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Background How to select healthy reference subjects in deriving 99th percentiles for cardiac troponin assays still needs to be clarified. To assist with global implementation of high sensitivity (hs)-cardiac troponin (cTn) I and hs-cTnT assays in clinical practice, we determined overall and sex-specific 99th percentiles in 9 hs-cTnI and 3 hs-cTnT assays using a universal sample bank (USB). Methods The Universal Sample Bank (USB) comprised healthy subjects, 426 men and 417 women, screened using a health questionnaire. Hemoglobin A1c (>URL 6.5%), NT-proBNP (>URL 125 ng/L) and eGFR ( Results Subjects were ages 19 to 91 years, Caucasian 58%, African American 27%, Pacific Islander/Asian 11%, other 4%, Hispanic 8%, and non-Hispanic 92%. The overall and sex-specific 99th percentiles for all assays, before and after exclusions (n = 694), were influenced by the statistical method used, with substantial differences noted between and within both hs-cTnI and hs-cTnT assays. Men had higher 99th percentiles (ng/L) than women. The Roche cTnT and Beckman and Abbott cTnI assays (after exclusions) did not measure cTn values at ≥ the limit of detection in ≥50% women. Conclusions Our findings have important clinical implications in that sex-specific 99th percentiles varied according to the statistical method and hs-cTn assay used, not all assays provided a high enough percentage of measurable concentrations in women to qualify as a hs-assay, and the surrogate exclusion criteria used to define normality tended to lower the 99th percentiles.

Limited data exist on rapid risk-stratification strategies using the U.S. Food and Drug Administration-cleared high-sensitivity cardiac troponin I (hs-cTnI) assays.This study sought to examine single measurement hs-cTnI to identify patients at low and high risk for acute myocardial infarction (MI).This was a prospective, multicenter, observational study of patients with suspected acute MI enrolled across 29 U.S. sites with hs-cTnI measured using the Atellica IM TnIH and ADVIA Centaur TNIH (Siemens Healthineers) assays. To identify low-risk patients, sensitivities and negative predictive values (NPVs) for acute MI and MI or death at 30 days were examined across baseline hs-cTnI concentrations. To identify high-risk patients, positive predictive values and specificities for acute MI were evaluated.Among 2,212 patients, acute MI occurred in 12%. The limits of detection or quantitation resulted in excellent sensitivities (range 98.6% to 99.6%) and NPVs (range 99.5% to 99.8%) for acute MI or death at 30 days across both assays. An optimized threshold of 5 ng/l identified almost one-half of all patients as low risk, with sensitivities of 98.6% (95% confidence interval: 97.2% to 100%) and NPVs of 99.6% (95% confidence interval: 99.2% to 99.9%) for acute MI or death at 30 days across both assays. For high-risk patients, hs-cTnI ≥120 ng/l resulted in positive predictive values for acute MI of ≥70%.Recognizing the continuous relationship between baseline hs-cTnI and risk for adverse events, using 2 Food and Drug Administration-cleared hs-cTnI assays, an optimized threshold of 5 ng/l safely identified almost one-half of all patients as low risk at presentation, with hs-cTnI ≥120 ng/l identifying high-risk patients.

Our objective was to examine the appropriateness of cardiac troponin (cTn) testing among patients with cTn increases.This is a planned secondary analysis of the Use of TROPonin In Acute coronary syndromes (UTROPIA, NCT02060760) observational cohort study. Appropriateness of cTn testing was adjudicated for emergency department patients with cTn increases99Appropriateness was determined from 1272 and 1078 adjudication forms completed for 497 and 422 patients with contemporary and hs-cTnI increases, respectively. Appropriateness of cTnI testing across adjudication forms was 71.5% and 72.0% for cTnI and hs-cTnI, respectively. Compared with emergency physicians, cardiologists were less likely to classify cTnI orders as appropriate (cTnI: 79% vs 56%, P.0001; hs-cTnI: 82% vs 51%, P.0001). For contemporary cTnI, appropriateness of 95%, 70%, and 39% was observed among adjudication forms completed by cardiologists for type 1 myocardial infarction, type 2 myocardial infarction, and myocardial injury, respectively; compared with 90%, 86%, and 71%, respectively, among emergency physicians. Similar findings were observed using hs-cTnI. Discordance in appropriateness adjudication forms occurred most frequently in cases of myocardial injury (62% both assays) or type 2 myocardial infarction (cTnI 31%; hs-cTnI 23%).Marked differences exist in the perception of what constitutes appropriate clinical use of cTn testing between cardiologists and emergency physicians, with emergency physicians more likely to see testing as appropriate across a range of clinical scenarios. Discordance derives most often from cases classified as myocardial injury or type 2 myocardial infarction.

