In this study, the investigators aim to identify the underlying fistula in patients with a perianal abscess with the help of an MRI Scan done in the acute setting. Participants with a confirmed fistula on the MRI scan have their abscess treated as per convention. However, a repeat examination under anaesthetic is performed 7-`10 days later when the fistula tract is identified and treated with injection of the porcine collagen paste into the fistula tract. Participants are followed up clinically and radiologically to assess the effectiveness of the intervention.