A nurse is performing a pelvic exam on a laboring woman. What does the term “-1 station 1 cm above iliac spine” indicate?

Question

Question

This question was previously asked in

AIIMS NORCET 7 Prelims Memory Based Paper 2024

Answer 1

Correct Answer: The fetal head is 1 cm above the ischial spines

Rationale:

In obstetrics, the station refers to the position of the fetal head in relation to the ischial spines of the pelvis. The ischial spines are bony protrusions located in the mid-pelvis and serve as a reference point for assessing the descent of the fetal head.
Station is measured in centimeters above (-) or below (+) the ischial spines, which are considered 0 station. A station of -1 means the fetal head is 1 cm above the ischial spines, indicating it has not yet descended into the mid-pelvis.
A -1 station generally suggests that labor is progressing, but the fetal head has not yet fully engaged with the ischial spines.

Explanation of Other Options:

The fetal head is at the level of the ischial spines

Rationale: This describes a station of 0. When the fetal head is at the level of the ischial spines, it is considered engaged and at 0 station. The correct answer indicates the head is 1 cm above this point.

The fetal head is 1 cm above the pelvic inlet

Rationale: The pelvic inlet is the upper opening of the true pelvis, not the ischial spines. Station measurements are related to the ischial spines, not the pelvic inlet.

The fetal head is 1 cm below the pelvic inlet

Rationale: This is incorrect as the station describes the position in relation to the ischial spines, not the pelvic inlet. The pelvic inlet is a different anatomical landmark higher up than the ischial spines.

Conclusion:

The correct interpretation of "-1 station" is that the fetal head is 1 cm above the ischial spines. Understanding the position of the fetal head in relation to these bony landmarks helps healthcare providers assess the progress of labor and make necessary clinical decisions.