Background Sofosbuvir use in patients with decompensated cirrhosis may be associated with reduced liver transplant waitlist mortality and reduced need for transplant. Methods Data from the Scientific Registry of Transplant Recipients were linked with a national database of pharmacy claims. All adult patients on the liver transplant waitlist on January 1, 2014, or added to the list during 2014, with hepatitis C virus as reason for listing were identified (2009 patients). A subgroup of 1093 unique patients had consistent pharmacy claim capture and observations. We compared patients who were and were not treated with all sofosbuvir-based regimens. Results During the study period, 154 patients received sofosbuvir-based regimens. These patients had lower model for end-stage liver disease scores and significantly longer waiting times. We found a trend toward significance for more sofosbuvir-treated than untreated patients being removed from the waitlist due to improved condition (4.54% vs 3.19%, p=0.03). In a propensity score-adjusted analysis, sofosbuvir-treated patients were less likely to undergo transplant (hazard ratio 0.57, 95% confidence interval 0.37-0.89, p=0.01). Conclusion During the study period reflecting early sofosbuvir use, few liver transplant candidates received sofosbuvir. Use was associated with lower incidence of transplant and a trend toward more waitlist removals due to improved condition.

No abstract available Keywords: United States; acute coronary syndrome; biomarkers; myocardial infarction; triage; troponin.

Aims: First, describe how acute myocardial infarction criteria are used to diagnose type 1 (T1MI) and 2 (T2MI) myocardial infarction. Second, determine whether subjective or objective criteria are used for T2MI. Third, examine outcomes for T2MI based on the presence or absence of objective evidence of myocardial ischemia compared with myocardial injury. Methods and results: Post-hoc analysis of UTROPIA (NCT02060760), a prospective, observational, cohort study involving 1640 consecutive emergency department patients with serial high-sensitivity cardiac troponin I among whom 74 (4.5%) had T1MI, 103 (6.3%) T2MI, and 245 (15%) myocardial injury. Compared with T1MI, patients with T2MI were less likely to have ischemic symptoms (97% vs. 83%), Q waves (24% vs. 1%), new ST-T wave changes (74% vs. 51%), new regional wall motion abnormality (64% vs. 11%), and a culprit lesion on coronary angiography (59% vs. 0%) (all p Conclusions: Among patients with T2MI, many cases are diagnosed using subjective criteria. The presence of objective evidence of myocardial ischemia may identify a higher-risk group of T2MI patients in whom early outcomes are worse than myocardial injury. Emphasis on using objective evidence of myocardial ischemia to diagnose T2MI may result in a more precise and specific disease definition.

Our purpose was to determine a) overall and sex-specific 99th percentile upper reference limits (URL) and b) influences of statistical methods and comorbidities on the URLs.Heparin plasma from 838 normal subjects (423 men, 415 women) were obtained from the AACC (Universal Sample Bank). The cobas e602 measured cTnT (Roche Gen 5 assay); limit of detection (LoD), 3ng/L. Hemoglobin A1c (URL 6.5%), NT-proBNP (URL 125ng/L) and eGFR (60mL/min/1.73m355 men and 339 women remained after exclusions. Overall50% of subjects had measureable concentrations ≥ LoD: 45.6% no exclusion, 43.5% after exclusion; compared to men: 68.1% no exclusion, 65.1% post exclusion; women: 22.7% no exclusion, 20.9% post exclusion. The statistical method used influenced URLs as follows: pre/post exclusion overall, NP 16/16ng/L, HDE 17/17ng/L, R not available; men NP 18/16ng/L, HDE 21/19ng/L, R 16/11ng/L; women NP 13/10ng/L, HDE 14/14ng/L, R not available.We demonstrated that a) the Gen 5 cTnT assay does not meet the IFCC guideline for high-sensitivity assays, b) surrogate biomarkers significantly lowers the URLs and c) statistical methods used impact URLs. Our data suggest lower sex-specific cTnT 99th percentiles than reported in the FDA approved package insert. We emphasize the importance of detailing the criteria used to include and exclude subjects for defining a healthy population and the statistical method used to calculate 99th percentiles and identify outliers.

