Systematic, noninvasive endometriosis diagnosis in transvaginal sonography by the Swiss Society of Ultrasound in Medicine.

We present a new systematic, comprehensive, checklist-based sonographic assessment of endometriosis in the female true pelvis. Emphasis is placed on practical skills teaching. The newly introduced White Sliding Line (WSL) is the core structure. The WSL separates five compartments (anterior, central, posterior, and lateral right and left) containing dedicated endometriosis signs of mobility and morphology to be checked. This approach relies on the 2016 IDEA Consensus and further developments. It directly connects to the 2021 #ENZIAN Classification Standard. In practice, evaluation follows the proposed checklist in all compartments, judging first sliding mobility between organs and structures in a highly dynamic investigation. A rigorous search for deep endometriosis (DE) is then performed. We treat adhesions due to their great clinical importance and possible, reliable diagnosis by TVS as the fifth endometriosis unit, next to endometrioma, DE, adenomyosis, and superficial endometriosis. Including superficial (peritoneal) endometriosis is a future goal.

The Predictive Value of Decisive and Soft Ultrasound Criteria for Ectopic Pregnancy Identification in 321 Preoperative Cases.

PURPOSE: To define the predictive value of morphological types (MTs) and further criteria in diagnosing ectopic pregnancy (ECP) by transvaginal sonography (TVS) prior to operative confirmation and treatment. MATERIALS AND METHODS: Retrospective cohort analysis of 321 consecutive patients with suspected ECP who were advised to undergo operation. RESULTS: ECP was investigated by TVS in all 321 patients. Application of the five selected MTs (blob sign, bagel sign, yolk sac, embryo, heart action) resulted in 85 % of cases receiving a conclusive diagnosis and 12 % receiving a presumed ECP diagnosis. 3 % remained nondiagnostic due to large or multiple ovarian cysts, large myoma, extended hemoperitoneum, or severe pain. ECP diagnosis was confirmed intraoperatively in 97 % of cases and was otherwise (3 %) immediately followed by curettage (CUR). The assessment of free fluid by TVS was achieved in most cases and correlated significantly with free blood. In the majority of cases, free blood was not bound to transmural ECP rupture. Histology confirmed the ECP diagnosis directly or by exclusion in 99 % of cases. Three cases of tubal ECP were diagnosed by TVS but not confirmed by LSC (1 %) and, finally, histology from CUR proved miscarriage (false-positive rate 1 %). CONCLUSION: We confirm the high accuracy of TVS diagnosis of ECP relying on five clearly different MTs, independent of its location. The blob and bagel sign emerged as important types (75 % of all ECPs). Histology from CUR was needed when ECP could not be visualized in LSC. Assessment of free fluid was essential and accurate in predicting free blood.

Judging Urgency in 343 Ectopic Pregnancies Prior to Surgery - The Importance of Transvaginal Sonographic Diagnosis of Intraabdominal Free Blood.

OBJECTIVES: Assessing urgency in ectopic pregnancies (ECP) remains controversial since the disorder covers a large clinical spectrum. Severe conditions such as acute abdomen or hemodynamic instability are mostly related to intra-abdominal blood loss diagnosed as free fluid (FF) on transvaginal sonography (TVS). The aims of the current study were to investigate the value of FF and to assess other potentially predictive parameters for judging urgency. METHODS: Retrospective cohort analysis on prospectively collected cases of proven ECP (n = 343). Demographics, clinical and laboratory parameters, and findings on TVS and laparoscopy (LSC) were extracted from the digital patient file. FF on TVS and free blood (FB) in LSC were evaluated. Low urgency was defined as FB (LSC) < 100 ml and high urgency as FB (LSC) ≥ 300 ml. The best subset of variables for the prediction of FB was selected and predictors of urgency were evaluated using receiver operator characteristic (ROC) curves. RESULTS: Clinical symptoms, age, ß-HCG, hemoglobin (HB) preoperative, and FF were examined in multivariate analysis for the cutoff values of 100 ml and 300 ml. FF was the only independent predictor for low and high urgency; HB preoperative was only significant for high urgency offering marginal improvement. ROC analysis revealed FF as an excellent discriminatory parameter for defining low (AUC 0.837, 95% CI 0.794-0.879) and high urgency (AUC 0.902, 95 % CI 0.860-0.945). CONCLUSION: Single assessment of FF on TVS is most valuable for judging urgency. However, the exact cutoff values for a low- and high-risk situation must still be defined.

