Intraobserver and interobserver reproducibility of ultrasound measurements of endometrial thickness in postmenopausal women

The role of timing in frozen embryo transfer

The process of implantation is characterized by a complex cross-talk between the endometrium and the blastocyst, with the endometrium only being receptive to implantation during a transient window of implantation of approximately 2-3 days during the midsecretory phase. The timing of embryo transfer, including frozen embryo transfer, is therefore critical to the success of implantation. In this article, we discuss various elements that may guide the timing of frozen embryo transfer, including the role of endometrial characteristics such as thickness, days postovulation or length of progesterone administration, stage of the embryo, and the application of endometrial receptivity tests to guide personalized embryo transfer.

Frozen Blastocyst Embryo Transfer: Comparison of Protocols and Factors Influencing Outcome

Background: Various factors, including treatment protocols, can influence the outcomes of frozen embryo transfers (FETs). The study objectives were to compare different endometrial preparation protocols of FET cycles and to evaluate the factors, including the endometrial thickness (ET), that affect outcomes. Methods: This observational cohort study involved 5037 women undergoing FETs at eight tertiary clinics in the UK between January 2016 and March 2019. The endometrial preparation protocols used were natural cycle (NC-FETs), artificial hormone support cycle with oestradiol valerate but without pituitary downregulation (AC-FETs) and artificial hormone support cycle with agonist downregulation (ACDR-FETs). Results: The mean (±SD) ages across NC-FET, AC-FET and ACDR-FET groups were 36.5 (±4.2), 35.9 (±5.0) and 36.4(±4.9) years, respectively. LBRs were comparable (40.7%, 175/430; 36.8%, 986/2658; and 36.7%, 716/1949, respectively) across the three groups. Clinical pregnancy, implantation, multiple pregnancies, miscarriage and ectopic pregnancy rates were also similar. In the regression analysis of variables including age, duration of infertility, number of embryos transferred, protocol type and endometrial thickness, age was the only significant predictor of LBRs, although its predictive ability was poor (AUC: 0.55). With the overall LBR of the study population being 37.1%, the post-test probability of a live birth at an ET of <5 mm was 0%, and at 5–5.9, 6–6.9, 7–7.9 and 8–8.9 mm, the probabilities were 16.7%, 33.8%, 36.7% and 37.7%, respectively. The LBR remained above 35% up to the 14–14.9 mm range and then declined gradually to 23% for the 17–25 mm range. Conclusions: The FET outcomes were similar for the three protocols used for endometrial preparation. The protocol type and endometrial thickness were not predictive of FET outcomes; age was the only predictive variable, despite its low predictive ability.

Multiparametric transvaginal ultrasound in the diagnosis of endometrial cancer in post-menopausal bleeding: diagnostic performance of a transvaginal algorithm and reproducibility amongst less experienced observers

OBJECTIVE

(a) To comparatively evaluate the performance of grayscale ultrasound features, power Doppler (PD) blood flow characteristics, and gel infusion sonography (GIS) in diagnosing endometrial cancer during real-time examination, (b) to compare the performance of real-time diagnosis of endometrial cancer by experienced observers with offline analysis by blinded observers using similar sonographic criteria during review of cine loop clips.

METHODS

152 females with post-menopausal bleeding (PMB) had ET ≥ 4 mm at first-line ultrasound were included. Two experienced radiologists evaluated endometrial patterns at real-time evaluation (grayscale ultrasound, PD, and GIS), then examinations were stored as video clips for later evaluation by two less-experienced radiologists. The reference standard was hysteroscopy (HY) and/or hysterectomy with the histopathological examination. The area under (AUC) the receiver operating characteristic (ROC) curve was calculated to assess the diagnostic performance for the prediction of endometrial cancer.

RESULTS

Among 152 females with ET ≥ 4 mm at first line TVUS, 88 (57.9%) patients had endometrial cancer on final pathologic analysis. Real-time ultrasound criteria (ET ≥ 5 mm with the presence of irregular branching endometrial blood vessels or multiple vessels crossing EM or areas with densely packed color-splash vessels with non-intact or interrupted EMJ at the grayscale ultrasound and/or GIS) correctly diagnosed 95% of endometrial cancers with 92% diagnostic efficiency.There is comparable accuracy of real-time evaluation (96%) and offline analysis (92%) after the exclusion of poor quality videos from the analysis. The diagnostic criteria showed good to an excellent agreement between real-time ultrasound and offline analysis.

