From the Research
The ischial spines are the critical bony landmark that determines fetal station during labor, with station 0 defined as the level of the ischial spines. When the presenting part of the fetus (typically the head) is at the level of the ischial spines, it is designated as station 0. Stations above the spines are measured in centimeters and given negative values (-1, -2, -3, etc.), indicating the fetal presenting part is still high in the pelvis. Stations below the spines receive positive values (+1, +2, +3, etc.), showing descent toward delivery. This measurement system is essential for assessing labor progress, as normal labor involves progressive descent of the fetus through these stations. Healthcare providers use vaginal examinations to determine station by feeling the relationship between the fetal presenting part and these bony prominences. Accurate assessment of station helps clinicians evaluate whether labor is progressing normally, determine if intervention might be needed, and predict how close delivery may be. The ischial spines are particularly useful as reference points because they are consistent anatomical structures that can be readily identified during examination, providing standardization in the assessment of fetal descent across different providers and institutions 1.
Key Points
- The ischial spines serve as a reference point for determining fetal station during labor
- Station 0 is defined as the level of the ischial spines
- Stations above the spines are given negative values, while stations below the spines receive positive values
- Accurate assessment of station is crucial for evaluating labor progress and determining the need for intervention
- The ischial spines provide a consistent and reliable anatomical landmark for assessing fetal descent 2, 3
Clinical Significance
The use of ischial spines as a reference point for determining fetal station has significant implications for clinical practice. It allows healthcare providers to accurately assess labor progress and make informed decisions about the need for intervention. Additionally, the use of ischial spines as a reference point can help reduce the risk of complications during labor and delivery. The most recent study 1 supports the use of ischial spines as a reference point for determining fetal station, and provides evidence for the importance of accurate assessment of station in evaluating labor progress.