At a time when political protesting regarding racial injustice is
commonly seen, medical professionals ought to recognize when racial and
ethnic insensitivity may exist in our collective medical practice. A
case in point relates to the use of prediction models for successful
vaginal trials of labor after Cesarean (VTOL). 1-3Such algorithms can include verifiable correlates to vaginal births
after Cesarean (VBAC), such as prior vaginal births, estimated fetal
weight (EFW), persistent cesarean indications, body mass index (BMI),
and even type of labor onset. The accuracy of these algorithms used to
predict successful VBAC in a patient contemplating a VTOL has been
recently questioned. 4-6 The inclusion of a racial
component may be of questionable value here, since the anthropomorphic
indicators of pelvic dimensions are less clear cut, 7especially when soft tissue description may offer a different
correlation to the capacity for vaginal delivery. 8
Although this last reference examined the obligate contribution of the
soft tissues to the birth canal dimensions beyond its bony limitations,
it related this to the prediction of soft tissue injuries. It
nonetheless describes the consequential role of the pelvic soft tissues
as part of the birth canal, unrelated to the possibly genetically
determined bony pelvis dimensions. Pertinent to this discussion is the
notion that Race, and ethnicity, have a role in determining vaginal
delivery capability (e.g. in VBAC), when a sociodemographic basis may be
confused with a biologically defined one.
Measurement of the bony pelvic dimensions with magnetic resonance
imaging (MRI), relating to an individual’s Race, has revealed the usual
range as would be expected in any population, somewhat correlated with
Race. Whether these described dimensions (e.g. inter-tuberous or ischial
spinous diameter or pelvic inlet size) meaningfully correlates with the
capacity to vaginally deliver, is open to some question, since there may
be an essential role of the pelvic soft tissues (e.g. the levator
muscles of the pelvic floor) with regard to vaginal delivery capability.
X-Ray pelvimetry, and pelvimetry through other imaging modalities, has
long been abandoned as a predictor of the capacity to vaginally deliver,
due to its repeated documented failure.9 So, the
inclusion of Race or ethnicity in an algorithm used to predict VBAC
success, may inappropriately be using this demographic indicator. When
the use of this specific factor (i.e. race/ethnicity) in a prediction
model was shown to not be successful, the interpretation was simply
articulated as “not predictive of VBAC success” and
“unexpected”.10 In fact though, the underestimation
of the probability of a successful VBAC because of a patient’s
assignment of ethnicity or race, should be highlighted, as the
ramifications of such counseling of a low probability of success, is
significant when it can be shown to be inaccurate.
This is of considerable importance since these prediction models can
influence shared decision-making. The tendency to desire having a
vaginal birth has been shown to correlate with certain racial/ethnic
groups, and this influence is indeed relevant.11 The
relationship of VBAC success prediction in the Latina community is
particularly worthy of note, given some reported disparate
findings.11 Interestingly, whatever the complex
interactions of the pelvic bony dimensions and soft tissue dynamics are,
the vaginal birth statistics do not appear to show significant
differences between women in different racial/ethnic groups, in the
United States. 12 The use of racial identity may not
therefore be statistically relevant to any of the algorithms used for
successful VTOL prediction. If encouragement of vaginal births is
desirable when appropriate, then perhaps this racial categorization
should be avoided. At least, we may need to properly establish and
validate these algorithms within appropriately selected populations and
follow described prediction model development.13