Measurement error in computed tomography pelvimetry

Anderson, N.; Humphries, N.L.; Wells, J. Elisabeth

doi:10.1111/j.1440-1673.2005.01417.x

Cited by 19 publications

(14 citation statements)

References 25 publications

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“…Anteroposterior outlet measurements have been shown to be subject to such large observer variation as to be of little clinical use. 19 This study is further evidence undermining the usefulness of CT pelvimetry. More than this, our findings also provide evidence that measurements from the CT scanogram cannot be completely relied upon even when the CT is calibrated according to the manufacturer's recommendations.…”

Section: Discussionmentioning

confidence: 84%

Intrinsic measurement bias on computed tomography scout view is unpredictable: Computed tomography pelvimetry using a phantom

Anderson

Fenwick

Wells

2006

Australasian Radiology

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Our aim was to determine the degree of bias in CT scanogram measurements. We obtained standard lateral and anteroposterior (AP) pelvimetry scanograms of a phantom pelvis after placing ball bearings or aluminium rods to mark bony landmarks. Computed tomography pelvimetry was carried out at the manufacturer-recommended table height on two commercial CT scanners and at 10-mm increments up to 50 mm above and below this height. The AP inlet, AP outlet, interspinous distance and transverse diameters were each measured three times for each scanogram. The true measurements were obtained directly from the disassembled phantom. Bias was defined as the difference between the CT measurement and the true measurement. Observer error was negligible. The transverse diameter was overestimated at high table positions and underestimated at low table positions on both scanners (+6 to -10 mm). After correcting for geometric distortion, up to 6 mm bias was still present. The point at which no bias occurred was different for each scanner and did not correspond to the manufacturers' recommended table height. The outlet was overestimated on both scanners by up to 5 mm. The true inlet measurement was overestimated by 1.2 mm. The interspinous distance was minimally underestimated on both scanners. The measurements on CT scanogram were underestimated or overestimated in an inconsistent and unpredictable fashion, varying from one type of measurement to another and from CT scanner to CT scanner. This has implications for the accuracy and clinical utility of measurements obtained from a CT scanogram.

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Section: Discussionmentioning

confidence: 84%

Intrinsic measurement bias on computed tomography scout view is unpredictable: Computed tomography pelvimetry using a phantom

Anderson

Fenwick

Wells

2006

Australasian Radiology

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Section: Discussionmentioning

confidence: 99%

“…As for the clinical assessment of the size of the pelvic inlet, if the distance between the ischial tuberosities exceeds 8 cm, then this is considered normal [7]. To predict a vaginal delivery, a pelvimetry measuring the bony structure of the pelvis is a method of assessing the materanl pelvis with using radiography or CT. X-ray pelvimetry has been widely over the years and has been generally accepted as one of the clinical tools in evaluating cephalopelvic disproportion but since labor and its outcome are a very delicate and dynamic process [7]. The results of pelvis radiography, which have been reported on in Korea, show that the frequency of a cesarean operation was relatively higher for the cases for which the anterior and posterior width of pelvic inlet were smaller than 10 cm and the transverse length of the midpelvis was smaller than 8.5 cm [8].However, Pattinson [9] suggested that in regard to the pelvimetry, for the women for whom a pelvic radiography was performed, the frequency of cesarean operation was more than two times higher and the perinatal outcome was not particularly improved.…”

Section: Discussionmentioning

confidence: 99%

Compare the architectural differences in the bony pelvis of Korean women and their association with the mode of delivery by computed tomography

