[Inter-observer variability of decision concerning the route of delivery in case of one previous cesarean section and abnormal pelvic measures]. / Étude de la variabilité inter-observateur de la décision de la voie d'accouchement en cas d'utérus uni-cicatriciel et bassin anormal.

OBJECTIVES: To study inter-observer variability of decision concerning the route of delivery using pelvimetry in case of one previous cesarean section and abnormal pelvic measures. MATERIALS AND METHOD: Observational study conducted in 2014 in 4 university maternity units among 36 obstetricians. Two groups of obstetricians - as they practiced in a center where pelvimetry was routinely performed (n=12) or not (n=24) - had to choose a route of delivery for 10 clinical cases of women with a single uterine scar and a tight pelvis. The "routine pelvimetry" group had pelvimetry results. The group "no pelvimetry" became aware of pelvimetry results as a second step and had to indicate whether this information changed or not their management. The measurement of the inter-observer variability was estimated by estimating the proportion of agreement according to Grant method. RESULTS: The proportion of agreements of an attempted vaginal delivery between obstetricians in the group "routine pelvimetry" was 64.7% (95% CI [61-68.5]) and 97.3% (95% CI [96.4 to 98.3]) in the group "no pelvimetry", prior knowledge of pelvimetry results. An attempted vaginal delivery was decided in 77.5% versus 98.7% (P<0.001). After knowledge of pelvimetry results in the group "no pelvimetry" had, the number of attempted vaginal deliver was not different (77.5% vs. 78%, P=0.920). CONCLUSION: In women with one previous cesarean section, in case of tight pelvis discovered after pelvimetry, inter-observer variability of decision concerning the route of delivery is increased. Centers that choose to continue using the routine pelvimetry should develop procedures to limit this variability.

The diagnostic accuracy of external pelvimetry and maternal height to predict dystocia in nulliparous women: a study in Cameroon.

OBJECTIVE: In many developing countries, most women deliver at home or in facilities without operative capability. Identification before labour of women at risk of dystocia and timely referral to a district hospital for delivery is one strategy to reduce maternal and perinatal mortality and morbidity. Our objective was to assess the prediction of dystocia by the combination of maternal height with external pelvimetry, and with foot length and symphysis-fundus height. DESIGN: A prospective cohort study. SETTING: Three maternity units in Yaoundé, Cameroon. POPULATION: A total of 807 consecutive nulliparous women at term who completed a trial of labour and delivered a single fetus in vertex presentation. METHODS: Anthropometric measurements were recorded at the antenatal visit by a researcher and concealed from the staff managing labour. After delivery, the accuracy of individual and combined measurements in the prediction of dystocia was analysed. MAIN OUTCOME MEASURES: Dystocia, defined as caesarean section for dystocia; vacuum or forceps delivery after a prolonged labour (>12 hours); or spontaneous delivery after a prolonged labour associated with intrapartum death. RESULTS: Ninety-eight women (12.1%) had dystocia. The combination of a maternal height less than or equal to the 5th percentile or a transverse diagonal of the Michaelis sacral rhomboid area less than or equal to the 10th percentile resulted in a sensitivity of 53.1% (95% CI 42.7-63.2), a specificity of 92.0% (95% CI 89.7-93.9), a positive predictive value of 47.7% (95% CI 38.0-57.5) and a positive likelihood ratio of 6.6 (95% CI 4.8-9.0), with 13.5% of all women presumed to be at risk. Other combinations resulted in inferior prediction. CONCLUSION: The combination of the maternal height with the transverse diagonal of the Michaelis sacral rhomboid area could identify, before labour, more than half of the cases of dystocia in nulliparous women.

[Pelvimetry with compute tomography]. / Bekkenmåling med computertomografi.

BACKGROUND: In 1993, Ullevaal University Hospital started CT pelvimetry. The accuracy of CT pelvimetric measurements and a low fetal dose are very important. In our study we tested the accuracy of CT pelvimetry and measured the fetal dose and the effective dose to the mother. METHOD: A lead scalar was exposed in different heights compared to the isocentre. Measurements were done at front and side scout views and compared to the real scale. Dose estimates were done in CT dosimetry (NRPB). Effective doses to patient as well as fetal doses were measured in this study. Fetal dose was estimated as uterus dose. RESULTS: Our results show that the measurements are overestimates when the table is moved away from the isocentre against the tube. If the table is moved away from the tube and against the detector, the measurements are underestimates. The measurements in the isocentre are accurate. This means that CT pelvimetric measurements are accurate if the patient is placed in the isocentre. In our study the estimated fetal dose was 0.74 mGy and mother's effective dose was 0.3 mSv. INTERPRETATION: Our results show that the fetal dose is as low or lower than with conventional pelvimetry. The CT pelvimetric measurements are accurate if they are performed on patients in the isocentre. We recommend that CT pelvimetry replace conventional pelvimetry.

[Low dose helical CT pelvimetry: evaluation of radiation dose and image processing]. / Pelviscanner hélicoïdal en basse dose: évaluation de la dose d'irradiation et du traitement d'images.