CONCLUSION

When real-time ultrasound is performed with good technique, utilizing multiple parameters, it is possible to diagnose endometrial cancer with a high degree of accuracy and reproducibility.

ADVANCES IN KNOWLEDGE

when real-time ultrasound is performed with good technique, utilizing multiple parameters, it is possible to diagnose endometrial cancer with a high degree of accuracy and reproducibility.

Deep Learning-Based Automatic Endometrium Segmentation and Thickness Measurement for 2D Transvaginal Ultrasound

Endometrial thickness is closely related to gyneco-logical function and is an important biomarker in transvaginal ultrasound (TVUS) examinations for assessing female reproductive health. Manual measurement is time-consuming and subject to high inter- and intra- observer variability. In this paper, we present a fully automated endometrial thickness measurement method using deep learning. Our pipeline consists of: 1) endometrium segmentation using a VGG-based U-Net, and 2) endometrial thickness estimation using medial axis transformation. We conducted experimental studies on 137 2D TVUS cases (74/63 secretory phase/proliferative phase). On a test set of 27 cases/277 images, the segmentation Dice score is 0.83. For thickness measurement, we achieved mean absolute error of 1.23/1.38 mm and root mean squared error of 1.79/1.85 mm on two different test sets. The results are considered well within the clinically acceptable range of ±2 mm. Furthermore, our phase-stratified analysis shows that the measurement variance from the secretory phase is higher than that from the proliferative phase, largely due to the high variability of the endometrium appearance in the secretory phase. Future work will extend our current algorithm toward different clinical outcomes for a broader spectrum of clinical applications.

Validation of ultrasound strategies to assess tumor extension and to predict high-risk endometrial cancer in women from the prospective IETA (International Endometrial Tumor Analysis)-4 cohort

OBJECTIVES

To compare the performance of ultrasound measurements and subjective ultrasound assessment (SA) in detecting deep myometrial invasion (MI) and cervical stromal invasion (CSI) in women with endometrial cancer, overall and according to whether they had low- or high-grade disease separately, and to validate published measurement cut-offs and prediction models to identify MI, CSI and high-risk disease (Grade-3 endometrioid or non-endometrioid cancer and/or deep MI and/or CSI).

METHODS

The study comprised 1538 patients with endometrial cancer from the International Endometrial Tumor Analysis (IETA)-4 prospective multicenter study, who underwent standardized expert transvaginal ultrasound examination. SA and ultrasound measurements were used to predict deep MI and CSI. We assessed the diagnostic accuracy of the tumor/uterine anteroposterior (AP) diameter ratio for detecting deep MI and that of the distance from the lower margin of the tumor to the outer cervical os (Dist-OCO) for detecting CSI. We also validated two two-step strategies for the prediction of high-risk cancer; in the first step, biopsy-confirmed Grade-3 endometrioid or mucinous or non-endometrioid cancers were classified as high-risk cancer, while the second step encompassed the application of a mathematical model to classify the remaining tumors. The 'subjective prediction model' included biopsy grade (Grade 1 vs Grade 2) and subjective assessment of deep MI or CSI (presence or absence) as variables, while the 'objective prediction model' included biopsy grade (Grade 1 vs Grade 2) and minimal tumor-free margin. The predictive performance of the two two-step strategies was compared with that of simply classifying patients as high risk if either deep MI or CSI was suspected based on SA or if biopsy showed Grade-3 endometrioid or mucinous or non-endometrioid histotype (i.e. combining SA with biopsy grade). Histological assessment from hysterectomy was considered the reference standard.

RESULTS

In 1275 patients with measurable lesions, the sensitivity and specificity of SA for detecting deep MI was 70% and 80%, respectively, in patients with a Grade-1 or -2 endometrioid or mucinous tumor vs 76% and 64% in patients with a Grade-3 endometrioid or mucinous or a non-endometrioid tumor. The corresponding values for the detection of CSI were 51% and 94% vs 50% and 91%. Tumor AP diameter and tumor/uterine AP diameter ratio showed the best performance for predicting deep MI (area under the receiver-operating characteristics curve (AUC) of 0.76 and 0.77, respectively), and Dist-OCO had the best performance for predicting CSI (AUC, 0.72). The proportion of patients classified correctly as having high-risk cancer was 80% when simply combining SA with biopsy grade vs 80% and 74% when using the subjective and objective two-step strategies, respectively. The subjective and objective models had an AUC of 0.76 and 0.75, respectively, when applied to Grade-1 and -2 endometrioid tumors.

