External validation of models to predict the outcome of pregnancies of unknown location: a multicentre cohort study.

OBJECTIVE: To validate externally five approaches to predict ectopic pregnancy (EP) in pregnancies of unknown location (PUL): the M6P and M6NP risk models, the two-step triage strategy (2ST, which incorporates M6P), the M4 risk model, and beta human chorionic gonadotropin ratio cut-offs (BhCG-RC). DESIGN: Secondary analysis of a prospective cohort study. SETTING: Eight UK early pregnancy assessment units. POPULATION: Women presenting with a PUL and BhCG >25 IU/l. METHODS: Women were managed using the 2ST protocol: PUL were classified as low risk of EP if presenting progesterone ≤2 nmol/l; the remaining cases returned 2 days later for triage based on M6P. EP risk ≥5% was used to classify PUL as high risk. Missing values were imputed, and predictions for the five approaches were calculated post hoc. We meta-analysed centre-specific results. MAIN OUTCOME MEASURES: Discrimination, calibration and clinical utility (decision curve analysis) for predicting EP. RESULTS: Of 2899 eligible women, the primary analysis excluded 297 (10%) women who were lost to follow up. The area under the ROC curve for EP was 0.89 (95% CI 0.86-0.91) for M6P, 0.88 (0.86-0.90) for 2ST, 0.86 (0.83-0.88) for M6NP and 0.82 (0.78-0.85) for M4. Sensitivities for EP were 96% (M6P), 94% (2ST), 92% (N6NP), 80% (M4) and 58% (BhCG-RC); false-positive rates were 35%, 33%, 39%, 24% and 13%. M6P and 2ST had the best clinical utility and good overall calibration, with modest variability between centres. CONCLUSIONS: 2ST and M6P performed best for prediction and triage in PUL. TWEETABLE ABSTRACT: The M6 model, as part of a two-step triage strategy, is the best approach to characterise and triage PULs.

External validation of risk prediction model M4 in an Australian population: Rationalising the management of pregnancies of unknown location.

BACKGROUND: The prediction model M4 can successfully classify pregnancy of unknown location (PUL) into a low- or high-risk group in developing ectopic pregnancy. M4 was validated in UK centres but in very few other countries outside UK. AIM: To validate the M4 model's ability to correctly classify PULs in a cohort of Australian women. MATERIALS AND METHODS: A retrospective analysis of women classified with PUL, attending a Sydney-based teaching hospital between 2006 and 2018. The reference standard was the final characterisation of PUL: failed PUL (FPUL) or intrauterine pregnancy (IUP; low risk) vs ectopic pregnancy (EP) or persistent PUL (PPUL; high risk). Each patient was entered into the M4 model calculator and an estimated risk of FPUL/IUP or EP/PPUL was recorded. Diagnostic accuracy of the M4 model was evaluated. RESULTS: Of 9077 consecutive women who underwent transvaginal sonography, 713 (7.9%) classified with a PUL. Six hundred and seventy-seven (95.0%) had complete study data and were included. Final outcomes were: 422 (62.3%) FPULs, 150 (22.2%) IUPs, 105 (15.5%) EPs and PPULs. The M4 model classified 455 (67.2%) as low-risk PULs of which 434 (95.4%) were FPULs/IUPs and 21 (4.6%) were EPs or PPULs. EPs/PPULs were correctly classified with sensitivity of 80.0% (95% CI 71.1-86.5%), specificity of 75.9% (95% CI 72.2-79.3%), positive predictive value of 37.8% (95% CI 33.8-42.1%) and negative predictive value of 95.3% (95% CI 93.1-96.9%). CONCLUSIONS: We have externally validated the prediction model M4. It classified 67.2% of PULs as low risk, of which 95.4% were later characterised as FPULs or IUPs while still classifying 80.0% of EPs as high risk.

False-Negative Urine Human Chorionic Gonadotropin Testing in the Clinical Laboratory.

