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Revista Española de Enfermedades Digestivas

versión impresa ISSN 1130-0108

Rev. esp. enferm. dig. vol.96 no.12 Madrid dic. 2004



Open lateral internal anal sphincterotomy under local anesthesia as the gold standard in the treatment of chronic anal fissures. A prospective clinical and manometric study

A. Sánchez Romero, A. Arroyo Sebastián, F. Pérez Vicente, P. Serrano Paz, F. Candela Polo, A. Tomás Gómez, D. Costa Navarro,
A. Fernández Frías and R. Calpena Rico

General Surgery Department and Service of Digestive Diseases. Hospital General Universitario. Elche. Alicante, Spain



Background: chronic anal fissure is one of the most frequent proctological disorders in Western populations. Open lateral internal sphincterotomy is one of the therapeutic options accepted as the treatment of choice for chronic anal fissure, since it reduces the hypertonia of the internal anal sphincter (the main etiopathogenic mechanism of fissures), decreases anal pain, and allows the fissure to heal.
Material and methods
: we carried out a prospective study of 120 patients operated on for chronic anal fissure with open sphincterotomy under local anesthesia at our Proctology Outpatient Unit from 1998 to 2001. No preoperative studies, bowel preparation, or antibiotic prophylaxis were carried out. All patients were followed up after 1 week, 2 months, 6 months, and 1 year, and underwent an anal manometry before and after surgery.
early complications: 3 hematoma-ecchymosis of the wound (2.5%), 3 self-limited hemorrhage events (2.5%). No hemorrhoidal thrombosis, fistulas, or perianal abscesses occurred. Fissures recurred in nine patients (7.5%) within one year. The initial rate of incontinence of 7.5% at two months dropped down to 5% at six months.
The mean resting pressure (MRP) in incontinent patients was lower than in continent patients (55±7 mmHg versus 80.7 ± 21 mmHg). The difference in mean squeeze pressure (MSP) between incontinent patients and continent patients was not statistically significant.
open sphincterotomy under local anesthesia has a long-term rate of healing and a morbidity rate similar to other techniques. It may therefore be considered an effective treatment for chronic anal fissure.

Key words: Chronic anal fissure. Internal sphincterotomy. Anal manometry.

Sánchez Romero A, Arroyo Sebastián A, Pérez Vicente F, Serrano Paz P, Candela Polo F, Tomás Gómez A, Costa Navarro D, Fernández Frías A, Calpena Rico R. Open lateral internal anal sphincterotomy under local anesthesia as the gold standard in the treatment of chronic anal fissures. A prospective clinical and manometric study. Rev Esp Enferm Dig 2004; 96: 856-863.

Recibido: 21-11-03.
Aceptado: 28-04-04.

Correspondencia: Ana María Sánchez Romero. Servicio de Cirugía General y Aparato Digestivo. Hospital General Universitario de Elche. C/ Camino de Almazara, 11. 03203 Elche. Alicante. Tel.: 609 609 248. Fax: 966 679 377. e-mail:



Chronic anal fissure (CAF) is one of the most frequent proctological disorders in the Western world, and may sometimes affect the patient's quality of life. Thus, rapid effective treatment is a priority (1-3).

The etiology of this condition is controversial, but it is generally accepted that spasm of the internal anal sphincter plays a fundamental role in its pathogenesis. Therefore there is a vicious circle: fissure - internal anal sphincter spasm - pain (4,5). Consequently, internal lateral sphincterotomy (ILS) has been widely accepted as the treatment of choice in chronic anal fissure, since it relaxes the hypertonic sphincter, thereby reducing anal pain and allowing the fissure to heal (6). Open ILS performed under local anesthesia is a rapid effective technique for the treatment of CAF.

We investigated the results of open sphincterotomy performed under local anesthesia in the Outpatient Clinic at our Coloproctology Unit in terms of both fissure healing and postoperative complications.


We carried out a prospective study of 120 patients operated on for chronic anal fissure from September 1998 to September 2001 in the Coloproctology Unit, General University Hospital, Elche. Detailed written consent was obtained beforehand.

The diagnosis of chronic anal fissure was established on clinical examination (visualization), and over 1 month of unsuccessful medical treatment (high residue diet, analgesics, and warm sitz baths). We collected information regarding age, sex, symptoms, bowel habits, findings on examination, and manometric values before surgery. Mean age of patients was 40.45 years (range: 21-74); 42 were women (35%) and 78 men (65%); length of symptoms was 17.6 months (range: 1-70). Chronic constipation, anal pain, and bleeding were the symptoms present in over 60% of patients, as shown in table I.

