US Measurements Research Articles

A finite element updating approach for identification of the anisotropic hyperelastic properties of normal and diseased aortic walls from 4D ultrasound strain imaging

Computational analysis of the biomechanics of the vascular system aims at a better understanding of its physiology and pathophysiology and eventually at diagnostic clinical use. Because of great inter-individual variations, such computational models have to be patient-specific with regard to geometry, material properties and applied loads and boundary conditions. Full-field measurements of heterogeneous displacement or strain fields can be used to improve the reliability of parameter identification based on a reduced number of observed load cases as is usually given in an in vivo setting. Time resolved 3D ultrasound combined with speckle tracking (4D US) is an imaging technique that provides full field information of heterogeneous aortic wall strain distributions in vivo.In a numerical verification experiment, we have shown the feasibility of identifying nonlinear and orthotropic constitutive behaviour based on the observation of just two load cases, even though the load free geometry is unknown, if heterogeneous strain fields are available. Only clinically available 4D US measurements of wall motion and diastolic and systolic blood pressure are required as input for the inverse FE updating approach. Application of the developed inverse approach to 4D US data sets of three aortic wall segments from volunteers of different age and pathology resulted in the reproducible identification of three distinct and (patho-) physiologically reasonable constitutive behaviours. The use of patient-individual material properties in biomechanical modelling of AAAs is a step towards more personalized rupture risk assessment.

How can we measure bladder volumes in women with advanced pelvic organ prolapse?

To compare bladder volumes determined by three different formulae using measurements obtained from two-dimensional translabial ultrasound (2D-US), with true bladder volumes, in women with advanced pelvic organ prolapse (POP). This was a prospective observational multicenter study of consecutive women on the waiting list for prolapse surgery in 24 gynecology departments. All women had a symptomatic genital prolapse Stage 2 or higher according to the Pelvic Organ Prolapse Quantification System (POP-Q). Bladder volumes were calculated before and after spontaneous voiding by 2D-US, and true bladder volumes were determined by micturition and catheterization. Volumes determined by US were calculated using three formulae (Haylen, Dietz and Dicuio). Correlation was calculated between the volume determined by US measurement before micturition and the true volume, and also between the volume determined by US measurements after micturition and the true volume. Correlations (Spearman's rho) and concordance (intraclass correlation coefficient (ICC)) were estimated for each of the three formulae considered. One-hundred and eighty-six women with POP were included in the study. A total of 349 bladder volumes (186 before micturition and 163 after micturition) were obtained. Good correlation (rho, 0.818-0.849) and concordance (ICC, 0.827-0.898) were found between total measured volume (volume of spontaneous bladder voiding + volume obtained from catheterization) and the volume determined by US using the three different formulae, as well as between the post-void residual volume measured by catheterization and the post-void volume calculated by US using the three formulae (rho, 0.739-0.777; ICC, 0.840-0.877). Bladder volumes in women with advanced POP can be measured easily by 2D-US. Volumes determined using the three different formulae show good correlations and concordance with true bladder volume.

Interrater agreement between expert and novice in measuring inferior vena cava diameter and collapsibility index

In critical care medicine, US views of the inferior vena cava (IVC) and its change with respiration are used to estimate the intravascular volume status of unwell patients and, in particular, to answer the question: 'Is this patient likely to be fluid responsive?' Most commonly in the literature, the subxiphisternal (SX) window in the longitudinal plane is utilised. To date, no study has specifically assessed interrater agreement in estimating IVC diameter between emergency medicine specialists (experts) and trainees (learners). To determine the interrater agreement between an expert (senior emergency specialist with US qualifications) and learner (emergency medicine trainee) when measuring IVC diameter (IVCD) and IVC collapsibility index (IVCCI) in the SX longitudinal US window in healthy volunteers. Healthy volunteers (ED staff) were scanned in the supine position using a sector (cardiac) probe of a portable US machine, in the SX longitudinal position. The maximum and minimum diameters of the IVC were measured in each of these positions and the IVCCI calculated. Results were analysed using Bland-Altman plots. In the longitudinal SX window, the operators' measurements of maximum IVCD differed by an average of 1.9 mm (95% limits of agreement -9.4 mm to +5.5 mm) and their measurement of IVCCI differed by an average of 4% (95% limits of agreement -30% to 38%). The wide 95% limits of agreement demonstrate a poor interrater agreement between the IVC US measurements obtained by expert and learner users in the assessment of fluid status. These ranges are greater than clinically acceptable.