CONCLUSIONS

In the hands of experienced ultrasound examiners, SA was superior to ultrasound measurements for the prediction of deep MI and CSI of endometrial cancer, especially in patients with a Grade-1 or -2 tumor. The mathematical models for the prediction of high-risk cancer performed as expected. The best strategies for predicting high-risk endometrial cancer were combining SA with biopsy grade and the subjective two-step strategy, both having an accuracy of 80%. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Six-month recovery needed after dilation and curettage (D and C) for reproductive outcomes in frozen embryo transfer

In this study, the endometrial developmental and reproductive outcomes of frozen embryo transfers (FETs) which were performed subsequent to miscarriages managed by dilation and curettage (D and C) were investigated. The intracytoplasmic sperm injection (ICSI) blastocyst freeze-all cycles performed between January 2014 and August 2016 were screened for the patients who had undergone their FET (first), miscarriages (>5 < 14 weeks), D and C, and the patients who had undergone their FET (second) (study group; n = 71); and patients who underwent FET (1st), a chemical pregnancy loss (PL) (<5 weeks) and FET (2nd) (reference group; n = 38). The live births (LB; delivery >20 weeks) of FET (2nd) were analysed in two time-interval sub-groups: ≤6 months or >6 months. In the study and reference groups, the median endometrial thickness at the second FET of the ≤6 months sub-groups was found to be significantly reduced. The relative risk for LB was significantly higher (1.65 [0.994-2.723] p = .043) in the >6 months study sub-group, with a lower risk for PL (0.62 [0.268-1.427] p = .329), whereas, there were no significant differences between the reference sub-groups. The management of miscarriage with D and C results in a significant and transient decrease in reproductive function in subsequent FET. Impact Statement What is already known on this subject? Approximately, 15-30% of positive pregnancies in assisted reproductive technology (ART) end in biochemical pregnancy losses (PLs) or miscarriages. Cervical dilation with suction or blunt curettage (D and C), has been the procedure most often used to manage the retained products of conception (RPOC) after miscarriage. Intrauterine surgery has the potential to directly affect reproduction, depending on the endometrial impact. What the results of this study add? The endometrium after D and C surgery may require 6 months to recover normal reproductive function, in terms of both live birth and PL. The extent of the damage to endometrial function is not found to be reflected in the endometrial thickness. What the implications are of these findings for clinical practice and/or further research? Patients who undergo miscarriage after their ART treatment may need to delay further treatment for 6 months to optimise their chances of LB. Alternative miscarriage management procedures need to be investigated; procedures that have lower risks for an adverse reproductive function and allow for shorter time intervals between treatments.

Reproducibility of Endometrial Pathologic Findings Obtained on Hysteroscopy, Transvaginal Sonography, and Gel Infusion Sonography in Women With Postmenopausal Bleeding

STUDY OBJECTIVE

To evaluate and compare interobserver variation in endometrial pattern recognition with hysteroscopy (HY) and transvaginal sonography (TVS) and gel infusion sonography (GIS) with regard to the diagnosis of endometrial pathology.

DESIGN

Prospective study (Canadian Task Force II-1).

SETTING

University clinic.

PATIENTS

One hundred twenty-two consecutive women with postmenopausal bleeding and an endometrium thickness ≥ 5 mm.

INTERVENTION

Two observers using HY and 2 others using TVS and GIS evaluated the endometrial pattern in recorded video clips. Interobserver agreement regarding findings obtained with TVS, GIS, and HY for a diagnosis of cancer, hyperplasia, polyps, and no endometrial pathology was expressed by κ coefficients and compared.

MEASUREMENT AND MAIN RESULTS

Interobserver agreement (κ) was as follows: identification of normal endometrium: HY (.74), TVS (.68), and GIS (.48); diagnosis of cancer: HY (.56), TVS (.59), and GIS (.34); classification in all categories of endometrial pathology: HY (.70), TVS (.47), and GIS (.41) (p < .05 HY vs GIS). The presence of additional endometrial polyps decreased agreement on HY in patients with hyperplasia or cancer. Observer agreement was poor regarding the diagnosis of hyperplasia by all techniques.

CONCLUSION

Observer agreement regarding both HY and TVS was reliable for the diagnosis of a normal endometrium but poor with HY, TVS, and especially GIS for a diagnosis of cancer. In patients with hyperplasia or cancer, agreement between observers was especially low in the presence of additional polyps when HY was used. These findings call attention to the need for systematic methods to improve reliability in endometrial pattern recognition.

