MPO and isolated hemihyperplasia: We conducted a systematic literature review, following PRISMA guidelines and registered with PROSPERO (CRD42024559035), on the five most common causes of prenatal scrotal masses: inguinoscrotal hernia (IH), meconium periorchitis (MPO), testicular solid tumors (TST), hydrocele (H), and testicular torsion (TT).