Measures of cardiac troponin (cTn) may have lower specificity for myocardial infarction in patients with CKD. We examined the diagnostic accuracy of baseline and serial high-sensitivity cTnI (hs-cTnI) measurements for myocardial infarction and 30- and 180-day mortality according to renal function. hs-cTnI was measured (Abbott assay) using sex-specific 99th percentiles (women, 16 ng/L; men, 34 ng/L) in 1555 adults presenting to the emergency department with symptoms suggesting ischemia (NCT02060760). Myocardial infarction was adjudicated along universal definition classification. Renal function did not significantly affect sensitivity or negative predictive values. Specificity decreased with impaired renal function from 93%–95% with normal function (eGFR≥90 ml/min per 1.73 m2; n=722) to 57%–61% with severely impaired renal function (eGFR

Rationale & Objective The associations between ischemic stroke and time to dialysis initiation and/or death in adults with late-stage chronic kidney disease (CKD) have not been explored. We sought to measure the rate and factors associated with stroke in CKD stages 4 and 5 (CKD4-5) and assess the association of stroke with initiation of dialysis and death. Study Design Retrospective cohort. Setting & Participants Patients with CKD4-5 in Medicare 2007 to 2014. Exposure or Predictor Ischemic stroke in CKD4-5. Outcomes Initiation of maintenance dialysis or death. Analytical Approach Cox proportional hazard modeling assessed factors associated with ischemic stroke. A matched analysis (stroke/no stroke) estimated the cumulative incidence of incident kidney failure and death, treated as competing events. Simulations using a state transition model determined differences in expected time to kidney failure or death and death alone for patients with and without stroke with CKD5. Results 123,251 patients with CKD4 and 22,054 with CKD5 were identified. Mean ages were 81.0 and 79.2 years, respectively. Female sex (HRs of 1.21 [95% CI, 1.12-1.31] and 1.39 [95% CI, 1.04-1.86] for CKD4 and CKD5, respectively) and black race (HRs of 1.25 [95% CI, 1.12-1.39] and 1.12 [95% CI, 0.80-1.58] for CKD4 and CKD5, respectively) were factors associated with ischemic stroke. Rates for 30-day mortality were 13.3% and 18.8%, and for 1-year mortality, 40.0% and 38.2%. For patients with CKD5, kidney failure or death occurred an average of 3.6 months sooner for patients with an ischemic stroke, and death (irrespective of kidney failure), a mean of 24.3 months sooner. Limitations Study design cannot determine causality; lack of data for stroke severity. Conclusions Female sex and black race were associated with increased risk for stroke in CKD4 and CKD5. In CKD5, stroke was associated with a shorter time to kidney failure or death by nearly 4 months, and to death, by more than 2 years.

We sought to determine the prevalence and correlates of conventional and expanded adverse childhood experiences (ACEs), including exposure to violence and racism, in perinatal women with mental illness. 133 perinatal women with mental illness completed the original ACEs (conventional ACEs) survey and the 6-question adverse environmental experiences (expanded ACEs) survey from the Philadelphia ACEs study. Associations between racial groups and ACE scores, mental health and psychosocial variables were evaluated. Subjects were predominantly white (68%) and married/partnered (66%), and 57% had at least 4 conventional ACEs. Compared to White women, Black women were significantly more likely to report conventional and expanded ACEs including experiencing racism and witnessing violence. Early life adversity was exceedingly common among pregnant and postpartum women with moderate to severe mental illness. Childhood exposure to racism and environmental trauma are important risk categories for perinatal mental illness.

