Sources and Guidelines Referenced

The clinical information in this guide is derived from established international oncological guidelines and landmark peer-reviewed studies: National Comprehensive Cancer Network (NCCN) Guidelines for Colon and Rectal Cancer (v1.2024); American Society of Colon and Rectal Surgeons (ASCRS) Clinical Practice Guidelines for the Surgical Treatment of Colon Cancer (2022) and Management of Rectal Cancer (2020); European Society for Medical Oncology (ESMO) Clinical Practice Guidelines for Colon and Rectal Cancer (2020/2021); National Institute for Health and Care Excellence (NICE) Guideline NG151 (2020, updated 2023); and evidence from the COLOR II and CLASICC randomized clinical trials.

Colorectal Cancer Surgery: A Comprehensive Patient Guide

1. Definition and Medical Identity

Colorectal cancer surgery is a primary surgical operation to remove malignant tumors from the colon or rectum. It involves resecting the cancerous intestine, removing adjacent lymph nodes, and reconnecting healthy tissue or creating an abdominal stoma. Its core goal is achieving complete tumor excision with clear surgical margins to cure or control local disease.

Surgical resection remains the definitive treatment modality across the spectrum of gastrointestinal oncology. The colon and rectum form the final sections of the human digestive tract, responsible for water absorption, electrolyte balance, and waste storage. When malignant neoplasms invade the intestinal wall, surgical management requires removing the primary lesion alongside its mesentery—the vascular and fatty tissue containing the primary regional drainage nodes. Depending on the exact anatomical site of the disease, procedures are classified as a colectomy (surgical removal of all or part of the colon) or a proctectomy (surgical removal of all or part of the rectum).

2. The Underlying Condition or Need

Colorectal cancer arises when abnormal mucosal cells in the large intestine undergo genetic mutations, forming benign polyps (tissue growths) that progressively transform into invasive adenocarcinomas. Without surgical removal, these primary tumors invade deeper muscular layers, cause intestinal obstruction or hemorrhage, and metastasize through lymphatic vessels and blood vessels to distant organs.

According to the American Cancer Society (ACS) and World Health Organization (WHO), adenocarcinoma accounts for over 90% of all colorectal malignancies. As tumor cells breach the basement membrane and penetrate the submucosa (the connective tissue layer beneath the intestinal lining), they enter a dense network of lymphatic capillaries. Unchecked tumor growth gradually occludes the lumen of the bowel, leading to chronic iron-deficiency anemia, altered bowel habits, abdominal distension, severe pain, and life-threatening bowel perforation. Surgical excision removes the primary tumor burden before systemic spread becomes uncontrollable, eliminating the source of bleeding, pain, and physical obstruction.

3. How the Treatment Works — Mechanism

Colorectal cancer surgery functions by physically removing the cancerous bowel segment alongside its regional vascular and lymphatic drainage pathways. By performing an en bloc resection (removing the tumor and surrounding tissue together), surgeons eliminate visible disease, clear micrometastatic regional lymph nodes, and allow pathologists to accurately stage the cancer for further treatment planning.

The fundamental oncological principle underpinning this surgery is central vascular ligation along anatomical embryological planes. The arterial blood supply to the colon and rectum runs within the mesentery, mirrored by parallel lymphatic channels. Surgeons isolate and divide the main feeding arteries—such as the superior mesenteric artery branches or the inferior mesenteric artery—at their origin. This approach, known as complete mesocolic excision (CME) for colon cancer or total mesorectal excision (TME) for rectal cancer, ensures that the envelope containing potential lymph node metastases is resected intact without tumor spillage. Following resection, the remaining healthy intestinal ends are joined together in an anastomosis (surgical reconnection) using specialized surgical staplers or manual sutures to restore natural bowel continuity.

4. Types and Variations

Colorectal cancer surgery encompasses several specialized procedures determined by anatomical tumor location, depth of invasion, and surgical access technique. Common surgical variations range from localized segmental bowel removals to complex total mesorectal excision (surgical removal of the rectum and surrounding fatty envelope), performed via open incision, laparoscopic keyhole surgery, or robotic-assisted methods.

Surgical techniques are tailored to the precise anatomical sub-site of the tumor within the large bowel. The table below details the primary surgical types, their anatomical targets, and clinical descriptions based on ASCRS surgical consensus guidelines.