Evaluating myometrial and cervical invasion in women with endometrial cancer: comparing subjective assessment with objective measurement techniques

OBJECTIVE

To compare the diagnostic accuracy of subjective ultrasound assessment with that of objective measurement techniques in the evaluation of myometrial and cervical invasion in women with endometrial cancer.

METHODS

This was a prospective multicenter study including 144 women with endometrial cancer undergoing transvaginal ultrasound. Myometrial and cervical invasion was evaluated subjectively, as well as objectively measured in different ways: endometrial thickness, tumor/uterine anteroposterior (AP) diameter ratio, minimal tumor-free margin, minimal tumor-free margin/uterine AP diameter ratio, tumor volume (three-dimensional (3D)), tumor/uterine volume (3D) ratio, and distance from outer cervical os to lower margin of tumor (Dist-OCO). Histological assessment following hysterectomy was the gold standard.

RESULTS

The sensitivity (72%) and specificity (76%) of tumor/uterine AP diameter (at cut-off, 0.53) were not significantly different from those of subjective evaluation (sensitivity, 77% (P = 0.44); specificity, 81% (P = 0.32)) for the prediction of deep myometrial invasion; all other objective measurement techniques had either a significantly lower sensitivity or a lower specificity. For all objective measurement techniques, except minimal tumor-free margin/uterine AP diameter ratio, fixing the sensitivity at the same level as that of subjective evaluation (i.e. 77%) gave a significantly lower specificity. Dist-OCO was the only parameter that might have potential to predict cervical invasion; it had a non-significantly higher sensitivity than did subjective evaluation (73% vs 54%, P = 0.06), but a significantly lower specificity (63% vs 93%, P < 0.001).

CONCLUSION

Subjective assessment of cervical and myometrial invasion is as good as or better than any objective measurement technique. The tumor/uterine AP diameter ratio and minimal tumor-free margin/uterine AP diameter ratio seem to be the best objective measurement techniques to predict deep myometrial invasion. It remains to be shown if objective measurements are useful to predict cervical invasion.

Ultrasonographic quantification of the endometrium during the menstrual cycle using computer-assisted analysis

OBJECTIVE

Sonographic gray-scale histogram is used to assess the endometrial changes in the different phases of the menstrual cycle. The objective was to examine the usefulness of a gray-scale histogram and computer-assisted image analysis software in assessing normal physiologic states of the endometrium with sonography.

MATERIALS AND METHODS

Thirty-eight patients, who visited the Taipei Medical University-Wan Fang Hospital and matched the eligibility criteria, were categorized into one of three groups: (1) menstrual phase; (2) follicular phase; and (3) luteal phase of the menstrual cycle. Ultrasonography of the uterus was performed on each patient and the endometrium was analyzed with ImageJ image analysis software.

RESULTS

A statistically significant difference in signal intensity scores of the gray-level histogram, represented as m(j), was found among the three groups.

CONCLUSION

Sonographic images analyzed by using computer-assisted image analysis software and gray-level histogram are proven to be useful in assessing the physiological state of the endometrium.

A standardized measurement technique may improve the reliability of measurements of endometrial thickness and volume

OBJECTIVE

To investigate whether standardization of the multiplanar view (SMV) when evaluating the uterus using three-dimensional ultrasonography (3D-US) improves intra- and interobserver reliability and agreement with regard to endometrial measurement.

METHODS

Two-dimensional (2D) and 3D-US was used to measure endometrial thickness by two observers in 30 women undergoing assisted reproduction treatment. Endometrial volume was measured with Virtual Organ Computer-aided AnaLysis (VOCAL(™)) in the longitudinal (A) and coronal (C) planes using an unmodified multiplanar view (UMV) and a standardized multiplanar view (SMV). Measurement reliability was evaluated by intraclass correlation coefficient (ICC) and agreement was examined using Bland-Altman plots with limits of agreement (LoA). The ease of outlining the endometrial-myometrial interface was compared between the A- and C-planes using subjective assessment.

RESULTS

Endometrial volume measurements using the SMV and A-plane were more reliable (intra- and interobserver ICCs, 0.979 and 0.975, respectively) than were measurements of endometrial thickness using 2D-US (intra- and interobserver ICCs, 0.742 and 0.702, respectively) or 3D-US (intra- and interobserver ICCs, 0.890 and 0.784, respectively). The LoAs were narrower for SMV than for UMV. Reliability and agreement were not much different between the A- and C-planes. However the observers agreed that delineating the endometrial-myometrial interface using the A-plane was easier (first and second observer, 50.0 and 46.7%, respectively) or 'comparable' (50 and 53.3%, respectively), but never more difficult than using the C-plane.

