Anus Flashcards
RUSH–ANUS
54F comes to your office complaining of incontinence. Hx of 3 vaginal deliveries, last one 20 yrs ago. Which of the following is true regarding her anal sphincteric mechanism?
A. Longitudinal muscle of the rectal wall eventually forms the internal anal sphincter
B. Internal sphincter is made up of smooth muscle and its lowest edge is above the lowest edge of the external sphincter
C. Puborectalis is part of the levator ani muscle
D. Anorectal ring is composed entirely of the palpable deep portion of the external sphincter
E. Pudendal nerve is completely responsible for her condition
B
Taeniae of sigmoid fuse at the upper aspect of the rectum to completely encircle it with longitudinal muscle, in addition to an inner circular muscle layer. In the anal canal, longitudinal muscle forms the conjoined longitudinal, which descend in the plane between the internal and external sphincters.
Circular muscle of the rectum thickens to form the involuntary internal anal sphincter. It is smooth muscle and in a state of continuous contraction until relaxation is induced by a bolus of feces or gas. Lowest edge of the int. sphinct. is 1.0-1.5 cm below the dentate and is cephalad to the lowest portion of the ext. sphinct.
External sphinct is formed from 3 parts–subcutaneous, superficial and deep, which are striated muscles, under voluntary control, and are innervated by the pudendal nerve. Not distinguishable as separate layers.
Puborectalis muscle is fuses with the deep portion of the external sphincter and is innervated by the pudendal nerve. Not part of levator muscle. Originates from the posterior surface of the symphysis pubis and runs in a posterior direction to form a U shaped loop around the rectum. Contraction pulls rectum forward, establishing a resting angle of 90-110 degrees. Unhindered defecation requires relaxation of puborectalis. Inappropriate contraction during straining renders the angle more acute , which impairs defecation.
Puborectalis, and deep portion of external sphincter, along with the upper portion of the int sphincter, form the palpable anorectal ring
RUSH–ANUS
All of the following are accepted applications of EUS except:
A. Assessing sphincter integrity in patients complaining of fecal incontinence
B. Determining whether rectal cancer is suitable for local excision
C. Ruling out recurrent cancer
D. Evaluating anal fistulas
E. Routine screening for rectal cancer
E
Initial use of endorectal US was staging for rectal cancers. Depth of penetration and presence of abN LNs were used to determine the stage of cancer and its suitability for transanal, local excision. Tumors that demonstrate deep penetration of rectal wall have an incr likelihood of LN mets and are not suitable candidates for transanal excision b/c of unacceptably high recurrence rates assoc with local excision. Use has been expanded to determine whether lesion is advanced enought to warrant preop raidation and chemo. Used to assess the rectal wall and extraluminal tissue for any sign of recurrent cancer after surgery. Advantages over other imaging modalities, such as CT, in that the probe is placed in direct contact with the area of maximal interest, namely, the operative site. Resolution capabilities are much better with US than with CT.
EUS can also be used to image the sphincter mechanism in patients c/o fecal incontinence. Before a dx of idiopathic or neurogenic incontinence is made, an US must be done to inspect the integrity of the sphincter. IS has proved useful for determining the extent of abscess collections laterally and in a cephalad direction. Furthermore, relation of tract of the fistula to the sphincter muscle can be assessed with US; internal opening identified as a hypoechoic disruption of the int sphinct muscle. In some instances, hydrogen peroxide has been injected into the fistula tract during US to delilneate the tract.
RUSH–ANUS
35M with chronic constipation has noticed the passage of BRBPR. Anoscopy demonstrates hemorrhoids. Which of the following is true regarding the anatomy of the anal canal?
A. The dentate line lies above the columns of Morgagni
B. Anal gland ducts are completely separate from the anal crypts
C. Columns of Morgagni overlie the internal hemorrhoidal plexus
D. Typical locations for internal hemorrhoids are R lateral and L anterior
E. Anal glands are frequently found in the ischiorectal space
C
Dentate line is at the level of the anal crypts. Above it are vertical mucosal folds, columns of Morgagni, that overlie internal hemorrhoid plexus.