Audit of the first > 7500 noninvasive prenatal aneuploidy tests in a Swiss genetics center.

OBJECTIVES: Noninvasive prenatal testing (NIPT) is actually the most accurate method of screening for fetal chromosomal aberration (FCA). We used pregnancy outcome record to evaluate a complete data set of single nucleotide polymorphism-based test results performed by a Swiss genetics center. MATERIALS AND METHODS: The Panorama® test assesses the risk of fetal trisomies (21, 18 and 13), gonosomal aneuploidy (GAN), triploidy or vanishing twins (VTT) and five different microdeletions (MD). We evaluated all 7549 test results meeting legal and quality requirements taken in women with nondonor singleton pregnancies between April 2013 and September 2016 classifying them as high or low risk. Follow-up ended after 9 months, data collection 7 months later. RESULTS: The Panorama® test provided conclusive results in 96.1% of cases, detecting 153 FCA: T21 n = 76, T18 n = 19, T13 n = 15, GAN n = 19, VTT n = 13 and MD n = 11 (overall prevalence 2.0%). Pregnancy outcome record was available for 68.6% of conclusive laboratory results, including 2.0% high-risk cases. In this cohort the Panorama® test exhibited 99.90% sensitivity for each trisomy; specificity was 99.90% for T21, 99.98% for T18 and 99.94% for T13. False positive rate was 0.10% for T21, 0.02% for T18 and 0.06% for T13. CONCLUSION: SNP-based testing by a Swiss genetics center confirms the expected accuracy of NIPT in FCA detection.

Cervical length after cerclage: comparison between laparoscopic and vaginal approach.

PURPOSE: The aim of our study was to investigate the sonographic changes of the cervical length during pregnancy after the placement of a transvaginal cervical cerclage (TVC) or a laparoscopic abdominal cerclage (LAC) in patients with cervical insufficiency (CI). METHODS: Between January 2008 and March 2015, a retrospective analysis of all women undergoing a prophylactic laparoscopic (LAC group) or transvaginal (TVC group) cerclage due to cervical insufficiency was conducted. Nonparametric variables were analysed with the Mann-Whitney (U) test, and categorical-type outcomes were analysed with the Fisher's exact test. A p value <0.05 was considered as significant. Data analysis was performed using Prism 5 for Mac OS X. RESULTS: Thirty-eight patients were included. Of these, 18 and 20 underwent an LAC and a TVC, respectively. Mean gestational age at surgery in the LAC and TVC groups was 11.4 ± 1.6 and 17 ± 3 weeks, respectively (p < 0.05). The cervical length prior to surgery was similar among the two groups. After cerclage placement, the distance between the tape and the external cervical os differed significantly between the two groups (LAC: 31.5 ± 8.8 mm vs TVC: 13.5 ± 4.9 mm; p < 0.0001) (Fig. 1). During pregnancy, the cervical length in the TVC group showed a significant shortening (from 26.6 ± 7 mm before surgery to 13.2 ± 7 mm at 33 weeks; p < 0.0001), while in the LAC group, the cervical length remained unchanged. CONCLUSIONS: In patients with CI, LAC is associated with a better preservation of the cervical length throughout pregnancy as compared to TVC.

Fundus Thickness Assessment by 3D Transvaginal Ultrasound Allows Metrics-Based Diagnosis and Treatment of Congenital Uterine Anomalies.

Purpose The development of a metric fundus assessment and definition of the uterine fundus thickness (FTH) for supporting objective diagnosis and treatment of congenital uterine anomalies (CUAs). Materials and Methods A) In a prospective cohort study, FTH was systematically assessed by 3 D transvaginal ultrasound (TVS) in patients, who presented a normal uterus. B) The mean normal FTH recorded was applied to uteri with fundal protrusions and septations, and compared to two CUA classification systems (ASF and ESHRE/ESGE). C) FTH was studied for preoperative metric planning and evaluation of the postoperative outcome. Results A) From August 2013 to January 2014, FTH was assessed in 100 normal uteri. An FTH of 12.02 +/- 2.03 mm (mean +/- SD) was recorded. B) Evaluating the 8 detected abnormal uteri, excellent correlation with the new ESHRE/ESGE classification system was observed, taking an FTH of 12 mm as the overall normal FTH equivalent to the individual normal wall thickness (WTH) stipulated in the classification and an FTH of 18 mm as the WTH + 50 %, serving as a cut-off value of (abnormal) septation. C) Metric fundus assessment was initially applied before and after septum resection and the following pregnancy could be monitored. Conclusion An FTH measurement in 3 D TVS paves the way for metric fundus diagnostics. This objectively distinguishes normal from abnormal fundi. It also has the potential to support accurate septum resection planning and objective postoperative evaluation. The value of the fundus assessment and metrics proposed in this study is not known. It should be investigated in prospective randomized controlled trials.