CONCLUSIONS

Endometrial volume measurements are more reliable than endometrial thickness measurements and are best performed using SMV and the A-plane.

Sensitivity of transvaginal ultrasound screening for endometrial cancer in postmenopausal women: a case-control study within the UKCTOCS cohort

BACKGROUND

The increase in the worldwide incidence of endometrial cancer relates to rising obesity, falling fertility, and the ageing of the population. Transvaginal ultrasound (TVS) is a possible screening test, but there have been no large-scale studies. We report the performance of TVS screening in a large cohort.

METHODS

We did a nested case-control study of postmenopausal women who underwent TVS in the United Kingdom Collaborative Trial of Ovarian Cancer Screening (UKCTOCS) following recruitment between April 17, 2001, and Sept 29, 2005. Endometrial thickness and endometrial abnormalities were recorded, and follow-up, through national registries and a postal questionnaire, documented the diagnosis of endometrial cancer. Our primary outcome measure was endometrial cancer and atypical endometrial hyperplasia (AEH). Performance characteristics of endometrial thickness and abnormalities for detection of endometrial cancer within 1 year of TVS were calculated. Epidemiological variables were used to develop a logistic regression model and assess a screening strategy for women at higher risk. Our study is registered with ClinicalTrials.gov, number NCT00058032, and with the International Standard Randomised Controlled Trial register, number ISRCTN22488978.

FINDINGS

48,230 women underwent TVS in the UKCTOCS prevalence screen. 9078 women were ineligible because they had undergone a hysterectomy and 2271 because their endometrial thickness had not been recorded; however, 157 of these women had an endometrial abnormality on TVS and were included in the analysis. Median follow-up was 5·11 years (IQR 4·05-5·95). 136 women with endometrial cancer or AEH within 1 year of TVS were included in our primary analysis. The optimum endometrial thickness cutoff for endometrial cancer or AEH was 5·15 mm, with sensitivity of 80·5% (95% CI 72·7-86·8) and specificity of 86·2% (85·8-86·6). Sensitivity and specificity at a 5 mm or greater cutoff were 80·5% (72·7-86·8) and 85·7% (85·4-86·2); for women with a 5 mm or greater cutoff plus endometrial abnormalities, the sensitivity and specificity were 85·3% (78·2-90·8) and 80·4% (80·0-80·8), respectively. For a cutoff of 10 mm or greater, sensitivity and specificity were 54·1% (45·3-62·8) and 97·2% (97·0-97·4). When our analysis was restricted to the 96 women with endometrial cancer or AEH who reported no symptoms of postmenopausal bleeding at the UKCTOCS scan before diagnosis and had an endometrial thickness measurement available, a cutoff of 5 mm achieved a sensitivity of 77·1% (67·8-84·3) and specificity of 85·8% (85·7-85·9). The logistic regression model identified 25% of the population as at high risk and 39·5% of endometrial cancer or AEH cases were identified within this high risk group. In this high-risk population, a cutoff at 6·75 mm achieved sensitivity of 84·3% (71·4-93·0) and specificity of 89·9% (89·3-90·5).

INTERPRETATION

Our findings show that TVS screening for endometrial cancer has good sensitivity in postmenopausal women. The burden of diagnostic procedures and false-positive results can be reduced by limiting screening to a higher-risk group. The role of population screening for endometrial cancer remains uncertain, but our findings are of immediate value in the management of increased endometrial thickness in postmenopausal women undergoing pelvic scans for reasons other than vaginal bleeding.

Ultrasonographic evaluation of endometrial changes using computer assisted image analysis

AIM

To examine the usefulness of a gray scale histogram and computer assisted image analysis software in assessing physiologic states of the endometrium with ultrasonography.

METHODS

Seventy patients at the Taipei Medical University-Wan Fang Hospital who matched eligibility criteria were categorized into one of three groups: (i) normal menstrual cycle, (ii) postmenopausal, and (iii) post incomplete abortion. Ultrasonography of the uterus was performed on each patient and the endometrium was analyzed with ImageJ image analysis software.

RESULTS

A statistically significant difference in signal intensity scores of the gray level histogram, represented as m(j), was found between the groups.

CONCLUSION

Ultrasonographic images analyzed using computer assisted image analysis software and gray level histogram are useful in assessing the physiological state of the endometrium.

