At 3 hours postpartum, a gravida 2, para 2 complains of rectal pressure and increasing perineal pain. She is unable to void. This woman had a low forceps delivery with a midline episiotomy and a third-degree laceration. The fundus is firm and one fingerbreadth below the umbilicus. Lochia is moderate, bright red and without clots. The nurse is correct to assess further for