PURPOSE: to estimate from phantom measurements the radiation dose and the accuracy of helical ct pelvimetry. MATERIALS AND METHODS: Eight helical CT acquisitions using different tube current (100, 50, 25 or 10mAs) and pitch factor (1.125 or 1.375) settings but identical collimation (2mm) and kilovoltage (120 kVp) were evaluated using a four-channel MDCT scanner and compared with conventional CT pelvimetry including a single scout and two transverse images. A plexiglas phantom combined with an ionization chamber was used to calculate the CTDIw and DLP for each acquisition. Then, an ex vivo phantom of bony pelvis was used to evaluate the accuracy of helical acquisitions for the measurement of pelvic diameters (i.e. the antero-posterior inlet, the transverse inlet and the interspinous distance). Reconstructions of helical acquisitions were performed using 2D MPR, 3D MIP and 3D SSD algorithms. RESULTS: CTDIw and DLP of conventional pelvimetry were 26 mGy and 42 mGy.cm respectively. The radiation dose of helical acquisitions decreased linearly with tube current (CTDIw: from 13 to 1.3 mGy, DLP: from 218.3 to 18.7 mGy.cm). Compared to conventional CT, the dose was nearly similar at 25 mAs and reduced at 10 mAs. Helical acquisitions provided accurate measurements of pelvic diameters with a pitch of 1.125 and a 2D MPR algorithm to evaluate the AP inlet and a 3D MIP algorithm to evaluate the transverse inlet and the interspinous distance. Variations of tube current did not influence the accuracy of pelvic diameter measurement. CONCLUSION: Our results suggest that accurate low-dose helical CT pelvimetry using 10-25 mAs and a pitch factor of 1.125 combined with 2D MPR and 3D MIP reconstructions is possible.

An appraisal of computed tomography pelvimetry in patients with previous caesarean section.

This study was conducted to determine the value of computed tomography (CT) pelvimetry in patients with previous caesarean section. Of 219 pregnant women with one previous caesarean section, 100 had antenatal CT pelvimetry and a control group of 119 women had no CT pelvimetry. In the CT pelvimetry group, 51.0% delivered by caesarean section, 28.0% underwent elective caesarean section for contracted pelvis based on the findings of CT pelvimetry and 23% underwent emergency caesarean section after a trial labour. In the control group, 21.8% underwent emergency caesarean section. The differences in birth weight and Apgar scores between the groups were not statistically significant. CT pelvimetry increased the rate of caesarean delivery, suggesting that CT pelvimetry before a vaginal birth after a previous caesarean delivery is of limited value.

[Intraobserver and interobserver variation in measurement of the pelvic diameter using DeLee's internal pelvimeter in Cesarean section]. / Intra- og interobservatørvariation ved måling af conjugata vera obstetrica med DeLee's interne pelviometer ved sectio caesarea.

The method of measuring the true conjugata with DeLee's Internal Pelviometer at caesarean section was evaluated. In 58 women the true conjugata were blindly measured three times by the surgeon and also, in fifty cases, three times by the assistant. Only a slight intraobserver difference was found: median range was 0.42 cm. There was no significant interobserver variation. We conclude that DeLee's Internal Pelviometer can be used to measure the true conjugata at caesarean section, but the use of pelviometry in modern obstetrics is questioned.

Efficacy of the fetal-pelvic index in nulliparous women at high risk for fetal-pelvic disproportion.

OBJECTIVE: The null hypothesis of this study is that the fetal-pelvic index will not determine the presence or absence of fetal-pelvic disproportion in 137 nulliparous women at high risk for fetal-pelvic disproportion. STUDY DESIGN: This study was undertaken by comparing the blinded fetal-pelvic index values and two other methods of identifying fetal-pelvic disproportion, ultrasonography-derived estimated fetal weight greater than or equal to 4000 gm and Mengert's index, to delivery outcomes in 137 nulliparous women at high risk for fetal-pelvic disproportion. RESULTS: After adequate labor trials, 55 of 73 patients who required operative intervention had a positive fetal-pelvic index (sensitivity = 75%). Seventeen of the 18 patients with a false-negative fetal-pelvic index value had persistent malpositions (15 occipitoposterior, 1 occipitotransverse, and 1 face presentation). Spontaneous vaginal deliveries occurred in 64 patients with 62 of them having a negative fetal-pelvic index (specificity 97%). The overall predictability of the fetal-pelvic index in this patient population was 85% and the positive predictability was 96%. However, neither ultrasonography-derived estimated fetal weight nor x-ray pelvimetry, when used alone, accurately detected the presence or absence of fetal-pelvic disproportion in nulliparous women at high risk for the condition. CONCLUSION: The fetal-pelvic index is efficacious in determining the presence or absence of fetal-pelvic disproportion in nulliparous women at high risk for the condition.

Reliability of radiographic pelvimetry. A methodological study.

The purpose of this study was to assess the reliability of radiographic pelvimetry. 48 radiologists were asked to estimate the pelvic inlet and outlet diameters from copies of 20 pelvimetry radiographs. We found that every third patient will have the sum of her pelvic outlet over- or underestimated by at least 4 mm, and 3% by more than 10 mm. The random measurement error of the sum of the pelvic outlet is about four times greater than the systematic error. The random error of the sagittal outlet diameter contributes to almost half of the total measurement error of the pelvic outlet sum. The measurement values of radiographic pelvimetry are often expressed in mm, which may give an impression of exactness that is obviously not well founded. Only in a few cases where the measurements suggest a severe feto-pelvic disproportion is it justified to do an elective cesarean section on the basis of radiographic pelvimetry only.