After performing a sterile vaginal exam on a client who has just been admitted to the unit in active labor and placed on an electronic fetal monitor, the RN assesses that the fetal head is at 21 station. She documents this on the monitor strip.
Fetal head at 21 station means that the fetal head is located where in the pelvis?
A. One centimeter below the ischial spines
B. One centimeter above the ischial spines
C. Has not entered the pelvic inlet yet
D. Located in the pelvic outlet
Answer: B
Explanation:
(A) The ischial spines are located on both sides of the midpelvis. These spines mark the diameter of the narrowest part of the pelvis that the fetus will encounter. They are not sharp protrusions that will harm the fetus. Station refers to the relationship between the ischial spines in the pelvis and the fetus. The ischial spines are designated at 0 station. If the presenting part of the fetus is located above the ischial spines, a negative number is assigned, noting the number of centimeters above the ischial spines. Therefore, 1 centimeter below the ischial spines is designated as +1 station.
(B) See explanation in A. One centimeter above the ischial spines is designated as +1 station.
(C) The pelvic inlet is the first part of the pelvis that the fetus enters in routine delivery. The midpelvis is the second part of the pelvis to be entered by the fetus. The ischial spines are located on both sides of the midpelvis.
(D) The pelvic outlet is the last part of the pelvis that the fetus will enter. When the fetus reaches this part of the pelvis, birth is near.
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