Typical locations for hemorrhoids are L lateral, R anterior, and R posterior.
Anal mucosa proximal to dentate is innervated by ANS and is insensitive to most painful stimuli. By contrast, the anoderm distal to the dentate line is supplied by somatic nerves and is quite sensitive.
Anal glands, which number between 6 and 10, usually lie in the intersphincteric space, and their ducts open into the anal crypts
RUSH–ANUS
42M with no prev med hx has had a 4 day hx of increasing rectal pain and difficulty sitting. Exam shows a 3 cm area of erythema and fluctuance consistent with a perirectal abscess. Which of the following is true regarding the perirectal spaces where this might occur?
A. Supralevator space is situated above the levator muscle and is connected with the contralateral side anteriorly
B. Retrorectal space lies between the rectum and the sacrum but below the retrosacral fascia
C. Deep post anal space lies between the levator ani and the superficial external sphincter posteriorly
D. Perianal space and superficial postanal space lies deep to the superficial anal sphincter
E. Intersphincteric space lies just outside the conjoined longitudinal muscle.
C
Supralevator space is located above levator ani on both sides and communicates with the contralateral side posteriorly. Bound superiorly by peritoneum, laterally by the pelvic side wall, medially by the rectum and inferiorly by the levator ani. Infection in this space can arise from a pelvic source (e.g. diverticulitis or PID) or as an upward extension from an anorectal source.
Rectrorectal space lies above retrosacral fascia between upper 2/3rds of rectum and sacrum. Fascia runs downwards and forward from sacrum to the anorectal junction. Contains loose connective tissue and is a site for the formation of tumors arising from embryologic remnants (i.e. dermoids, teratomas, and chordomas). Bounded anteriorly by rectum, posteriorly by presacral fascia, laterally by pelvic side wall, superiorly by peritoneal reflection, and inferiorly by rectrosacral fascia, below which is the supralevator space.
Ischiorectal space lies below the levator muscle, above the transverse septum of the ischiorectal fossa and between the external sphincter and the lateral pelvic wall. Communicates posteriorly through the deep postanal space, which lies between the levator ani and the superficial external sphincter. The lower border of the deep postal anal space is the anococcygeal ligament, which originates from the superficial portion of the external sphincter in the posterior midline. Communication allows an abscess in the deep postanal space to extend to both ischiorectal spaces (horseshoe abscess).
Perianal space (most common space involved in an abscess) lies superficial to the superficial external anal sphincter. Intersphincteric space lies within the conjoined longitudinal muscle, where the anal glands are also located.
Perianal, ischiorectal and supralevator spaces may connect posteriorly with their counterparts on the contralateral side to form a horseshoe connection in any of these spaces
RUSH–ANUS
36F has prolapsing rectal tissue and blood both in the toilet following forceful defecation and on toilet paper. On exam, she has several large vascular lesions that are reducible with direct pressure. Which of the following statements regarding her most likely condition is true?
A. Internal hemorrhoids are vascular cushions above the dentate line and are covered by anoderm
B. Prolapsing hemorrhoids are external hemorrhoids covered by anoderm
C. Bleeding internal hemorrhoid are best managed by surgical excision
D. Thrombosed hemorrhoids are best tx by hemorrhoidectomy with the patient under GA
E. Recurrence is uncommon after surgical hemorrhoidectomy
E
Internal hemorrhoids are submucosal cushions normally located above the dentate line and therefore covered by the transitional mucosa of the anal canal and not by anodem.
Ext hemorrhoids are dilated vins of the inf hemorrhoidal plexus located below the dentate line and are covered by anoderm.
Prolapsing hemorrhoids are int hemorrhoids that prolapse beyond the dentate line. Bleeding is the main manifestation of smaller int hemorrhoids and is managed initially by rubber banding, infrared coagulaiton or injection sclerotherapy. Sx is reserved for int hemorrhoids that do not respond to these conservative measures. Sx is best initial therapy for prolapsing hemorrhoids that require manual reduction or for those that are incarcerated.
