You are in: eMedicine Specialties > General Surgery > Colorectal Anal FissureArticle Last Updated: Jun 28, 2006AUTHOR AND EDITOR INFORMATIONSection 1 of 12
  Author: Lisa S Poritz, MD, Assistant Professor, Department of Surgery, Section of Colon and Rectal Surgery, Milton S Hershey Medical Center, Pennsylvania State University Lisa S Poritz is a member of the following medical societies: American College of Surgeons, American Society of Colon and Rectal Surgeons, Association for Academic Surgery, and Society for Surgery of the Alimentary Tract Editors: Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; David L Morris, MD, PhD, Professor, Department of Surgery, St George Hospital, University of New South Wales, Australia; Paolo Zamboni, MD, Professor of Surgery, Chief of Day Surgery Unit, Chair of Vascular Diseases Center, University of Ferrara, Italy; John Geibel, MD, DSc, MA, Professor, Department of Surgery, Section of Gastrointestinal Medicine and Department of Cellular and Molecular Physiology, Yale University School of Medicine; Director of Surgical Research, Department of Surgery, Yale-New Haven Hospital Author and Editor Disclosure Synonyms and related keywords: anal canal, anus, low-fiber diet, high-fiber diet, hard stool, anal canal stenosis, bowel movement, anal skin tag, hypertrophied anal papillae, anal canal tear, anal canal crack, tear in anal canal, crack in anal canal, constipation, hard stool, anal canal tethering, hypertonic anal sphincter, hypertrophic anal sphincter, anal sphincter hypertonicity, anal sphincter hypertrophy, sphincterotomy, sphincter stretch INTRODUCTIONSection 2 of 12
  ProblemAn anal fissure is a painful linear tear or crack in the distal anal canal, which, in the short term, usually involves only the epithelium and, in the long term, involves the full thickness of the anal mucosa (see Media files 1-2). For excellent patient education resources, visit eMedicine's Esophagus, Stomach, and Intestine Center. Also, see eMedicine's patient education articles Anal Abscess, Rectal Pain, and Rectal Bleeding. FrequencyAnal fissures occur with equal frequency in both sexes. Additionally, anal fissures tend to occur in younger and middle-aged persons. EtiologyThe exact etiology of anal fissures is unknown, but the initiating factor is thought to be trauma from the passage of a particularly hard or painful bowel movement. Low-fiber diets, such as those lacking in raw fruits and vegetables, are associated with the development of anal fissures. No occupations are associated with a higher risk for the development of anal fissures. Prior anal surgery is a predisposing factor because scarring from the surgery may cause either stenosis or tethering of the anal canal, which makes it more susceptible to trauma from hard stool. Initial minor tears in the anal mucosa due to a hard bowel movement probably occur often, and, in most people, these heal rapidly without long-term sequelae. In patients with underlying abnormalities of the internal sphincter, these injuries progress to acute and chronic anal fissures. Studies of the internal anal sphincter and of anal canal physiology have been performed with varied results, but at least one abnormality is likely present in the internal anal sphincter of many anal fissure patients. The most commonly observed abnormalities are hypertonicity and hypertrophy of the internal anal sphincter, leading to elevated anal canal and sphincter resting pressures. The internal sphincter maintains the resting pressure of the anal canal, and anal-rectal manometry can be used to measure this pressure. Most patients with anal fissures have an elevated resting pressure, and this resting pressure returns to normal levels after surgical sphincterotomy. The posterior anal commissure is the most poorly perfused part of the anal canal. In patients with hypertrophied internal anal sphincters, this delicate blood supply is further compromised, thus rendering the posterior midline of the anal canal relatively ischemic. This is thought to account for why many fissures do not heal spontaneously and may last for several months. Pain accompanies each bowel movement as this raw area is stretched and the injured mucosa is abraded by the stool. The internal sphincter also begins to spasm when a bowel movement is passed, which has 2 effects. First, the spasm itself is painful; second, the spasm further reduces the blood flow to the posterior midline and the anal fissure, contributing to the poor healing rate. PathophysiologySee Etiology. ClinicalTypically, the symptoms of an anal fissure are relatively specific, and the diagnosis can often be made based on history findings alone. The patient reports severe pain during a bowel movement, with the pain lasting several minutes to hours afterward. The pain recurs with every bowel movement, and the