Anal Repair and Diamond Flap in Patient with Moderate Anal Stenosis After Open Hemorrhoidectomy Surgery: A Case Report

Background

Anal stenosis is an anatomical narrowing of the anal canal and can be caused by excisional hemorrhoidectomy, radiation therapy, congenital malformation, and inflammatory bowel disease [1]. Other causes of anal stenosis are inflammatory processes (Crohn disease and ulcerative colitis), tuberculosis, venereal diseases, radiotherapy, and laxative addiction. However, research has suggested that overzealous hemorrhoidectomy is responsible for up to 90% of cases of anal stenosis [2]. Anal stenosis is formed due to constricted and non-elastic fibrous scar tissue that replaces the anal canal tissue. The incidence of anal stenosis is 5%, usually with clinical symptoms such as severe constipation, outlet obstruction, and anal pain that cannot be relieved with stool softeners or dietary changes [3].

Anal stenosis can be diagnosed with rectal examination to visualize the scar tissue. Milsom and Mazier classified anal stenosis into 3 classes [4]: (1) mild: tight anal canal that can be examined by a well-lubricated index finger; (2) moderate: forceful dilatation is required to insert the index finger; and (3) severe: the little finger cannot be inserted unless forceful dilation is employed.

There are a few surgical techniques to treat anal stenosis, namely the mucosal advancement flap, house flap, Y-V flap, rhomboid flap, U flap, and rotational S plasty. In this study, the diamond flap method was used as an alternative flap to treat the anal stenosis [4].

Case Report

A 57-year-old female patient presented with difficulty and discomfort in defecation due to anal stenosis 2 years after an open hemorrhoidectomy surgery. There were no other gastrointestinal tract symptoms. Physical examination showed forceful dilatation using the index finger was required, and a 6-mm hegar dilator was used to measure the anal canal, as seen in Figure 1. We concluded that the anal stenosis in this case report was moderate.

Laboratory test results were normal. An anal repair and diamond flap method was then scheduled for this patient. The scar tissue was excised at the directions of 6 and 9 o’clock. A diamond-shaped graft was incised carefully, with attention to the vascular supply. The graft was then fixed without any tension into the anal canal. After the operation, the diameter of the anal canal was 2 cm. The surgical method is shown in Figure 2.

The patient was discharged 2 days after the procedure in stable condition and without any complications. Ten days after the surgery, the diamond flap was found to be in good condition and without any complications, as seen in Figure 3. The patient was scheduled for further follow-up in the Digestive Surgery Division.

Discussion

Anal stenosis can develop as a result of any condition that causes scarring in the anoderm, although it is most commonly associated with surgical trauma. The primary causes of anal stenosis include a history of perianal surgery, radiotherapy, sexually transmitted diseases, trauma from various sources, inflammatory bowel disease, chronic laxative use, and tuberculosis. In this particular case report, anal stenosis occurred in a patient with a history of hemorrhoidectomy. Brisinda et al estimated that approximately 90% of anal stenosis cases develop after hemorrhoidectomy [5].

Anal stenosis can significantly decrease the patient’s quality of life. Common clinical symptoms include a constant urge to defecate, straining during bowel movements, incomplete defecation, constipation, bleeding, and discomfort during defecation [6]. In the present case report, the patient had difficulty and discomfort in defecation. Mild anal stenosis can be treated effectively with non-surgical options, but surgical reconstruction is necessary for moderate to severe cases causing severe anal pain and an inability to defecate [7].

Unlike anal fissures, anal stenosis presents a problem owing to limited skin stretchability resulting from chronic fibrosis due to surgery. Therefore, a lateral internal sphincterotomy is not an effective treatment for anal stenosis [8]. Anal fissure and anal stenosis are 2 different conditions that affect the anus, with distinct differences between them. An anal fissure refers to a tear or cut in the skin lining of the anus, which can occur due to various factors, such as a hard bowel movement, constipation, diarrhea, or anal sex. Symptoms of an anal fissure can include pain during bowel movements, bright red blood in the stool or on the toilet paper, itching, and discomfort around the anus. In contrast, anal stenosis refers to a narrowing of the anal canal, which can be caused by scar tissue from surgery, radiation therapy, inflammatory bowel disease, or congenital defects. Symptoms of anal stenosis can include difficulty passing stool, constipation, pain during bowel movements, and a feeling of incomplete evacuation [9].

Surgical treatment for anal stenosis typically involves using various shapes and sizes of flaps to reconstruct and improve the caliber and flexibility of the anal canal [4].

Several flap techniques have been described for the treatment of anal stenosis and are mainly classified as advancement, island (adjacent tissue transfer), or rotational flaps. The main principle of these techniques is to provide a more pliable anoderm to the anal canal to replace the inflexible scar tissue. The extent of the anal canal stricture and the availability of adequate perianal skin determine whether the surgical technique is performed unilaterally or in several quadrants. However, there are no comparative prospective randomized studies demonstrating the superiority of any of these flap types over the others. The few comparative studies found in the literature did not classify patients according to the etiology, level, or severity of anal stenosis, and the efficacy of the various flaps was not compared within homogenous patient groups. Additionally, in these studies, it is unclear what the ideal anal canal caliber should be after flap application, or which flap method is best for achieving this caliber. In one study, using diamond advancement flaps to achieve an anal canal caliber of 25 to 26 mm resulted in favorable outcomes [10].

The diamond flap technique was first described in 1986 by Caplin and Kodner, and it has been one of the preferred treatment options for moderate and severe anal stenosis ever since [11]. Although there is no standard final target for anal caliber, Gulen et al reported a clinical success rate of 88.9% with a final anal caliber of 25 to 26 mm in 18 patients [10]. After 12 months of follow-up, the obstructed defecation syndrome scores were found to be significantly improved. One advantage of the diamond flap compared to others is its ability to cover the defect in the anal canal while sparing the sphincter complex [3].

For the diamond flap procedure, the patient is first positioned in the prone jack-knife position. An incision is made longitudinally on the scar tissue until the dentate line is reached. At this step, it is recommended to check the anal caliber and to ensure that the external sphincter is spared. The diamond flap is constructed as close as possible to the affected anal canal, and then it is dissected out along with its vascular pedicle to be advanced into the anal canal. To avoid postoperative complications, it should be noted that the flap should be tension-free [1]. Another case reported by Balci and Leventoglu in 2021 also discussed the use of the diamond-shaped flap in a 24-year-old female patient, in which the outcome was favorable [12].

Conclusions

Anal stenosis is a potential complication that can occur after an overzealous hemorrhoidectomy, but it is entirely preventable. The importance of having skilled and experienced surgical teams cannot be overstated in preventing anal stenosis. Surgeons with better insights into anorectal anatomy and the use of delicate techniques to treat anal tissue will help to reduce complications during anorectal surgery.

In addition to the surgeon’s expertise, the patient’s clinical condition and the severity of the disease should be considered when selecting the appropriate surgical technique. Different surgical approaches are available, and the choice of technique will depend on various factors. For example, the experience and preferences of the surgeon and the clinical setting can also play a role in determining the most suitable surgical technique to use.

One promising surgical technique for managing moderate to severe anal stenosis is the diamond flap method. This technique has been found to have a high success rate with minimal complications. Another advantage of the diamond flap technique is that it allows for the coverage of the anal canal defect while sparing the sphincter complex. The diamond flap could be an option for moderate to severe anal stenosis surgery management with high a success rate and few complications.