Traditional Pelvic Assessment in Pregnancy
Traditional clinical pelvimetry should not be performed as part of routine prenatal care, as it does not change management, lacks evidence for predicting delivery outcomes, and represents an outdated practice rooted in racist methodology. 1, 2
Why Clinical Pelvimetry Is Not Recommended
Clinical pelvimetry has no clinical utility in modern obstetric practice. A retrospective review of 660 pregnant women found that despite 70% having pelvimetry documented, no admission note, progress note, or operative note during labor and delivery referenced these results, and abnormal findings made no difference in mode of delivery or treatment. 1
Evidence Against Traditional Pelvimetry
The Caldwell-Moloy classification system and clinical pelvimetry measurements cannot predict obstetric outcomes. The human obstetric pelvis varies in complex ways such that neither individual pelvimetric dimensions nor artificial typologies correlate clearly with delivery success. 2
Current obstetric practice allows all women a trial of labor regardless of pelvimetry results, making routine performance of clinical pelvimetry a waste of time, potential liability, and unnecessary patient discomfort. 1
The foundational techniques were developed on biased, non-representative samples and perpetuate racism that has clinical consequences today. 2
What Should Be Done Instead
For Routine Prenatal Assessment
Transabdominal ultrasound assessment of the cervix is recommended as part of standard second and third trimester obstetric evaluation. 3, 4
For Cervical Assessment in High-Risk Patients
Transvaginal ultrasound is the reference standard for assessing the gravid cervix when there are concerns about preterm birth risk or cervical competence. 3
The transvaginal approach provides the shortest distance between transducer and cervix, offering higher frequency evaluation and complete visualization including the internal os. 3
Transperineal ultrasound is a suitable alternative when transvaginal ultrasound is declined or contraindicated (e.g., placenta previa, suspected preterm premature rupture of membranes). 3
For Labor Progress Assessment
Vaginal examinations during active labor should be performed only as indicated by clinical circumstances, not routinely at fixed intervals. 5
- A study comparing routine four-hourly vaginal examinations versus examinations as indicated found that routine examinations resulted in more labor augmentation without improving outcomes. 5
Special Circumstances Requiring Different Approach
Women with skeletal dysplasia require cesarean delivery as pelvic anatomy precludes vaginal delivery, representing the only clear scenario where maternal pelvic anatomy determines delivery route. 4
Common Pitfalls to Avoid
Do not perform or document clinical pelvimetry measurements (diagonal conjugate, ischial spines, pubic arch angle, etc.) as these have no evidence base and create unnecessary documentation. 1, 2
Do not use pelvimetry results to counsel patients about likelihood of vaginal delivery success, as these measurements do not predict outcomes. 2
Do not default to routine timed vaginal examinations during labor without clinical indication, as this increases interventions without improving outcomes. 5