In addition to anatomical extent, clinicians select the surgical access platform: conventional open laparotomy (a single long abdominal incision), laparoscopic surgery (using multiple small ports, camera guidance, and specialized instruments), or robotic-assisted surgery (utilizing 3D high-definition visualization and wristed robotic arms to operate within tight pelvic spaces).

5. Who the Treatment Is For — Indications

Colorectal cancer surgery is indicated for individuals diagnosed with non-metastatic Stage I through Stage III colon or rectal carcinomas, and select Stage IV cases with resectable oligometastases. Eligibility depends on histological verification via biopsy (tissue sample analysis), preliminary radiological staging, adequate cardiopulmonary reserve, and the absence of unmanageable systemic medical comorbidities.

According to NCCN and ESMO clinical practice guidelines, clear indications for surgical intervention include:

• Stage I-III Colon Cancer: Primary radical surgical resection is the standard of care for localized invasive adenocarcinoma.
• Stage II-III Rectal Cancer: Radical proctectomy with TME, typically following neoadjuvant chemoradiotherapy or total neoadjuvant therapy (TNT).
• Malignant Colorectal Polyps: High-risk endoscopic lesions demonstrating positive resection margins, poor histological differentiation, or lymphovascular invasion.
• Resectable Stage IV Disease: Patients with isolated, limited liver or lung metastases (oligometastatic disease) who can undergo combined or staged primary tumor and metastatic lesion resections.
• Oncological Emergencies: Acute intestinal obstruction, perforation, or refractory GI hemorrhage caused by colorectal neoplasms.

6. Who the Treatment Is NOT For — Contraindications

Colorectal cancer surgery is contraindicated in patients with unresectable widespread metastatic disease where surgery offers no survival benefit, or those with severe organ failure who cannot tolerate general anesthesia. Relative contraindications include active uncorrected coagulopathies, severe severe malnutrition, or diffuse peritoneal carcinomatosis where non-surgical palliative systemic therapies are preferred.

Contraindications are broadly categorized as absolute or relative based on clinical risk assessment:

• Absolute Contraindications: Severe end-stage cardiopulmonary failure precluding general anesthesia; unresectable, high-volume multi-organ metastatic disease without obstructive symptoms; and terminal medical comorbidities with a life expectancy under 30 days.
• Relative Contraindications: Uncontrolled severe coagulopathy or bleeding disorders; extensive frozen abdomen due to multiple prior surgeries; severe active systemic sepsis; and profound malnutrition (serum albumin below 2.5 g/dL), which markedly increases anastomotic failure rates unless corrected pre-operatively.

7. Alternatives and Clinical Comparison

Non-surgical alternatives and adjuncts to colorectal cancer surgery include chemotherapy, radiation therapy, targeted molecular treatments, and endoscopic mucosal resections for early-stage lesions. While non-surgical approaches can shrink tumors or palliate symptoms, surgical resection remains the sole definitive curative treatment modality for invasive, non-metastatic colorectal adenocarcinomas according to global oncological guidelines.

The table below summarizes how surgical resection compares with alternative and non-surgical management modalities:

8. Pre-Treatment Phase

The pre-treatment phase establishes accurate tumor staging, optimizes physical health, and prepares the bowel for surgical intervention. Patients undergo complete colonoscopy, chest and abdominopelvic computed tomography, laboratory blood evaluations, cardiac clearance, nutritional assessment, and pre-operative bowel preparation (cleansing the intestine) alongside multimodal prehabilitation (pre-operative physical and nutritional conditioning) to enhance post-surgical recovery.

Diagnostic workup follows NCCN staging guidelines:

• Diagnostic Endoscopy: Complete colonoscopy with tissue biopsy to confirm histology and evaluate for synchronous polyps or second primary tumors.
• Radiological Staging: Contrast-enhanced CT scans of the chest, abdomen, and pelvis. For rectal cancer, high-resolution pelvic Magnetic Resonance Imaging (MRI) or endorectal ultrasound (ERUS) is required to assess depth of invasion (T-stage) and mesorectal lymph node involvement (N-stage).
• Laboratory Biomarkers: Baseline serum carcinoembryonic antigen (CEA) level testing, complete blood count (evaluating anemia), renal function panels, and liver enzymes.
• Prehabilitation & Bowel Prep: Structured exercise, high-protein nutritional supplementation, smoking cessation, and oral osmotic mechanical bowel preparation combined with non-absorbable oral antibiotics 24 hours prior to surgery to reduce surgical site infection risks (ASCRS 2022 guidelines).