BACKGROUND: Human chorionic gonadotropin (hCG) assays are used to detect pregnancy, and urine point-of-care tests are frequently used to triage patients. Under certain conditions, urine tests can fail to detect pregnancy, which can have serious consequences for patient management. OBJECTIVES: To understand the prevalence of different factors contributing to false-negative urinary hCG testing results at our institution. METHODS: Clinical data for patients with negative urine hCG results and subsequent positive or equivocal serum hCG results within a 1-year period were reviewed. RESULTS: Out of 9447 negative urine hCG results, 11 potential missed diagnoses were identified, with early gestational age as the most common factor, followed by ß-core hook effects. CONCLUSIONS: Although false-negative urine hCG test results are rare, understanding the commonly encountered reasons for inaccurate testing results can help clinical centers develop strategies to minimize risk for patients.

Performance of a quick pregnancy test on whole blood in early pregnancy units: a prospective cohort study.

OBJECTIVE: To assess the diagnostic performance of the NG-Test human chorionic gonadotropin (hCG) WB, which is a new point-of-care (POC) hCG whole-blood test. MATERIALS AND METHODS: This prospective study included women consulted in early pregnancy units for vaginal bleeding and/or pelvic pain with unknown pregnancy status after medical consultation including a pelvic ultrasound scan. A new POC test (the NG-Test hCG WB) and the usual laboratory serum test (considered the gold standard) were performed in patients. The results were interpreted in a blinded manner. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for the NG-Test hCG WB. RESULTS: During the study period, 200 patients were included. The pregnancy rate was 17%. For the laboratory test, with a 5 UI/l hCG positivity threshold, the sensitivity, specificity, PPV, NPV, and Youden index of the NG-Test hCG WB were 89.7, 100, 100, 97.9, and 0.90%, respectively. Considering a 10 UI/l hCG positivity threshold, test sensitivity, specificity, PPV, NPV, and Youden index were 96.3, 100, 100, 99.3, and 0.96%, respectively. False-negative cases were either extremely brief pregnancies or residual hCG after miscarriage. The result was obtained within 5 min with the NG-Test hCG WB versus 90±31 min with the laboratory test. It was easy to use. CONCLUSION: The NG-Test hCG WB showed a high sensitivity, specificity, PPV, and NPV. Its use as triage in the case of a negative pelvic ultrasound exam is a potential strategy to improve patient flow, with an average time saving of 85 min.

Pregnancy and Cancer Treatment: Developing a Standardized Testing Policy and Procedure

Systematic gaps for pregnancy screening and testing of patients with cancer persist. Absent or inconsistent guidelines and policies are barriers to standardized practice. Awareness among oncology nurses is needed to promote safe cancer care, prevent patient harm, and uphold patient-centered care.

False-positive pregnancy test after transfusion of solvent/detergent-treated plasma.

BACKGROUND: The transmission of pathogens, antibodies, and proteins is a possible consequence of blood product transfusion. A female patient had an unexpected positive serum ß-human chorionic gonadotropin result, indicative of pregnancy, after she had received a transfusion with 1 unit of platelet concentrate, 4 units of red blood cells, and 4 units of pooled solvent/detergent-treated plasma (Octaplas). STUDY DESIGN AND METHODS: To investigate the possibility of passive transfusion of ß-human chorionic gonadotropin from the plasma transfusion, one additional unit from the same batch was thawed and analyzed. To validate the ß-human chorionic gonadotropin assay for use in solvent/detergent-treated plasma and to investigate any interference in the assay, dilution experiments were performed using the implicated plasma batch diluted with male and non-pregnant female sera. Also, plasma from a known pregnant woman was diluted with Octaplas (tested negative for ß-human chorionic gonadotropin) and with a male serum to validate the assay for use in solvent/detergent-treated plasma. RESULTS: The implicated solvent/detergent-treated plasma had a mean ß-human chorionic gonadotropin level of 91.5 mIU/mL. Results from the dilution experiments revealed an excellent correlation (r > 0.99) between ß-human chorionic gonadotropin measurement in solvent/detergent-treated plasma and male serum and no over or under recovery of the expected results. Further measurements of ß-human chorionic gonadotropin levels in the female recipient revealed an estimated half-life of 6 hours. CONCLUSION: This case demonstrates the importance of considering the possibility of passive transmission of analytes to a patient from the transfusion of blood products. Furthermore, the measurement of ß-human chorionic gonadotropin is valid in solvent/detergent-treated plasma using a Roche Cobas analyzer.

Predictive value of serum HCG concentrations in pregnancies achieved after single fresh or vitrified-warmed blastocyst transfer.

