A transcervical amniotic fluid collector: a new medical device for the assessment of amniotic fluid in patients with ruptured membranes.

AIM: To describe a new device for the transcervical collection of amniotic fluid (AF) in patients with ruptured membranes, and to compare the concentration of proteins in fluid retrieved by transabdominal amniocentesis and the transcervical AF collector. STUDY DESIGN: Paired AF samples were collected in patients with preterm prelabor rupture of membranes (PROM) (n=11) by transabdominal amniocentesis and with the transcervical AF collector (Yoon's AF Collector™). Three proteins known to have high concentrations in AF [α-fetoprotein (AFP), ß-human chorionic gonadotrophin (ß-hCG), and prolactin] were measured. RESULTS: (1) There was a significant correlation between the concentrations of analytes in AF obtained by transabdominal amniocentesis and by the transcervical AF collector (r=0.94, P<0.001 for AFP; r=0.96, P<0.001 for ß-hCG; r=0.72, P<0.05 for prolactin); (2) Bland-Altman plots showed no evidence of heteroscedasticity between transabdominal or transcervical AF concentrations of these markers. CONCLUSIONS: There was a strong correlation between the concentrations of proteins in AF collected by amniocentesis or with the transcervical device.

The impact of local guidelines on the tumour marker requesting patterns of a General Surgery Department.

BACKGROUND: The inappropriate use of tumour markers (TMs) is a common problem. The aim of this audit was to evaluate the impact of local guidelines on the TM requesting patterns of a General Surgery Department. METHODS: CA 125, CA 19-9, CA15-3, CEA, AFP and HCG requests from all hospital surgical locations were audited over two periods of eight months before and after the implementation of local requesting guidelines. RESULTS: Postintervention, total TM requests decreased by 32% while patient requests decreased by 9.8%. Single TM requesting increased and requests for panels containing four or more TMs decreased from 279 to 60 requests (78% reduction). CONCLUSION: Interdepartmental collaboration and the implementation of local guidelines have resulted in a change in requesting behaviour, most notably a reduction in multiple TM panel requests.

Rechargeable battery-triggered electrochemiluminescence detection on microfluidic origami immunodevice based on two electrodes.

A low-cost, portable rechargeable battery was firstly used to fabricate a battery-triggered, screen-printed two-electrode electrochemiluminescent immunoassay on a 3D microfluidic origami electronic device.

Validación del método de valoración biológica de gonadotrofina coriónica humana / Validation of the biological potency test for human chorionic gonadotropin

Introducción: en el Centro de Investigación y Desarrollo de Medicamentos se cuenta con una serie de ensayos biológicos para el control de calidad que deben ser sujetos a validación, entre ellos se encuentra la valoración biológica de gonadotrofina coriónica humana. Objetivo: evaluar el desempeño del método de valoración biológica de gonadotrofina coriónica humana. Métodos: se evaluaron la exactitud, la precisión y la especificidad como parámetros de validación siguiendo la metodología descrita en la Regulación 41-2007 del Centro para el Control Estatal de la Calidad de los Medicamentos (CECMED) para la Validación de métodos de análisis. Resultados: en el estudio de exactitud no se observaron diferencias significativas entre los valores de peso del útero obtenidos al ensayar la muestra y el material de referencia a las tres dosis administradas. En el estudio de la repetibilidad se alcanzaron coeficientes de variación menor del 50 por ciento. No se observaron diferencias significativas entre las precisiones alcanzadas por dos analistas diferentes en días diferentes. El estudio de especificidad mostró que los excipientes o sustancias auxiliares de la formulación no interfieren en la valoración biológica del producto. Conclusiones: el método biológico validado resultó ser específico, exacto y preciso en el rango de concentraciones estudiadas, lo que corrobora su calidad, teniendo un valor agregado

