Imaging of perineal suppurations: a pictorial essay

Perineal suppuration encompasses a broad spectrum of pathologies involving the anatomically complex perineal region. While anal fistula, with or without abscess, is the most frequent cause, infections may also originate from the skin, accessory urinary or genital glands, pelvic and perineal implants, or supralevator digestive structures. Clinical presentations range from benign acute episodes to severe life-threatening conditions or chronic relapsing infections. Diagnosis is often challenging due to overlapping symptoms and variable anatomical involvement. Imaging plays a pivotal role in delineating the extent and origin of disease, particularly in distinguishing anal from extra-anal sources, an essential step for appropriate management. Ultrasonography (US) and Magnetic Resonance Imaging (MRI) are well suited for evaluating anal fistulas; MRI is preferred for chronic, recurrent, or deep-seated infections, particularly those of cutaneous origin or associated with implant infection, while Computed tomography (CT) is favored for supralevator digestive involvement and Fournier's gangrene. A detailed understanding of perineal anatomy and its imaging correlates is crucial for accurate diagnosis and treatment planning. This pictorial essay illustrates the imaging features of perineal suppurations from diverse etiologies, emphasizing the diagnostic value of cross-sectional imaging and the central role of radiology in clinical decision-making.