In vivo assessment of the biomechanical properties of the uterine cervix in pregnancy.

Measuring the stiffness of the cervix might be useful in the prediction of preterm delivery or successful induction of labor. For that purpose, a variety of methods for quantitative determination of physical properties of the pregnant cervix have been developed. Herein, we review studies on the clinical application of these new techniques. They are based on the quantification of mechanical, optical, or electrical properties associated with increased hydration and loss of organization in collagen structure. Quasi-static elastography determines relative values of stiffness; hence, it can identify differences in deformability. Quasi-static elastography unfortunately cannot quantify in absolute terms the stiffness of the cervix. Also, the current clinical studies did not demonstrate the ability to predict the time point of delivery. In contrast, measurement of maximum deformability of the cervix (e.g. quantified with the cervical consistency index) provided meaningful results, showing an increase in compliance with gestational age. These findings are consistent with aspiration measurements on the pregnant ectocervix, indicating a progressive decrease of stiffness along gestation. Cervical consistency index and aspiration measurements therefore represent promising techniques for quantitative assessment of the biomechanical properties of the cervix.

Sustained Physiological Stretch Induces Abdominal Skin Growth in Pregnancy.

Supraphysiological stretches are exploited in skin expanders to induce tissue growth for autologous implants. As pregnancy is associated with large levels of sustained stretch, we investigated whether skin growth occurs in pregnancy. Therefore, we combined a mechanical model of skin and the observations from suction experiments on several body locations of five pregnant women at different gestational ages. The measurements show a continuous increase in stiffness, with the largest change observed during the last trimester. A comparison with numerical simulations indicates that the measured increase in skin stiffness is far below the level expected for the corresponding deformation of abdominal skin. A new set of simulations accounting for growth could rationalize all observations. The predicted amount of tissue growth corresponds to approximately 40% area increase before delivery. The results of the simulations also offered the opportunity to investigate the biophysical cues present in abdominal skin along gestation and to compare them with those arising in skin expanders. Alterations of the skin mechanome were quantified, including tissue stiffness, hydrostatic and osmotic pressure of the interstitial fluid, its flow velocity and electrical potential. The comparison between pregnancy and skin expansion highlights similarities as well as differences possibly influencing growth and remodeling.

Cervical softening occurs early in pregnancy: characterization of cervical stiffness in 100 healthy women using the aspiration technique.

OBJECTIVE: To quantitatively describe the evolution of ectocervical stiffness in normal pregnancy. METHODS: The stiffness of ectocervical tissue was measured by using the aspiration method. This non-invasive technique allows to safely and objectively determine the pressure required to displace cervical tissue to a predefined deformation level (pcl ). In this prospective study, 448 aspiration measurements were carried out on pregnant women (n = 50) at each of the eight routine pregnancy consultations and on nonpregnant subjects (reference, n = 50). pcl values were grouped as nonpregnant, first, second, third trimester, and postpartum. RESULTS: Stiffness in early pregnancy (first trimester) is significantly lower, by a factor >2 for the mean value than for the nonpregnant group. pcl continuously decreases during gestation, with significant differences between first and second trimester, but not between second and third trimester. After delivery, consistency is recovered to the level of early pregnancy. CONCLUSIONS: The aspiration method allows an objective description of the consistency of the ectocervix during pregnancy, indicating that the tissue softens already at the beginning of gestation, transforms continuously to lower consistency in the first two trimesters, stabilizes at a low level in the third trimester, and recovers its stiffness after delivery.

Hysteroscopic placement of tubal sterilization implants: virtual reality simulator training.