Introduction: a number of biological tests for quality control used in the Center for Drug Research and Development should be validated. Biological potency test of human chorionic gonadotropin is one of them. Objective: to evaluate the performance of the human chorionic gonadotropin biological potency test. Methods: the accuracy, precision and specificity were evaluated as validation parameters according to the 41-2007 Regulation of the Center for the State Control of Drug Quality (CEDMED) for analysis method validation. Results: in the accuracy test, no significant differences were observed between the uterus weight values from tested sample and the reference material at the 3 tested doses. Variation coefficients were less than 50 percent in the repeatability test. There were no significant differences between the precision values of two different analysts at different times. The specificity test showed that excipients or auxiliary substances in the formulation did not interfere with the results of the biologic potency test of the final product. Conclusions: the validated biological method showed good accuracy, precision and specificity in the range of studied concentrations, all of which proved its quality, so it has added value

Use of ethnic-specific medians for Hispanic patients reduces ethnic disparities in multiple marker screening.

OBJECTIVE: To estimate whether midtrimester maternal serum analyte concentrations differ between Caucasian and Hispanic women and whether using ethnic-specific medians affects quad screen performance. METHOD: Caucasian and Hispanic patients with singletons who underwent maternal serum screening in our laboratory were identified. Alfa-fetoprotein (AFP), estriol, human chorionic gonadotrophin (hCG), and inhibin-A medians were derived separately for Caucasians, Hispanics, and for the composite group. Using composite medians, intergroup mean multiples of the medians (MoMs) for each analyte were compared. Using ethnic-specific medians, new MoMs were calculated and utilized in a risk estimation algorithm. RESULTS: A total of 5478 Caucasian and 2246 Hispanic pregnancies were evaluated. Intergroup MoMs were significantly different for all analytes. AFP, hCG, and inhibin-A were lower in Hispanics, while estriol was higher (P < 0.0001). Using composite medians, the screen-positive rate (SPR) for trisomy 21 was 5.39% in Caucasians and 3.29% in Hispanics. Ethnic-specific medians reduced this disparity: 4.76% in Caucasians and 4.05% in Hispanics. The SPR for neural tube defects with composite medians was 1.44% for Caucasians and 0.89% for Hispanics; with ethnic-specific medians, the SPR was 1.42% for Caucasians and 1.07% for Hispanics. CONCLUSION: Serum analyte concentrations differ between Caucasian and Hispanic gravidas. Use of ethnic-specific medians reduces the disparity in SPR for trisomy 21 and neural tube defects.

Cross-trimester repeated measures testing for Down's syndrome screening: an assessment.

OBJECTIVES: To provide estimates and confidence intervals for the performance (detection and false-positive rates) of screening for Down's syndrome using repeated measures of biochemical markers from first and second trimester maternal serum samples taken from the same woman. DESIGN: Stored serum on Down's syndrome cases and controls was used to provide independent test data for the assessment of screening performance of published risk algorithms and for the development and testing of new risk assessment algorithms. SETTING: 15 screening centres across the USA, and at the North York General Hospital, Toronto, Canada. PARTICIPANTS: 78 women with pregnancy affected by Down's syndrome and 390 matched unaffected controls, with maternal blood samples obtained at 11-13 and 15-18 weeks' gestation, and women who received integrated prenatal screening at North York General Hospital at two time intervals: between 1 December 1999 and 31 October 2003, and between 1 October 2006 and 23 November 2007. INTERVENTIONS: Repeated measurements (first and second trimester) of maternal serum levels of human chorionic gonadotrophin (hCG), unconjugated estriol (uE3) and pregnancy-associated plasma protein A (PAPP-A) together with alpha-fetoprotein (AFP) in the second trimester. MAIN OUTCOME MEASURES: Detection and false-positive rates for screening with a threshold risk of 1 in 200 at term, and the detection rate achieved for a false-positive rate of 2%. RESULTS: Published distributional models for Down's syndrome were inconsistent with the test data. When these test data were classified using these models, screening performance deteriorated substantially through the addition of repeated measures. This contradicts the very optimistic results obtained from predictive modelling of performance. Simplified distributional assumptions showed some evidence of benefit from the use of repeated measures of PAPP-A but not for repeated measures of uE3 or hCG. Each of the two test data sets was used to create new parameter estimates against which screening test performance was assessed using the other data set. The results were equivocal but there was evidence suggesting improvement in screening performance through the use of repeated measures of PAPP-A when the first trimester sample was collected before 13 weeks' gestation. A Bayesian analysis of the combined data from the two test data sets showed that adding a second trimester repeated measurement of PAPP-A to the base test increased detection rates and reduced false-positive rates. The benefit decreased with increasing gestational age at the time of the first sample. There was no evidence of any benefit from repeated measures of hCG or uE3. CONCLUSIONS: If realised, a reduction of 1% in false-positive rate with no loss in detection rate would give important benefits in terms of health service provision and the large number of invasive tests avoided. The Bayesian analysis, which shows evidence of benefit, is based on strong distributional assumptions and should not be regarded as confirmatory. The evidence of potential benefit suggests the need for a prospective study of repeated measurements of PAPP-A with samples from early in the first trimester. A formal clinical effectiveness and cost-effectiveness analysis should be undertaken. This study has shown that the established modelling methodology for assessing screening performance may be optimistically biased and should be interpreted with caution.