Abstract 158: Central arterial elasticity in patients post Kawasaki Disease - a Cardiac Magnetic Resonance Imaging (CMR) study

Background: Measures of central arterial elasticity such as aortic pulse wave velocity (APWV) have been shown to correlate with development of atherosclerosis. Endothelial dysfunction after Kawasaki disease has been shown to persist despite resolution of anatomically demonstrable coronary anomalies and this may be reflected in abnormal central arterial elasticity. Measurement of APWV by CMR is most robust but has seldom been reported in KD patients. Aim: In a novel pilot study, we measured the APWV using CMR in patients with no coronary complications post KD. We compared this to age and gender matched published controls and APWV values measured on ultrasound. Methods: 10 KD patients (with no coronary involvement) in our hospital database, at least 12 years post KD diagnosis, with no known personal cardiovascular risk factors or family history of premature cardiovascular disease, were recruited. Each subject underwent both MRI and ultrasound investigations to determine the APWV. The results were compared using standard (z) scores calculated from published norms. Results: 3 of the 10 KD subjects had significant z scores using CMR measurements of APWV ranging from +2.07 to +3.35. However, no significant difference was found on overall non parametric comparisons of measurements. The US measurements of APWV all did not yield significant z scores. Z scores obtained from US and CMR measurements for the same subject showed no concordance. Conclusion: Central arterial stiffness tends to be higher in KD patients many years following the acute illness when assessed by CMR methods. CMR may be a more sensitive method than ultrasound for assessing central arterial stiffness post KD. The clinical implication of these findings require longitudinal follow up.

Reliability of coronal curvature measurements on 3D ultrasound images for AIS

Methods Forty participants (35F, 5M; mean age 14.0±2.0 years) who (1) were diagnosed with AIS, (2) had no prior spine surgical treatment, (3) had radiographs on the study day that were not in-brace, and (4) had the major Cobb angle less than 45°, were recruited consecutively from the local scoliosis clinics. All US images and radiographs were acquired in standing positions within an hour of each other. Three raters, who were blinded to the clinical information, measured the Cobb angles from the US and x-ray images at least 3 days apart. The raters repeated these measurements at least 1 week apart to minimize memory bias. The mean absolute deviation (MAD) and the standard deviation (SD) between the two measurements methods were used to estimate the reliability of the US measurement. The intraand interrater reliabilities were assessed by calculating the interclass correlation coefficients and standard errors of measurement (SEM).

Comparison of ocular anterior segment parameters measured by three kinds of biometric measuring methods in myopic eyes

Background It is essential to measure and assess the parameters of ocular anterior segment for refractive surgery in myopic eyes.Some different imaging devices can be used for biometric measurement of ocular anterior segment,but which is more accurate and convenient is still under investigation.Objective This study was to compare the anterior segment parameters in myopic eyes measured by anterior segment optical coherence tomography (AS-OCT),Orbscan topography and ultrasonic pachymetry (US).Methods One hundred and forty eyes of 70 myopic subjects with the diopter of-0.75 to-10.25 D,who intended to receive corneal refractive surgery in the Second Affiliated Hospital of Zhejiang University School of Medicine from November 2011 to May 2012,were retrospectively analyzed.Central corneal thickness (CCT) was measured using AS-OCT,Orbscan Ⅱ and US,respectively,and anterior chamber depth (ACD) was measured by AS-OCT and Orbscan Ⅱ,and the angle to angle (ATA) distance and corneal white-to-white corneal distance (WTW) were measured by AS-OCT and Orbscan Ⅱ,respectively.The parameters from different apparatuses were statistically compared.Results The mean CCT were (516.57±30.25) μm in AS-OCT,(523.68±31.87) μm in US and (514.69±38.40) μm in Orbscan Ⅱ,without significant difference among them (F =2.775,P =0.063).Then the patients were divided into three groups based on the US measurement of CCT (＜500 μm group,500-569 μm group,and ≥ 570 μm group).In the ＜500 μm group,there was a significant difference in the CCT among the three methods (F =22.236,P =0.000),significant differences were found between AS-OCT and Orbscan Ⅱ,or Orbscan Ⅱ and US(both at P＜0.05).In the 500-569 μm group,there was no significant difference in the CCT among the three methods (F =3.011,P =0.051).In the ≥ 570 μm group,there was a significant difference in the CCT among the three methods (F =4.133,P =0.021),a significant difference was found between AS-OCT and US(P＜0.05),but there was no significant difference between AS-OCT and Orbscan Ⅱ (P＞0.05).The ACD values measured by AS-OCT was (3.83±0.21) mm,which was higher than (3.75 ± 0.21) mm by Orbscan Ⅱ,with a significant difference between them (t =-8.520,P =0.000).In addition,the ATA value by AS-OCT (12.43 mm±0.74 mm) was higher than the WTW value (11.42 mm±0.33 mm) by OrbscanⅡ,with a significant difference between them(t=-18.088,P=0.000).Conclusions AS-OCT,US and Orbscan Ⅱ can offer accurate CCT value,and they can provide references to one another before refractive surgery.However,the ACD,ATA and WTW values by AS-OCT and Orbscan]Ⅱ have large differences. Key words: Anterior segment optical coherence tomography; Orbscan topography; Ultrasonic pachymetry; Central corneal thickness; Anterior chamber depth; White to white corneal distance; Angle to angle distance