9. The Procedure — Step-by-Step Clinical Detail

Colorectal cancer surgery follows a standardized intraoperative sequence beginning with general anesthesia administration and patient positioning. The surgical team establishes abdominal access, explores the abdominal cavity, isolates the primary vascular pedicles, performs an en bloc tissue resection with adequate margins, evaluates regional lymph nodes, constructs an anastomosis (bowel reconnection), and closes incisions.

The core clinical stages of a standard laparoscopic or open radical colectomy include:

Phase 1: Anesthesia and Access

The patient receives general anesthesia paired with an epidural or spinal block for post-operative analgesia. Tromboprophylaxis (compression stockings) and intravenous prophylactic antibiotics are administered. For minimally invasive approaches, a pneumoperitoneum (insufflation of the abdominal cavity with carbon dioxide gas) is established, and laparoscopic trocars are introduced.

Phase 2: Abdominal Exploration and Vascular Ligation

The surgeon explores the peritoneal cavity to confirm the absence of unexpected liver or peritoneal metastases. The primary feeding vascular pedicle (e.g., the inferior mesenteric artery) is identified, skeletonized, and ligated at its root (high ligation). This step ensures the complete excision of regional lymphatic channels draining the tumor site.

Phase 3: Mobilization and Mesenteric Dissection

The target intestinal segment is mobilized off retroperitoneal structures (such as the ureters and duodenum) along avascular embryological planes. In rectal procedures, sharp dissection is performed along the mesorectal fascia to complete a Total Mesorectal Excision (TME), preserving adjacent autonomic pelvic nerves responsible for urinary and erectile function.

Phase 4: Resection and Anastomosis Construction

Proximal and distal intestinal resection margins are measured (targeting at least 5 cm proximal/distal for colon cancer and 1-2 cm distal for rectal cancer). The bowel is transected, and the specimen is removed. Intestinal continuity is re-established by performing an end-to-end, side-to-side, or end-to-side anastomosis using circular or linear surgical staplers. A temporary protective ileostomy (a temporary loop of small intestine brought through the abdominal wall) may be constructed for ultra-low rectal anastomoses to divert stool during healing.

Phase 5: Closure and Recovery Transfer

The surgical bed is irrigated, homeostasis is confirmed, and port sites or laparotomy incisions are closed in anatomical layers using absorbable sutures. The patient is awakened from anesthesia and transferred to the post-anesthesia care unit (PACU).

10. Immediate Post-Procedure Period

The immediate post-procedure period spans the first 24 to 48 hours following surgery in a specialized surgical ward or intensive care unit. Care focuses on early mobilization, multimodal analgesia to minimize opioids, monitoring vital signs and urine output, managing surgical drains or stomas, and initiating fluid intake under Enhanced Recovery After Surgery (ERAS) pathways.

Under modern ERAS society guidelines, post-operative protocols bypass traditional prolonged fasting and bed rest:

• Analgesia: Opioid-sparing multimodal pain management utilizing intravenous acetaminophen, non-steroidal anti-inflammatory drugs (NSAIDs), and local nerve blocks to facilitate deep breathing and early movement.
• Mobilization: Out-of-bed sitting and assisted walking within 12 to 24 hours post-operatively to stimulate gastrointestinal motility and reduce deep vein thrombosis risk.
• Nutrition: Early oral intake, starting with clear fluids on day 0/1 and progressing to soft food as tolerated, avoiding routine prolonged nasogastric tube decompression.
• Monitoring: Tracking surgical incision sites, stoma perfusion, urinary catheter drainage, urine output, and systemic markers of infection or internal bleeding.

11. Recovery — Short and Long Term

Recovery from colorectal cancer surgery extends across short-term inpatient rehabilitation and long-term outpatient recovery lasting six to twelve weeks. Physical strength, bowel function, and nutritional absorption gradually stabilize over time, while routine oncological surveillance ensures early detection of potential disease recurrence through physical examinations, blood tests, and periodic endoscopic and imaging evaluations.

Short-Term Recovery (Weeks 1 to 4)

Inpatient discharge typically occurs between days 3 and 7 once the patient tolerates a solid diet, passes flatus or stool, demonstrates controlled pain on oral analgesics, and walks independently. During the initial four weeks at home, patients experience variable bowel habits (frequency, loose stools) as the remaining intestine adapts. Lifting restrictions (nothing over 5-10 pounds) prevent incisional hernia formation.

