Despite the established safety and efficacy of midurethral slings (MUS), which are the current gold standard treatment for stress urinary incontinence (SUI), the potential for postoperative complications remains a significant concern for both healthcare professionals and patients. Meanwhile, sonography has emerged as a significant diagnostic tool in urogynecology, and one of the applications of this imaging modality may be the evaluation of complications arising from MUS procedures. This review, based on a comprehensive literature search, focuses on the use of pelvic floor ultrasound (US) in the context of MUS complications. It includes analyses of randomized controlled trials, prospective, and retrospective studies, covering preoperative and postoperative investigations, to assess complications such as persistent and recurrent SUI, urinary retention and obstructive voiding, de novo urgency/overactive bladder, vaginal exposure, sling erosion, pain, and hematoma. The review critically examines the existing literature, with a particular focus on recent publications. Despite the variability in findings, it appears that for each of the discussed complications, the application of pelvic floor US can significantly support the diagnostic and therapeutic process. The paper also identifies potential future directions for the development of US applications in diagnosing MUS complications.