Possible differences between serum HCG levels in pregnancies achieved after transfer of a single fresh or a vitrified-warmed blastocyst were evaluated. Out of 1130 single blastocyst transfers resulting in positive HCG results, 789 were single fresh blastocyst transfers and 341 single vitrified-warmed blastocyst transfers. The initial serum HCG levels of 869 clinical intrauterine pregnancies were evaluated, 638 after the transfer of a single fresh blastocysts and 231 after the transfer of a single vitrified-warmed blastocysts. The HCG levels from cycles resulting in a clinical intrauterine pregnancy were significantly higher after the transfer of a single vitrified-warmed blastocyst (383 ± 230 IU/l) versus a fresh transfer (334 ± 192 IU/l; P = 0.01). Threshold values for predicting a clinical pregnancy for a fresh blastocyst were 111 IU/l and for a vitrified-warmed blastocyst 137 IU/l. Our study shows that the overall beta-HCG levels are comparable after the transfer of a fresh or vitrified-warmed blastocyst, suggesting that vitrification most probably does not affect the ability of the embryos to produce beta-HCG. This study further shows that when clinicians counsel patients, they should take into account that higher HCG levels are needed after a vitrified-warmed blastocyst transfer to predict a clinical intrauterine pregnancy.

Self-administered multi-level pregnancy tests in simplified follow-up of medical abortion in Tunisia.

BACKGROUND: This study was conducted to assess the efficacy and acceptability of using a multi-level pregnancy test (MLPT) combined with telephone follow-up for medical abortion in Tunisia, where the majority of providers are midwives. METHODS: Four hundred and four women with gestational age ≤ 70 days' LMP seeking medical abortion at six study sites were enrolled in this open-label trial. Participants administered a baseline MLPT at the clinic prior to mifepristone administration and were asked to take a second MLPT at home and to call in its results before returning the day of their scheduled follow-up visit 10-14 days later. RESULTS: Almost all women with follow-up (97.1 %, n = 332/342) had successful abortions without the need for surgical intervention. The MLPT worked extremely well among women ≤63 days' LMP in ruling out ongoing pregnancy (negative predictive value (NPV) =100 % (n = 298/298)) and also detecting women with ongoing pregnancies (sensitivity = 100 %; 2/2) as needing follow-up due to non-declining hCG. Among women 64-70 days' LMP, the test also worked well in ruling out ongoing pregnancy (NPV = 96.9 % (n = 31/32) but not as well in terms of sensitivity (50 %), with only one of two ongoing pregnancies detected by MLPT as needing follow-up. Most women (95.1 %) found the MLPT to be very easy or easy to use and would consider using the MLPT again (97.4 %) if needed. CONCLUSIONS: Self-administered pre and post MLPT are very easy for women to use and accurate in assessing medical abortion success up to 63 days' LMP. MLPT use for medical abortion follow-up has the potential to facilitate task sharing services and eliminate the burden of routine in-person follow-up visits for the large majority of women. Additional research is warranted to explore the accuracy of the MLPT in identifying ongoing pregnancy among women with gestational ages > 63 days. TRIAL REGISTRATION: This study was registered on May 13, 2010, on clinicaltrials.gov as NCT01150279 .

Pathology consultation on human chorionic gonadotropin testing for pregnancy assessment.

OBJECTIVES: To provide clarity on the use of qualitative and quantitative human chorionic gonadotropin (hCG) tests for the assessment of pregnancy. METHODS: A case scenario and a brief review of the relevant literature describing clinical and analytical considerations regarding hCG testing are presented. RESULTS: In pregnancy, hCG is nearly always detectable in serum and urine within 16 days after ovulation. Serial hCG testing is valuable in the evaluation of suspected ectopic pregnancy. hCG assays vary in their analytical specificity, and qualitative tests may be less analytically sensitive than claimed. Erroneous hCG test results can occur for several reasons. CONCLUSIONS: hCG assays are reliable diagnostic tests for pregnancy assessment, but a clear understanding of their limitations is necessary for appropriate result interpretation.

Analytical performance evaluation of the i-STAT Total ß-human chorionic gonadotropin immunoassay.