Thrombosed hemorrhoids are bex tx by excising the overlying anoderm w/evacuation of the thrombus.
Recurrence should be rare after surgical hemorrhoidectomy. When it does occur, it is usually related to inadequate removal of the rectal mucosa and hemorrhoidal tissue.
RUSH–ANUS
40F is evaluated for pain with defecation. Pain started acutely after a large BM , is exquisitely severe following the passage of any stool, and persists for several hrs. She is barely able to tolerate examination, which demonstrates a small defect in the anoderm located at the posterior midline. Which of the following statements regarding her condition is true?
A. Most are located above the dentate line
B. It is located at the posterior midline in all patients
C. The operation of choice for a posterior midline lesion is excision and posterior internal sphincterotomy
D. Lateral partial subcutaneous sphincterotomy for lesions in the midline is considered definitive treatment
E. Pharmacologic therapy with nitroglycerin, CCB, or botox may prove beneficial
E
Anal fissure is a tear of the skin lined part of the anal canal, is located at or below the dentate line. 90% of fissures (acute or chronic) are located in the posterior midline, an area where the anoderm is least supported by the sphincter and blood flow is poorest. Anterior midline is second most common location and is involved in 10% of women. Fissures located laterally should arouse suspicion of Crohn’s, UC, syphilis, TB, leukemia or other causes and therapy is directed at underlying disease.
Initial tx of midline fissure is conservative and invovles lubricants and bulk laxatives. Topical nitroglycerin or CCB may produce healing of the fissure in 60%; however, several wks of tx may be needed. Botox injected directly into the internal sphincter on either side of the fissure may produce healing. Operative tx consists of lateral subcutaneous partial internal sphincterotoy to relax the internal sphincter, with the sphincterotomy carries up to the dentate line. Posterior fissurectomy and sphincterotomy can lead to a keyhole defect and constant soiling. It can be avoided by performing the sphincterotomy in a lateral location. External sphincterotomy should not be performed b/c it leads to higher rates of incontinence.
RUSH–ANUS
37M with suspected Crohn’s disease has a recurrent perirectal abscess. Abscess was drained in emerg and he is now being seen for FU. Which of the following is true about perirectal supparation?
A. Pathophysiology of perirectal abscesses is related to infection of the perianal skin
B. Horseshoe abscess is best drained at the bedside with the use of local anesthesia
C. An intersphincteric abscess causes pain deep in the rectum, frequent without external manifestations
D. Ischiorectal abscesses should be drained with the patient under GA, and the fistula must be identified and treated
E. B/C of Crohn’s disease, this patient is low risk for recurrent disease
C.
Perirectal abscess starts in anal glands lying in the intersphincteric space.
Horseshoe abscesses include bilateral ischiorectal, supralevator or perianal abscesses that communicate. Horseshoes abscesses usually arise from infection in the posterior midline glands. Starts in deep post anal space and extends in U-shaped manner into ischiorectal space. Tx by excising skin from external sphincter to coccyx, exposing the superficial external sphincter, which is split longitudinally but not transected. Provides access to deep postanal space. Probe inserted into posterior midline crypt and then into deep postanal space. Seton placed and wrapped around internal and superficial external sphincter. Small counterincisions made laterally along extensions of the abscess. Sequential tightening of seton should result in minimal, if any sphincter impairment.
Intersphincteric abscess is usually accompanied by pain, and bulging inside the rectum but no external swelling. Tx consists of transanally laying open the internal sphincter, beginning at the lower edge of the abscess and extending cephalad to the top of the abscess cavity.
Take patient to OR for GA if high fever, significant leukocytosis or extreme pain
Identification of fistula may be deferred until there are clinical signs that a fistula is present, namely, nonhealing of an abscess wound or recurrence of the abscess in the same location.
