37: Anal and Rectal Flashcards
What are the following characteristics of anorectal abscesses?
- 3 locations in which an anorectal abcess can be drained through the skin
- 1 location in which an anorectal abscess must be drained transrectally
- 3 locations in which an anorectal abcess can be drained through the skin: Perianal, intersphincteric, and ischiorectal
- 1 location in which an anorectal abscess must be drained transrectally: Supralevator
[Antibiotics for cellulitis, Diabetes, immunosuppressed, or prosthetic hardware.]
What is the arterial and venous supply to the anus?
- Artery: Inferior rectal artery
- Veins: Internal hemorrhoid plexus (above dentate line) and external hemorrhoid plexus (below the dentate line)
What is the treatment for anorectal fistulas?
Fistula located in the lower 1/3 of the external sphincter: Fistulotomy (open tract, curettage, let it heal by secondary intention)
Fistula located in the upper 2/3 of the external sphincter: Rectal advancement flap (most worrisome complication is risk of incontinence)
[One must avoid damage to external anal sphincter so fistulotomy is not used for fistulas above the lower 1/3 of the external anal sphincter.]
What are the following characteristics of anal margin (below dentate line) squamous cell cancer?
- Nodes to which it metastasizes
- Treatment for lesions < 5cm
- Treatment for lesions > 5cm
- Nodes to which it metastasizes: Inguinal nodes
- Treatment for lesions < 5cm: Wide local excision (need 0.5cm margins)
- Treatment for lesions > 5cm: Chemo-XRT (5-FU and cisplatin
[Basal cell cancer of the anal margin is treated with wide local excision. Only need 3mm margins. APR is rarely needed unless the sphincter is involved.]
[UpToDate:Tumors arising within the hair-bearing skin at or distal to the squamous mucocutaneous junction have been referred to as anal margin cancers. However, the most recent (eighth) edition of the American Joint Committee on Cancer (AJCC) cancer staging manual defines tumors that arise within the skin at or distal to the squamous mucocutaneous junction that can be seen in their entirety with gentle traction placed on the buttocks and are within 5 cm of the anus as perianal skin cancers. Most clinicians treat SCC lesions of the perianal skin in a manner identical to anal canal cancers, using radiation therapy (RT) and concurrent chemotherapy. Local treatment, surgery, or local RT (electrons) is used only when the lesion is distinctly separated from the mucosal tissue at the anal verge and is, therefore, a discrete skin lesion.]
What is the treatment for adenocarcinoma of the anal canal (above dentate line)?
- Wide local excision if < 3cm, < 1/3 circumference, limited to submucosa, well differentiated, and no vascular/lymphatic invasion (2-3mm margins for T1, Otherwise need 1 cm margins)
- Abdominal peritoneal resection (APR) if above criteria not met
[UpToDate: For patients with adenocarcinoma of the anal canal, we suggest surgery (typically an abdominoperineal resection [APR]) rather than initial chemoradiotherapy. The postoperative approach should parallel treatment of rectal adenocarcinoma.
Primary adenocarcinoma of the anal canal is rare, and many of these tumors represent rectal cancer with downward spread. Determination of the anatomic site of origin of carcinomas that overlap the anorectal junction can be problematic. For staging purposes, such tumors are classified as rectal cancers if their epicenter is located more than 2 cm proximal to the dentate line or proximal to the anorectal ring on digital examination, and as anal canal cancers if their epicenter is 2 cm or less from the dentate line.
Prognosis of anal adenocarcinomas is worse than it is with either anal squamous cell cancer or distal rectal adenocarcinoma. The management of adenocarcinomas arising in the anal canal should follow the same principles as those applied to the treatment of rectal cancer. The primary treatment is surgical resection (typically an APR). Survival rates are better in patients receiving multimodality management with chemotherapy and RT given as preoperative or postoperative therapy to improve local and systemic control.
The primary importance of resection in the management of adenocarcinomas arising in the anal canal was illustrated in a series from MD Anderson Cancer Center in which 16 patients with adenocarcinoma of the anal canal were treated with primary RT or chemoradiation without surgery. There was an unacceptable rate of both local and systemic recurrence at five years (54% and 66%, respectively).]
Which has a better prognosis: Anal canal (above dentate line) tumors or anal margin (below dentate line) tumors?
Anal margin lesions have a better prognosis than anal canal lesions
Where do 90% of anal fissures occur?
Posterior midline
[Fissures cause pain and bleeding after defecation. Chronic ones will see a sentinel pile.]