BACKGROUND: Despite adverse prognoses of type 2 myocardial infarction and myocardial injury, an effective, practical risk stratification method remains an unmet clinical need. We sought to develop an efficient clinical bedside tool for estimating the risk of major adverse cardiovascular events at 180 days for this patient population. METHODS: The derivation cohort included patients with type 2 myocardial infarction or myocardial injury admitted to a tertiary hospital between 2012 and 2013 (n = 611). The primary outcome was a major adverse cardiovascular event (death or readmission for heart failure or myocardial infarction). The score included clinical variables significantly associated with the outcome. External validation was conducted using the UTROPIA cohort (n = 401). RESULTS: The TARRACO Score included cardiac troponin (cTn) concentrations and 5 independent clinical predictors of adverse cardiovascular events: age, hypertension, absence of chest pain, dyspnea, and anemia. The score exhibited good discriminative accuracy (area under the curve = 0.74; 95% CI, 0.700.79). Patients were classified into low-risk (score 0-6) and high-risk (score >= 7) categories. Major adverse cardiovascular events rates were 5 times more likely in high-risk patients compared with those at low risk (78.9 vs 15.4 events/100 patient-years, respectively; logrank P < .001). The external validation showed equivalent prognostic capacity (area under the curve=0.71, 0.65-0.78). CONCLUSION: A novel risk score based on bedside clinical variables and cTn concentrations allows risk stratification for death and cardiac-related rehospitalizations in patients with type 2 myocardial infarctions and myocardial injury. This score identifies patients at the highest risk of adverse events, a subset of patients who may benefit from close observation, medical intensification, or both. (C) 2018 Elsevier Inc. All rights reserved.

Objective To evaluate how selection of patients for high sensitivity cardiac troponin testing affects the diagnosis of myocardial infarction across different healthcare settings. Design Prospective study of three independent consecutive patient populations presenting to emergency departments. Setting Secondary and tertiary care hospitals in the United Kingdom and United States. Participants High sensitivity cardiac troponin I concentrations were measured in 8500 consecutive patients presenting to emergency departments: unselected patients in the UK (n=1054) and two selected populations of patients in whom troponin testing was requested by the attending clinician in the UK (n=5815) and the US (n=1631). The final diagnosis of type 1 or type 2 myocardial infarction or myocardial injury was independently adjudicated. Main outcome measures Positive predictive value of an elevated cardiac troponin concentration for a diagnosis of type 1 myocardial infarction. Results Cardiac troponin concentrations were elevated in 13.7% (144/1054) of unselected patients, with a prevalence of 1.6% (17/1054) for type 1 myocardial infarction and a positive predictive value of 11.8% (95% confidence interval 7.0% to 18.2%). In selected patients, in whom troponin testing was guided by the attending clinician, the prevalence and positive predictive value were 14.5% (843/5815) and 59.7% (57.0% to 62.2%) in the UK and 4.2% (68/1631) and 16.4% (13.0% to 20.3%) in the US. Across both selected patient populations, the positive predictive value was highest in patients with chest pain, with ischaemia on the electrocardiogram, and with a history of ischaemic heart disease. Conclusions When high sensitivity cardiac troponin testing is performed widely or without previous clinical assessment, elevated troponin concentrations are common and predominantly reflect myocardial injury rather than myocardial infarction. These observations highlight how selection of patients for cardiac troponin testing varies across healthcare settings and markedly influences the positive predictive value for a diagnosis of myocardial infarction.

BACKGROUND We examined the diagnostic performance of high-sensitivity cardiac troponin I (hs-cTnI) vs contemporary cTnI with use of the 99th percentile alone and with a normal electrocardiogram (ECG) to rule out acute myocardial infarction (MI) and serial changes (deltas) to rule in MI. METHODS We included consecutive patients presenting to a US emergency department with serial cTnI onclinical indication. Diagnostic performance for acute MI, including MI subtypes, and 30-day outcomes were examined. RESULTS Among 1631 patients, MI was diagnosed in 12.9% using the contemporary cTnI assay and in 10.4% using the hs-cTnI assay. For ruling out MI, contemporary cTnI ≤99th percentile at 0, 3, and 6 h and a normal ECG had a negative predictive value (NPV) of 99.5% (95% CI, 98.6–100) and a sensitivity of 99.1% (95% CI, 97.4–100) for diagnostic and safety outcomes. Serial hs-cTnI measurements ≤99th percentile at 0 and 3 h and a normal ECG had an NPV and sensitivity of 100% (95% CI, 100–100) for diagnostic and safety outcomes. For ruling in MI, contemporary cTnI measurements had specificities of 84.4% (95% CI, 82.5–86.3) at presentation and 78.7% (95% CI, 75.4–82.0) with serial testing at 0, 3, and 6 h, improving to 89.2% (95% CI, 87.1–91.3) by using serial cTnI changes (delta, 0 and 6 h) >150%. hs-cTnI had specificities of 86.9% (95% CI, 85.1–88.6) at presentation and 85.7% (95% CI, 83.5–87.9) with serial testing at 0 and 3 h, improving to 89.3% (95% CI, 87.3–91.2) using a delta hs-cTnI (0 and 3 h) >5 ng/L. CONCLUSIONS hs-cTnI and contemporary cTnI assays are excellent in ruling out MI following recommendations predicated on serial testing and the 99th percentile with a normal ECG. For ruling in MI, deltas improve the specificity. ClinicalTrials.gov Identifier: NCT02060760

