Oral Antibiotics for Anal Abscess

METHODS This project is a 3-year study.

Trial Design:

This is a multicentre, double-blind placebo trial to investigate the effect of oral antibiotics after anal abscess drainage to diminish the development of an anal fistul.

This Clinical Trial will consist of two parallel study groups with a (1:1) randomization, masking by double-blind technique and placebo control.

Participants:

The participants of this study will be eligible among those who will be attended on the emergency department of each participant hospital during inclusion period.

Interventions:

This study will include patients who come to the emergency room due to perianal abscesses and who will be incised and drained of the lesion by local anaesthesia (in emergency boxes) or by regional or general anaesthesia (in the operating room). A standard procedure will be followed with draining the purulent contents and then instilling a solution composed of saline and iodine through the wound; as well as manual exploration and lysis of intracavity septa.

In all cases as it it standardized, the wound will be left open with insinuated gauze or a latex drainage (Penrose) when necessary.

The patients, once selected, will be randomly distributed (by specific software) in two parallel groups, in one of which the intervention will be evaluated. In the study group, patients will receive oral treatment with Ciprofloxacin at a dose of 500 mg every 12 hours and Metronidazole 500 mg every 8 hours for a period of 7 days. The control group will receive two types of placebo tablets that look identical to Ciprofloxacin and Metronidazole respectively, with similar doses and frequencies.

Postoperative controls and follow-up will be carried out at 1, 3, 6 and 12 months after treatment and will include an endoanal ultrasound (US) at 6 months.

Studied variables:

The following variables will be analysed:

- Epidemiological variables: Age, gender.

- Smoking status

- Comorbidities

- Obesity (Body Mass Index)

- Cultures of abscess

- Characteristics of anal abscess: Location, type of drainage.

- Selected arm: Group treatment (antibiotics) vs. Control group (placebo)

- Clinical follow up (anal fistula or not) at 1, 3, 6 and 12 months.

The diagnosis of anal fistula is standarized by specialist in General Surgery.

- Type of anal fistula developed

- Endoanal US at 6 months

- Adverse events of treatment

- Quality of life (general health with SF-36 test and an specific test related to quality of life in patients with anal fistula, both tests validated to Spanish language) at 12 months (end of follow up)

Expected outcomes:

Once the patients with diagnosis of perianal abscess treated with incision and drainage were included, the objective of our study will be to evaluate the proportion of patients who developed perianal fistula between the two study groups (with oral antibiotics and with placebo). It will be recorded as the presence of a perianal fistula when the participants present a history of symptoms compatible with it, as well as the existence of a communication between the perianal cutaneous tissue and the anal canal during the clinical examination performed or even evidenced in the endoanal ultrasound during the controls that will be carried out up to 12 months after the intervention. For better evaluation and registration abscesses will be classified according to their complexity: subcutaneous, intersphincteric, ischiorectal and according to their anatomical location: anterior, posterior, lateral, right and left. These data will be collected at the time of the surgical exploration during the initial treatment with incision and drainage.

Fistulas will be classified by Parks classification in the following: subcutaneous, intersphinterian, transphincteric, suprasphinteric, extraphincteric. These data will be collected at the time of the clinical examination during the controls.