***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Objective To investigate the value of transvaginal ultrasonography ( TVU ) in the evaluation of the endometrium in postmenopausal women without vaginal bleeding . Methods This was a prospect i ve , cohort , observational study which included 259 consecutive , asymptomatic , postmenopausal women who were referred to the outpatient clinics of Shiraz University of Medical Sciences . All the participants underwent TVU by the same gynecologist at the same time as hysteroscopy and endometrial biopsy were performed . Both 3 mm and 5 mm were considered as cut-off values . Endometrial histopathology was considered the gold-st and ard diagnosis and the sensitivity , specificity , positive predictive value ( PPV ) and negative predictive value ( NPV ) of TVU were calculated on the basis of pathologic reports . Results The mean age of the patients was 54.2 ± 7.46 years ( range 36–79 years ) .  The mean endometrial thickness was found to be 3.83 ± 2.95 mm ( range 1–25 mm ) ; it was > 5 mm in 41 ( 15.8%% ) patients . The sensitivity , specificity , PPV and NPV were 62.2%% , 93.9%% , 68.3%% and 92.2%% , respectively . The receiver-operating characteristics curve showed an area under the curve of 0.853 ( 95%% confidence interval 0.788–0.917 ) , indicating a moderate accuracy . Conclusion TVU is a moderately accurate test in asymptomatic postmenopausal women . Due to its high false-positive rate , its positive results can not be interpreted BACKGROUND Transvaginal ultrasonography is a noninvasive procedure that may be used to detect endometrial disease . However , its usefulness in screening for asymptomatic disease in postmenopausal women before or during treatment with estrogen or estrogen-progesterone replacement is not known . METHODS We compared the sensitivity and specificity of transvaginal ultrasonography and endometrial biopsy  for the detection of  endometrial disease  in 448 postmenopausal women who received estrogen alone , cyclic or continuous estrogen-progesterone , or placebo for three years . RESULTS Concurrent ultrasonographic and biopsy results were available for 577 examinations in the 448 women , 99 percent of whom were undergoing routine annual follow-up .  Endometrial thickness was less than 5 mm in 45 percent of the examinations , 5 to 10 mm in 41 percent , more than 10 mm in 12 percent , and not measured in 2 percent , and it was higher in the women receiving estrogen alone than in the other groups . Biopsy detected 11 cases of serious disease : 1 case of adenocarcinoma , 2 cases of atypical simple hyperplasia , and 8 cases of complex hyperplasia . Biopsy also detected simple hyperplasia in 20 cases . At a threshold value of 5 mm for endometrial thickness , transvaginal ultrasonography had a positive predictive value of 9 percent for detecting any abnormality , with 90 percent sensitivity , 48 percent specificity , and a negative predictive value of 99 percent . With this threshold , a biopsy would be indicated in more than half the women , only 4 percent of whom had serious disease . CONCLUSIONS Transvaginal ultrasonography has a poor positive predictive value but a high negative predictive value for detecting serious endometrial disease in asymptomatic postmenopausal women The aim of this study was to assess endometrial thickness using transvaginal sonography in a representative sample of postmenopausal women and to evaluate whether the technique can be used for screening of endometrial cancer . A r and om sample ( n = 1000 ) of the total population of women aged 45 - 80 years resident in the city of Göteborg in 1993 was invited to attend for transvaginal sonography .  The only exclusion criterion was hysterectomy . Transvaginal sonography was performed in 827 women . An endometrium of < or = 4 mm was not investigated further . Women with an endometrium of 5 - 7 mm and non-measurable cases were re-assessed 1 year later , and women with an endometrial thickness of > or = 8 mm were investigated directly with hysteroscopy and /or dilatation and curettage .  A total of 559 women were postmenopausal and 183 were taking some form of hormonal substitution ( 33 % ) . One case of endometrial cancer ( endometrial thickness 19 mm ) , 23 cases of polyps without atypia ( endometrial thickness 8 - 18 mm ) and no cases of endometrial hyperplasia were diagnosed . Endometrial thicknesses were as follows ( mean + /- SEM ; respectively grouped as < or = 4 mm , 5 - 7 mm and > or = 8 mm ) : total population of postmenopausal women ( 3.4 + /- 0.1 mm , 82 % , 13 % and 6 % ) ; postmenopausal women without estrogens ( 3.0 + /- 0.1 mm , 90 % , 7 % and 3 % ) ; postmenopausal women on medium-potency estrogens + gestagen ( 5.1 + /- 0.3 mm , 49 % , 40 % and 11 % ) and women with low-potency estrogens only ( 3.6 + /- 0.3 mm , 85 % , 6 % and 9 % ) . The