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1.
BACKGROUND: There is circumstantial evidence that human sperm count may have declined during past decades. The purpose of this study was to identify the association between semen quality and year of birth. METHODS: The study comprised 8608 men consulting four Danish medical centres from 1968 to 1992 because of infertility. Data on semen quality and urogenital disorders were obtained from medical records while lifestyle data were collected from a subset of the population by a postal questionnaire (response 80%). Semen characteristics were analysed as a linear function of year of birth, centre, season and calendar year at time of semen examination, sexual abstinence and lifestyle factors. Effects of age were accounted for by restriction and stratified analysis. RESULTS: The sperm count declined with increasing year of birth at two of the four centres, but this association disappeared when confounders were adjusted for. Within the subset of men born 1950-1970 we revealed a decrease in the average sperm count by 1.9 mill/ml (95% confidence interval [CI]: 1.45, 2.27) per one advancing year of birth. This finding was consistent across centres even after adjustment for effects of covariates. The proportion of morphologically normal sperm cells changed in parallel with the sperm count, while semen volume did not decline in any time periods. CONCLUSIONS: We found a birth cohort effect on sperm count and morphology among Danish infertile men born after 1950 but not in men born in the first part of the century. The findings are compatible with an environmental impact during prenatal life but the evidence is far from unequivocal.  相似文献   

2.
OBJECTIVES: In Spain the number of new acquired immunodeficiency syndrome (AIDS) cases among injection drug users continues to rise. The time trend up to 1994 has been analyzed, with special attention paid to the different generations. METHODS: The source for injection drug use-related cases was the Spanish AIDS Register. Independent analyses of annual specific rates were run for each sex with the use of an age-period-cohort log-linear model. RESULTS: After adjustment for age and year of diagnosis, AIDS incidence related to injection drug use is associated with specific birth cohorts. Rising values are observed in the successive generations born during the 1950s, peaking in men born in 1962 and women born in 1964. In subsequent cohorts, there is a marked falloff in incidence for both sexes, but this decline is seen to halt in men from the 1972 birth cohort onwards. The overall period effect is upward, yet the trend flattens in the last years. There is a pronounced age effect with maximum values in men and women at ages 29 and 27, respectively. CONCLUSIONS: It is essential to urge avoidance of risk behaviors in new generations.  相似文献   

3.
OBJECTIVES: To determine whether plasma concentrations of inactive and active renin in adult life are related to foetal development. DESIGN: A follow-up study of a group of men and women whose weight and other measurements of body size had been recorded at birth. SETTING: Sheffield, England. SUBJECTS: In total 148 men and women born in the Jessop Hospital, Sheffield, during 1939-40 and now aged 50-53 years. MAIN OUTCOME MEASUREMENT: Plasma concentrations of inactive and active renin in adult life. RESULTS: Plasma concentrations of inactive and active renin in adult life tended to be higher in people who had been large at birth. The strongest relationship was between concentrations of inactive renin and abdominal circumference at birth; the median plasma concentration of inactive renin was 88.5 mu/ml in people whose abdominal circumference at birth had been 13 inches (33.02 cm) or more compared with 61 mu/ml in people whose abdomens had measured 11.5 inches (29.21 cm) or less. CONCLUSION: Impairment of foetal growth is associated with lower plasma concentrations of inactive renin in adult life. Alterations in the activity of the renin-angiotensin system may be a mechanism by which reduced foetal growth leads to raised adult blood pressure.  相似文献   

4.
OBJECTIVE: To investigate the effect of antibiotic therapy on seminal infection. STUDY DESIGN: The seminal plasma of 50 men was evaluated in three groups: (1) men with seminal infection (20), (2) men with leukocytospermia only (18), and (3) men of proven fertility (12). The evaluation protocol included semen analysis, culture and antibiotic sensitivity test, total antioxidant activity, alpha-tocopherol and retinol, T-helper cytokines, IL-2, IL-8, IL-4 and antisperm antibodies. RESULTS: Sperm parameters were worse with seminal infection: 25 versus 84 million per milliliter for fertile men. Antioxidant activity, total alpha-tocopherol and retinol were reduced in leukocytospermia (P < .02, .01) and seminal infection (P < .01, .05) as compared to controls. Antisperm antibodies IL-2 and IL-8 were highly expressed, while IL-4 was low in men with leukocytospermia and bacteriospermia. Gram-negative organisms were more associated with expression of T-helper 1 cytokines than T-helper 2 cytokines. Antibiotic therapy significantly improved the sperm parameters, antioxidant activity and IL-4 but reduced IL-2 and IL-8 and had no effect on antisperm antibody titer. CONCLUSION: Antibiotic therapy improves sperm parameters by increasing antioxidant activity and IL-4 and by reducing IL-2 and IL-8.  相似文献   

