Thursday, September 29, 2011
Stations of Presentation
In the past few weeks I have had calls from three attorneys with traumatic birth injury cases. Each one needed last minute help with demonstrative evidence to illustrate the basics of labor and delivery. They had all waited to the last minute, thinking they didn’t need anything very specific and that they could get something very quickly. Unfortunately, each of these clients was unable to answer one vital question about their case, which forced them to rush back to their experts for more information and nearly prevented them from acquiring their exhibits in time. The vital question they could not answer was, “What system of classification was used in this case to notate the station of presentation?”
If you’ve ever taken part in any litigation regarding labor and delivery, certainly you’re familiar with stations of presentation. Basically, this system allows the healthcare provider to record the progress the baby makes down through the birth canal during the process of labor. It is vital to chart this progress because any deviation from the normal range can give vital clues that there is a problem that might require action. Delays in fetal progress down the birth canal during labor could be a sign of a variety of problems including an insufficient size of the mother’s pelvis, inadequate contractions, shoulder dystocia or other serious complications. The records regarding this progression may be the only evidence of what was happening during labor in a case that eventually results in litigation, so the records of the fetal stations is vital. There are two separate systems in use out there and to get an accurate picture of what occurred, you must know what system was in use.
Fetal station refers to the level of the leading edge of the fetus within the birth canal (either the head in a vertex presentation, or the foot or buttocks in a breech presentation). This level is measured in relation to the location of small protrusions of the pelvis of the mother called ischial spines. The station refers to how far above or below the ischial spines the fetus has progressed. Unfortunately, there are two distinct systems for determining fetal station in use. We’ll refer to these two systems as the “thirds” system and the “fifths” system.
Traditionally, the thirds system of measuring the station of presentation was the standard. In this system the level of the birth canal level with the ischial spines is referred to as 0 station. Above the 0 station, the distance from the pelvic inlet at the top of the pelvis down to the ischial spines is divided into thirds and referred to as -3, -2 and -1 from top to bottom. Below the 0 station, the distance from the ischial spines down to the pelvic outlet where the baby emerges from the birth canal is also divided into thirds and referred to as +1, +2 and +3 as the baby progresses. So, you take the total distance between these landmarks and divide the distance into thirds.
In 1988, the American College of Obstetricians and Gynecologists began to change the system and divide these spaces into fifths. In the fifths system, the ischial spines still represent the 0 station, but the new system refers to the stations as -5, -4, -3, -2, -1, 0, +1, +2, +3, +4 and +5. More importantly, these stations are no longer just arbitrary divisions of the total space. In the fifths system each station is divided by 1 cm, so an actual measurement can be taken to more accurately determine the station, depending on how many centimeters above or below the ischial spines the leading edge has reached.
Although 0 station is the same in the thirds and fifths system, none of the other stations coincide, so it is important to know what system was used. Regretfully, no consistency is seen in the world of obstetrics and it depends on where and when the obstetrician was trained, as well as the standards of the hospital where the delivery is performed. Early in your research and discovery phase of the case, you must determine which system was in use in order to properly understand the stations that are recorded in the records. Certainly, if the time comes for you to depict the events of the case accurately in demonstrative evidence you must be sure that the illustrations you use reflect the proper system.