US not bright but right method of thyroid volume estimation even in large and substernal extended goitres. Comparison of US and three methods of CT thyroid evaluation – prospective study

Ultrasound is nowadays a method of choice for thyroid volume assessment. However, its disadvantage is some inaccuracy, which is said to be higher in huge, especially substernally extended goitres. The aim of the study was to compare the US and CT thyroid volumetric measurements: multi-observers (CT MO) and one-observer (CT OO) to CT planimetry results (CT Pl) in patients with large goitres. The study material comprised 70 thyroid imaging examinations obtained from 35 patients with nontoxic goitres, scanned twice before and after radioiodine treatment. Mean thyroid volume was 88·97 ± 60·21 ml. Thirty-three thyroid scans revealed the extension below the jugular notch (mean of 2·46 cm). Thyroid volume in US, CT MO and CT OO was estimated using the ellipsoid formula. CT Pl was established a reference method. The mean thyroid volume in CT Pl was 88·97 ml (median 80·73, range 11·81 to 315·97). US underestimates thyroid volume by 7·55 ml (7·7%) with a sufficient correlation (R(2) = 0·89) and precision (20·37). CT OO is the closest and CT MO the most distant from CT Pl, with US between them in thyroid volume estimation. The percentage US bias is constant through all range of thyroid volume. There is no difference for percentage bias between US and CT Pl for goitres with (8·67%), and without (6·70%) substernal part. US examination is sufficient for epidemiological studies, radioiodine activity calculation and goitre size assessment in everyday medical practice. Neither initial size of the goitre nor its substernal extension affects US assessment precision.

THU0358 Gray Scale and Power Doppler Ultrasound Assessment of the Median Nerve: A Biomarker That Can Help in Setting A Treat to Target Approach Tailored for Carpal Tunnel Syndrome Patients

BackgroundThough there are various carpal tunnel syndrome (CTS) treatment options, their outcomes and long-term effects are still debatable. An accurate understanding of the predictive factors of CTS management outcomes would...

OP0054 Ultrasound Synovitis Reflects Synovial Inflammation at A Histopathological Level

BackgroundUltrasound (US) is widely used by rheumatologists to assess inflammatory burden on patients with inflammatory arthritis. Some studies have shown that US measures of inflammation reflects aspects of histological synovitis...

SAT0168 Validation of Musculoskeletal US of Hands and Wrists in Patients with Systemic Sclerosis

BackgroundThere is no published work validating the techniques for examining joint and tendon pathology with musculoskeletal ultrasound (MSUS) in systemic sclerosis (SSc).ObjectivesTo examine MSUS of the joints and tendons of...

Anderson-Hynes Pyeloplasty in Patients Less Than 12 Months Old. Is the Laparoscopic Approach Safe and Feasible?