First trimester screening for Down syndrome using free beta hCG, total hCG and PAPP-A: an exploratory study.

OBJECTIVE: To investigate the potential utility of first trimester screening for Down syndrome using Free beta-hCG, total hCG and PAPP-A. MATERIALS AND METHODS: Using estimates from the literature, a simulation study was undertaken to estimate the performance of tests incorporating, Free beta-hCG, total hCG and PAPP-A at gestations of 8-12 weeks. We used sensitivity analysis to assess the effect of departures from the assumed model. RESULTS: We estimate that detection rates in excess of 75% for a false positive rate (FPR) of 3% can be achieved with first trimester measures of PAPP-A, total hCG and Free beta-hCG at 8 weeks-the addition of total hCG adding 11%. Detection rates of around 90% for a FPR of 3% can be achieved through the inclusion of nuchal translucency (NT) at 12 weeks to these early first trimester biochemical markers. Our analysis indicates that the marginal benefit of adding total hCG diminishes rapidly with gestational age and that there is little benefit from adding total hCG later than 10 weeks of gestation. CONCLUSION: The performance of first trimester screening using early combinations of total hCG, Free beta-hCG and PAPP-A should be assessed in further studies.

Epidermal growth factor contamination and concentrations of intact human chorionic gonadotropin in commercial preparations.

It is well-known that many urinary-derived human chorionic gonadotropin (hCG) preparations contain a variety of contaminating agents that may influence the efficacy and possible safety of their application. Herein, we report the finding of epidermal growth factor (EGF) contamination and high hCG beta core levels in two leading brands of hCG - findings that will promote the use of recombinant hCG instead of the cruder, urinary-derived formulations.

Current concepts in risk factor assessment for advanced germ cell cancer.

Disseminated germ cell tumors (GCT) have come to represent the model for a curable malignancy, as cure rates with cisplatin-based chemotherapy coupled with appropriate surgery are 70% to 80%. For patients with favorable prognostic factors who achieve and maintain a complete response, the outlook is good. However, despite advances in the treatment of this disease, a significant number of patients with metastatic GCT fail to respond either primarily or secondarily. Being able to identify poor-risk patients up front would allow for appropriate selection of candidates for high-risk trials. Several different classification systems were previously developed at several treatment centers in the United States and Europe. These models recognized different clinical variables as prognosticators and had unique functional properties. However, these served as precursors to the International Germ Cell Consensus Classification that was developed to establish a universally accepted standard. The development of this system has allowed for valid comparisons of ongoing and future trials. Furthermore, this system will serve to encourage international collaboration for the study of high-risk GCT.

The roles of clinical assessment, human chorionic gonadotropin assays, and ultrasonography in medical abortion practice.