Long-Term Recovery and Surveillance (Months 1 to 6 and Beyond)

Full physical and functional recovery is usually reached by weeks 6 to 8. If pathological staging reveals Stage III disease or high-risk Stage II disease, adjuvant systemic chemotherapy is initiated within 4 to 8 weeks post-operatively. According to NCCN surveillance guidelines, patients enter a structured 5-year follow-up program consisting of:

• Clinical physical exam and serum CEA biomarker testing every 3 to 6 months for the first 2 years, then every 6 months for years 3 through 5.
• Annual contrast-enhanced chest, abdomen, and pelvis CT imaging for 3 to 5 years.
• Surveillance colonoscopy at 1 year post-surgery, repeated at 3 years and every 5 years thereafter if normal.

12. Risks, Side Effects, and Complications

Colorectal cancer surgery carries inherent risks ranging from mild temporary side effects to severe surgical complications. Adverse events include wound infections, post-operative ileus (temporary bowel paralysis), bleeding, cardiac or respiratory complications, deep vein thrombosis, and serious surgical events such as an anastomotic leak (breakdown of the reconnected bowel junction) requiring intervention.

The risk severity matrix below outlines potential post-operative complications, expected incidence rates, and clinical management strategies based on international surgical audit data.

Immediate emergency medical evaluation is mandatory if a patient develops warning signs such as a high fever (>38.5°C / 101.3°F), severe worsening abdominal pain, persistent vomiting, severe redness or purulent discharge from incisions, or sudden severe rectal bleeding.

13. Lifestyle and Behavioural Considerations

Lifestyle and behavioral modifications significantly influence recovery outcomes and long-term quality of life after colorectal cancer surgery. Pre-operative smoking cessation, dietary optimization, structured physical activity, and appropriate stoma care education facilitate wound healing, optimize bowel function adaptation, minimize metabolic complications, and support comprehensive psychological rehabilitation during the post-operative period.

Key evidence-based lifestyle adaptations include:

• Nutritional Management: Following surgery, patients benefit from a low-residue diet initially, gradually reintroducing high-fiber foods as bowel transit stabilizes. Small, frequent meals reduce gas, bloating, and frequency. Maintaining adequate fluid hydration (1.5 to 2 liters daily) is critical, particularly for patients with an ileostomy who experience higher sodium and water loss.
• Physical Activity: Light walking is encouraged immediately post-discharge. Resistance training and high-impact abdominal exercise must be avoided for 6 to 8 weeks to allow complete fascial healing and reduce incisional herniation risks. Long-term regular aerobic physical activity is associated with reduced colorectal cancer recurrence rates (ACS guidelines).
• Stoma Care Education: Patients undergoing temporary or permanent stoma creation receive pre- and post-operative instruction from specialized Enterostomal Therapy (ET) nurses regarding appliance fitting, skin barrier protection, and routine stoma bag management.

14. How Outcomes Are Measured

Surgical outcomes in colorectal cancer are evaluated using pathological criteria, operational quality indicators, and long-term oncological survival metrics. Key measurement parameters include achieving R0 resection (microscopically clear surgical margins), harvesting a minimum threshold of twelve regional lymph nodes, evaluating 5-year overall survival, disease-free survival rates, and post-operative patient-reported outcome measures.

Pathological analysis of the resected specimen provides objective quality indicators:

• Resection Margin Status: Classified as R0 (microscopically negative margins, no tumor cells within 1 mm of circumferential or longitudinal edges), R1 (microscopically positive margin), or R2 (macroscopically incomplete resection). An R0 clearance is the primary predictor of local control.
• Lymph Node Yield: ASCRS and NCCN quality metrics mandate the examination of at least 12 regional lymph nodes in the resected mesentery to ensure accurate pathological N-staging and prevent understaging.
• Oncological Survival Metrics: Clinical success is measured by 5-year Overall Survival (OS) and Disease-Free Survival (DFS). According to pooled global cancer registry data, localized Stage I disease carries a 5-year OS exceeding 90%, Stage II ranges from 75% to 85%, Stage III (node-positive) ranges from 50% to 75%, and selected resectable Stage IV disease achieves 5-year survival rates of 20% to 35% when complete surgical clearance of primary and metastatic sites is accomplished.