STUDY OBJECTIVE: To assess face and construct validity of a new virtual reality (VR) training simulator for hysteroscopic placement of tubal sterilization implants. DESIGN: Nonrandomized, controlled trial comparing responses and performance of novices and experts on the simulator. DESIGN CLASSIFICATION: Canadian task force II-1. SETTING: Forty-six gynecologists were personally invited or recruited at the 33rd Conference of the French National College of Gynecologists and Obstetricians (CNGOF) from December 9 to 12, 2009, grouped as 20 experts and 26 novices. They all performed the defined sequence of virtual procedures on the simulator (case 1 for familiarization, case 4 for study assessment) and finally completed the study questionnaire. MEASUREMENTS AND MAIN RESULTS: Responses to realism, educational potential, and general opinion were excellent, proving face validity. Significant differences between novices and experts were assessed for 7 of the 15 metrics analyzed, proving construct validity. CONCLUSIONS: We established face and construct validity for EssureSim, an educational VR simulator for hysteroscopic tubal sterilization implant placement. The next steps are to investigate convergent and predictive validity to affirm the real capacity of transferring the skills learned on the training simulator to the patient in the operating room.

Self-supervised representation learning for surgical activity recognition.

PURPOSE: Virtual reality-based simulators have the potential to become an essential part of surgical education. To make full use of this potential, they must be able to automatically recognize activities performed by users and assess those. Since annotations of trajectories by human experts are expensive, there is a need for methods that can learn to recognize surgical activities in a data-efficient way. METHODS: We use self-supervised training of deep encoder-decoder architectures to learn representations of surgical trajectories from video data. These representations allow for semi-automatic extraction of features that capture information about semantically important events in the trajectories. Such features are processed as inputs of an unsupervised surgical activity recognition pipeline. RESULTS: Our experiments document that the performance of hidden semi-Markov models used for recognizing activities in a simulated myomectomy scenario benefits from using features extracted from representations learned while training a deep encoder-decoder network on the task of predicting the remaining surgery progress. CONCLUSION: Our work is an important first step in the direction of making efficient use of features obtained from deep representation learning for surgical activity recognition in settings where only a small fraction of the existing data is annotated by human domain experts and where those annotations are potentially incomplete.

Establishing construct validity of a virtual-reality training simulator for hysteroscopy via a multimetric scoring system.

BACKGROUND: The aims of this study are to determine construct validity for the HystSim virtual-reality (VR) training simulator for hysteroscopy via a new multimetric scoring system (MMSS) and to explore learning curves for both novices and experienced surgeons. METHODS: Fifteen relevant metrics had been identified for diagnostic hysteroscopy by means of hierarchical task decomposition. They were grouped into four modules (visualization, ergonomics, safety, and fluid handling) and individually weighted, building the MMSS for this study. In a first step, 24 novice medical students and 12 experienced gynecologists went through a self-paced teaching tutorial, in which all participants received clearly stated goals and instructions on how to carry out hysteroscopic procedures properly for this study. All subjects performed five repeated trials on two different exercises on HystSim (exploration and diagnosis exercises). After each trial the results were presented to the participants in the form of an automated objective feedback report (AOFR). Construct validity for the MMSS and learning curves were investigated by comparing the performance between novices and experienced surgeons and in between the repeated trials. To study the effect of repeated practice, 23 of the novices returned 2 weeks later for a second training session. RESULTS: Comparing novices with the experienced group, the ergonomics and fluid handling modules resulted in construct validity, while the visualization module did not, and for the safety module the experienced group even scored significantly lower than novices in both exercises. The overall score showed only construct validity when the safety module was excluded. Concerning learning curves, all subjects improved significantly during the training on HystSim, with clear indication that the second training session was beneficial for novice surgeons. CONCLUSIONS: Construct validity for HystSim has been established for different modules of VR metrics on a new MMSS developed for diagnostic hysteroscopy. Careful refinement and further testing of metrics and scores is required before using them as assessment tools for operative skills.

[Pelvic Inflammatory Disease - Synergies between Family Practices and Gynaecological Specialised Assessment]. / Pelvic Inflammatory Disease ­ Schnittstellen zwischen Hausarztpraxis und gynäkologischer Spezialabklärung.

Pelvic Inflammatory Disease - Synergies between Family Practices and Gynaecological Specialised Assessment Abstract. The 'pelvic inflammatory disease' (PID) describes an ascending inflammation of the upper female genital tract, beginning with a local cervicitis and proceeding to endometritis and adnexitis. It is a common clinical picture with rising numbers in recent years, and it occurs both in gynaecological and general practice. The symptoms are often unspecific, discrete or althogehter lacking. In order to reduce long-term risks of chronic pelvic pain, sterility and/or ectopic pregnancies, rapid diagnosis followed by immediate therapy and a good interdisciplinary cooperation are necessary. Screening programs for chlamydia and gonococcus as the most common pathogens of PID have not yet been implemented in Switzerland so far.