[UpToDate: Chronic anal fissures are often accompanied by external skin tags (sentinel pile) at the distal end of the fissure, and hypertrophied anal papillae at the proximal end. The features of a chronic fissure are attributed to chronic infection and the development of fibrotic connective tissue.]
What are the following characteristics of hemorrhoids?
- Management/Prevention
- Treatment of a thrombosed external hemorrhoid
- Treatment of internal hemorrhoids
- Management/Prevention: Fiber, stool softeners, and sitz baths
- Treatment of a thrombosed external hemorrhoid: Lance if > 72 hours or elliptical excision if < 72 hours to releive pain (do not band external hemorrhoids because it hurts)
- Treatment of internal hemorrhoids: Can band primary and secondary internal hemorrhoids, surgery for tertiary and quaternary internal hemorrhoids (3 quadrant resection)
[Need to resect down to the internal anal sphincter (do not go through it). Post op sitz baths, stool softener, high-fiber diet.]
What are the following characteristics of anal fissures?
- Medical treatment
- Surgical treatment
- Most serious complication of surgical treatment
- Contraindication to surgical treatment
- Diagnosis to consider with lateral or recurrent fissures
- Medical treatment: Sitz baths, bulk, lidocaine jelly, and stool softeners (90% heal)
- Surgical treatment: Lateral subcutaneous internal sphincterotomy
- Most serious complication of surgical treatment: Fecal incontinence
- Contraindication to surgical treatment: Fissures secondary to Crohn’s or ulcerative colitis
- Diagnosis to consider with lateral or recurrent fissures: Inflammatory bowel disease
To which nodes do tumors of the following locations metastasize?
- Superior and middle rectum
- Lower rectum
- Upper 2/3 of anal canal
- Lower 1/3 of anal canal
- Superior and middle rectum: Inferior mesenteric artery nodes
- Lower rectum: Inferior mesenteric artery nodes and internal iliac nodes
- Upper 2/3 of anal canal: Internal iliac nodes
- Lower 1/3 of anal canal: Inguinal nodes
What is the most common symptoms of melanoma of the anal canal (above dentate line) and what is the treatment?
- Symptom: Rectal bleeding
- Treatment: Abdominal peritoneal resection (APR) with margins dictated by depth of lesion in standard fashion for melanoma
[UpToDate: The primary goal of surgery is to perform a negative margin, sphincter-sparing excision. Abdominoperineal resection is reserved for patients with bulky local disease and for carefully selected patients with local recurrence. Inguinal lymphadenectomy is reserved for patients with clinically apparent disease, given the morbidity of bilateral inguinal node dissection and lack of proven benefit from an elective dissection.
Multiple retrospective series have looked at the impact of the extent of surgery on long-term outcomes. Some series suggested improved local control with abdominoperineal resection, a procedure accompanied by a high morbidity rate and functional limitations; however, retrospective data suggest that there is no difference in overall survival with more conservative wide local excision.
The benefit of improved local control upon survival is limited. Most patients ultimately develop distant disease regardless of the primary surgical procedure; thus patient preference and quality-of-life considerations are critical in determining the extent of surgery.
The most important factor in surgery appears to be the ability to achieve negative (R0) surgical resection margins. In a series of 251 cases from the Swedish National Cancer Registry, the five-year survival rates following surgical excision for those in whom an R0 resection was achieved was 19 percent, compared with 6% in those in whom a complete local excision was not possible. On multivariate analysis, resection status and tumor stage were significantly associated with prognosis, but the type of resection (abdominoperineal resection or local excision) was not significant.
Mesorectal, pelvic sidewall, and inguinal lymph nodes are at risk for involvement in anorectal mucosal melanoma. However, available data suggest that lymph node metastasis does not predict outcome in patients undergoing radical resection, and sentinel lymph node biopsy does not have an established role in these patients.
Adjuvant radiation therapy for anorectal melanoma may improve locoregional control despite a lack of demonstrable impact upon overall survival. Sphincter-sparing local excision followed by hypofractionated RT has been used as an alternative to abdominoperineal resection in an effort to prevent local recurrence and preserve quality of life. In a series of 54 patients from MD Anderson Cancer Center treated over a 20-year period, this approach achieved local control in 82% of cases; however, the five-year overall survival rate was only 30%.]
How does squamous cell cancer of the anal canal (above dentate line) present and what is the treatment?
Symptoms: Pruritus, bleeding, palpable mass
Treatment: Nigro protocol (Chemo-XRT with 5-FU and mitomycin), not surgery
[Nigro protocol cure 80% of patients. APR for treatment failure or recurrent cancer.]