Validation of three-dimensional perineal ultrasound and magnetic resonance imaging measurements of the pubovisceral muscle at rest

OBJECTIVE

To compare biometric measurements of the pubovisceral muscle during rest, measured using transperineal three-dimensional (3D) ultrasound and magnetic resonance imaging (MRI).

METHODS

In this prospective study, 18 female volunteers underwent 3D perineal ultrasound examination and MRI. All women were examined at rest in the supine position and the following measurements were taken: area and anteroposterior and transverse diameters of the levator hiatus; thickness of the pubovisceral muscle, measured lateral to the vagina and to the rectum, on the right and left sides; length of the levator-urethra gap (LUG), measured from the center of the urethra to the insertion of the pubovisceral muscle on the pubic bone. Interclass correlation coefficients (ICC) between the measurements obtained with 3D ultrasound and with MRI were calculated. To quantify the intermeasurement agreement, the bias and SDs were calculated, and limits of agreement constructed. One investigator performed all the analyses.

RESULTS

There was no significant difference between the mean values of the measurements by 3D perineal ultrasound and those by MRI. The ICC values showed very good agreement (range, 0.80-0.97). There was a significant positive bias for LUG on the left side and muscle thickness on the right side of the vagina.

CONCLUSION

These results suggest that 3D ultrasound could be used instead of MRI when evaluating static pelvic floor anatomy in women without pelvic organ prolapse at rest.

Reproductive ecology and the endometrium: physiology, variation, and new directions

Endometrial function is often overlooked in the study of fertility in reproductive ecology, but it is crucial to implantation and the support of a successful pregnancy. Human female reproductive physiology can handle substantial energy demands that include the production of fecund cycles, ovulation, fertilization, placentation, a 9-month gestation, and often several years of lactation. The particular morphology of the human endometrium as well as our relative copiousness of menstruation and large neonatal size suggests that endometrial function has more resources allocated to it than many other primates. The human endometrium has a particularly invasive kind of hemochorial placentation and trophoblast that maximizes surface area and maternal-fetal contact, yet these processes are actually less efficient than the placentation of some of our primate relatives. The human endometrium and its associated processes appear to prioritize maximizing the transmission of oxygen and glucose to the fetus over efficiency and protection of maternal resources. Ovarian function controls many aspects of endometrial function and thus variation in the endometrium is often a reflection of ecological factors that impact the ovaries. However, preliminary evidence and literature from populations of different reproductive states, ages and pathologies also suggests that ecological stress plays a role in endometrial variation, different from or even independent of ovarian function. Immune stress and psychosocial stress appear to play some role in the endometrium's ability to carry a fetus through the mechanism of inflammation. Thus, within reproductive ecology we should move towards a model of women's fecundity and fertility that includes many components of ecological stress and their effects not only on the ovaries, but on processes related to endometrial function. Greater attention on the endometrium may aid in unraveling several issues in hominoid and specifically human evolutionary biology: a low implantation rate, high rates of early pregnancy loss, prenatal investment in singletons but postnatal support of several dependent offspring at once, and higher rate of reproductive and pregnancy-related pathology compared to other primates, ranging from endometriosis to preeclampsia. The study of the endometrium may also complicate some of these issues, as it raises the question of why humans have a maximally invasive placentation method and yet slow fetal growth rates. In this review, I will describe endometrial physiology, methods of measurement, variation, and some of the ecological variables that likely produce variation and pregnancy losses to demonstrate the necessity of further study. I propose several basic avenues of study that leave room for testable hypotheses in the field of reproductive ecology. And finally, I describe the potential of this work not just in reproductive ecology, but in the resolution of broader women's health issues.

Lower uterine segment thickness measurement in pregnant women with previous Cesarean section: reliability analysis using two- and three-dimensional transabdominal and transvaginal ultrasound

OBJECTIVE

To evaluate the reliability of two- and three-dimensional ultrasonographic measurement of the thickness of the lower uterine segment (LUS) in pregnant women by transvaginal and transabdominal approaches.

METHODS

This was a study of 30 pregnant women who had had at least one previous Cesarean section and were between 36 and 39 weeks' gestation, with singleton pregnancies in cephalic presentation. Sonographic examinations were performed by two observers using both 4-7-MHz transabdominal and 5-8-MHz transvaginal volumetric probes. LUS measurements were performed using two- and three-dimensional ultrasound, evaluating the entire LUS thickness transabdominally and the LUS muscular thickness transvaginally. Each observer measured the LUS four times by each method. Reliability was analyzed by comparing the mean of the absolute differences, the intraclass correlation coefficients, the 95% limits of agreement and the proportion of differences < 1 mm.