The aim of our study is to compare the outcomes of open and laparoscopic pyeloplasty in children less than 12 months of age. We reviewed all medical charts of patients less than 12 months old who underwent pyeloplasty from January 2007 to February 2013. We divided them in two groups: Open pyeloplasty (OP) and laparoscopic pyeloplasty (LP). The following data were analyzed: age, sex, weight, US measurements, operative time, hospital stay, complications, and success rate. Quantitative data were analyzed with the Student t test or Mann-Whitney U test, and chi-square test or Fisher test for qualitative data. Fifty-eight patients (46 boys and 12 girls) with a mean age of 4.66 months (±3.05) were included. Mean age was 4.25 months and 5.15 months in OP and LP group respectively. Mean weight was 6.78 kg and 7.02 kg in OP and LP groups. There were no statistical differences in age, weight, and sex between OP and LP groups. There were no statistical differences in preoperative ultrasonography measurements. Mean posterior-anterior (PA) pelvis diameter was 28.57 mm and 23.94 mm in OP and LP groups, respectively. Mean calices diameter were 10.86 mm and 10.96 mm in OP and LP groups, respectively. Mean operative time was 129.53 minutes in the OP group and 151.92 minutes in the LP group with statistical differences (P=0.018). Mean hospital stay was 6.34 days in the OP group and 3.46 in the LP group with statistical differences (P<0.05). No intraoperative and postoperative complications were found in either group. Hydronephrosis improved in all patients, and no patient needed a repeated pyeloplasty. The laparoscopic approach of Anderson-Hynes pyeloplasty in patients less than 12 months old is a safe procedure with the same outcomes as the open approach.

Do Measurements of Uterine Septum Using Three-Dimensional Ultrasound and Magnetic Resonance Imaging Agree?

ObjectiveTo evaluate the agreement between measurements of uterine septum by 3-D ultrasound (3-D US) and magnetic resonance imaging. MethodsFourteen women with a uterine septum underwent both a 3-D US and an MRI followed by hysteroscopic metroplasty in a tertiary care infertility clinic within a university teaching hospital. The agreement between 3-D US and MRI measurements of septum length (SL), septum width (SW) and the distance between fundal serosa and septal tip (SSD) was compared using the Bland Altman limit of agreement analysis. Results3-D US correctly identified all women who had a uterine septum identified with MRI. The mean difference in SL was 2.7mm (upper limit of agreement and lower limit of agreement were 10.3mm and −4.8mm, respectively). The mean difference in SW was 2.3mm (upper limit of agreement and lower limit of agreement of 10.4mm and −9.2mm, respectively). The SSD mean difference was 2.8mm (upper limit of agreement and lower limit of agreement of 10.6mm and −5mm, respectively). ConclusionsCategorical agreement in diagnosis was 100% and agreement between 3-D US and MRI measurements was good with narrow differences. Variations were unlikely to be greater than intra- and inter-observer variations anticipated in MRI readings. 3-D US can replace MRI for diagnosis and measurement of uterine septa.

What is not so Cool about US–COOL Regulations? A critical analysis of the Appellate Body's ruling on US–COOL

AbstractIn US–COOL, the Appellate Body (AB) of the World Trade Organization (WTO) found that the US measure imposing country of origin labelling (COOL) requirements on livestock of domestic, foreign, and mixed origin was in violation of the obligation to avoid discrimination embedded in Article 2.1 of the WTO Agreement on Technical Barriers to Trade (TBT). We argue that the AB could not and should not have reached this decision based on the information available to it. The AB adopted an erroneous methodology: under its view, the consistency of a measure coming under the purview of the TBT can be examined under Article 2.1 irrespective of its evaluation under Article 2.2 thereby making the two obligations distinct. The AB also failed to address the central question raised by this dispute: Does there exist an alternative to COOL that is less trade restrictive? We argue that the over-arching issue in this case should have been to determine what, if anything, the TBT Agreement did to alter or enhance the obligation of non-discrimination that was already embedded in the arsenal of the multilateral trading rules. Unless the AB asks this question in subsequent case law pertaining to the TBT, we risk seeing repetitions of similar mistakes in the future.

A SYSTEMATIC REVIEW TO INVESTIGATE THE RELIABILITY OF ULTRASOUND IMAGING IN MEASURING TENDON THICKNESS

BackgroundPathological tendons are known to increase their AP diameter. Ultrasound is an important complementary technique to MRI for assessment of musculoskeletal disorders. Although systematic reviews have confirmed its reliability for...