The clinical assessment of patients who request early medical abortion includes confirmation of the diagnosis of pregnancy and estimation of gestational age. Accurate gestational dating is essential, because the efficacies of medical abortion regimens decline as pregnancy advances. Whereas medical abortion researchers in the United States have relied on routine ultrasonography for gestational dating, abortion providers experienced with mifepristone and prostaglandin regimens outside the United States have reported high efficacy and safety primarily with clinical dating parameters. Diligent follow-up of patients allows clinicians to confirm that complete abortion has occurred without complications. In cases of uncertain outcome or suspected ectopic pregnancy, transvaginal ultrasonography and beta-human chorionic gonadotropin assays can assist in prompt diagnosis and management. As medical abortion with mifepristone and misoprostol becomes more prevalent in the United States, studies will be needed to further evaluate the effects of these modalities on medical abortion outcomes.

Incremental cost-effectiveness analysis: the optimal strategy depends on the strategy set.

Evaluating the incremental cost-effectiveness of a technology is critical to understanding the impact of its adoption. The purpose of this study was to evaluate, using a particular example, how the specific alternatives selected for a cost-effectiveness analysis may influence the results of the analysis. In this example, we analyzed the incremental cost-effectiveness of estriol screening for Down syndrome. Model assumptions of expected costs and effectiveness were based on previously published work involving four clinical strategies, including a "do nothing" (no screening) strategy. When the analysis started with all four strategies, two of the strategies could not be considered cost-effective because of extended dominance. However, when we eliminated the "do nothing" from the strategy set because of its clinical irrelevance, all three remaining strategies might be considered cost-effective from a policy perspective. We concluded that the incremental cost-effectiveness of clinical strategies could be strongly affected by the starting point for the analysis.

Why do immunoassays for tumour markers give differing results?--a view from the UK National External Quality Assessment Schemes.

External Quality Assessment schemes can provide unique insight into how current methods are performing in the field. Results from the UK National External Quality Assessment Schemes, which monitor performance of immunoassays for a number of tumour markers and peptide hormones in serum, show that in spite of considerable improvements resulting from increased assay automation, major discrepancies in results obtained are still observed. Reasons for this include poor calibration, use of antibodies of differing specificity, and vulnerability to clinically relevant interferences. Variation in quoted reference ranges is also a cause of concern. Each of these important aspects of performance will require attention if improved between-method and between-laboratory agreement is to be achieved.

Assessment of the functional affinity constant of monoclonal antibodies using an improved enzyme-linked immunosorbent assay.

The use of an enzyme-linked immunosorbent assay (ELISA) for the determination of affinity constants implies heterogeneous measurements. Therefore, despite their simplicity, direct solid-phase binding assays are not common. Many investigators have serious, and mostly justified, reservations about the application of solid-phase affinity methods. They refer to problems such as diffusion effects and difficulties in reaching equilibrium due to heterogeneous binding and co-operativity. Accordingly, functional affinity determinations are often described as meaningless. These objections apply to the measurement of the affinity of a monoclonal antibody using the enzyme-linked immunosorbent assay of Beatty et al. (J. Immunol. Methods (1987) 100, 173), which is based on the effect of antibody affinity on the sigmoidal dose response curve. The affinity constant is calculated by mathematical equations, based on the Law of Mass Action and the authors made a number of important assumptions--avoiding the above mentioned problems--in order to justify the use of the Law of Mass Action. By carefully examining these assumptions we have developed an improved ELISA procedure for functional affinity determinations on the basis of a primary coating with the antigen only. the coating conditions were validated by employing gold labelled colloidal particles and physical counting of the bound particles under the scanning electron microscope. Since monovalent binding between human chorionic gonadotropin and its monoclonal antibody could be achieved under equilibrium conditions, the application of the Law of Mass Action and hence of the Beatty formula became possible. We conclude that under these conditions functional affinity determinations are appropriate.

Medical management should be routinely used as primary therapy for ectopic pregnancy.

It does not appear that methotrexate can or should be used to totally replace laparoscopic salpingostomy. However, given its success rate in selected patients, its cost-effectiveness, and its low incidence of side effects, methotrexate therapy certainly can be used as an alternative therapy. The next step in developing this treatment option will be to conduct a randomized clinical trial comparing laparoscopic salpingostomy with intramuscular methotrexate. This type of study will answer questions regarding the patient's health related quality of life and economic impact of the two treatment modalities. For now, it seems prudent to offer methotrexate to those patients with an unruptured ectopic gestational mass 3.5 cm or less in greatest dimension.