prevalence of endometrial cancer was 0.2 % and for benign polyps 3.2 % in this representative sample of postmenopausal women . Our results do not support generalized endometrial screening with transvaginal sonography OBJECTIVE To assess the utility of performing routine sonohysterography in conjunction with endometrial thickness measurement for detecting intrauterine pathology in asymptomatic postmenopausal women . DESIGN Asymptomatic postmenopausal women ( n = 60 , mean age 52.7 + /- 4.5 years , amenorrhea > or = 6 months , follicle stimulating hormone > or = 40 mIU/mL ) were evaluated with sonohysterography followed by endometrial biopsy before initiating hormone replacement therapy . RESULTS Hyperplasia was detected in 5 of 22 ( 22.7 % ) patients with endometrial thickness of > 5 mm and in 0 of 38 ( 0.0 % ) patients with endometrial thickness of < or = 5 mm . When sonohysterography was performed , intracavitary pathology was discovered in 14 of 38 ( 36.8 % ) patients with endometrial thickness of < or = 5 mm ( 10 polyps , three submucosal myomas , and one septate uterus ) and 14 of 22 ( 63.6 % ) patients with endometrial thickness of > 5 mm ( nine polyps , four submucosal myomas , and one Asherman 's syndrome ) . CONCLUSIONS Endometrial thickness of < or = 5 mm excludes hyperplasia but does not eliminate other intrauterine pathology that may be discovered by sonohysterography Diagnosis is a critical component of health care , and clinicians , policymakers , and patients routinely face a range of questions regarding diagnostic tests . They want to know whether testing improves outcome ; what test to use , purchase , or recommend in practice guidelines ; and how to interpret test results . Well- design ed  diagnostic test accuracy studies can help in making these decisions , provided that they transparently and fully report their participants , tests , methods , and results as facilitated , for example , by the STARD ( St and ards for Reporting of Diagnostic Accuracy ) statement ( 1 ) . That 25-item checklist was published in many journals and is now adopted by more than 200 scientific journals worldwide . As in other areas of science , systematic review s and meta- analysis of accuracy studies can be used to obtain more precise estimates when small studies addressing the same test and patients in the same setting are available . Review s can also be useful to establish whether and how scientific findings vary by particular subgroups , and may provide summary estimates with a stronger generalizability than estimates from a single study . Systematic review s may help identify the risk for bias that may be present in the original studies and can be used to address questions that were not directly considered in the primary studies , such as comparisons between tests . The Cochrane Collaboration is the largest international organization preparing , maintaining , and promoting systematic review s to help people make well-informed decisions about health care ( 2 ) . The Collaboration decided in 2003 to make preparations for including systematic review s of diagnostic test accuracy in their Cochrane Data base of Systematic Review s. To enable this , a working group ( Appendix ) . was formed to develop methodology , software , and a h and book The first diagnostic test accuracy review was published in the Cochrane Data base in October 2008 . In this paper , we review recent method ological developments concerning problem formulation , location of literature , quality assessment , and meta- analysis of diagnostic accuracy studies by using our experience from the work on the Cochrane H and book . The information presented here is based on the recent literature and up date s previously published guidelines by Irwig and colleagues ( 3 ) . Definition of the Objectives of the Review Diagnostic test accuracy refers to the ability of a test to distinguish between patients with disease ( or more generally , a specified target condition ) and those without . In a study of test accuracy , the results of the test under evaluation , the index test , are compared with those of the reference st and ard determined in the same patients . The reference st and ard is an agreed-on and accurate method for identifying patients who have the target condition . Test results are typically categorized as positive or negative for the target condition . By using such binary test outcomes , the accuracy is most often expressed as the test 's sensitivity ( the proportion of patients with positive results on the reference st and ard that are also positive on the index test ) and specificity ( the proportion of patients with negative results on the reference st and ard that are also negative on the index test ) . Other measures have been proposed and are in use ( 46 ) . It has long been recognized that test accuracy is not a