Kim

Lee

et al. 2011

Korean J Obstet Gynecol

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ObjectiveWe investigated the structural differences in the pelvic bone architecture of Korean women and their association with the mode of delivery by performing computed tomography (CT) pelvimetry. MethodsThis study was conducted on 175 women who underwent CT between March of 2006 and May of 2008. For making an objective assessment, one specialist in obsterics and gynecology measured the obstetrical conjugate, the true conjugate and the diagonal conjugate on the sagittal plane and the transverse diameter, the intertuberous diameter and the interspinous diameter on the coronal plane. The patients who underwent total hysterectomy or those who had a disease of the uterus were excluded from the current analysis. ResultsA total of 175 Korean women were examined, and their ages ranged from 20 to 50 years. The mean age was 37.6 ± 7.4 years. The interspinous diameter that was measured on CT scans was 94.6 ± 7.8 mm in the vaginal delivery group (n=84) and this was 90.9 ± 6.6 mm in the cesarean section group (n=20). This difference reached statistical signifi cance. ConclusionOur study examined the difference in the pelvic architecture with using CT and we found that the interspinous diameter can be the important determinant that affects normal vaginal delivery. Of these pelvimetric parameters, a wider interspinous diameter was signifi cantly associated with vaginal delivery. Multi-displinary approaches are warranted to examine this relation with regard to the various factors that are involved in delivery. Th is is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/ by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Keywords Copyright © 2011. Korean Society of Obstetrics and GynecologyThe maternal bony pelvis is an important factor that affects the degree of soft tissue damage that occurs during parturition and for choosing the mode of delivery [1]. It is known that such factors as a spacious inlet, a large interspinous diameter and a wide suprapubic arch are associated with a normal vaginal delivery [1]. Childbirth is a major cause of pelvic prolapse, and so conducting anatomical studies on the materal pelvic structure are essential for examining the structural changes of the pelvic bone that occur during parturition and the possible subsequent prolapse of organs in the pelvic fl oor. However, there have been no such studies due to a lack of measurement methods in this fi eld. Recent studies [2][3][4] have found that computed tomography (CT) pelvimetry is easier to perform and more accurate and it causes less distortion than Korean J

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“…Intra-observer assessment was then compared to assess the standard error of measurement (SEM) [8,9], i.e., the square root of the variance (or standard deviation). Measurements with an SEM of ≤4 mm are deemed accurate and those outside this range considered inaccurate [8]. Korhonen et al [9 ]considered a cut-off of ≥5 mm.…”

Section: Methodsmentioning

confidence: 99%

Which Foetal-Pelvic Variables Are Useful for Predicting Caesarean Section and Instrumental Assistance

Frémondière

Thollon

Adalian³

et al. 2017

Med Princ Pract

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Objective: To assess the variables useful to predict caesarean delivery (CD) and instrumental assistance, through the analysis of a large number of foetal-pelvic variables, using discriminant analysis. Materials and Methods: One hundred and fourteen pregnant women were included in this single-centre prospective study. For each mother-foetus pair, 43 pelvic and 18 foetal variables were measured. Partial least squares-discriminant analysis was performed to identify foetal-pelvic variables that could statistically separate the 3 delivery modality groups: spontaneous vaginal delivery (SVD), CD, and instrument-assisted delivery (IAD). Results: For the SVD versus CD model, voluminous foetuses and women with a narrow pelvic inlet had a greater risk for requiring CD. The most efficient variables for discrimination were the transverse diameter and foetal weight. The antero-posterior inlet and obstetric conjugate were considered in this model, with the former being a useful variable but not the latter. For the SVD versus IAD model, the most important variables were the foetal variables, particularly the bi-parietal diameter. Women with a reduced antero-posterior outlet diameter and a narrow pubic arch were more at risk of requiring an IAD. Conclusion: The antero-posterior inlet was an efficient variable unlike the obstetric conjugate. The obstetric conjugate diameter should no longer be considered a useful variable in estimating the arrest of labour. Antero-posterior inlet diameter was a sagittal variable that should be taken into account. The comparison of sub-pubic angle and bi-parietal and antero-posterior outlet diameters was useful in identifying a risk of requiring instrumental assistance.

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Measurement error in computed tomography pelvimetry

Cited by 19 publications

References 25 publications

Intrinsic measurement bias on computed tomography scout view is unpredictable: Computed tomography pelvimetry using a phantom

Intrinsic measurement bias on computed tomography scout view is unpredictable: Computed tomography pelvimetry using a phantom

Compare the architectural differences in the bony pelvis of Korean women and their association with the mode of delivery by computed tomography

Which Foetal-Pelvic Variables Are Useful for Predicting Caesarean Section and Instrumental Assistance

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