Exclusion criteria included: associated anal pathologies (incontinence, stenosis, abscess, fistula, and hemorrhoids), other comorbidities (IBD, AIDS, tuberculosis, sexually transmitted diseases, and immunodepression), anticoagulant therapy, and documented allergy to local anesthesia.

All patients were operated on by three surgeons specialized in coloproctology. The procedure was performed with the patient in jack-knife position. Patients were monitored with a pulsioximeter. No preoperative studies, bowel preparation, or antibiotics were required. Local anesthesia (20 cc of 2% mepivacaine) was injected with a 25G needle, infiltrating the skin, intersphincteric space, internal anal sphincter, and submucosa on the left and right sides, as well as the bed of the fissure.

The right lower anal canal was exposed using an anal retractor, and a 1-2 cm incision made in the skin of the intersphincteric groove. The anal mucosa was separated from the internal anal sphincter up to the dentate line. The intersphincteric space was dissected and the distal internal sphincter was divided using electric diathermy under direct vision. The incision was not closed, and digital direct pressure was applied for 5 minutes. Hospital admission and patient observation were unnecessary. Instructions were given concerning a high-residue diet, analgesics, and warm sitz baths.

The patients were visited in our coloproctology outpatient clinic after 1 week, 2 months, 6 months, and 1 year. We collected information on symptoms, bowel habits, findings on examination, manometric values, early and late complications, healing, and fissure recurrence. Healing was defined as an epithelization of the fissure with absence of symptoms. Continence was determined using the Cleveland Score (Table II).

Anal manometry was done using a water perfusion system (Ardorfer Medical Specialities Inc., Greendale, WI) with a 6-lumen catheter (external diameter, 4 mm). Both the mean resting pressure (MRP) and the mean squeeze pressure (MSP) were recorded. Results were then compared to normal values for healthy control patients in our lab: MRP = 66 ± 23 mmHg, and MSP = 164 ± 60 mmHg (control group). Manometric values were statistically compared using Student's t test.


Fissures were mostly located in the posterior midline (70%). In most cases there was a single fissure, with 7 patients having more than one. On physical examination there was a high incidence of associated hypertonia of the sphincter -slight in 18 patients (15%), moderate in 72 patients (60%), and inexplorable in 30 patients (25%) who could not tolerate digital rectal examination-. A "sentinel hemorrhoid or polyp" was found in 84 patients (70%) as shown in table I.

The complications and results of treatment are shown in table III. After the first week, three patients (2.5%) had self-limited bleeding of the wound, and ecchymosis was found in other 3 patients (2.5%). There were no anal abscesses, perianal fistulas, hemorrhoidal thrombosis, or urine retention, nor was there any admission to hospital due to surgical complications.

After 2 months, fissure persistence or recurrence was found in 3 patients (2.5%). With regard to incontinence, 3 patients (2.5%) were found to be incontinent to fluids, 2 patients (1.66%) had sporadic incontinence to flatus, and 4 patients (3.33%) had occasional incontinence to stools. The overall rate of incontinence was 7.5%. At revision after 6 months, fissure recurrence was found in another 3 patients (2.5%). Incontinence reverted in three patients at 2 months' follow-up.

After 1 year, another 3 recurrences were found. Therefore, the final rate of fissure healing was 92.5%, with 7.5% of recurrence. Incontinence was seen in 5% (6 patients), and occasional to flatus in all cases.

Table IV shows the mean MRP and MSP before and after treatment. MRP was reduced in 32.7%, being directly related to a higher percentage of fissure healing. MRP after 1 year in healed patients was 75.65 mmHg, whereas it was 112.85 mmHg in patients with fissure recurrence, and this difference was statistically significant (p < 0.001). There were no significant differences in MSP. Therefore, in terms of healing, MRP before open sphincterotomy was similar to MRP in patients with recurring fissures, while MRP in the control group was similar to that of healed patients. On a multivariate analysis, fissure recurrence or persistence was related to the presence of a sentinel hemorrhoid and to having had the fissure for over 12 months. No relationship was found between the other variables and healing.

As far as incontinence is concerned, MRP in incontinent patients was lower than that of continent patients (55 ± 7 mmHg versus with 80.7 ± 21 mmHg), and this difference was statistically significant (p < 0.001). The difference in MSP between incontinent patients (157.4 ± 56.7 mmHg) and continent patients (176.7 ± 68.4 mmHg) was not statistically significant. Of all the variables analyzed, only age > 50 years was associated with incontinence. All incontinent patients were older than 50. Nine out of 20 patients older than 50 presented postoperative disturbances of continence, whereas no case of incontinence was reported in patients younger than 50.