BACKGROUND: The ability to perform quantitative hCG testing in whole blood at the point-of-care is desirable. The purpose of this study was to perform an analytical validation of the Abbott i-STAT Total ß-hCG test. METHODS: Whole blood, plasma, and serum samples were prepared by the addition of hCG and were used to evaluate precision, linearity, analytical sensitivity, accuracy, the high-dose hook effect, and dilution recovery. RESULTS: Imprecision was highest with whole blood (CV = 16.0% and 6.7% at 10 and 1184 IU/l, respectively) and lowest in serum (CV = 8.1% and 4.3% at 11 and 1305 IU/l, respectively). The limits-of-quantitation were 8 and <5 IU/l for whole blood and both plasma and serum, respectively. The assay was linear between 5 and 2000 IU/l in all sample types (R(2) ≥ 0.998). i-STAT results agreed most closely with the Architect Total ß-hCG assay and with greater differences observed with Beckman DxI Total ßhCG and Roche Cobas e601 hCG+ß assays (mean differences across all sample types were 9.3% and 12.3%, respectively). A high-dose hook effect was observed at concentrations > 400,000 IU/l. Accuracy was achieved in samples diluted with serum but not saline. CONCLUSIONS: The i-STAT Total ß-hCG test demonstrates acceptable performance for quantifying hCG in whole blood, plasma and serum.

Analytical sensitivity of four commonly used hCG point of care devices.

BACKGROUND: Point of care (POC) hCG assays are often used to rule-out pregnancy and therefore diagnostic sensitivity, especially at low concentrations of hCG, is important. There are very few studies in the literature that seek to verify the claimed analytical sensitivity of hCG POC devices. METHODS: The analytical sensitivity of four commonly used hCG POC devices (Alere hCG Combo Cassette, ICON 20 hCG, OSOM hCG Combo Test, and Sure-Vue Serum/Urine hCG-STAT) was challenged using urine samples (n=50) selected based on quantitative hCG concentrations. The majority of these specimens (n=40) had an hCG concentration between 20 and 200 U/L. Each specimen/device combination was reviewed by three individuals. Statistical calculations were performed using Stata 12. RESULTS: The analytical sensitivity of the OSOM was significantly lower inferior than that of the other POC devices. There was no significant difference in the sensitivity of the Alere, ICON 20 and Sure-Vue devices. There was no significant difference in the individual interpretation of the hCG POC results. CONCLUSIONS: All hCG POC devices evaluated in this study were susceptible to false negative results at low concentrations of urine hCG. Laboratorians and clinicians should be aware that there are limitations when using urine hCG POC devices to rule out early pregnancy.

Comparison of analytical sensitivity and women's interpretation of home pregnancy tests.

BACKGROUND: Internationally there are no defined standards for expressing the performance of home-based pregnancy tests, nor any pre-defined accuracy standard requirements. The aim of this study was to evaluate the accuracy of a selection of home-based pregnancy tests relative to their packaging/product insert claims. METHODS: Eight home-based pregnancy tests were evaluated using human chorionic gonadotrophin (hCG) urine standards (0, 15, 25 mlU/mL). Testing was performed by a technician and results were read by a technician and a panel of consumer volunteers (each blinded to the expected result) and compared with the expected result based on the manufacturer's claimed accuracy. Volunteers also completed questionnaires relating to various device attributes. RESULTS: The overall agreement between the technician reading and expected reading from the hCG concentration was >90% for the Clearblue® DIGITAL, Clearblue® PLUS, Confirme® Plus, David® and Haus™ tests, and approximately 80% for Predictor® Early; agreement was <50% for Femitest® Jet Ultra and Cyclotest® Early tests. RESULTS were available from 72 volunteers (aged 18-45 years). Overall the percentage agreement between volunteer result and expected result was >95% for Clearblue DIGITAL and Clearblue PLUS tests; agreement for all other tests was <75% (lowest were Cyclotest Early and Femitest Jet Ultra, 33.0% and 39.4%, respectively). The Clearblue DIGITAL test was scored most highly by volunteers in the questionnaires. CONCLUSIONS: Many home-based pregnancy tests commonly used by women are not as accurate as their packaging information claims. International test standards which define appropriate performance characteristics for home pregnancy tests are urgently required.

Clinical follow-up compared with self-assessment of outcome after medical abortion: a multicentre, non-inferiority, randomised, controlled trial.