Patient’s with anorectal crohn’s may experience recurrent abscesses despite maximal therapy. Anorectal abscesses may be the first manifestation of Crohn’s disease in 5-30% of patients, whereas in 20-50% of patients with Crohn;s, fistula in ano develops at some point in their disease process
RUSH–ANUS
49M with Crohn’s found to have recurrent perianal abscesses. Brought into OR and found to have a fistula in ano. Which of the following is true?
A. Internal openings of fistuals whose external opening is in the posterior quadrants are always in the posterior midline
B. Most common type of fistula is intersphincteric
C. Excision of entire fistulous tract is necessary for cure
D. Fistulas assoc with Crohn’s disease are usually lower and less complex than spontaneous ones
E. Fibrin glue is the most effect means of treating most fistulas
B
Anal fistulas are classified as intersphincteric (most common), trans-sphincteric, suprasphincteric, and extrasphincteric.
Goodsall’s rule states that if the external opening is anterior to an imaginary line drawn between the the ischial tuberosities, the fistula usually runs directly into the anal canal, and if the external opening is posterior, the tract curves to the posterior midline
Anal fistulotomy and establishment of adequate drainage constitute sufficient therapy. Excision of tract is unnecessary and prolongs healing.
High trans-sphincteric fistulas can be managed by means of a seton suture. Alternatives include the use of fibrin glue, collagen plugs, and a rectal advancement flap to close the internal opening. Success rates with fibrin glue are variable but 30-60% heal over time. Collagen plugs inserted directly into the fistula tract and serve as a template for migrating fibroblasts. With advancement flaps, internal opening is excised and a flap consisting of mucosa, submucosa, and circular muscle is raised, advanced and sutured. Success rates are high even for patient’s with Crohn’s provided the rectum is healthy. Horseshoe fistula, which starts with infection at the posterior midline anal glands, is best tx by opening the deep postanal space and identifying and performing curetting of the lateral extensions. Laying open the extensions would result in large gaping wounds.
External opening in posterior midline can be managed by placement of a seton. Fistulas assoc with Crohn’s are typically higher and more complex than spontaneously occurring ones. If there is mucinous drainage or an inflammatory tract that persists, bx should be done b/c there is incr risk for perianal carcinoma.
RUSH–ANUS
41F with pruritus ani is seen for further mgmt after having undergone bx. Which of the following statements is correct regarding disease of an anal margin?
A. Bowen disease progresses rapidly to invasive cancer and requires urgent WLE
B. Paget diseas of the perianal skin is often assoc with an underlying breast malignancy
C. BCC of the anal margin have an excellent prognosis
D. Buschke-Lowenstein tumors are primarily tx by chemo
E. Bowen disease and Paget disease both require 5 cm margins of resection
C
Precursors to malignant disease found in anal margin. Anal intraepithelial neoplasias, such as Bowen or Paget disease, can cause symptoms such as itching. Skin changes are usually present and bx is indicated whenever the pruritus does not resolve with conservative mgmt.
Bowen disease represents high grade dysplasia or squamous cell carcinoma in situ of the perianal skin. Assoc with HPV especially types 16 and 18. Usually indolent and <5% progress to invasive cancer. Tx is WLE>
Paget disease is adenocarcinoma in situ of the perianal skin. 50-70% assoc with an underlying lower GI malignancy, and typically these are rectal or anal carcinomas. Tx is WLE and search for underlying malignancy is indicated.
Margins of resection for Bowen’s and Paget’s determined by mapping bxs or frozen section
Basal cell carcinoma of the perianal skin is rare and has a 5 yr survival of almost 100% following surgery.
Buschke-Lowenstein tumors are also call giant condylomas and are verrucous tumors that resemble condylomas microscopically. Rarely metastatic but may invade local structures around anal canal or margin. Tx consists of WLE or APR if the sphincter is compromised. Radiation may be used preop to shrink large cancers or for pts with recurrent tumors
RUSH–ANUS
59F complains of mucus d/x, fecal incontinence and tensemus. DRE and anoscopy demonstrate a 2 cm lesion in the anal canal. Bx of the lesion demonstrates SCC/ When compared with similar tumors of the anal margin, which of the following is true?