The relationship between carotid intima–media thickness and global atherosclerosis

BackgroundThe aim of this study was to investigate the relationship between (i) carotid intima–media thickness (CIMT) at baseline as well as (ii) change in CIMT over 5 years (ΔCIMT) and atherosclerotically induced luminal narrowing in non-coronary arterial territories assessed by whole-body magnetic resonance angiography (WBMRA).Methods and resultsIn subgroups of the Prospective Investigation of Vasculature in Uppsala Seniors (PIVUS) study, US measurements of CIMT in the common carotid arteries were analysed at 70 and 75 years and ΔCIMT was calculated (n = 272). WBMRA, assessing arterial stenosis in five different territories by which also a total atherosclerotic score (TAS) was calculated, was performed at 70 years (n = 306).ResultsCarotid intima–media thickness in the carotid artery at baseline was correlated with TAS (P = 0·0001) when adjusted to a set of traditional risk factors for atherosclerosis, as well as to stenosis in two of the different investigated territories (aorta and lower leg, P = 0·013 and P = 0·004), but there was no significant correlation between ΔCIMT and TAS (P = 0·41).ConclusionsIn the present study, CIMT, but not ΔCIMT over 5 years, in the carotid artery was related to overall stenoses in the body, as assessed by WBMRA. These findings support CIMT as a general marker for atherosclerosis.

Efficacy and safety of drug with plant extract of saw palmetto in patients with lower urinary tract symptoms because of benign prostatic enlargement

Background : Benign prostatic enlargement (BPE) is the most frequent cause of lower urinary tract symptoms (LUTS) in men. The objective of this study was to evaluate the efficacy and safety of Prostasan, the plant extract of saw palmetto in men with LUTS/BPE. Methods : The study was approved by the Ethical Committee of the Republic of Slovenia. In a prospective, open clinical study, men between 45 and 80 years of age with at least moderate LUTS/BPE, normal serum PSA, in a good physical condition were included after having given their written informed consent . At the beginning of this study, the digito-rectal examination of the prostate was performed together with the evaluation of IPSS and quality of life, total PSA in serum, uroflow and transabdominal US measurement of prostate volume. They were also asked about their erectile dysfunction and libido. All patients received Prostasan 320 mg per day for 12 months. The same parameters as at the beginning of the study were assessed after 6 and 12 months. The subjective assessments of the efficacy and safety of the drug were also recorded byinvestigators and by patients. The side effects of the treatment were recorded at both follow-ups. For statistical analyses, t-test and chi-square tests were used. Results : 72 men out of 76 (94.7 %) with LUTS/BPE completed the trial. They were 62.7 ± 8.54 years old. IPSS score and quality of life were reduced from 14.46 ± 5.36 to 11.08 ± 3.92 (p = 0.0000) and from 2.72 ± 0,96 to 2.25 ± 1.05 (p = 0.0001) respectively after 12 months of treatment. The uroflow increased from 13.94 ± 5.00 to 15.34 ± 4.07 ml/s (p = 0.0005). Total PSA did not change significantly. After 12 months, prostate volume decreased by 3 % (p = 0.0392). Prostasan had no important influence on erectile function or libido. The majority of patients and doctors rated the efficacy of drug as good (69.7 % and 72.4 % ) and safe (86.8 % and 88.2 %), respectively. Seven patients (9.2 %) reported drug-related side effects. Conclusions : According to our 12-month clinical trial, we could conclude that Prostasan is a safe and efficient natural drug for the treatment of men with mild to moderate LUTS/BPE.

Active Surveillance of the Adolescent with Varicocele: Predicting Semen Outcomes from Ultrasound

We hypothesized that active surveillance of the adolescent varicocele is not associated with a high prevalence of suboptimal semen analysis and that patients with abnormal semen analysis have smaller testicular volumes and larger volume differentials. We conducted an institutional review board approved retrospective cohort study of adolescents with a clinically detected varicocele. Patients were initially observed by serial scrotal ultrasound evaluating testicular size and differential. Semen analysis was routinely collected in Tanner V cases, around age 18 years. Prevalence of normal semen analysis parameters was calculated, and logistic regression was used to model the ability of age at presentation and testicular volume parameters to predict a normal semen analysis. A cohort of 73 patients underwent surveillance with a mean ± SD age at presentation of 15.5 ± 2.3 years. Median followup was 2.7 years, during which time subjects underwent a median of 3 scrotal ultrasounds. A low total motile count was found in 48 patients (66%). Neither age at presentation nor testicular volume differential could predict normal semen volume, density, sperm motility or total motile count. Total testicular volume from the final ultrasound predicted total motile count (p = 0.008). However, the collective observations of volume during the entire period of surveillance could not predict total motile count (p = 0.847). There is a high prevalence of suboptimal semen analysis in adolescents with a varicocele who are followed with active surveillance. Total testicular volume can predict total motile count at the end of adolescence but not throughout.