BACKGROUND: Medical abortion with mifepristone and prostaglandins is well established. We compared clinical assessment with self-assessment of abortion outcome. METHODS: This randomised, controlled, non-inferiority trial was done in four clinics in Austria, Finland, Norway, and Sweden, between Aug 16, 2011, and Jan 31, 2013. Women aged 18 years and older who had requested medical termination of a pregnancy up to 63 days of gestation were eligible. Computer-generated block randomisation (block size ten) assigned women in a 1:1 ratio to attend routine clinical follow-up or to self-assess outcome at home with a semiquantitative urine human chorionic gonadotropin (hCG) test 1-3 weeks after abortion. The primary outcome was the percentage of women with complete abortion not requiring further medical or surgical intervention within 3 months. Analysis was per protocol and by intention to treat. The non-inferiority margin was five percentage points. This trial is registered with ClinicalTrials.gov, number NCT01487213. FINDINGS: 924 women were assigned routine follow-up (n=466) or self-assessment (n=458) and included in the intention-to-treat analysis. 901 were included in the per-protocol analysis (n=446 and n=455, respectively). Complete abortion was reported in 432 (95%) of 455 in the routine follow-up group and 419 (94%) of 446 women in the self-assessment group (crude difference -1·0, 95% CI -4·0 to 2·0). 20 (4%) women in the routine follow-up group and 17 (4%) in the self-assessment group required surgery. No women in the routine follow-up group versus three in the self-assessment group had undetected continuing pregnancies. Eight (1·8%) and one (0·2%) women, respectively, had infections (p=0·038). INTERPRETATION: Self-assessment was non-inferior to routine follow-up and could save resources. FUNDING: Nordic Federation of Obstetrics and Gynaecology, European Society of Contraception, Helsinki University Central Hospital, Helse Finnmark, Swedish Research Council, and Stockholm County Council and Karolinska University Hospital.

Comparison of accuracy of pregnancy-associated glycoprotein (PAG) concentration in blood and milk for early pregnancy diagnosis in cows.

The aim of this study was to compare two methods of early pregnancy diagnosis by determining pregnancy-associated glycoprotein (PAG) concentration in blood and PAG concentration in milk. Blood and milk samples were obtained on days 0 (AI day), 14, 21, 28, 35, 49, 63, 77, 91 and 105 of gestation from 60 lactating Holstein Frisian cows from one herd, carrying live fetuses. To determine PAG concentration a specific RIA system (RIA-706) was used. PAG concentration in blood and milk increased after 28 days of pregnancy, with blood concentrations being significantly higher than in milk. However, the accuracy of both tests at this time point was similar (sensitivity: 92 % in blood, 93 % in milk; specificity 53 % and 60 % respectively). None of the tests were able to detect open cows properly at this stage. On day 35 of gestation sensitivity (100 % for blood, 97 % for milk) and specificity (100 % for blood, 100 % for milk) were high enough to be used for reliable pregnancy diagnosis. The accuracy (sensitivity and specificity) for PAG concentrations in blood and milk for the rest of the study was 100 %. Our investigation shows that PAG determination in milk is a stress-free and non-invasive method for early pregnancy diagnosis in cattle.

Le but de cette étude était de comparer les concentrations de glycoprotéines associées à la gestation (PAG) dans le sang et le lait en vue d'un diagnostic de gestation précoce chez la vache. Des échantillons de sang et de lait ont été prélevés aux jours 0 (IA), 14, 21, 28, 35, 49, 63, 77, 91 et 105 de la gestation sur 60 vaches Holstein Frisonnes en lactation avec un fœtus vivant. On a utilisé pour mesurer la concentration de PAG une méthode RIA spécifique (RIA-706). Les concentrations de PAG dans le sang et le lait s'élevaient à partir du 28ème jour de gestation, les concentrations mesurées dans le sang étant nettement plus élevée que celles mesurées dans le lait. L'exactitude des deux tests était à ce moment-là similaires (sensitivité: 92 % dans le sang, 93 % dans le lait, spécificité: 53 % respectivement 60 %). Aucune des deux méthodes n'était, à ce stade, à même de distinguer une vache non portante avec justesse. Au 35ème jour de gestation, la sensitivité des deux méthodes (100 % dans le sang, 97 % dans le lait) et leur spécificité (100 % dans le sang, 100 % dans le lait) était assez élevées pour permettre un diagnostic de gestation sûr. L'exactitude (sensitivité et spécificité) des mesures de concentration de PAG dans le sang et le lait durant la suite de la gestation était de 100 %. Ces études montrent donc que la mesure de PAG dans le lait représente une méthode non-invasive et exempte de stress pour le diagnostic précoce de gestation chez la vache.