Pressure-dependent hydrometra dimensions in hysteroscopy.

AIM: To investigate the relation between intrauterine pressures and volumes for virtual-reality-based surgical training in hysteroscopy. MATERIAL AND METHODS: Ten fresh extirpated uteri were insufflated by commercial hysteroscopy pump and imaged by computer tomography (CT) under intrauterine air pressure in distension-collapse cycles between 0 , 20 (150 mmHg), and 0 kPa, performing a CT scan at every step at about 2.7 kPa (20 mmHg). RESULTS: An initial threshold pressure to distend the cavity was avoided by introducing the insufflation tube up to the fundus. The filling and release phases of seven uteri that were completely distended showed the typical characteristics of a hysteresis curve which is expected from a viscoelastic, nonlinear, anisotropic soft tissue organ like the uterus. In three cases tightening the extirpated uterus especially at the lateral resection lines caused significant problems that inhibited registration of a complete distension-collapse cycle. Interpolated volumes for complete distended cavities and extrapolated for incomplete data sets, derived from the digitally reconstructed three-dimensional (3D) geometries, ranged from 0.6 to 11.4 mL at 20 kPa. These values highly correlate with the uterine volume (not insufflated) considering different biometric data of the uteri and patient data. Linear (R(2) = 0.66) and quadratic least-squares fits (R(2) = 0.74) were used to derive the formulas y = 0.069x and y = 0.00037x(2) + 0.036x, where x is the uterine volume in mL (not insufflated) and y is the cavity volume in mL at 20 kPa intrauterine pressure. CONCLUSIONS: Our experimental hysteroscopical setup enabled us to reconstruct the changes in volumes of insufflated uteri under highly realistic conditions in 3D. The relation between intrauterine pressure and cavity volume in distension-collapse cycles describes a typical hysteresis curve.

Evaluation of a new virtual-reality training simulator for hysteroscopy.

BACKGROUND: To determine realism and training capacity of HystSim, a new virtual-reality simulator for the training of hysteroscopic interventions. METHODS: Sixty-two gynaecological surgeons with various levels of expertise were interviewed at the 13(th) Practical Course in Gynaecologic Endoscopy in Davos, Switzerland. All participants received a 20-min hands-on training on the simulator and filled out a four-page questionnaire. Twenty-three questions with respect to the realism of the simulation and the training capacity were answered on a seven-point Likert scale along with 11 agree-disagree statements concerning the HystSim training in general. RESULTS: Twenty-six participants had performed more than 50 hysteroscopies ("experts") and 36 equal to or fewer than 50 ("novices"). Four of 60 (6.6%) responding participants judged the overall impression as "7--absolutely realistic", 40 (66.6%) as "6--realistic", and 16 (26.6%) as "5--somewhat realistic". Novices (6.48; 95% confidence interval [CI] 6.28-6.7) rated the overall training capacity significantly higher than experts (6.08; 95% CI 5.85-6.3), however, high-grade acceptance was found in both groups. In response to the statements, 95.2% believe that HystSim allows procedural training of diagnostic and therapeutic hysteroscopy, and 85.5% suggest that HystSim training should be offered to all novices before performing surgery on real patients. CONCLUSION: Face validity has been established for a new hysteroscopic surgery simulator. Potential trainees and trainers assess it to be a realistic and useful tool for the training of hysteroscopy. Further systematic validation studies are needed to clarify how this system can be optimally integrated into the gynaecological curriculum.

Ultrasound simulation with deformable and patient-specific scatterer maps.

PURPOSE: Ray-tracing-based simulations model ultrasound (US) interactions with a custom geometric anatomical model, where US texture can be emulated via real-time point-spread function convolutions of a tissue scatterer representation. Such scatterer representations for realistic appearance are difficult to parameterize or model manually and do not respond to volumetric deformations such as those caused with tissue compression by the probe. Herein we utilize brightness mode (B-mode) estimated scatterer maps for ray tracing and propose to enhance the realism of ray-tracing-based simulations by incorporating dynamic speckle patterns that change compliant with tissue deformation. METHODS: In this work, we realistically simulate US texture deformations in the scatterer domain via back-projection of ray segments into a nominal state before sampling during simulation runtime. We estimate scatterer maps from background in vivo images using a pretrained generative adversarial network. RESULTS: We demonstrated our proposed scatterer estimation and runtime background fusion method on simulated transvaginal US scans of detailed surface-based foetal models. We show the viability of modelling deformations in the scatterer domain at interactive frame rates of 28 frames per second. A quantitative and a qualitative evaluations indicated improved realism in comparison to the state of the art. CONCLUSIONS: Transferring a background image in a scatterer representation enables us to capture anatomical content in a physical space, in which deformations can be incorporated physically consistently before convolving with a US point-spread function during simulation runtime. This then uses the same imaging model on both the background and the hand-crafted models leading to a consistent and seamless compounding of contents in the scatterer space.