A 3D ultrasound scanning system for image guided liver interventions

Two-dimensional ultrasound (2D US) imaging is commonly used for diagnostic and intraoperative guidance of interventional liver procedures; however, 2D US lacks volumetric information that may benefit interventional procedures. Over the past decade, three-dimensional ultrasound (3D US) has been developed to provide the missing spatial information. 3D US image acquisition is mainly based on mechanical, electromagnetic, and freehand tracking of conventional 2D US transducers, or 2D array transducers available on high-end machines. These approaches share many problems during clinical use for interventional liver imaging due to lack of flexibility and compatibility with interventional equipment, limited field-of-view (FOV), and significant capital cost compared to the benefits they introduce. In this paper, a novel system for mechanical 3D US scanning is introduced to address these issues. The authors have developed a handheld mechanical 3D US system that incorporates mechanical translation and tilt sector sweeping of any standard 2D US transducer to acquire 3D images. Each mechanical scanning function can be operated independently or may be combined to allow for a hybrid wide FOV acquisition. The hybrid motion mode facilitates registration of other modalities (e.g., CT or MRI) to the intraoperative 3D US images by providing a larger FOV in which to acquire anatomical information. The tilting mechanism of the developed mover allows image acquisition in the intercostal rib space to avoid acoustic shadowing from bone. The geometric and volumetric scanning validity of the 3D US system was evaluated on tissue mimicking US phantoms for different modes of operation. Identical experiments were performed on a commercially available 3D US system for direct comparison. To replicate a clinical scenario, the authors evaluated their 3D US system by comparing it to CT for measurement of angle and distance between interventional needles in different configurations, similar to those used for percutaneous ablation of liver tumors. The mean geometrical hybrid 3D reconstruction error measured from scanning of a known string phantom was less than 1 mm in two directions and 2.5 mm in the scanning direction, which was comparable or better than the same measurements obtained from a commercially available 3D US system. The error in volume measurements of spherical phantom models depended on depth of the object. For a 20 cm(3) model at a depth of 15 cm, a standard depth for liver imaging, the mean error was 3.6% ± 4.5% comparable to the 2.3% ± 1.8% error for the 3D US commercial system. The error in 3D US measurement of the tip distance and angle between two microwave ablation antennas inserted into the phantom was 0.9 ± 0.5 mm and 1.1° ± 0.7°, respectively. A 3D US system with hybrid scanning motions for large field-of-view 3D abdominal imaging has been developed and validated. The superior spatial information provided by 3D US might enhance image-guidance for percutaneous interventional treatment of liver malignancies. The system has potential to be integrated with other liver procedures and has application in other abdominal organs such as kidneys, spleen, or adrenals.

Body composition in sport: a comparison of a novel ultrasound imaging technique to measure subcutaneous fat tissue compared with skinfold measurement

BackgroundExtremely low weight and rapid changes in weight and body composition have become major concerns in many sports, but sufficiently accurate field methods for body composition assessment in athletes are...

Association Between Obstetric Conjugate Diameter Measured by Transabdominal Ultrasonography During Pregnancy and the Type of Delivery

BackgroundNormal morphological features of the maternal pelvis are an important prerequisite to vaginal delivery.ObjectivesWe aimed to evaluate the association between obstetric conjugate diameter (OCD) measured by ultrasonography and the type of delivery, vaginally (V) or by cesarean (C) section.Patients and MethodsPelvimetry was performed in 200 primigravid women for fetal cephalic presentation. The OCD was measured twice by transabdominal ultrasonography during 25-30 weeks and 30-35 weeks of pregnancy.ResultsThe mean OCD of both sonographies in groups V and C was 125.51± 8.35 mm (105-144.5) and 112.99 ± 8.53 mm (96-134.5), respectively, which was significantly lower in group C (P<0.001). The values of OCD between the first and second measurements were not different significantly (P=0.065). C-section was indicated in 65 (32.5%) mothers. The optimal cut-off point for the OCD in the prediction of vaginal delivery was ≥ 119.75 mm, with a sensitivity and specificity of 80% and 78.5%, respectively.ConclusionThe US measurement of OCD might be an accurate method that almost always remains constant during late pregnancy; it is easy to measure and might be confidentially employed for predicting C-section, but needs more precise studies to be used widely.