RESULTS

Transvaginal ultrasound provided greater reliability in LUS measurements than did transabdominal ultrasound. The use of three-dimensional ultrasound improved significantly the reliability of the LUS muscular thickness measurement obtained transvaginally.

CONCLUSIONS

Ultrasonographic measurement of the LUS muscular thickness transvaginally appears more reliable than does that of the entire LUS thickness transabdominally. The use of three-dimensional ultrasound should be considered to improve measurement reliability.

Reproducibility of endometrial vascular patterns in endometrial disease as assessed by transvaginal power Doppler sonography in women with postmenopausal bleeding

OBJECTIVE

The purpose of this study was to assess the intraobserver and interobserver agreement for identifying different endometrial vascular patterns using power Doppler sonography in women with postmenopausal bleeding and a thickened endometrium.

METHODS

Digitally stored sonographic images from a random sample of 65 patients with postmenopausal bleeding and a thick endometrium (>5 mm) on B-mode sonography and evaluated by transvaginal power Doppler sonography for assessment of endometrial blood flow mapping were evaluated by 5 different examiners with different levels of expertise in Doppler sonography. Intraobserver and interobserver agreement according to the level of experience were assessed by calculating the kappa index.

RESULTS

Intraobserver agreement was good or very good for all experienced examiners (kappa = 0.78-0.96) and moderate (kappa = 0.52) for the inexperienced examiner. Interobserver agreement was moderate among all experienced examiners (kappa = 0.45-0.80). The inexperienced examiner showed fair or moderate interobserver agreement (kappa = 0.32-0.45).

CONCLUSIONS

Our results indicate that endometrial blood flow mapping using transvaginal power Doppler sonography is acceptably reproducible. More experience was associated with better intraobserver and interobserver agreement.

Measurement of endometrial stripe thickness by obstetrics and gynecology residents

OBJECTIVE

How well do obstetrics and gynecology residents measure the endometrial stripe by transvaginal sonography?

STUDY DESIGN

Three obstetrics and gynecology residents at the University of Texas Medical Branch from each year level were tested for their ability to perform endometrial stripe measurements. Measurements of endometrial stripe thickness within 1 mm of the reference value that was obtained by an expert sonographer were deemed to be correct.

RESULTS

Residents correctly measured the endometrial stripe in 14 of 24 cases (58%). Postgraduate year-4 residents correctly measured endometrial stripe thickness in 5 of 6 cases (83%); lower level residents were correct in 9 of 18 cases (50%). The most common error that was noted was an incorrect image plane in 25 of 47 attempts (53%). Fewer errors were committed by upper level as compared with lower level residents (P < .05).

CONCLUSION

By the end of residency, residents can accurately measure the endometrial stripe using transvaginal sonography. Emphasis should be placed on the improvement of the measurement skills.

Intraobserver and interobserver reproducibility of fetal biometry

OBJECTIVE

To assess the intra- and interobserver reproducibility of ultrasound measurements of fetal biometric parameters.

METHODS

We assessed the intraobserver and the interobserver agreement in measurements of fetal biparietal diameter (BPD), abdominal circumference (AC), head circumference (HC) and femur length (FL) on 122 singleton pregnancies. Patients were each examined twice by the first sonographer to determine the intraobserver reliability of measurements of fetal biometry. Subsequently, during the same ultrasound examination, a second blinded sonographer measured fetal biometric parameters to assess interobserver reliability. The consensus between and among observers was analyzed using the intraclass correlation coefficient (intra-CC) and interclass correlation coefficient (inter-CC) and the reliability coefficients (RC, alpha) for the four biometric measurements. A value > 0.75 was considered a reliable consensus for the intra-CC and inter-CC. A Bland and Altman plot was also created for the fetal biometric parameters to assess the repeatability of the measurements.

RESULTS

Reliable consensus was observed for both the intra-CC and inter-CC and RC for all four biometric parameters. The intra-CC with the 95% CI and RC for the BPD, AC, HC and FL were as follows: 0.996 (0.995, 0.997), alpha 0.998; 0.994 (0.992, 0.996), alpha 0.997; 0.996 (0.994, 0.997), alpha 0.998; and 0.994 (0.992, 0.996), alpha 0.997, respectively. Similarly, the inter-CC with the 95% CI and RC for the same parameters were as follows: 0.995 (0.993, 0.997), alpha 0.998; 0.980 (0.971, 0.990), alpha 0.990; 0.994 (0.992, 0.996), alpha 0.997; and 0.990 (0.985,0.993), alpha 0.995, respectively. The Bland and Altman plots demonstrated a high degree of repeatability of BPD, AC, HC, and FL measurements.

