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Beverly Hills · 435 N. Bedford Dr., Suite 308Mon–Fri 9:00 am – 5:00 pmMost PPO insurance accepted
Allen KamravaMD · MBA · FACS · FASCRS

Procedure

Operative

Low Anterior Resection (LAR)

Removal of the diseased rectum — most often for rectal cancer — with the colon reconnected low in the pelvis so the sphincter muscles, and the normal route to the bathroom, are preserved.

Request a consultationSurgery is arranged with a coordinator by phone.
Setting
Operative
Anesthesia
General anesthesia, in the operating room
Back to work
3-6 weeks
Success rate
Greater than 95% (curative intent)
Recurrence
5-10% (local recurrence)

What it is

What is a Low Anterior Resection?

A Low Anterior Resection (LAR) is a common surgical procedure for the treatment of rectal cancer located in the upper and mid rectum. The primary goal is to remove the tumor along with the surrounding mesorectum, which contains the lymph nodes at risk for metastatic disease. The procedure is considered sphincter-preserving, as the anal sphincter muscles are not removed, and intestinal continuity is restored by creating an anastomosis between the colon and the remaining rectum. This allows patients to avoid a permanent colostomy.

Am I a candidate?

Who is a Good Candidate for an LAR?

Ideal candidates are patients with biopsy-proven rectal adenocarcinoma located in the mid-to-upper rectum (generally >5-6 cm from the anal verge). The procedure is suitable for both early-stage tumors and locally advanced tumors that have been downstaged after neoadjuvant chemoradiation. The decision to perform an LAR depends on the tumor's location, the patient's overall health, and their baseline sphincter function. For very low tumors, an LAR with a coloanal anastomosis may be possible, but this carries a higher risk of functional problems.

How it's done

  1. 1Under general anesthesia, usually through small keyhole (laparoscopic or robotic) incisions.
  2. 2The rectum is removed together with the envelope of tissue around it, which carries the nearby lymph nodes — for cancer, clearing those nodes matters as much as removing the tumor itself.
  3. 3The colon is brought down and joined to the remaining rectum or the top of the anal canal (an anastomosis). The sphincter muscles stay — this is what makes it a sphincter-preserving operation.
  4. 4For low connections, a temporary loop ileostomy is often part of the plan: a small stoma on the abdomen that diverts stool while the new join heals. It is usually closed in a second, smaller operation about 2 to 3 months later.
  5. 5A hospital stay of several days follows, while the bowel wakes up and you get back to eating and walking.

What to expect

  1. Days 1–5

    In hospital — walking early, diet building back up, a urinary catheter for the first few days.

  2. Home

    Usually within about a week, depending on how the bowel recovers.

  3. 2–3 months

    If a temporary ileostomy was made, it is typically closed in a second, smaller operation once the join has healed.

  4. First year

    Bowel function settles gradually. Frequency, urgency and clustered bowel movements are common early on and usually improve with time — diet, medication and pelvic floor therapy all help.

Risks & considerations

What are the Risks?

While LAR is a standard and safe procedure, it carries significant risks, including:

  • Anastomotic Leak: This is the most feared complication, where the new connection between the colon and rectum fails to heal properly, leading to leakage of stool into the pelvis. This can cause a severe infection (pelvic abscess or peritonitis) and often requires a temporary or even permanent stoma.
  • Bleeding: Intra-abdominal or pelvic bleeding can occur, sometimes requiring blood transfusions or reoperation.
  • Infection: Surgical site infections, including wound infections and intra-abdominal abscesses, are possible.
  • Urinary and Sexual Dysfunction: The dissection in the deep pelvis can injure the autonomic nerves that control bladder and sexual function, leading to urinary retention, erectile dysfunction, or retrograde ejaculation.
  • Low Anterior Resection Syndrome (LARS): This is a common constellation of bowel function problems after surgery, including frequency, urgency, clustering of bowel movements, and incontinence.
  • Stoma-Related Complications: If a temporary ileostomy is created, it carries risks of dehydration, blockage, and complications related to its closure.

The risks that matter

Every operation carries a long list of possible complications. These are the ones that are serious enough — and common enough — to understand in real numbers before you decide.

Anastomotic leak

observational

Where the new connection between the colon and the rectum or anal canal doesn't fully seal, letting intestinal contents escape into the pelvis.

about 8–9% overall; reported from 5% up to 20% for the lowest connections— roughly 1 in every 11 operations, more often when the join is very low
Why it happens
A low pelvic connection has to heal in the most demanding spot in the abdomen — deep, narrow, with a tighter blood supply, and often in tissue that has been through radiation as part of good cancer care. Even in expert hands a fraction won't seal fully. It is a recognized complication of the operation itself, not a sign anything was done carelessly; every colorectal surgeon manages leaks over a career.
If it happens
It's watched for closely with exams, blood tests, and a CT scan at any concern. Treatment ranges from antibiotics and a drain to a return to the operating room. When a diverting ileostomy was made at the first operation, it usually keeps a leak from making you seriously ill while the join heals.
How we lower the odds
A tension-free, well-perfused connection tested during surgery; a planned temporary ileostomy for low joins, which markedly reduces the chance a leak becomes a serious illness; and getting you as healthy as possible beforehand — nutrition, blood sugar, stopping smoking — with close monitoring in recovery.

Lowering the odds is not the same as removing them. Even when everything is done right, this can still happen — that is the nature of the operation, not a failure of your care.

Source: Cong Z-J, et al. Systematic review of anastomotic leakage rate following anterior resection for rectal cancer (40 studies, 24,288 patients). PLOS ONE. 2013;8(9):e75519. Range for low anastomoses: Prevention, Recognition, and Management of Anastomotic Leakage and Pelvic Sepsis After Rectal Cancer Surgery: A Structured Narrative Review. J Clin Med. 2026. doi:10.3390/jcm15166427.

Low anterior resection syndrome (LARS)

observational

A lasting change in how the bowel works after the rectum is removed — more frequent trips, urgency, bowel movements arriving in clusters, and sometimes trouble holding on.

major LARS in about 40% of patients— roughly 4 in every 10 people after this operation
Why it happens
The rectum is the body's reservoir and early-warning system, and this operation removes it. The colon that takes its place never signals quite the same way. LARS is a consequence of the anatomy of the cure, not of how the surgery was done — radiation and very low joins make it more likely.
If it happens
Most people improve over the first one to two years. Diet adjustments, fiber and anti-diarrheal medication, and pelvic floor physical therapy help most; transanal irrigation and sacral nerve stimulation are options for symptoms that persist.
How we lower the odds
Preserving as much rectum as the cancer safely allows, careful sphincter-sparing planning, and honest counseling beforehand so treatment starts early rather than after months of quiet suffering.

Lowering the odds is not the same as removing them. Even when everything is done right, this can still happen — that is the nature of the operation, not a failure of your care.

Source: Croese AD, et al. A meta-analysis of the prevalence of Low Anterior Resection Syndrome and systematic review of risk factors. International Journal of Surgery. 2018;56:234–241.

Sources

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