15. Recent Advances and Current Standard of Care

Recent advances in colorectal cancer surgery focus on minimally invasive technologies, personalized neoadjuvant protocols, and organ-preservation strategies. Minimally invasive robotic-assisted surgery, complete mesocolic excision, indocyanine green fluorescence angiography for anastomotic perfusion assessment, and total neoadjuvant therapy for rectal cancer represent contemporary standards that reduce surgical morbidity while optimizing oncological outcomes.

Key innovations driving current surgical standards include:

• Robotic-Assisted Pelvic Surgery: The use of multi-articulated wristed robotic platforms provides superior visualization and dexterity in narrow pelvic spaces during low anterior resections, reducing autonomic nerve injury and conversion rates to open surgery compared to standard laparoscopy (as demonstrated in the ROLARR trial).
• Indocyanine Green (ICG) Angiography: Intraoperative near-infrared fluorescence imaging with intravenous ICG dye allows real-time assessment of intestinal tissue perfusion prior to constructing an anastomosis, significantly lowering anastomotic leak rates.
• Total Neoadjuvant Therapy (TNT) and Watch-and-Wait: For locally advanced rectal cancer, delivering all systemic chemotherapy and radiation prior to surgery improves complete pathologic response rates. In select patients achieving a Clinical Complete Response (cCR), radical surgery may be safely deferred under strict observational surveillance protocols (OPRA trial guidelines).

16. Common Myths and Misconceptions

Numerous misconceptions surround colorectal cancer surgery, causing unnecessary anxiety regarding stoma necessity, surgical safety, and long-term functional recovery. Evidence-based clinical guidelines refute common myths regarding mandatory permanent stomas, laparoscopic oncological inferiority, and age-related surgical contraindications, helping patients make informed decisions alongside their multidisciplinary surgical oncology team.

Myth: Having surgery for colorectal cancer always results in a permanent colostomy bag.
Reality: The majority of colorectal cancer surgeries do not require a permanent stoma. Permanent stomas (such as an abdominoperineal resection) are reserved for low rectal tumors directly invading the anal sphincter muscle. Most colon resections and upper rectal resections permit immediate primary bowel reconnection without a stoma.

Myth: Laparoscopic and robotic surgery are less thorough in removing cancer than open abdominal surgery.
Reality: Multiple landmark international clinical trials (including the COLOR, COST, and CLASSICC trials) have proven that minimally invasive laparoscopic and robotic colectomies achieve equivalent lymph node yields, clear surgical margins, and identical long-term survival rates compared to open surgery, while offering significantly faster recovery times.

Myth: Elderly patients are too frail to undergo radical colorectal cancer surgery.
Reality: Chronological age alone is not a contraindication to surgery. Modern physiological risk assessments focus on frailty scores, functional performance status, and specific organ comorbidities. With Enhanced Recovery pathways and laparoscopic techniques, elderly patients can undergo successful curative surgery with acceptable risk profiles (ASCRS 2022 guidelines).

Myth: Exposing a colorectal tumor to air during surgery causes the cancer to spread.
Reality: Tumor exposure to atmospheric air does not cause cancer dissemination. Surgical spread is prevented by meticulous anatomical technique, early vascular ligation, en bloc resection without breaching the tumor capsule, and thorough abdominal irrigation during the procedure.

Myth: If lymph nodes are removed during surgery, the body can no longer clear infections.
Reality: Surgery removes only the specific regional lymph nodes draining the affected bowel segment. Thousands of other lymph nodes throughout the body remain fully functional, maintaining normal systemic immune defense and fluid drainage.

Myth: Chemotherapy can fully replace surgery for localized colon cancer.
Reality: Systemic chemotherapy alone cannot cure invasive Stage I-III colon cancer. While systemic treatment clears microscopic circulating disease, physical resection of the primary intestinal tumor and mesentery remains necessary to eliminate localized bulk disease and prevent intestinal blockage.

17. Frequently Asked Questions

How long does a colorectal cancer surgery operation take?

A standard colectomy or proctectomy typically takes between 2 and 5 hours to complete. Operative time varies based on anatomical tumor location, surgical approach (open, laparoscopic, or robotic), patient body habitus, presence of abdominal adhesions from prior procedures, and whether complex mesorectal dissection or stoma creation is required.

Will I need a temporary or permanent stoma bag after surgery?