A pregnancy detection assay using milk samples: evaluation and considerations.

Two experiments were conducted to evaluate a pregnancy-detection assay based on the measurement of pregnancy-associated glycoproteins (PAG) in milk samples. In experiment 1, milk samples were collected on the day of first pregnancy check (33-52 d postinsemination; n=119) or second check (60-74 d postinsemination; n=60). The accuracy in identification of pregnant and nonpregnant cows was 99% at first check. Only 6% of samples were found to be within an intermediate range of PAG concentrations and classified as requiring recheck by the assay. At second check, the accuracy of the assay was 98%. Fifteen percent of these samples were classified as requiring recheck. In experiments 2a (n=17 cows) and 2b (n=16 cows), milk and plasma samples were collected from cows at weekly intervals beginning 2 (experiment 2a) or 4 d (experiment 2b) after insemination. The earliest time point at which pregnant cows were accurately classified as pregnant by the assay was on d 30 postinsemination. A transient decline in PAG levels into the intermediate range was observed on d 46 to 72 postinsemination. This coincides with the time of recheck in experiment 1. Results obtained with the plasma samples were essentially the same. The accuracy of pregnancy identification based on milk samples from nonpregnant and pregnant cows was 99%. Levels of PAG in milk were useful in identifying 6 incidences of embryonic mortality. No consistent relationship was noted between the timing of the decline in PAG levels and the timing of luteal regression in this small number of cows.

[Pregnancy tests: urine versus blood pregnancy tests]. / Zwangerschapstesten: urinetest versus bepaling in bloed.

In this article, we discuss possible explanations for the discrepancy in results between urine and blood pregnancy tests. The first patient, a 26-year-old woman, had breast tenderness, was tired and suffered from abdominal pain. A urine pregnancy test was negative, but blood human chorion gonadotropin (hCG) concentration was 455 U/l (reference value < 6 U/l). It was concluded that the patient was pregnant and she was followed in the outpatient clinic. Three days later she suffered blood loss and her hCG levels returned to normal. The diagnosis was a spontaneous abortion. The second patient, a 45-year-old woman, complained of abdominal pain, nausea and more blood loss than with a normal period. The urine pregnancy test was negative, but the hCG level in her blood was 470.000 U/l. Echography showed a thickened, irregular endometrium. A molar pregnancy was suspected and curettage was performed. The hCG level dropped initially but had increased at follow-up. Persistent trophoblastic disease was suspected and the patient underwent additional treatment.

Comparison of volunteers' experience of using, and accuracy of reading, different types of home pregnancy test formats.

BACKGROUND: Women suspecting pregnancy need an accurate result when they conduct a home pregnancy test. A variety of tests are available from simple professional style strips to midstream tests with a digitally displayed result. However, it is not known whether all these formats can be used and read correctly by untrained women. OBJECTIVES: The aim of this study is to evaluate usability and reading accuracy of home pregnancy test formats. METHODS: Female volunteers, 18 - 45 years (Manchester, UK) completed questionnaires on their home-use experience of six pregnancy tests (strip, cassette, midstream visual and digital formats). These volunteers then evaluated device results using hCG-urine standards at a study centre, thereafter completing a questionnaire and ranking evaluation. RESULTS: Data were available from 111 volunteers. Women preferred midstream test formats; > 70% scored branded midstream digital and easy-use visual tests as 1or 2 (7-point Likert score), compared with ∼ 30% for store-brand and branded midstream visual tests, and < 10% for cassette or strip tests. Many cassette tests (23%) failed to provide a result (4, ≤ 2% for strips, midstream, respectively). Volunteers disagreed with study co-ordinator reading of test results in 30 and 40% of cases for the cassette and strip test results, respectively, compared with < 3% when using midstream digital or easy-use visual tests. Volunteers preferred the branded midstream digital, followed by branded midstream easy-use and visual tests. CONCLUSIONS: In this study, the branded midstream digital test was superior to other tests evaluated and fulfilled the criteria of being an easy-to-use and interpret test; strip and cassette tests showed poor performance in women's hands.