Valoración de alfa fetoproteína y gonadotropina coriónica en el diagnóstico de 290 tumores germinales testiculares / Evaluation of alpha-fetoprotein and chorionic-gonadotropin in the diagnosis of 290 testicular germinal tumors

Desde el punto de vista terapéutico y pronóstico, los tumores germinales de testículo se dividen en seminoma puro y no seminoma. El diagnóstico definitivo toma en cuenta la histología, la presentación clínica, y los niveles séricos de alfa fetoproteína (AFP) y fracción beta de gonadotropina coriónica humana (HGC). Objetivo: Correlacionar los valores de AFP y HGC con la variedad histológica y etapa clínica para determinar si cambia el diagnóstico final del tumor. Material y métodos: Se tomó suero en la valoración inicial de 290 pacientes con tumores germinales testiculares determinando niveles de AFP y HGC (ELISA, Quantum II de Abbott). Se revisaron los expedientes para conocer estirpe histológica y estadio clínico. Se consideraron seminomas los tumores con histología de seminoma puro sin elevación de AFP y HGC menor de 500 mUI/ml; los tumores germinales no seminomatosos de testículo (TGNST) presentaron histología de no seminoma o de seminoma con elevación de AFP o HGC mayor de 500 mUI/ml. Resultados: Histológicamente se encontraron 120 seminomas puros y 170 TG-NST. Se reclasificó a 13 casos de seminomas como TGNST ya que 10 presentaron elevación de AFP (tres AFP únicamente y siete AFP más HGC) y tres casos tuvieron elevación de HGC > 500 mUI/ml. La distribución final fue de 107 seminomas y 83 seminomas. Conclusiones: Al analizar los niveles séricos de AFP y HGC con la histopatología se obtiene el diagnóstico definitivo de la estirpe tumoral testicular mejorando la selección del tratamiento

MOMs (multiples of the median) and DADs (discriminant aneuploidy detection): improved specificity and cost-effectiveness of biochemical screening for aneuploidy with DADs.

OBJECTIVE: Our purpose was to assess the efficacy of double- and triple-screening paradigms for Down syndrome and to develop a more logical, statistical approach to risk prediction that will decrease the cost of screening and allow the incorporation of new parameters appropriately weighted for their contribution. STUDY DESIGN: Data from 24,504 patients who had biochemical screening for Down syndrome by single (alpha-fetoprotein), double (alpha-fetoprotein, beta-human chorionic gonadotropin), or triple screening (alpha-fetoprotein, beta-human chorionic gonadotropin, unconjugated estriol) who had complete outcome information were analyzed by (1) existing gaussian-based methods, (2) the Glasgow ratio method, and (3) a new statistical approach (i.e., directly adjusted data sets for discriminant aneuploidy detection [DADs]) RESULTS: By use of individual risk-based thresholds for "at risk" status, both double and triple screening performed far better than single screening, but the percentages of patients at risk varied widely. When the percentages at risk were held constant, the sensitivity of double and triple screenings was similar, suggesting that there are no benefits of using estriol as a third marker. For 25,000 patients the use of only alpha-fetoprotein and beta-human chorionic gonadotropin would save about $500,000, with no decrease in sensitivity. With the DADs approach a statistically sound model giving more stable estimates was developed that permits each factor to be analyzed for its own explained proportion of variance and allows each parameter to have different weighting. For this data set the same sensitivity was seen with, conservatively, a 1% reduction in the percentage of patients at risk, which would reduce by 250 the number of amniocenteses, at a further savings of about $400,000. CONCLUSIONS: By use of existing methods, double screening is equally as effective as triple screening, so that the expense of estriol is unnecessary. The DADs approach, by allowing for variable weighting of parameters, lowers the at risk percentage and will permit a much more flexible approach as new parameters become available. Changing to DADs and eliminating estriol should achieve higher specificity for the same sensitivity and save, conservatively, about $900,000 in this series. Extrapolated nationally, if confirmed, the annual savings could approach $72,000,000.

