterial load in the gut. This combination, used for over three decades, remains the standard approach recommended by the American Society of Colon and Rectal Surgeons. You’ll be asked to stop eating solid food about six hours before the operation, though clear liquids are usually allowed up to two hours beforehand. Some programs also provide a carbohydrate-rich drink the night before to help maintain energy levels heading into surgery.
Recovery in the Hospital
Modern recovery programs focus on getting patients moving and eating as quickly as possible after surgery. You’ll likely be encouraged to sit up and walk within hours of waking from anesthesia, and offered clear fluids the same day or the next morning. Chewing gum is sometimes provided because it stimulates gut motility and helps the intestines “wake up” faster. Pain management typically relies on a combination of non-opioid medications to minimize the constipating effects of stronger painkillers.
The median hospital stay after colorectal surgery is about 4 days, though the average stretches to 7 days because some patients experience complications that keep them longer. Laparoscopic patients consistently leave the hospital sooner than those who had open surgery. If a laparoscopic procedure has to be converted to open surgery midway through, the expected stay roughly triples in length.
Long-Term Changes in Bowel Function
Most people recover well and return to a normal diet within several weeks, but the specific section of bowel removed can permanently change how digestion works. The type of long-term bowel changes depends on which part was taken out.
Patients who have a sigmoid colectomy are about three times more likely to experience long-term constipation compared to those who had a right or left hemicolectomy. The sigmoid colon normally acts as a holding area before a bowel movement, so removing it disrupts that storage function. On the other hand, patients who have a right hemicolectomy are more than twice as likely to experience loose stools and fecal urgency, because the right colon is where the body absorbs most of the water from digested food.
These changes happen in part because the surgery disrupts the nerve supply to the remaining colon, reducing its ability to sense fullness and coordinate contractions. Scar tissue from healing can also affect motility. For most people, symptoms improve over the first year as the remaining bowel adapts, but some degree of change in bowel habits can be permanent. Dietary adjustments, fiber supplementation, and in some cases medication can help manage these shifts.
When a large portion of the small intestine is removed, the body may struggle to absorb enough nutrients and fluids from food. This is more of a concern with small bowel resections than colon resections, and the severity depends on how much length is taken out and which segment is involved.