patient commonly becomes afraid or unwilling to have a bowel movement, leading to a cycle of worsening constipation, harder stools, and more anal pain. Approximately 70% of patients note bright red blood on the toilet paper or stool. Occasionally, a few drops may fall in the toilet bowl, but significant bleeding does not usually occur with an anal fissure. Initially, the fissure is just a tear in the anal mucosa and is defined as an acute anal fissure. If the fissure persists over time, it progresses to a chronic fissure that can be distinguished by its classic features. The fibers of the internal anal sphincter are visible in the base of the chronic fissure, and often, an enlarged anal skin tag is present distal to the fissure and hypertrophied anal papillae are present in the anal canal proximal to the fissure. Most anal fissures occur in the posterior midline, with the remainder occurring in the anterior midline (99% of men, 90% of women). Two percent of patients have both anterior and posterior fissures. Fissures occurring off the midline should raise the possibility of other etiologies (eg, Crohn disease), an infectious etiology (eg, sexually transmitted disease, AIDS), or cancer. INDICATIONSSection 3 of 12
Failure of medical therapy to resolve the acute fissure is an indication for surgical intervention. The presence of a symptomatic chronic fissure is also an indication for surgery because few of these heal spontaneously. RELEVANT ANATOMYSection 4 of 12
Thorough knowledge of the anatomy of the anal canal is vital for surgical treatment of an anal fissure (see Media file 2). Anal canal The anal canal has 2 definitions. The first is the functional or surgical anal canal, and the second is the anatomic anal canal. The terms are often used interchangeably, even though they do not mean the same thing. The surgical anal canal is approximately 4 cm long and extends from the anal verge or intersphincteric groove distally to the anorectal ring proximally. The anatomic anal canal is only approximately 2 cm long and extends from the anal verge distally to the dentate line proximally. Anal verge The anal verge is an anocutaneous line approximately 2 cm distal to the dentate line. The anal verge marks the beginning of the anal canal. Dentate line The dentate line is the junction of the ectoderm and endoderm in the anal canal. Internal anal sphincter The internal anal sphincter is a smooth muscle that is the most distal extension of the inner circular smooth muscle of the colon and the rectum. It is 2.5-4 cm long and is normally 2-3 mm thick. The internal sphincter is not under voluntary control and is continuously contracted to prevent unplanned loss of stool. External anal sphincter The external anal sphincter is striated muscle that forms a circular tube around the anal canal. Proximally, it merges with the puborectalis muscle and the levator ani to form a single complex. Control of the external anal sphincter is voluntary. CONTRAINDICATIONSSection 5 of 12
The main contraindication to surgery for an anal fissure is impaired fecal continence because this could be worsened with surgery. This contraindication mostly applies to patients with minor incontinence (occasional seeping). Patients with gross fecal incontinence (solid material) rarely develop fissures; however, those with irritable bowel syndrome and incontinence to liquid stool can develop fissures if they become constipated. These patients are at the most risk for surgical treatment of an anal fissure because their typical bowel pattern is loose and more difficult to control. WORKUPSection 6 of 12
Lab Studies
Imaging Studies
Diagnostic Procedures
Histologic FindingsThe fissure is not usually excised; therefore, no pathology specimen is available for examination. When it is excised, the tissue typically exhibits nonspecific inflammation. If some of the muscle is accidentally excised with the fissure, the internal sphincter usually demonstrates fibrosis. TREATMENTSection 7 of 12
Medical therapyInitial therapy for an anal fissure is medical in nature, and more than 80% of acute anal fissures resolve without further therapy. The goals of treatment are to relieve the constipation and to break the cycle of hard bowel movement, associated pain, and worsening constipation. Softer bowel movements are easier and less painful for the patient to pass. First-line medical therapy consists of therapy with stool-bulking agents, such as fiber supplementation and stool softeners. Laxatives are used as needed to maintain regular bowel movements. Mineral oil may be added to facilitate passage of stool without as much stretching or abrasion of the anal mucosa, but it is not recommended for indefinite use. Sitz baths after bowel movements and as needed provide significant symptomatic relief because they relieve some of the painful