Doppler assessment of the uterine circulation and the clinical behaviour of gestational trophoblastic tumours requiring chemotherapy.

The haemodynamics of the uterine arteries and myometrium were assessed using Doppler ultrasound in forty consecutive patients requiring treatment for invasive mole and choriocarcinoma. The investigations were performed prior to the commencement of chemotherapy and the subjects followed prospectively. The Doppler waveforms from the uterine arteries were analysed using the pulsatility index. It was found that patients with a pulsatility index of 1.1 or less were significantly more likely to develop drug resistance than those with a higher value (P < 0.04). There was no significant association between the pulsatility index and metastatic disease or uterine bleeding. Five out of eight patients who developed drug resistance could have avoided initial inadequate treatment if the Doppler findings were included in the scoring system for selecting chemotherapy for these tumours. It can be concluded that assessment of the uterine arteries using the pulsatility index prior to the treatment of patients with invasive mole and choriocarcinoma is of help in predicting those who will develop drug resistance.

Prenatal biochemical screening for Down's syndrome and neural tube defects.

Antenatal serum screening for Down's syndrome is now becoming established in many centers throughout the world. The screening method is based on the measurement of alpha-fetoprotein, unconjugated estriol, and human chorionic gonadotropin between 15 and 22 weeks of pregnancy. These measurements, used in conjunction with a woman's age, provide risk estimates of having a pregnancy with Down's syndrome for every woman screened. By identifying the 5% of women with highest risk and offering them an amniocentesis, about 60% of Down's syndrome pregnancies can be identified. If an ultrasound scan examination is used routinely to estimate gestational age, the detection rate can be increased by 5% to 10%. Recent information on the distribution of the three serum markers in twin pregnancies and pregnancies with insulin-dependent diabetes mellitus now means that screening can be carried out in such pregnancies. Various other serum markers of Down's syndrome have been reported, but at present they do not have a place in routine antenatal screening for Down's syndrome. The role of amniotic fluid acetylcholinesterase measurement, alone and in combination with amniotic fluid alpha-fetoprotein measurement, in the antenatal diagnosis of open neural tube defects has recently been clarified. The best policy is to perform an amniotic fluid alpha-fetoprotein measurement as the primary test and an acetylcholinesterase determination for those women who have an amniotic fluid alpha-fetoprotein measurement of two times the normal median or greater. The acetylcholinesterase can be measured either by the standard method (gel electrophoresis) or by a new quantitative monoclonal antibody method.

[Sense and nonsense of tumor markers in practice]. / Sinn und Unsinn von Tumormarkern in der Praxis.

Tumor markers can be used for screening, diagnosis, planning and monitoring of therapy, for early detection of relapse and for psychological reasons. Unfortunately none of the currently available tumor markers can be used for all these purposes. An ever increasing number of tumor markers can be determined; however, the advantage for the individual patient's management is less obvious. We therefore critically review the routine use of some tumor markers such as CEA, AFP, beta-HCG, LDH, CA-125, CA 19-9, prostate acid phosphatase, prostate specific antigen and CA 15-3. The use of tumor markers requires a sound knowledge of the biology of the marker, the neoplastic disease and the available treatment. When tumor markers do not add new information and have no diagnostic or therapeutic consequences, their use becomes an expensive medical nonsense!

Biochemical assessment and prediction of gestational well-being.

It is apparent from this brief review of serum markers that there is no ideal biochemical screen available to either assure fetal well-being or reliably predict fetal compromise. At present, MSAFP has become the dominant serum marker, but much work needs to be done to refine its usefulness as a screen and its utility in association with other measurements of fetoplacental well-being. The trend in modern obstetric management is toward an array of biophysical tests of fetal well-being, particularly in the last trimester of pregnancy. Biochemical screening in early gestation is used increasingly to assess future fetoplacental status and to predict risk for later pregnancy complications. Combinations of these biochemical and biophysical modalities will likely achieve the greatest predictive success in assessing fetal and placental well-being.