Introduction

The real incidence of anorectal abscesses and anal fistulas in emergency department (ED) is difficult, since many of them drain spontaneously or are drained in primary care services without any sequelae. It is estimated that 40% of patients with anorectal abscesses will develop an anal fistula during its evolution¹-³. In Spain, the incidence of anal fistulae is around 1.04/10,000 inhabitants/year⁴, which corresponds to the general perception of its relatively low incidence, although it seems a little higher compared to other series that placed it around 0.86/10,000 inhabitants/year⁵. Anorectal infections are especially frequent in patients with Crohn disease, acquired immune deficiency syndrome, or immunosuppressed due to any other cause⁶.

Regarding the management of anorectal abscesses in the ED, there is great heterogeneity in the standards of clinical practice. Although the clinical guidelines for the management of anorectal abscesses and anal and rectovaginal fistulas have been recently published⁷, the reality of daily practice is that the assessment of these patients, in a high percentage of cases, is performed by physicians without the necessary experience for its correct diagnosis and treatment⁸. The objective of this study is the evaluation of the treatment performed in patients with anorectal abscesses in the ED and its impact on disease recurrence.

Methods

We have retrospectively evaluated all patients with anorectal abscess diagnosed during one year. Those cases that required evaluation under anesthesia (EUA) were included. Patients undergoing evaluation without anesthesia, soft-tissue abscess different from the anorectal region and those with Fournier gangrene were excluded from the study. All patients provided informed consent, and the study was approved by the ethics committee.

Socio-demographic aspects, associated comorbidity, seasonality of the disease, as well as the type of treatment performed in the ED were analyzed.

We studied the type of antibiotic prescribed, the criteria for its prescription as well as for the taking of cultures. Patients were divided according to the sensitivity to the prescribed empirical antibiotic treatment, ranging from "sensitive," "resistant," or "indeterminate," being understood as "indeterminate" those cases, in which the sensitivity of the bacteria could not be determined (multiple flora) or did not have relevance given that an empirical antibiotic was not prescribed. The relationship between antibiotic sensitivity and the abscess recurrence was assessed.

Finally, we evaluated those patients referred to the specialized coloproctology outpatient department (COD) after abscess drainage in the ED. We analyzed general parameters (sex and age), associated comorbidity, referral criteria to specialized consultation, and presence of anal fistula compared with the previous existence of it in the emergency surgical exploration. To do this, a physical evaluation was performed, accompanied by an endoanal ultrasound to determine the type of fistula.

Results

During the period of study, 220 anorectal abscesses were diagnosed, corresponding to 190 patients (127 men, mean age 46.4 years ± 14.9) (Fig. 1). Eighty-nine patients (46.8%) had abscess recurrence, 63 (70.7%) at the time of inclusion in this study.

Figure 1 Flowchart of study patients. ER: emergency room. 

Most patients had no significant medical history, 28 (14.7%) were diabetic and 12 (6.3%) had Crohn disease (Table 1). In terms of seasonality, most cases (64%) occurred in the months of autumn and winter. The most frequent treatment performed in the ED was simple drainage (75.8%), followed by drainage + seton placement (17.9%). At the time of drainage, 66 patients (34.7%) had an associated anal fistula. Cultures were taken in 26 patients (13.7%) and 119 were prescribed antibiotics (62.6%). Forty-one patients (21.6%) required hospital admission, while 78 (41.1%) were referred to our specialized COD.

Follow-up of patients referred to specialized COD

A total of 78 patients (41.1%) were referred to specialized consultation, most of them (74.4%) had no significant medical history. All were clinically evaluated and 3D endoanal ultrasound was performed in 65 patients (83%).

The analysis of referral criteria to specialized consultation showed that most of cases were patients with recurrence of anorectal abscess with or without associated anal fistula (79.5%). Nine (11.5%) patients presented only anal fistula as derivation criteria and one (1.2%) due to medical history of Crohn disease. No clear referral criteria were found in six patients (7.6%).

Regarding the presence of anal fistulas, of the 66 patients in whom they were diagnosed in the emergency room, 55 (83.3%) were referred to the specialized consultation for this reason. On arrival at the consultation, the fistula had disappeared in 29 (52.8%) patients. Of the patients without an anal fistula objectified in the emergency room exploration, it was developed on arrival to the specialized coloproctology consultation in 14 cases (60.8%); most of these patients had been referred under the indication of recurrent anorectal abscess. Transsphincteric fistula was the most frequently diagnosed (65%) (Fig. 2).

Figure 2 Detailed flowchart of patients referred to specialized COD. Results are shown in absolute numbers and percentage (%). COD: coloproctology outpatient department; DM: diabetes mellitus; ER: emergency room. 

Discussion

Surgical treatment of anorectal abscesses is a frequent surgical emergency in ED. In our case is second only to acute appendicitis for EUA. However, its approach continues to be subject to great variability⁷,⁹-¹¹, not only from one hospital to another but also among professionals of the same hospital. As mentioned by Malik et al. in their work⁸, the treatment of anorectal abscesses, in the great majority of cases, is left to less experienced physicians (general surgery residents with little or no experience and young attending surgeons) with limited capacity for diagnosing associated complications or for the screening of associated fistulas.