internal sphincter muscle spasm. Recurrence rates range from 30-70% if the high-fiber diet is abandoned after the fissure is healed. This rate can be reduced to 15-20% if patients remain on a high-fiber diet. Second-line medical therapy is the topical application of 0.2% nitroglycerin (NTG) ointment directly to the internal sphincter. Some physicians use NTG ointment as initial therapy in conjunction with fiber and stool softeners, and others prefer to add it to the medical regimen if fiber and stool softeners alone fail to heal the fissure. NTG ointment is thought to relax the internal sphincter and to help relieve some of the pain associated with sphincter spasm; it also is thought to increase blood flow to the anal mucosa. Unfortunately, many people cannot tolerate the adverse effects of NTG, often limiting its use. The main adverse effects are headache and dizziness; therefore, instruct patients to use NTG ointment for the first time in the presence of others or directly before bedtime. The efficacy of NTG ointment has been debated in many studies, and its use is still controversial. NTG ointment is specially mixed at this lower concentration and is available only in pharmacies that specially make it. Analogous to the use of NTG ointment, nifedipine ointment is also available for use in clinical trials. It is thought to have similar efficacy to NTG ointment but with fewer adverse effects. A newer therapy for acute and chronic anal fissures is botulinum toxin (BOTOX®). The toxin is injected directly into the internal anal sphincter and, in effect, performs a chemical sphincterotomy. The effect lasts approximately 3 months, until the nerve endings regenerate. This 3-month period may allow acute fissures (and sometimes chronic fissures) to heal and symptoms to resolve. Initial relief of symptoms with BOTOX® injection but recurrence after 3 months suggests that the patient would benefit from surgical sphincterotomy. Surgical therapySurgical therapy is usually reserved for acute anal fissures that remain symptomatic after 3-4 weeks of medical therapy and for chronic anal fissures. Preoperative detailsTwo Fleet enemas the morning of surgery is sufficient bowel preparation for this procedure. If the anal fissure is too painful, the enemas may be omitted. No other preoperative preparation is necessary unless the patient has significant comorbidities that require attention. Intraoperative detailsSphincter dilatation This procedure is a controlled anal stretch or dilatation under general anesthetic. This is performed because one of the causative factors for anal fissure is thought to be a tight internal anal sphincter; stretching it helps correct the underlying abnormality, thus allowing the fissure to heal. The number of fingers used and the amount of time the stretch is applied varies among surgeons. While the sphincter stretch does provide symptomatic relief from the anal fissure, it is rarely performed today because of the high complication rate. Impaired continence is observed in 12-27% of patients because of the uncontrolled stretching and subsequent tearing of both the internal and external sphincter. Lateral internal sphincterotomy This is the current surgical procedure of choice. The procedure can be performed with the patient under general or spinal anesthesia. (Local anesthesia may even be used in the cooperative patient, although this is not always recommended). The purpose of an internal sphincterotomy is to cut the hypertrophied internal sphincter, thereby releasing tension and allowing the fissure to heal. When first described, the sphincterotomy was performed in the posterior midline at the site of the fissure with or without a fissurectomy. However, the incision for the sphincterotomy usually did not heal for exactly the same reason that the fissure did not heal. Now, sphincterotomies are normally performed in the lateral quadrants (right or left, depending on the comfort or handedness of the surgeon). In a properly performed lateral internal sphincterotomy, only the internal sphincter is cut; the external sphincter is not cut and must not be injured. The sphincterotomy can be performed in either an open or a closed manner. In a closed sphincterotomy, a No. 11 blade is inserted sideways into the intersphincteric groove laterally. It is then rotated medially and drawn out to cut the internal sphincter. Care is taken to not cut the anal mucosa because this could result in a fistula. After the knife is removed, the anal mucosa overlying the sphincterotomy is palpated, and a gap in the internal sphincter can be felt through it. The sphincterotomy is extended into the anal canal for a distance equal to the length of the anal fissure. In an open sphincterotomy, a 0.5- to 1-cm incision is made in the intersphincteric plane. The internal sphincter is then looped on a