fixed property of a test . It can vary between patient subgroups , with their spectrum of disease , with the clinical setting , or with the test interpreters and may depend on the results of previous testing . For this reason , inclusion of these elements in the study question is essential . In order to make a policy decision to promote use of a new index test , evidence is required that using the new test increases test accuracy over other testing options , including current practice , or that the new test has equivalent accuracy but offers other advantages ( 79 ) . As with the evaluation of interventions , systematic review s need to include comparative analyses between alternative testing strategies and should not focus solely on evaluating the performance of a test in isolation . In relation to the existing situation , 3 possible roles for a new test can be defined : replacement , triage , and add-on ( 7 ) . If a new test is to replace an existing test , then comparing the accuracy of both tests on the same population and with the same reference st and ard provides the most direct evidence . In triage , the new test is used before the existing test or testing pathway , and only patients with a particular result on the triage test continue the testing pathway . When a test is needed to rule out disease in patients who then need no further testing , a test that gives a minimal proportion of falsenegative results and thus a relatively high sensitivity should be used . Triage tests may be less accurate than existing ones , but they have other advantages , such as simplicity or low cost . A third possible role of a new test is add-on . The new test is then positioned after the existing testing pathway to identify false-positive or false-negative results after the existing pathway . The review should provide data to assess the incremental change in accuracy made by adding the new test . An example of a replacement question can be found in a systematic review of the diagnostic accuracy of urinary markers for primary bladder cancer ( 10 ) . Clinicians may use cytology to triage patients before they undergo invasive cystoscopy  , the reference st and ard for bladder cancer . Because cytology combines high specificity with low sensitivity ( 11 ) , the goal of the review was to identify a tumor marker with sufficient accuracy to either replace cytology or be used in addition to cytology . For a marker to replace cytology , it has to achieve equally high specificity with improved sensitivity . New markers that are sensitive but not specific may have roles as adjuncts to conventional testing . The review included studies in which the test under evaluation ( several different tumor markers and cytology ) was evaluated against cystoscopy or histopathology . Included studies compared 1 or more of the markers , cytology only , or a combination of markers and cytology . Although information on accuracy can help clinicians make decisions about tests , good diagnostic accuracy is a desirable but not sufficient condition for the effectiveness of a test ( 8) . To demonstrate that using a new test does more good than harm to patients tested , r and omized trials of test- and -treatment strategies and review s of such trials may be necessary . However , with the possible exception of screening , in most cases , such r and omized trials are not available and systematic review s of test accuracy may provide the most useful evidence available to guide clinical and health policy decision making and use as input for decision and cost-effectiveness analysis ( 12 ) . Identification and Selection of Studies Identifying test accuracy studies is more difficult than search ing for r and omized trials ( 13 ) . There is not a clear , unequivocal keyword or indexing term for an accuracy study in literature data bases comparable with the term r and omized , controlled trial . The Medical Subject Heading sensitivity and specificity may look suitable but is inconsistently applied in most electronic bibliographic data bases . Furthermore , data on diagnostic test accuracy may be hidden in studies that did not have test accuracy estimation as their primary objective . This complicates the efficient identification of diagnostic test accuracy studies in electronic data bases , such as MEDLINE . Until indexing systems properly code studies of test accuracy , search ing for them will remain challenging and may require additional manual search es , such as screening reference lists . In the development of a comprehensive search strategy , review authors can use search strings that refer to the 
    Output:
    
The results from this systematic review do not justify the use of endometrial thickness as a screening test for endometrial carcinoma and atypical endometrial hyperplasia in asymptomatic postmenopausal women not using HRT