One of the observations that we do share with most studies is that anorectal abscesses mainly affect the middle-aged male population. Although the exact causes of this association are still unknown, it is possible that it may reside in anatomical differences of the anal glands or that hormonal factors, not fully known, may be involved. We also observed that most cases (64%) occur in the autumn-winter period. This situation, although it lacks clinical relevance, represents the opposite that would be expected in a hospital with very hot summers where sweating is profuse and moisture/maceration of anal and anorectal tissue is the norm. It is intuitive that, according to this observation, the development of anorectal abscesses depends more on intrinsic factors than on those related to the environment.

As in the majority of published articles, the most frequent surgical treatment performed in the ED was simple drainage followed by drainage + seton placement. Emergency fistulotomy simultaneous to the drainage of the abscess was performed in only 0.5% of the cases. Although there is a systematic review that advocates its implementation in specific cases (simple fistulas with a high risk of recurrence)¹², it seems that seton placement may be an equally effective procedure without the added risk of fecal incontinence¹³-¹⁵.

Our study shows significantly higher rates of microbiological cultures and prescription of antibiotics than international standards, guidelines, and recommendations. We did not objectify clear criteria for the prescription of antibiotics or for the taking of cultures and, what is most important, neither the taking of cultures nor antibiotics significantly affected the recurrence rate of anal abscess. Even when the sensitivity of the bacteria to the empiric antibiotic treatment was confirmed by antibiogram, there were no lower anal abscess recurrence rates compared to when the bacterium was resistant. As mentioned by Leung et al.¹⁶, one of the main problems in taking cultures is that, in many cases, as they are outpatients without further follow-up, there is no physician in charge of reviewing the cultures and performing a targeted treatment, if needed. Therefore, based both on our results and in previous studies³,¹³,¹⁷,¹⁸, we support the recommendation to reserve the use of antibiotics for patients with anorectal abscesses and important cellulitis, signs of systemic disease, and/or in cases of immunosuppression. We also believe it is convenient to take cultures only in selected patients (persistent abscess with poor wound healing and/or suspected infection with methicillin-resistant Staphylococcus aureus [MRSA] or Pseudomonas). In the present study, of the 24 different types of bacteria and fungi isolated, we did not have any patient with MRSA but did find two cases of Pseudomonas infection. The majority of the observed antibiotic resistance corresponded to the group of beta-lactams + clavulanic acid.

Regarding the referral criteria to the specialized COD, we did not objectify any clear referral criteria in 7.6% of the cases. We believe that this value, although low compared to the total of treated and referred patients, could be easily improved, as it only implies giving greater responsibility to experienced surgeons and physicians in the diagnosis and treatment of anorectal abscesses.

With respect to the presence and development of anal fistulas in patients with anorectal abscesses, it has been classically established that it is present initially or develops later in 26-37% of cases²,¹⁹,²⁰. In the present study, higher values were obtained (50-60%). It is worth noting that about half of the fistulas diagnosed in the emergency room present spontaneous healing once the abscess is drained, without the need for additional treatments. However, on the other hand, there is a large percentage of patients (approximately 60%) who can develop it after anal abscess is treated in their acute form, especially in cases of abscess recurrence or immunosuppression (lymphoma, diabetes mellitus, and/or inflammatory bowel disease).

In this study and after specific complementary tests performed in specialized, the transsphincteric fistula was the most frequently diagnosed in about 65% of cases. Given that so far there is no gold standard treatment for this type of anal fistula, we share the consideration of Soliman et al.²¹ that this is a type of fistula whose management is complex and sometimes with disastrous consequences; therefore, its assessment, treatment, and follow-up should be carried out in third-level reference units, with extensive experience for the treatment of this complex pathology.

Conclusions

There is great variability regarding the management and treatment of anorectal abscesses in the ED. Simple drainage ± seton placement represents the most recommended treatment. Systematized prescription of antibiotics and taking of cultures should be avoided, except in selected cases. It is important to design specific clinical pathways adapted to the needs and microbiological characteristics of each region, to optimize the management of patients with anorectal abscesses with or without anal fistula. With regard to anal fistulas, simple abscess drainage can be curative in more than half of the cases. Consultation to the specialized COD is recommended in cases of recurrent anal abscesses, anal fistulas, and immunosuppressed patients, given its increased risk of chronic anal fistula. We can conclude that the optimal management of anal abscess in ED is still a pending task. A proper diagnosis and treatment both in the ED and in specialized outpatient consultation, will reduce antibiotic resistance, preventing annoying, unnecessary and expensive proceedings to the patient, as well as avoid additional costs for the National Health System.

Ethical disclosures

Protection of human and animal subjects. The authors declare that no experiments were performed on humans or animals for this study.

Confidentiality of data. The authors declare that they have followed the protocols of their work center on the publication of patient data.

Right to privacy and informed consent. The authors declare that no patient data appear in this article.