What Is Low Anterior Resection (LAR Surgery)?

Low anterior resection (LAR) is frequently used to treat rectal cancer. It may be performed electively or in an emergency. The cancer-affected part of the rectum is carefully removed, taking an important step toward improving the patient's health.

Colorectal (large bowel) cancer surgery varies according to the cancer's location and stage. The most commonly used surgical techniques are:

1. Colectomy: The most common operation for colon cancer. It removes the cancerous part of the colon and surrounding lymph nodes. There are two types:
   1. Total Colectomy: Removal of the entire colon.
   2. Segmental Colectomy or Hemicolectomy: Removal of only the cancerous part of the colon. It may be a right or left hemicolectomy, depending on the cancer's location.
2. Rectal Surgery for Rectal Cancer (Rectal Resection): Used to treat rectal cancer by removing the cancerous rectal area and surrounding tissues. Common types include:
   1. Low Anterior Resection (LAR): Used for cancers in the upper and middle rectum and sigmoid colon.
   2. Abdominoperineal Resection (APR): Used for cancers in the lower rectum and involves removing the entire rectum and anus.
3. Laparoscopic Surgery: A minimally invasive approach to colorectal cancer surgery performed through small incisions. It offers faster recovery and reduced postoperative pain.

The suitability and choice of these techniques depend on factors such as overall health, cancer stage, and extent of spread.

What to Know About Low Anterior Resection

LAR removes tumors in the upper and middle rectum and sigmoid colon. The affected bowel segment is cut at least 2 cm below and 10 cm above the tumor and removed with surrounding lymph nodes. The remaining rectum is joined to the sigmoid colon to restore bowel continuity. Surgery may be open, laparoscopic, or robotic. Laparoscopic and robotic approaches offer advantages such as less pain, faster recovery, fewer complications, and better cosmetic outcomes. LAR preserves the anus, allowing patients to continue passing stools through it.

LAR surgery is illustrated simply below. Some patients may need a temporary ileostomy to help the surgical area heal and reduce infection risk. Whether an ileostomy is necessary depends on factors such as overall health, rectal cancer stage, and how much of the rectum is removed during surgery. 

General anesthesia puts the patient to sleep before surgery. The team removes the cancerous part of the rectum and may also remove some surrounding healthy tissue and lymph nodes. The colon is then connected to the remaining rectum. LAR usually takes 4 hours.

LAR options include:

• Open surgery: Surgeons make a single long abdominal incision and remove the cancerous tissue through it.
• Minimally invasive surgery: Surgeons make several small abdominal incisions, insert a video camera and small instruments, and remove the cancer. This may use conventional laparoscopy (keyhole surgery) or a robotic device.

What Conditions Is LAR Used to Treat?

LAR is used particularly for stage 1, 2, and 3 cancers of the rectum and rectosigmoid junction.

A 2019 study compared success rates and complications of elective and emergency LAR in 80 people. Results suggest that emergency surgery may limit the surgeon's ability to remove cancer and preserve tissue.

The same study found a tendency toward more postoperative complications after emergency than planned LAR. However, researchers noted that long-term reassessment might be needed to fully understand emergency versus elective outcomes. This could include:

• Long-term survival rates
• Quality of life
• Other surgical complication rates, such as genital and urinary problems

Preparing for LAR

Certain factors can affect LAR surgery and increase the likelihood of complications. Before the operation, patients are asked:

• Whether they take medications such as blood thinners
• Whether they smoke
• Whether they drink alcohol
• Whether they have sleep apnea

Before surgery, it is helpful to plan the following:

• Find out whether the surgeon will create an ileostomy
• Arrange for a caregiver after surgery

After LAR

Most people wake up in the hospital's postanesthesia care unit immediately after surgery. Staff check:

• Blood pressure
• Oxygen levels
• Body temperature
• Heart rate

The patient will also have a catheter and one or two drains in the lower abdomen.

If necessary, a mask or nasal tube may help with breathing. Pain-relieving medication may also be given.

Most patients spend a few days in hospital after LAR. The stay depends on the type of surgery, how it went, and overall health.

What Are the Risks of LAR?

Potential risks include:

• Fistula (leakage of bowel contents)
• Intestinal (bowel) obstruction
• Peritoneal abscess
• Peritonitis
• Urinary problems
• Myocardial infarction (heart attack)
• Pulmonary thromboembolism
• Brain injury

What Is Recovery After LAR Like?

Recovery depends on overall health and whether treatment was received before surgery. Some people may have a temporary ileostomy. This involves surgically bringing the final part of the small intestine, usually called the ileum, to the abdominal wall and creating an external opening. A bag or pouch called an ileostomy bag is attached to collect digestive waste from the small intestine. An ileostomy may help the bowel heal or allow it to rest temporarily. A specialist explains how to care for it during this period.

Surgeons may reverse the ileostomy after approximately 8 weeks.

After LAR, a person may also need to:

• Follow a specific diet (such as BRAT) to control frequent bowel movements
• Regularly clean incision wounds and change dressings
• Maintain hydration (drink enough fluids)
• Avoid strenuous exercise and activities
• For most people, recovery at home takes approximately 3 to 6 weeks.

The BRAT diet contains Banana, Rice, Applesauce, and Toast and is generally used for digestive problems such as diarrhea, nausea, and vomiting.

What Is the Difference Between LAR and APR?

Abdominoperineal resection (APR) removes the anus, rectum, and part of the sigmoid colon. Surgeons then create a stoma through an opening in the abdomen.

APR is more invasive than LAR and results in a comparatively lower quality of life.

What Is the Difference Between Low and High Anterior Resection?

High anterior resection is similar to LAR. Surgeons make a higher incision to remove part of the left colon, upper rectum, and surrounding lymph nodes.

Is LAR a Major Operation?

Yes. It is a major surgical procedure requiring several weeks of recovery.

LAR Surgery in Brief

Low anterior resection (LAR) is an important operation for treating rectal cancer. It removes part of the sigmoid colon and the cancerous area of the rectum. Full recovery from this complex surgery generally takes three to six weeks. If a temporary ileostomy is created, the process of closing it and restoring normal bowel function may extend to eight weeks. Careful surgical follow-up and assessment are essential throughout this period to support complete recovery.