Inverse finite element characterization of the human myometrium derived from uniaxial compression experiments.

The low strain-rate behavior of the human myometrium under compression was determined. To this end, uniaxial, unconstrained compression experiments were conducted on a total of 25 samples from three excised human uteri at strain rates between 0.001 s(-1) and 0.008 s(-1). A three-dimensional finite element model of each sample was created and used together with an optimization algorithm to find material parameters in an inverse estimation process. Friction and shape irregularities of samples were incorporated in the models. The uterine specimens in compression were modeled as viscoelastic, non-linear, nearly incompressible and isotropic continua. Simulations of uniaxial, frictionless compressions of an idealized cuboid were used to compare the resulting material parameters among each other. The intra- and inter-subject variability in stiffness of specimens was found to be large and to cover such a wide range that the effect of anisotropy which is of minor influence under compressive deformations in the first place could be neglected. Material parameters for a viscoelastic model based on a decoupled, reduced quadratic strain-energy function were presented for the uterine samples representing a median stiffness.

In vivo characterization of the mechanics of human uterine cervices.

The uterine cervix has to provide mechanical resistance to ensure a normal development of the fetus. This is guaranteed by the composition of its extracellular matrix, which functions as a fiber-reinforced composite. At term a complex remodeling process allows the cervical canal to open for birth. This remodeling is achieved by changes in the quality and quantity of collagen fibers and ground substance and their interplay, which influences the biomechanical behavior of the cervix but also contributes to pathologic conditions such as cervical incompetence (CI). We start by reviewing the anatomy and histological composition of the human cervix, and discuss its physiologic function and pathologic condition in pregnancy including biomechanical aspects. Established diagnostic methods on the cervix (palpation, endovaginal ultrasound) used in clinics as well as methods for assessment of cervical consistency (light-induced fluorescence, electrical current, and impedance) are discussed. We show the first clinical application of an aspiration device, which allows in vivo testing of the biomechanical properties of the cervix with the aim to establish the physiological biomechanical changes throughout gestation and to detect pregnant women at risk for CI. In a pilot study on nonpregnant cervices before and after hysterectomy we found no considerable difference in the biomechanical response between in vivo and ex vivo. An outlook on further clinical applications during pregnancy is presented.

The mechanical response of human liver and its relation to histology: an in vivo study.

The mechanical response of human liver is characterized in vivo by means of intra-operative aspiration experiments. Mechanical characterization is combined with histological evaluation of liver tissue biopsies obtained from the resected liver at the site of mechanical testing. This procedure enables a quantitative analysis of the correlation between mechanical response and tissue micro-structure of normal and diseased liver. Ten organs were tested in vivo at multiple locations, as well as ex vivo immediately after resection. Biopsies were analyzed in terms of pathology and percentage of connective tissue content. The change of the mechanical parameters from in vivo to ex vivo has been determined, with an increase of 17% of the proposed stiffness index. The relationship between mechanical parameters and various pathologic conditions affecting the tissue samples has been quantified, with fibrosis leading to a response up to three times stiffer as compared with normal tissue. Increased stiffness can be detected by digital palpation (increased "consistency") and may suggest the presence of a tumor. The present observations suggest that stiffness increase cannot be attributed to the tumoral tissue itself, but rather to the fibrotic stroma that often arise within or adjacent to the tumor. Variation of the mechanical parameters as a function of connective tissue content has been evaluated based on the histological examinations and the results confirm a direct proportionality between stiffness index and connective tissue percentage. The approach described here might eventually lead to a diagnostic procedure and complement other clinical methods, like palpation and ultrasound examination of the liver.

Objective surgical performance assessment for virtual hysteroscopy.

We present robust methods for objective, structured, and automated assessment of surgical performance in virtual diagnostic hysteroscopy. Surgery specific metrics are based on a hierarchical task decomposition and have been integrated into our simulation setup. Measurements include visible surface quantification, fluid consumption and indicators for safety and economy of movement. Both visual and quantitative results from exemplary interventions of novice and expert surgeons are shown.