right angle and brought up into the incision. The internal sphincter is then cut under direct visualization. The 2 ends are allowed to fall back after being cut. A gap can then be palpated in the internal sphincter through the anal mucosa, as in the closed technique. The incision can be closed or left open to heal. In the treatment of chronic anal fissures, the surgeon may choose to excise the fissure in conjunction with the lateral sphincterotomy. Take care to not include a piece of the internal sphincter with the excision. More simply, instead of excising the fissure along with the sphincterotomy and worrying whether it will heal, the surgeon can excise the hypertrophied papillae and the skin tag and leave the fissure to heal on its own. Sometimes, long-standing chronic fissures do not heal, even with an adequate sphincterotomy, and an advancement flap must be performed to cover the defect in the mucosa. This can be performed either at the time of the sphincterotomy if the surgeon does not think the fissure will heal or as a second procedure if the fissure does not heal. Postoperative detailsSphincterotomy is performed either in an outpatient setting or as an office procedure, and patients return home the same day. Typically, minimal postoperative pain is associated with either the closed or open technique—usually no more than the fissure caused preoperatively. Pain from the fissure starts to abate almost immediately. The only postoperative restrictions are from the anesthetic, and many patients can return to normal activities the following day. Follow-upPrescribe stool softeners and fiber supplementation after the surgery, and recommend fiber supplementation indefinitely to prevent future problems with constipation. Follow-up care usually consists of a single postoperative visit to ensure that the wound is healing appropriately and that the fissure has resolved. COMPLICATIONSSection 8 of 12
Complications from surgery for anal fissure include infection, bleeding, fistula development, and—the most feared—incontinence. Infection Infection after sphincterotomy is rare and occurs as a small abscess in only 1-2% of patients, despite the inherent uncleanliness of the area. Treatment is drainage of the abscess. Antibiotics are necessary only if significant associated cellulitis occurs or if the patient is immunosuppressed. Bleeding Some ecchymosis may occur around the sphincterotomy site, but bleeding that requires therapy is extremely rare. Fistula formation Fewer than 1% of patients develop an anal fistula at the site of the sphincterotomy. This usually results from a breach of the mucosa at the time of the sphincterotomy. The fistula is often low and superficial and should be treated with fistulotomy. Incontinence The incidence and definition of incontinence vary dramatically from study to study and among the different procedures. Of patients undergoing the sphincter stretch, 12-27% report problems with continence after the procedure. This is most likely because this is an uncontrolled stretch of the anal sphincter and that both the internal and external sphincters are stretched. Incontinence rates are much lower with a properly performed internal sphincterotomy than with sphincter stretch, and these rates depend on the definition of incontinence. In most patients, the minor soiling or incontinence to flatulence that may occur in the immediate postoperative period usually resolves without any long-term sequelae. Recurrence or nonhealing of the fissure The recurrence rate or nonhealing rate for anal fissures after surgical treatment is 1-6%. Several studies have found that up to 50% of subjects who did not heal had underlying and undiagnosed Crohn disease as the etiology for their fissure. OUTCOME AND PROGNOSISSection 9 of 12
Approximately 1-6% of patients have a recurrence of their anal fissure after sphincterotomy. The recurrence rate is higher after a sphincter stretch. If a patient develops a recurrence after a sphincterotomy, it could be from recurrent disease or from an improperly or incompletely performed initial sphincterotomy. Medical management should be attempted again; but, if no relief is obtained, the surgeon must evaluate whether the original sphincterotomy was adequate. Evaluation can be performed by palpation during examination under anesthesia or by performing an endoanal ultrasound. If the sphincterotomy was incomplete, it can be completed on the initial side or redone on the opposite side. If the first sphincterotomy was complete, a second sphincterotomy can be completed on the opposite side. FUTURE AND CONTROVERSIESSection 10 of 12
Controversy mostly involves the continued efforts to find a medical therapy as successful as the surgical therapy. MULTIMEDIASection 11 of 12
REFERENCESSection 12 of 12
Article Last Updated: Jun 28, 2006 | ||||||||||||||