A. More common in men B. More often assoc with benign anal conditions C. More advanced when dx D. Infreq involve the anal sphincter E. Effectively tx by local excision
C
Anal canal is generally considered to be the region from the dentate line to the top of the anorectal ring
Anal margin is distal to dentate line.
SCC of the anal canal are more common in women. B/c the are often mistaken for benign anal disorders, they are usually advanced at the time of dx and therefore have worse prognosis.
Basaloid and cloacogenic carcinomas are a histologic variant of SCC of the anal canal. Conversely, perianal (anal margin) SCC is 4x more common in men and is usually slow growing and late to metastasize. Basaloid features are uncommon. WLE with 2 cm margin may be adequate therapy for superficial SCCs of the anal margin, whereas, SCC of the anal canal generally necessitates multimodality therapy involving radiation and chemo. Up to 50% exhibit local spread to perianal tissues or anal sphincter at time of dx.
RUSH–ANUS
Survival after tx of SCC of the anus is related to which of the following factors:
A. Tumor size, depth, and LN involvement
B. Tumor size, LN involvement and histologic features
C. Tumor size, depth and degree of differentiation
D. Basaloid vs squamous histologic features
E. HPV subtype detected
A
Prognosis is related to the delay in dx, which can lead to large tumor size, deep invasion and LN mets.
In basaloid cancers, there is good correlation between histologic differentiation and 5 year survival (90% for well, 50% for mod, and 0% for anaplastic). Presence of basaloid histologic features vs squamous histologic features alone has not been conclusively shown to affect prognosis. Similarly degree of differentiation does not in itself appear to affect prognosis (except that less differentiated tumors are often initially seen later with larger tumor size)
Although SCC of the anus is freq assoc with HPV (most freq 16), there is no prognostic significance for different types. In addition to HPV infection, risk factors for the development of anal cancer include infection with multiple HPV types, HIV, receptive anal intercourse, smoking and renal transplant.
RUSH–ANUS
27M who engages in anal intercourse has white, cauliflower shaped masses throughout his perianal region and in the anal canal. Which of the following statements regarding his most likely condition is true?
A. Causative agent appears to be HPV
B. Podophyllin, administered in a 25% solution, results in resolution of warts in 80% of patients, and recurrence rates are <10%
C. Immunotherapy with vaccination is used as initial tx of small lesions
D. Carcinoma freq develops if the lesions are left untx
E. Surgical tx involves excision and is not assoc with any risk of transmission to health care providers
A
Anal infection with HPV is responsible for condyloma accuminatum, which appears as a group of cauliflower shaped masses on the perianal skin and anal canal. Disease is transmitted by close contact and is seen in both genders regardless of whether anal intercourse is practiced. It is especially prevalent in anal-receptive men who have sex with men and in this popilation is seen more often than genital warts. Another high risk population consists of those receiving immunosuppression after organ transplant.
Podophyllin, a cytotoxic agent available in 10% and 25% solutions must be applied by a physician. Results are disappointing. Clearance of warts in 22-77%. Recurrence rates as high as 65%. May cause skin burns and can’t be used within the anal canal. Multiple tx may be necessary Failure to tx intra-anal lesions may cause higher recurrence rates
Autologous vaccine prepared from the condyloma can be injected weekly for 6 wks. No adverse reactions. Resolution of lesions in up to 95%. Such therapy is considered for extensive, persistent, or recurrent cases of condyloma. .
Although malignant transformation can occur, it rarely does so.
Surgical tx includes excision by one of three techniques (scissors, laser therapy, or electrocautery fulguration). Elecctrocautery is preferred and is assoc with recurrence rate of 10-25%. Risk of surgeon infection within the trachea from the inhalation of vaporized viral particles. Risk can be minimized by using smoke evacuators and special masks.