CAF is one of the main proctological disorders encountered in consulting rooms, due to its high prevalence and the great discomfort involved. It may be wrongly diagnosed as hemorrhoids and perianal fistula. Despite the lesion's small size, it causes great discomfort and pain, which sometimes becomes incapacitating (1,2).

As occurred in our series, CAF is reported to affect men and women alike, though more frequently men aged 20 to 40 years (1,7). The three typical symptoms of presentation are: constipation, bleeding, and proctalgia, with the latter being the main symptom. Clinical examination may require local anesthesia for local pain. The anal fissure is most often located to the mild posterior line, and frequently a "sentinel hemorrhoid or polyp" may be seen on it (1,7). Ninety per cent of acute fissures respond to conservative treatment with a fibre-rich diet and warm sitz baths. However, many persist for several weeks and may become chronic.

Identification of the etiology or predisposing factors may help prevent or reduce the high incidence of this disorder. Many studies have suggested various etiopathogenic theories for anal fissure, and so a multifactorial origin for this condition (constipation, diarrhea, local vascular or infectious conditions, idiopathic, etc) is most likely. Thus, in many cases the cause is not found (1,7). However, it is believed that hypertonia of the internal anal sphincter associated with increased pressure following a voluntary contraction plays an important role (4,5,8). For this reason, medical-surgical procedures to reduce the pressure of the internal anal sphincter have been used for fissure healing.

A great variety of therapeutic methods for the treatment of CAF have been proposed when conservative treatment fails: non-surgical treatments, as topical treatments such as botulinum toxin (9-14), nitrate preparations (8,15), and nifedipine (16); and surgical treatments such as anal dilatation (17,18), sphincterotomy (19-22), and advanced flap (20). All these techniques aim at a high rate of healing in association with a low morbidity rate. Internal lateral sphincterotomy has been proven the procedure of choice in various comparative studies, since it exhibits the highest rate of healing associated with the lowest indexes of incontinence.

Two types of internal lateral sphincterotomy have been widely discussed in the literature: open sphincterotomy, first described in 1951 by Eisenhamer (23), and closed or subcutaneous sphincterotomy, first described in 1971 by Notaras (24), with varying rates of recurrence (0-10%) and incontinence (0-66%) (1,3,6,14,17,25-27). Only two prospective randomized studies (28,29) compared these two surgical techniques, and no statistically significant differences were found to dispel the ideal option.

The results obtained in our study are comparable to those published for the closed or subcutaneous technique, with a healing rate higher than 90%, and a sporadic incontinence rate higher than 6%.

Recurrence is closely related to persistence of sphincter spasm or its manometric translation into a persistently raised MRP, which is a fundamental etiopathogenic mechanism of fissures (4,5,8). Patients with fissure recurrence or persistence exhibited an MRP after open sphincterotomy (112.85 mmHg) that was similar to their previous MRP (109 ± 29 mmHg), contrary to patients in whom the fissure healed, whose MRP after surgery was 75.65 mmHg, with a decrease in MRP of 33.6%.

We have found several clinical factors that relate to recurrence, such as the presence of a sentinel hemorrhoid or polyp, and the duration of symptoms for more than 12 months. As a matter of fact, both factors usually suggest chronic advanced disease associated with difficulties in ephitelization.

Incontinence in our study was related to a lower MRP due to an extensive section of the internal anal sphincter. MSP on the other hand remained unchanged, since its value mostly depends on the external anal sphincter, which by no means is altered with this technique. It should be noted that during follow-up the rate of incontinence initially reported decreased progressively over time, and so it did temporary incontinence, which was also reflected manometrically.

Various studies have pointed out the advantages of open sphincterotomy under local anesthesia, since results obtained in terms of healing and postoperative complications are similar to those obtained using other types of anesthesia. This technique has the added advantage of not requiring hospital admission, an operating theatre, or preoperative studies. Moreover, the lower morbidity associated with local anesthesia as compared to general or spinal anesthesia gives the patient a higher degree of satisfaction and comfort (21,28,29). The portion of the internal anal sphincter divided under local anesthesia tends to be smaller, due to the relative difficulty in identifing the sphincter and to the lesser relaxation of the perineum in comparison to other types of anesthesia, which results in fewer disturbances of continence (30) .

The results of our study confirm these facts, and we also obtained long-term healing and morbidity rates similar to those obtained with other techniques. Therefore, this technique may be considered a suitable and effective treatment for this condition.


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