Begin FHR monitoring.The greatest risk to the client and her fetus following a rupture of membranes is umbilical cord prolapse. The nurse should monitor the fetus closely to ensure well-being. Therefore, this is the priority action the nurse should take.The nurse should perform a Nitrazine test to determine the pH of the fluid. An alkaline pH can indicate rupture of membranes. However, this is not the first action the nurse should take.The nurse should observe the characteristics of the fluid to document color, odor, and amount. However, this is not the first action the nurse should take.The nurse should check the client's cervical dilation to assess progress of labor. However, this is not the first action the nurse should take.