Necessity of a stoma depends on tumor depth and proximity to the anal sphincter. Colon cancer resections rarely require a stoma. Ultra-low rectal resections often utilize a temporary diverting ileostomy for 8 to 12 weeks to protect the healing anastomosis. Permanent stomas are necessary only when the anal sphincter complex must be completely resected.

When can I eat solid food again after surgery?

Under Enhanced Recovery After Surgery (ERAS) protocols, patients are offered clear liquids within hours of waking from surgery. Soft solid foods are introduced on post-operative day 1 or 2 as tolerated. Patients no longer undergo prolonged post-operative fasting, as early oral feeding stimulates bowel recovery and reduces surgical complication rates.

How painful is colorectal cancer surgery recovery?

Post-operative pain is effectively managed using multimodal, non-opioid pain protocols, including epidural analgesia, local nerve blocks, acetaminophen, and anti-inflammatory medications. Patients experience mild to moderate abdominal soreness that steadily decreases over 1 to 2 weeks. Minimally invasive laparoscopic and robotic approaches significantly reduce post-operative pain compared to large open incisions.

How long will I need to stay in the hospital?

Typical hospital stay duration ranges from 3 to 5 days for laparoscopic or robotic procedures, and 5 to 7 days for open laparotomy surgeries. Discharge criteria require adequate pain control on oral medications, tolerance of solid food, independent mobility, and evidence of returning bowel function such as passing flatus or stool.

When can I return to work and regular physical exercise?

Most patients return to desk jobs and light daily activities within 2 to 4 weeks post-surgery. Return to strenuous manual labor, heavy lifting (>10 pounds), or high-impact athletic exercise requires 6 to 8 weeks to allow full healing of the abdominal muscle layers and prevent incisional hernia formation.

How does colon removal affect my bowel movements long-term?

After a partial colectomy, the remaining colon adapts within a few months, allowing most patients to regain near-normal bowel habits. Following low anterior resection for rectal cancer, patients may experience Low Anterior Resection Syndrome (LARS), involving increased stool frequency, urgency, or loose stools, which is managed with dietary adjustments, medications, and pelvic floor rehabilitation.

What is the difference between open, laparoscopic, and robotic colorectal surgery?

Open surgery uses a single, long abdominal incision. Laparoscopic surgery utilizes small keyhole incisions, a video camera, and rigid instruments. Robotic surgery uses small incisions with advanced 3D vision and wristed instruments controlled by the surgeon, offering enhanced precision within tight anatomical spaces like the pelvis.

When will the pathological staging results be available after surgery?

Final pathology reports are typically completed within 5 to 7 business days following surgery. Pathologists examine the tumor depth (T-stage), total lymph nodes retrieved and affected (N-stage), surgical margin clearance, histological grade, and molecular markers (such as Microsatellite Instability / MSI status) to guide further adjuvant therapy decisions.

Will I need chemotherapy after colorectal cancer surgery?

The need for post-operative adjuvant chemotherapy depends on pathological staging. Stage I colon cancer does not require chemotherapy. Stage III disease (node-positive) strongly indicates adjuvant chemotherapy. Stage II colon cancer requires chemotherapy selectively if high-risk pathological features are present, such as lymphovascular invasion, high grade, or inadequate lymph node yield.

Can colorectal cancer recur after complete surgical removal?

Cancer recurrence can occur locally or as distant metastases (most commonly in the liver or lungs), primarily within the first 3 years following surgery. Adhering to structured NCCN follow-up surveillance—including CEA blood tests, CT imaging, and colonoscopy—ensures early detection and potential surgical or systemic management of recurrent disease.

How do I care for my surgical incisions at home?

Incisional care involves keeping sites clean and dry. Most skin closures use absorbable hidden sutures or waterproof surgical glue, allowing light showering after 48 hours. Patients should avoid soaking in baths or swimming until incisions are fully healed, and should inspect wounds daily for signs of infection such as redness, swelling, or drainage.

How does surgery impact sexual and urinary function?

Pelvic surgery for rectal cancer carries a small risk of nerve irritation or injury to autonomic pelvic nerves running adjacent to the mesorectum. This can occasionally cause temporary or permanent urinary retention, retrograde ejaculation, or erectile dysfunction in men, and dyspareunia or vaginal dryness in women. Nerve-sparing surgical techniques minimize these risks.