CONCLUSION

Our results demonstrate that the intra- and interobserver reproducibility of ultrasound measurements of fetal biometry are highly reliable.

Ultrasound training: the virtual patient

OBJECTIVE

To evaluate an ultrasound training system designed to standardize teaching and learning of gynecological sonography using a virtual model.

METHODS

The 'virtual patient' was based on a three-dimensional freehand ultrasound system that allows two-dimensional sonographic offline investigations of previously recorded cases, imitating a real gynecological scan. In the first test phase designed to check the congruence of real and virtual scans, 25 doctors experienced in ultrasound examined three virtual cases. During the second test phase we assessed whether training with the virtual patient helped to establish a satisfactory practical knowledge of gynecological ultrasound. This phase was carried out with 24 medical students without ultrasound experience.

RESULTS

All 25 doctors successfully investigated the three cases and generated an accurate diagnosis for the first and second cases. In the third case 14 doctors made the correct diagnosis (uterus bicornis). The measurements of endometrial thickness and the diameter of a fibroid yielded acceptable results compared with the original investigation. After a short standardized video-based instruction, all 24 medical students were able to perform a basic transvaginal scan and to inspect the uterus, ovaries and the urinary bladder. Measurements of endometrial thickness by all students deviated minimally from the actual measurement.

CONCLUSIONS

Training with the virtual patient appears to be comparable to performing a live gynecological ultrasound investigation and allows standardized ultrasound teaching and learning.

Angiographic power 3-dimensional quantitative analysis in gynecologic solid tumors: feasibility and reproducibility

OBJECTIVE

To determine the reproducibility of a simplified method of power Doppler 3-dimensional (3D) sonographic examination.

METHODS

Twenty-nine patients with solid pelvic masses underwent transvaginal 3D power Doppler evaluation. The volume of interest was obtained by drawing the margins of the largest section of the mass in the 3 orthogonal planes. The 3D vascular parameters ("relative color," "average color," and "flow measure") obtained by our method were compared with those calculated by a manufacturer-suggested model based on several parallel section planes drawn on the longitudinal frames. The intraobserver variability was quantified on 5 different 3D images acquired by the same operator at 5-minute intervals for each patient. The intraobserver variability was also assayed in 10 patients at 24-hour intervals. Ten patients were scanned by a second sonographer for interobserver variability.

RESULTS

There was high agreement between the 3D parameters obtained with the 2 methods. The 3D indices were similar in repeated observations at 5-minute intervals (median coefficients of variation for relative color, average color, and flow measure, 10.9, 4.5, and 13.0, respectively) and at 24-hour intervals (intraclass correlation coefficients for relative color, average color, and flow measure, 0.920, 0.978, and 0.978) and by the second sonographer (interclass correlation coefficients for relative color, average color, and flow measure, 0.978, 0.966, and 0.997).

CONCLUSIONS

The acceptable rates of intraobserver and interobserver variability make this approach potentially suitable for research protocols.

Managing women with post-menopausal bleeding

Transvaginal ultrasound examination can reliably distinguish women with post-menopausal bleeding (PMB) who are at low risk of endometrial pathology (endometrial thickness < or =4 mm) from those who are at high risk (endometrium > or =5 mm) and can rule out focally growing lesions in the uterine cavity using saline infusion into the cavity as a negative contrast agent (hydrosonography). The 5 mm cut-off is applicable irrespective of the use of hormone replacement therapy. It is justified to refrain from endometrial sampling in women with PMB and an endometrial thickness of < or =4 mm because the risk of endometrial cancer in these women is low (0.1-1.0%). However, it is not known whether these women need follow-up. About 80% of women with PMB and an endometrium of > or =5 mm have focally growing pathological lesions in the uterine cavity. These should be removed by operative hysteroscopy because dilatation and curettage (D and C) will fail to diagnose and remove a large proportion of these lesions. However, D and C is a reliable diagnostic method for women without focal lesions in the uterine cavity. It is not known whether simple outpatient sampling devices (e.g. Pipelle) are as reliable as D and C in women without focal lesions. A measurement of endometrial thickness is a simple and accurate method for estimating the risk of endometrial cancer. The reliability of ultrasound evaluation of endometrial morphology and/or vascularization for risk estimation of endometrial malignancy remains to be determined.