Estimation of Pelvic Capacity

Mengert, William F.

doi:10.1001/jama.1948.02900030001001

Cited by 75 publications

(32 citation statements)

References 4 publications

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“…With the exception of the biiliac diameter, which is maximum pelvic breadth, the pelvic variables characterize the size and shape of the bony birth canal among the three planes typically recognized by obstetricians: inlet, midplane, and outlet. Except for the biiliac diameter, all pelvic variables are obstetrically relevant, though some variables are considered to be more important determinants of obstetric success than others (Allen, 1947a,b;Caldwell et al, 1939;Cunningham et al, 1989;Hanson, 1936;Ince and Young, 1940;Kenny, 1944;Mengert, 1948;Oxorn, 1980;Pettit et al, 1936;Tague, 1992;Thoms, 1935Thoms, , 1937; also see Discussion). Some of the pelvic measurements were either duplicated (e.g., anteroposterior and transverse diameters, shapes, area of inlet, and subpubic angle) or modified (e.g., posterior and anterior spaces, areas of midplane and outlet, and depth) from those reported in the obstetric literature (Caldwell et al, 1939;Cunningham et al, 1989;Ince and Young, 1940;Mengert, 1948;Oxorn, 1980;Steer, 1975;Thoms, 1935Thoms, , 1956.…”

Section: Methodsmentioning

confidence: 99%

Do big females have big pelves?

Tague

2000

Am. J. Phys. Anthropol.

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Previous studies have shown that maternal stature is a correlate of both pelvic size and reproductive efficiency. This study addresses the issue of body size and obstetric advantage. The relationship between pelvic size and three nonpelvic measures of body size is determined for females and males. The skeletal sample consists of blacks, whites, and Native Americans. The variables include 28 measures of the pelvis, length and head diameter of the femur, and clavicular length. The coefficient of multiple determination (CMD) is computed for each pelvic measure using multiple regression, with the three nonpelvic measures serving as the independent variables. Partial correlation coefficients are also calculated between each pelvic and nonpelvic variable, while controlling for the other two nonpelvic variables. The results show that all CMDs in females and all but one CMD in males are "low," i.e., below 33%. The sexes are nonsignificantly different in their CMDs for 22 of the 28 pelvic variables; of the six variables that are significantly different, five are of the midplane. The sexes are also broadly comparable in their partial correlations. The results are explained as follows. First, the concordance between the sexes in the relationship between pelvic size and nonpelvic measures of body size is due to their genetic similarity for homologous structures. Second, as pelvic size is at the minimum at the midplane, the sexual differences in CMDs are the result of selection with respect to obstetrics. Third, four explanations for the low CMDs are discussed: 1) lack of populationally or racially specific analysis; 2) nonlinear relationship between pelvic size and nonpelvic measures of body size; 3) combination of negative allometric selection between newborn body weight and maternal stature and weight with positive selection for maternal pelvic size; and 4) hormonally induced increase in pelvic capacity during parturition.

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Section: Methodsmentioning

confidence: 99%

Do big females have big pelves?

Tague

2000

Am. J. Phys. Anthropol.

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“…In 1948, Mengert described using the product of the two mid-pelvis planes to determine a contracted pelvis. 9 This report was based on 592 women who had undergone pelvimetry and delivered. The average value of the mid-pelvis product was 126-cm 2 , and a value less than 85% of this was associated with a cesarean delivery, mid-forceps, fetal death, and performance of craniotomy.…”

Section: Commentmentioning

confidence: 99%

Radiographic measures of the mid pelvis to predict cesarean delivery

Harper

Odibo

Stamilio

et al. 2013

American Journal of Obstetrics and Gynecology

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Objective To determine whether x-ray measures of the mid-pelvis can be used to predict cesarean delivery. Study Design Women were enrolled prospectively and x-ray pelvimetry was performed post-partum, with readers blinded to the outcome. Groups were determined by mid-pelvis measures (transverse diameter [TD], anterior-posterior diameter [APD], and circumference [MC]) ≤10th percentile. The primary outcome was cesarean delivery. Univariable, stratified, and multivariable analyses were performed to estimate the effect of midpelvis measures on cesarean delivery. Receiver operator characteristics (ROC) curves were created to estimate the predictive value of mid-pelvis measures of cesarean delivery. Results 426 women were included. Subjects with APD or MC ≤10th percentile were at greater risk of cesarean (risk ratio (RR) for APD 4.8, 95% confidence interval (CI) 3.9–5.8, RR for MC 3.8, 95% CI 3.1–4.8). TD ≤10th percentile was not associated with an increased risk of cesarean delivery. The area under the ROC curves for APD, MC and TD were 0.88, 0.85, and 0.69, respectively (p<0.01). Conclusion Simple radiographic measures of the mid-pelvis on x-ray can provide a useful adjunct to clinical information in determining who should attempt a vaginal delivery.

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“…A ‘contracted’ pelvic inlet can increase the risk of various obstetric complications . When either the anteroposterior diameter of the inlet is <10 cm or the transverse diameter is <12 cm, the risk of dystocia increases …”

Section: Introductionmentioning

confidence: 99%

“…1 When either the anteroposterior diameter of the inlet is <10 cm or the transverse diameter is <12 cm, the risk of dystocia increases. 2,3 The gynecoid shape is the most common pelvic type for the general population of women and is also an optimum shape for normal childbirth, while the flat type is the least suitable. 4 The android type, designated when masculine features are present in the pelvic inlet, has a relatively poor obstetric prognosis.…”

Section: Introductionmentioning

confidence: 99%