[UpToDate: Combined chemoradiotherapy has emerged as the preferred method of treatment for anal canal cancer because it can cure many patients while preserving the anal sphincter. We suggest initial concurrent chemoradiotherapy rather than surgery for most patients with anal canal squamous cell cancers (SCCs), even those with T1-2, N0, M0 tumors.
We suggest the concurrent use of fluorouracil (FU) plus mitomycin during radiation therapy (RT) rather than FU alone or FU plus cisplatin. Although the original regimen described as the “Wayne State or Nigro regimen” used infusional FU 1000 mg/m2 on days 1 to 4 and 29 to 32 (plus mitomycin 10 to 15 mg/m2 on day 1 only) concurrent with RT, consensus-based National Comprehensive Cancer Network (NCCN) guidelines suggest a modified regimen as was used in the Radiation Therapy Oncology Group (RTOG) 98-11 trial. The chemotherapy consists of infusional FU 1000 mg/m2 on days 1 to 4 and 29 to 32, plus mitomycin 10 mg/m2 on days 1 and 29 (as tolerated), maximum 20 mg per dose. European guidelines suggest a similar infusional FU plus mitomycin regimen, but utilizing mitomycin 12 mg/m2 on day 1 only (maximum 20 mg single dose).
Human immunodeficiency virus (HIV)-positive patients are generally treated similarly to those without HIV infection. Although outcomes appear to be comparable, treatment-related toxicity may be worse, particularly if the CD4 count is <200 cells/microL. Patients with a history of HIV related complications may require dosage adjustment or treatment without mitomycin.]
What is the treatment for anal incontinence after obstetrical trauma?
Anterior anal sphincteroplasty
[UpToDate: Anal sphincteroplasty is usually reserved for patients with fecal incontinence who do not respond to initial management and have evidence of anatomic sphincter injury on anorectal ultrasound/magnetic resonance imaging shortly after vaginal delivery.
Although short-term improvements in fecal incontinence have been reported in up to 85% of patients after anal sphincteroplasty, continence deteriorates thereafter, with an approximately 50% failure rate after 40 to 60 months.]
What is the treatment for a rectovaginal fistula as it pertains to below?
- Simple fistula (low to mid vagina)
- Complex (high in vagina)
- Simple fistula (low to mid vagina): Trans-anal rectal mucosa advancement flap
- Complex (high in vagina): Abdominal or combined abdominal and perineal approach with resection and re-anastomosis of rectum, closure of the hole in vagina, interposition of omentum, and temporary ileostomy
What are the criteria for grading internal hemorrhoids?
- Primary
- Secondary
- Tertiary
- Quaternary
- Primary: Slides below dentate with strain
- Secondary: Prolapse that reduces spontaneously
- Tertiary: Prolapse that has to be manually reduced
- Quaternary: Not able to reduce
What is Goodsall’s rule regarding fistula-in-ano?
- Anterior fistulas connect with anus/rectum in a straight line
- Posterior fistulas go toward a midline internal opening in the anus/rectum
[UpToDate: Optimal treatment depends upon correctly classifying the fistula. The external and internal opening, the course of the track, and the amount of sphincter muscle it incorporates should be identified. To accomplish this, it is often necessary to examine the patient in the operating room under anesthesia.
Surgical treatment is the mainstay of therapy and is required in patients with symptomatic anorectal fistulas, with the exception of patients with Crohn’s disease. The goal of surgical therapy is to eradicate the fistula while preserving fecal continence. The surgical approach depends upon the type of fistula. Thus, surgery begins by gently probing the fistula to determine its anatomy. This maneuver almost always requires that the patient be anesthetized. Identifying the internal opening of the fistula track is not always straightforward. Many principles and maneuvers have been devised to assist in this task.
One of the most commonly cited principles to assist in the surgical management of a fistula is Goodsall’s rule, which states:
- All fistula tracks with external openings within 3 cm of the anal verge and posterior to a line drawn through the ischial spines travel in a curvilinear fashion to the posterior midline.
- All tracks with external openings anterior to this line enter the anal canal in a radial fashion.
Although Goodsall’s rule is often quoted, it may not always be accurate. In one series of 216 patients who underwent surgery for complete submuscular anal fistulas, Goodsall’s rule was accurate only when applied to fistulas with posterior external anal openings. It was inaccurate for predicting the course of complete submuscular anal fistulas with an anterior external opening.]
What are the following characteristics of hemorrhoids?
- Symptoms of external hemorrhoids
- Symptoms of internal hemorrhoids
- Symptoms of external hemorrhoids: Pain (distal to the dentate line, covered by sensate squamous epithelium, can cause pain, swelling, and itching)
- Symptoms of internal hemorrhoids: Bleeding or prolapse
