Written and medically reviewed by: Assoc. Prof. Cengiz Dibekoğlu, MD, General SurgeryLast updated:
Rectal Cancer — Low Anterior Resection (LAR)
Sphincter-preserving rectal resection with TME and colorectal anastomosis — aiming for oncologic safety while keeping bowel emptying through the anus.
Low anterior resection (LAR) removes the rectum (and mesorectum with total mesorectal excision) for mid and selected low rectal cancers while preserving the sphincter mechanism, then joins colon to the remaining rectal stump (colorectal anastomosis). The goal is oncologic safety with continued defecation through the anus. A temporary ileostomy is often considered to protect low anastomoses. In selected cases the distal TME plane may be completed from below as TaTME; that does not rename the operation.
Educational schematic. Some structures may be simplified or emphasized for clarity; not an exact anatomical depiction.
© Cengiz Dibekoğlu — illustrative; not for unauthorized use
Figure summary
- This educational figure shows: Low anterior resection.
- Related figures on this page: TME plane.
Related educational figures
Tap a figure to enlarge.
TME plane Educational schematic. Some structures may be simplified or emphasized for clarity; not an exact anatomical depiction.
© Cengiz Dibekoğlu — illustrative; not for unauthorized use
Figure summary
TME plane
Who may be a candidate?
- Mid-rectal and selected low-rectal tumors
- No sphincter invasion on MRI / sphincter preservation feasible
- Cases where an adequate distal margin can be achieved
- Patients rendered suitable for sphincter-preserving surgery after neoadjuvant therapy / TNT
Possible advantages
- Preserves anal sphincters and avoids permanent colostomy when oncologically safe
- TME delivers the mesorectum as an intact package for local control
- Open, laparoscopic, or robotic access can deliver LAR principles
- Temporary ileostomy protects many low anastomoses and is later closed when healing is confirmed
Limits & realistic expectations
- Tumors invading the anal sphincter usually need Miles (APR) instead
- When a safe distal margin cannot be taken without sacrificing sphincters, LAR is not appropriate
- Some patients prefer APR after counseling about low anterior resection syndrome (LARS) function
- Low anastomoses carry leak risk and LARS (urgency, frequency, clustering)
Step-by-step overview
- 1
Exploration and colon mobilization
Abdominal and pelvic assessment. Left colon and splenic flexure are freed so the anastomosis can reach without tension.
- 2
Vascular pedicle
IMA (and usually IMV) are ligated at oncologic levels. Lymph pathways are cleared with the mesentery; ureters and autonomic nerves are protected when possible.
- 3
Pelvic TME
Dissection in the mesorectal fascial plane from behind and sides, keeping the mesorectum intact as a cylindrical package. Anteriorly, care near prostate or vagina.
- 4
Distal transection
Rectum is divided below the tumor with an adequate safety margin (stapler or open technique). The margin must be pathologically negative.
- 5
Specimen removal
Tumor-bearing rectum and mesorectum come out intact. Proximal colon is prepared for join.
- 6
Colorectal anastomosis
Colon is joined to the rectal stump with circular stapler (double-staple / circular) or suture. Perfusion, tension, and air–water leak testing are checked.
- 7
Temporary stoma (often for low LARs)
A loop ileostomy protects the anastomosis. Pelvic drain policy varies by center and case.
Key points
LAR together with TME
LAR is not merely ‘cutting the rectum.’ The mesorectum is removed intact (total mesorectal excision). Circumferential resection margin (CRM) and distal margin define oncologic quality.
Anastomosis height
The lower the anastomosis, the higher the potential LARS burden (frequency, urgency, gas–stool discrimination). That trade-off is discussed before consent.
Temporary ileostomy
Loop ileostomy is often used to reduce clinical impact of leak and protect healing. Weeks to months later, if the anastomosis is sound, it is closed.
High vs low anterior
Upper rectal / rectosigmoid tumors may have a higher join (anterior / high anterior). ‘Low’ anterior means the anastomosis sits closer to the pelvic floor.
After surgery
Early walking; pain and nausea control; ileostomy care teaching when applicable; leak vigilance (fever, tachycardia, pelvic pain, drainage); LARS education and pelvic-floor / diet support; stoma-closure timing; pathology ± adjuvant therapy.
- Early mobilization
- Ileostomy education if diverted
- Leak warning signs
- LARS counseling and rehab
- Stoma closure after confirmed healing
- Key note inside
Important
Educational information only — MRI height, sphincter status, and response to neoadjuvant therapy decide LAR versus ultra-low or Miles with your surgical team.
Frequently asked questions
Will I have a permanent bag after LAR?
The goal is no. Sphincters are preserved. Many patients have a temporary ileostomy that is later closed when healing is confirmed. Complications or oncologic necessity can change the plan.
How does LAR differ from Miles?
In LAR the anal canal and sphincters stay and an anastomosis is made. In Miles the anal canal is removed and a permanent colostomy is created.
Can LAR be laparoscopic or robotic?
Yes; selected cases can complete TME + LAR closed or robotically. Decision depends on anatomy, stage, and team experience.
When is the temporary ileostomy closed?
After imaging or endoscopy confirms anastomotic healing, and after adjuvant therapy and overall fitness are reviewed. Timing is often months but individualized.
What is LARS and can it be treated?
Low anterior resection syndrome includes frequent stools, urgency, fragmented emptying, and difficulty distinguishing gas from stool. Diet, medicines, pelvic-floor rehabilitation, and selected transanal irrigation can help.
More chapters in this hub
Rectal vs Colon Cancer
Differences from colon — explained for shared decision-making
Total Neoadjuvant Therapy (TNT)
Total neoadjuvant therapy — sequencing chemotherapy and radiation before surgery
Watch-and-Wait for Rectal Cancer
Non-operative management after clinical complete response — with strict surveillance
Rectal Cancer Operations
Operations: what the procedure aims to do and who it fits
Liver Metastases (colorectal)
When rectal cancer involves the liver: sequencing and hybrid liver treatment
Ultra-Low / Intersphincteric Resection
Very low anastomosis and the function trade-off
Abdominoperineal Resection (Miles)
When a permanent colostomy is the oncologically safer option
LARS After Rectal Surgery
Frequency, urgency, and leakage — diet, medicines, and pelvic rehab
TAMIS Surgery
Natural-orifice transanal local excision — no abdominal incision; single-port robotic TAMIS is a selected setup
TaTME
Selected mid and low rectal cancers: the lowest part is done through the anus, and the surgeon also works through the abdomen — not TAMIS
Recurrent Pelvic Rectal Cancer
Restaging, salvage surgery, and realistic goals after recurrence
Anal Canal Cancer
Squamous anal cancer — distinct from rectal adenocarcinoma; chemoradiation first
Appointment / info
This page is for education. It is not medical advice and does not replace a visit with your physician.
Medical editor: Assoc. Prof. Cengiz Dibekoğlu, MD · Last medically reviewed: August 2026 · English patient-education chapter.