Final answer:
The priority assessment when a client is in labor and is to have an amniotomy is the fetal heart rate. It is crucial for monitoring the fetus's immediate well-being and detecting any signs of distress or complications.
Step-by-step explanation:
When planning care for a client who is in labor and is to have an amniotomy, the priority assessment should be fetal heart rate. This assessment is crucial for determining the fetus's well-being immediately before and after the procedure. A sudden change in fetal heart rate can signal distress or complications such as umbilical cord prolapse, which requires immediate attention.
Other assessments like maternal blood pressure, cervical dilation, and amniotic fluid color are also important but secondary. For instance, the color of amniotic fluid can indicate meconium-stained fluid which has its own risks, but the immediate well-being of the fetus is gauged primarily by the heart rate.