Immediately before an amniotomy, the external fetal heart rate monitor tracing shows a baseline of 145 bpm, moderate variability, and no decelerations.Immediately following the procedure, the tracing shows a fetal heart rate of 100 bpm, moderate variability, and recurrent variable decelerations.A moderate amount of clear, amniotic fluid is seen on the bed linens.The nurse suspects which of the following complications has occurred?