* Abbreviation: SUDEP — : sudden unexpected (or unexplained) death in epilepsy persons The death of any child is tragic. When the death is sudden and unexpected, it can seem especially incomprehensible. Henry was 4 years old when he died only a few weeks after his epilepsy diagnosis; his parents were devastated and never knew that death could occur; no physician had discussed the possibility with them. Henry was an otherwise healthy child, had a history of febrile seizures, and died in his sleep before his epilepsy workup was complete and before his medication was likely therapeutic. Since Henry’s death 8 years ago, together and independently, Henry’s parents, pediatrician, and neurologist have sought understanding and opportunities to advance awareness and prevention around epilepsy-related mortality. These efforts have launched a multidisciplinary partnership between Children’s National Health System and the University of Virginia to develop an educational research program to systematically raise provider and patient awareness of sudden unexpected (or unexplained) death in epilepsy persons (SUDEP) and other risks associated with epilepsy. This article gives voice to these different experiences and underscores the value of families and providers working together to improve care and prevent death. Although epilepsy is a common childhood disorder, all of us were impacted by Henry, who died, suddenly and unexpectedly, as a result of his seizure disorder. Our partnership started with Henry’s mother, Henry’s pediatrician, and Henry’s neurologist and now includes an educational research program that incorporates parent advocacy, nursing, neuropsychology, psychiatry, neurology, and basic science expertise. As a bereaved mother, I was desperate to make sense out of our tragedy. I searched for understanding and connection to others who shared my experience and ultimately connected with other parents … Address correspondence to Madison M. Berl, PhD, Center for Neuroscience, Children’s National Health System, 111 Michigan Ave NW, Washington, DC 20010. E-mail: mberl{at}childrensnational.org

Background Studies addressing patients with type 2 myocardial infarction and myocardial injury, including the impact of using high-sensitivity (hs) cardiac troponin (cTn) assays on their incidence are needed. Methods Ours is a prospective, observational US cohort study. Consecutive emergency department patients with serial cTnI measurements were studied. Outcomes included 180-day mortality and major adverse cardiac events, including 2-year follow-up for those with myonecrosis. Results Among 1640 patients, using a contemporary cTnI assay, 30% (n = 497) had ≥1 cTnI >99 th percentile, with 4.7% (n = 77), 8.5% (n = 140), and 17% (n = 280) classified as type 1 myocardial infarction, type 2 myocardial infarction, and myocardial injury, respectively. Compared with patients without myonecrosis, 180-day mortality was higher for type 2 myocardial infarction (4% vs 13%, P P = .0005) and myocardial injury (4% vs 11%, P P = .02), both with mortality >20% at 2 years. Predictors of 2-year mortality for type 2 myocardial infarction included age, congestive heart failure, and beta-blockers. Relative to the contemporary cTnI assay, hs-cTnI had less myonecrosis (30% vs 26%, P = .003) and acute myocardial infarction (13.2% vs 10.8%, P = .032), including fewer type 2 myocardial infarctions (8.5% vs 6.3, P = .01), with no difference in myocardial injury (17% vs 15%, P = .1). Conclusions cTnI increases are encountered in approximately a third of patients, the majority due to nonatherothrombotic conditions. Compared with patients without myonecrosis, type 2 myocardial infarction and myocardial injury have worse short-term outcomes, with mortality rates >20% at 2 years. hs-cTnI assay does not lead to more myocardial injury or infarction.

