In a general aspect, a method of treating urinary incontinence can include slidably interfitting a first push tube into a first dilator tube disposed at an end of a sling assembly and slidably interfitting the first push tube onto an end of a shaft of a delivery device. The method can also include inserting the shaft transvaginally through a vaginal wall and removing the shaft to implant a portion of the sling assembly in periurethral tissue. The method can also include slidably interfitting a second push tube into a second dilator tube disposed at a second end of the sling assembly and slidably interfitting the second push tube onto the end of the shaft. The method can still further include inserting the shaft transvaginally through the vaginal wall and removing the shaft from the patient to implant a second portion of the sling assembly in periurethral tissue.