Overview
Definition:
Transperineal local excision is a surgical technique for removing anorectal tumors through an approach from the perineum, avoiding abdominal entry
It is primarily used for selected early-stage malignant and benign tumors of the anal canal and distal rectum.
Epidemiology:
Anorectal tumors are relatively uncommon, with squamous cell carcinoma of the anal canal being the most frequent malignancy
Incidence of rectal adenocarcinomas treated with local excision varies based on stage and tumor characteristics
Selection criteria are crucial for optimal outcomes.
Clinical Significance:
This technique offers a sphincter-sparing alternative to abdominoperineal resection (APR) for select patients, aiming to preserve anorectal function and improve quality of life
It is vital for residents to understand its indications, technique, and potential complications for effective patient management.
Indications
Malignant Tumors:
Early-stage (T1, some T2) squamous cell carcinomas of the anal canal with no evidence of nodal metastasis
Selected well-differentiated adenocarcinomas of the distal rectum or anal canal with favorable features (e.g., low grade, no lymphovascular invasion, favorable margins).
Benign Tumors:
Large or symptomatic anal papillomas, adenomas, or neuroendocrine tumors that cannot be removed endoscopically or via transanal endoscopic microsurgery (TEMS).
Contraindications:
Locally advanced tumors (T3/T4), tumors with threatened margins, significant lymph node involvement, distant metastases, patients with severe comorbidities precluding surgery, or inability to achieve adequate surgical margins transperineally.
Preoperative Preparation
Patient Assessment:
Thorough history and physical examination, including digital rectal examination (DRE) and anoscopy
Assessment of sphincter function and overall health status.
Staging Investigations:
Endorectal ultrasound (ERUS) for local staging, MRI pelvis for assessment of depth of invasion and nodal status, CT chest/abdomen/pelvis for distant metastasis screening, and CEA levels for rectal adenocarcinomas.
Bowel Preparation:
Standard mechanical bowel preparation with clear fluids the day before surgery
Prophylactic antibiotics, typically a cephalosporin with metronidazole, administered intravenously within one hour of incision.
Anesthesia Considerations:
General anesthesia or spinal anesthesia is typically employed
Adequate analgesia plan is crucial for postoperative recovery.
Procedure Steps
Patient Positioning:
Patient is placed in the lithotomy or prone position to provide optimal access to the perineum and anus.
Surgical Approach:
A curvilinear or transverse incision is made in the perineum encircling the anus, depending on the tumor location and extent
The dissection proceeds from the skin radially towards the tumor.
Tumor Excision:
Careful dissection is performed to identify the tumor and its surrounding tissues
The tumor is excised with adequate margins, typically at least 1 cm for malignancy, ensuring en bloc removal
If the tumor is in the distal rectum, a plane is developed between the levator ani muscles and the mesorectum.
Margin Assessment:
Intraoperative frozen section analysis of the margins is highly recommended to ensure complete tumor removal, especially for malignant lesions.
Closure Reconstruction:
Hemostasis is achieved
The defect is closed primarily if possible, or a local flap may be used for larger defects
A temporary perineal drain may be placed
In selected cases of rectal tumors, a diverting colostomy may be considered if significant rectal resection is performed.
Postoperative Care
Pain Management:
Aggressive pain control with multimodal analgesia, including opioids, NSAIDs, and local anesthetic blocks
Sitz baths are initiated once pain is manageable.
Wound Care:
Regular wound inspection and dressing changes
Maintaining perineal hygiene is critical
Monitoring for signs of infection or dehiscence.
Bowel Function Monitoring:
Assessing for early return of bowel function
Gradual resumption of diet
Stool softeners are often prescribed to minimize strain
Monitoring for fecal incontinence.
Monitoring For Complications:
Close observation for bleeding, infection, perineal wound complications, urinary retention, and functional issues like incontinence or obstruction.
Complications
Early Complications:
Bleeding (hematoma formation), infection (abscess, cellulitis), wound dehiscence, rectovaginal or rectourethral fistula, urinary retention, anal stricture.
Late Complications:
Chronic perineal pain, persistent anal stenosis, fecal incontinence, sexual dysfunction, recurrence of tumor.
Prevention Strategies:
Meticulous surgical technique with careful dissection and hemostasis
Adequate tumor margins
Prophylactic antibiotics
Careful wound closure and drain management
Aggressive pain control and early mobilization
Patient education on wound care and bowel management.
Prognosis
Factors Affecting Prognosis:
Histological type of tumor, grade, stage, completeness of excision (margin status), presence of lymphovascular invasion, and patient comorbidities
For malignant lesions, the need for adjuvant therapy significantly impacts prognosis.
Outcomes:
For appropriately selected early-stage anorectal tumors, transperineal local excision can achieve excellent oncological control and preserve anorectal function
Benign tumors are typically cured with complete excision.
Follow Up:
Regular follow-up appointments are essential, including clinical examination, anoscopy, and potentially repeat imaging, to monitor for recurrence
Frequency and duration of follow-up depend on the tumor type and stage
Surveillance for oncological recurrence and functional outcomes is crucial.
Key Points
Exam Focus:
Understand the precise indications and contraindications for transperineal local excision versus radical surgery (APR/LAR)
Crucial to remember margin assessment (intraoperative frozen section) and sphincter preservation goals.
Clinical Pearls:
Careful preoperative staging is paramount
Think about functional outcomes (incontinence, stenosis) as much as oncological outcomes
Multidisciplinary team discussion is vital for complex cases.
Common Mistakes:
Operating on inadequately staged tumors
Inadequate surgical margins leading to recurrence
Poor postoperative wound care resulting in dehiscence or infection
Failing to counsel patients adequately about functional sequelae.