Dynamic External Pelvimetry Test in Third Trimester Pregnant Women: Shifting Positions Affect Pelvic Biomechanics and Create More Room in Obstetric Diameters

Obesity and narrow pelvis prolong the operative time in conventional laparoscopic rectal cancer surgery, but not in a two-team transanal total mesorectal excision approach

PURPOSE

Narrow pelvis, tumor diameter, and obesity have been reported as clinical variables correlated with the difficulty of conventional laparoscopic low anterior resection (Lap-LAR). A two-team transanal total mesorectal excision (TaTME) approach where the transabdominal and TaTME are performed simultaneously might reduce the difficulty associated with these factors. This study aimed to clarify the factors associated with the longer time required for TME (TME time) in conventional Lap-LAR and a two-team approach for TaTME.

METHODS

We analyzed 52 patients with rectal carcinoma treated with Lap-LAR and 35 patients treated with TaTME. We performed simple linear regression analysis to assess the association between TME time and bony pelvic size using 3D pelvimetry, longest tumor diameter, and body mass index (BMI).

RESULTS

Linear regression analysis demonstrated a highly significant association between TME time and obstetric conjugate (R²  = 0.098, P = .024) and BMI (R²  = 0.307, P < .001) in the Lap-LAR group, while no significant association was observed in the TaTME group. Male patients, who had a narrower bony pelvis and higher BMI than female patients, had longer TME time than female patients in the Lap-LAR group (213 minutes vs 172 minutes, P = .021), while the TME time of male and female patients did not differ in the TaTME group (122 minutes vs 108 minutes, P = .451). The TME time in the TaTME group was significantly shorter than that in the Lap-LAR group (121 minutes vs 197 minutes, P < .001).

CONCLUSION

A two-team TaTME approach provided a shorter TME time compared to conventional Lap-LAR, regardless of pelvic size and BMI.

Textbook typologies: Challenging the myth of the perfect obstetric pelvis

Medical education's treatment of obstetric-related anatomy exemplifies historical sex bias in medical curricula. Foundational obstetric and midwifery textbooks teach that clinical pelvimetry and the Caldwell-Moloy classification system are used to assess the pelvic capacity of a pregnant patient. We describe the history of these techniques-ostensibly developed to manage arrested labors-and offer the following criticisms. The sample on which these techniques were developed betrays the bias of the authors and does not represent the sample needed to address their interest in obstetric outcomes. Caldwell and Moloy wrote as though the size and shape of the bony pelvis are the primary causes of "difficult birth"; today we know differently, yet books still present their work as relevant. The human obstetric pelvis varies in complex ways that are healthy and normal such that neither individual clinical pelvimetric dimensions nor the artificial typologies developed from these measurements can be clearly correlated with obstetric outcomes. We critique the continued inclusion of clinical pelvimetry and the Caldwell-Moloy classification system in biomedical curricula for the racism that was inherent in the development of these techniques and that has clinical consequences today. We call for textbooks, curricula, and clinical practices to abandon these outdated, racist techniques. In their place, we call for a truly evidence-based practice of obstetrics and midwifery, one based on an understanding of the complexity and variability of the physiology of pregnancy and birth. Instead of using false typologies that lack evidence, this change would empower both pregnant people and practitioners.

Can the Dynamic External Pelvimetry Test in Late Pregnancy Reveal Obstructed and Prolonged Labor? Results From a Pilot Study

Background The size and mobility of the maternal pelvic space are fundamental factors in successful childbirth and can allow operators to screen for dystocia. This pilot study including a group of 70 pregnant women aimed to test whether the external dynamic pelvimetry test can be used to predict the likelihood of obstructed labor. Methodology The study cohort consisted of 70 pregnant women in their third trimester. The cohort was divided retrospectively into an obstructed labor group and a control group. Obstructed labor was defined using the following obstetric outcomes: augmentation with oxytocin from the first phase of the dilating period, Kristeller's maneuvers, vacuum extractor (kiwi), forceps, and the cesarean section following the onset of labor. Results The measurements obtained for the longitudinal hemi-diameter of Michaelis, the inter-tuberous diameter, and the base of the Trillat's triangle were statistically significant in every position. The difference in the measurements of the transverse diameter of Michaelis between standing and hands-and-knees position and the difference in the sizes of the bi-cristal diameter between hands-and-knees and squatting position were statistically significant. Conclusions Dimension and biomechanical properties of the pelvic tissue and spaces influence the evolutionary childbirth process. After clinical confirmation on a large population, hypomobility of specified external pelvic diameters measured in shifting positions can become a screening tool to detect the contracted pelvis and prevent damage caused by dystocia and prolonged labor in women and newborns.