This study examined the performance of single high-sensitivity cardiac troponin I (hs-cTnI) measurement strategies to rule out acute myocardial infarction.This was a prospective, observational study of consecutive patients presenting to the emergency department (n = 1631) in whom cTnI measurements were obtained using an investigational hs-cTnI assay. The goals of the study were to determine 1) negative predictive value (NPV) and sensitivity for the diagnosis of acute myocardial infarction, type 1 myocardial infarction, and type 2 myocardial infarction; and 2) safety outcome of acute myocardial infarction or cardiac death at 30 days using hs-cTnI less than the limit of detection (LoD) (1.9 ng/L) or the High-STEACS threshold (5 ng/L) alone and in combination with normal electrocardiogram (ECG).Acute myocardial infarction occurred in 170 patients (10.4%), including 68 (4.2%) type 1 myocardial infarction and 102 (6.3%) type 2 myocardial infarction. For hs-cTnILoD (27%), the NPV and sensitivity for acute myocardial infarction were 99.6% (95% confidence interval 98.9%-100%) and 98.8 (97.2%-100%). For hs-cTnI5 ng/L (50%), the NPV and sensitivity for acute myocardial infarction were 98.9% (98.2%-99.6%) and 94.7% (91.3%-98.1%). In combination with a normal ECG, 1) hs-cTnILoD had an NPV of 99.6% (98.9%-100%) and sensitivity of 99.4% (98.3%-100%); and 2) hs-cTnI5 ng/L had an NPV of 99.5% (98.8%-100%) and sensitivity of 98.8% (97.2%-100%). The NPV and sensitivity for the safety outcome were excellent for hs-cTnILoD alone or in combination with a normal ECG, and for hs-cTnI5 ng/L in combination with a normal ECG.Strategies using a single hs-cTnI alone or in combination with a normal ECG allow the immediate identification of patients unlikely to have acute myocardial infarction and who are at very low risk for adverse events at 30 days.

The records of 1,029 consecutive patients undergoing bilateral vasectomy were reviewed. Of the 1,029 patients 375 (36%) never returned postoperatively and the partners of 2 of these 375 later became pregnant. A total of 560 patients (54%) was followed until the recommended demonstration of azoospermia occurred on 2 consecutive occasions. There were 84 patients (8%) who did not return after the first demonstration of azoospermia, while 7 (1%) still had sperm in the semen at the last examination. Three other patients had persistent nonmotile sperm postoperatively; 2 of them underwent repeat vasectomy followed by azoospermia and 1 was placed in a special clearance category of sterility as described. We discuss practical and legal considerations regarding the management of noncompliant patients.Urologists reviewed the medical charts of 1029 consecutive patients who had experienced a bilateral vasectomy (cauterization of the mucosa at each end and of the divided vas deferens) at the University of Louisville's School of Medicine in Kentucky between February and December 1986 to examine the medical and legal ramifications of vasectomized men not returning to have physicians examine their semen. Only 54.4% of the men returned for the recommended 2 semen examinations. 8.2% returned only once. 7 men (1% of the 654 who returned for semen examination) had sperm in their last semen sample. 36.4% (375) did not return at all after the vasectomy. Partners of 2 of these men conceived. 1 pregnancy occurred 29 months postoperatively. The men did not want to have his semen examined, however, for fear of learning he was sterile. The other pregnancy occurred 67 months after the vasectomy and the man's sperm had many motile sperm. Late recanalization of the vas deferens most likely occurred in this case. Other than recommending to patients before and during the vasectomy to submit 2 semen samples after the vasectomy, the urologists had no mechanisms in place to assure compliance. The high noncompliance rate in this study made the researchers consider their new legal responsibilities. Court cases for somewhat related medical situations have resulted in the jury finding the physician negligent because he/she did not fully inform the patient of the risk of noncompliance. Thus physicians, even though they may believe they are not responsible for noncompliance, should prudently inform patients of their risk of not complying by perhaps sending a punctually written notice. These warnings may protect them from potential litigation. Nevertheless the courts may appropriate more responsibility of patient actions to the physicians than is either morally justified or reasonable.

The purpose of the research reported herein was to associate prevention activities in the schools with abusing behaviors of the students, after statistically controlling relevant variables. Discrete activities and clusters of activities (“programs” or “models”) were studied with a randomly assigned control group design. This approach was selected so that effective activities could be identified even against an overall background of increasing abuse during and after the prevention experience.

A microsurgical laboratory model is described which uses optimally preserved human vasectomy segments. These preserved specimens retain their natural appearance and handling qualities, permitting ready availability of material for practice, which is mandatory before clinical performance. If laboratory facilities are not available, the model can be used for practice in a convenient area of the operating suite.