5.
6.
BACKGROUND: Cohorts born at different times of year differ in their risk of exposure to seasonal respiratory infections in early life, but are likely to have similar socioeconomic status and lifestyle thereafter. METHODS: We investigated the long-term consequences of acute chest illness in infancy for later development of chronic respiratory disease by analysing variations by month of birth in hospital admissions for respiratory illness (total n = 49,866), chronic respiratory symptoms and ventilatory function among British school children (n = 11,482) and middle-aged adults (total n = 55,829). RESULTS: Admission for bronchiolitis in the first year of life was three times more common for infants born September to November (autumn) than those born March to May, yet people born in the autumn experienced fewer respiratory symptoms and had better ventilatory function. In two surveys of middle-aged men, forced expiratory volume in one second/forced ventilatory capacity (FEV1/FVC) was significantly (P = 0.025) higher among autumn births. Hospital admissions for chronic bronchitis/emphysema and pneumonia varied little with season of birth. Admissions for asthma were significantly (P < 0.05) more common among children and young adults born in the autumn. CONCLUSIONS: These findings do not support the hypothesis of a causal link between chest illness in infancy and the later development of chronic bronchitis and emphysema. The variation in asthma admissions with month of birth deserves further investigation.  相似文献   

7.
In 1992, a statistical analysis of data from 61 studies of semen quality among normal men led to the conclusion that human sperm count fell of 40% from 1940 to 1990. This meta-analysis has since been invalidated for methodological reasons as well as for statistical reasons, but it caused enormous concern to both the scientific community and to the international media. A decline of human fertility was speculated. To date, the most popular hypothesis offered to explain this alleged decline has been increasing exposure to environmental estrogen mimicking chemicals. However, there is no evidence that male or mammal fertility is declining. Moreover, the sperm count of breeding mammals did not declined in the meanwhile. Since 1992, numerous papers reported on men investigated during the last 20 years have shown conflicting results, from sperm count improvement to sperm count decline. However, several publications included methodological and analytical biases. In fact, the techniques used for semen analysis have to be questioned. It is a subjective exam, lacking laboratory standards and quality control procedures. This induces very important variations between laboratories and between biologists. For the sperm count itself, numerous errors can occur, provoked by the technique, the equipment and the reader: for the same sperm, the coefficient of variation can exceed 40% between two technicians. Therefore, the current techniques of semen analysis cannot warrant epidemiological studies. It is indispensable to admit the limits of the semen analysis in order to improve as much as possible its quality and its reliability.  相似文献   

8.
OBJECTIVE: To determine whether there has been a decline in semen quality in a group of healthy men during the past 21 years. DESIGN: Retrospective analysis of the relationship between time and changes in semen parameters over 21 years using regression analysis. SETTING: A tertiary university center. PATIENTS: Five hundred ten healthy, normal men who donated multiple semen samples as participants in clinical studies between 1972 and 1993. MAIN OUTCOME MEASURES: Sperm concentration, semen volume, total numbers of sperm per ejaculate, and percent spermatozoa with normal morphology. RESULTS: There was no decrease in sperm concentration, semen volume, total number of sperm per ejaculate, and percent normal sperm morphology in 510 healthy men studied between 1972 and 1993. CONCLUSION: We conclude that in this population of healthy young men there has not been any decline in semen quality in the past 21 years.  相似文献   

9.
10.
PURPOSE: Intraoperative sperm banking has been recommended during vasectomy reversal. These specimens are maintained as insurance for possible future intracytoplasmic sperm injection. We evaluated the fate of specimens collected intraoperatively from 48 vasectomy reversal patients. MATERIALS AND METHODS: Of 75 men 48 (64.0%) agreed to intraoperative sperm banking during vasectomy reversal. A total of 135 vials of epididymal sperm, 81 vials of testicular tissue and 13 vials of vasal sperm were cryopreserved. RESULTS: Among couples who stored sperm 10 (20.8%) voluntarily discarded the specimens within 4 months of vasectomy reversal. Specimens from 31 couples (64.5%) remain in storage. Seven couples (14.6%) have used frozen sperm for intracytoplasmic sperm injection. In 3 of these couples the men were azoospermic after surgery, 2 men had 10,000 to 15,000 sperm per ml. in the ejaculate with limited motility and 2 had 1 to 2 million sperm per ml. with limited motility. The 7 women who underwent intracytoplasmic sperm injection ranged between 37 and 39 years old, which was older than the mean age of the remaining study group (32.7 years). With intracytoplasmic sperm injection fertilization was achieved in all cases and 20 of 47 eggs (42.5%) developed into embryos. Of 7 women 4 achieved biochemical pregnancies (57.1%) and 2 (28.6%) delivered newborns with epididymal sperm. Natural pregnancy occurred in 7 of 16 vasectomy reversal couples (43.7%) who were followed at least 18 months postoperatively but the time to pregnancy averaged 1 year. CONCLUSIONS: Cryopreservation of sperm collected at vasectomy reversal is recommended for patients undergoing vasoepididymostomy or vasovasostomy. The couples who used the cryopreserved sperm for intracytoplasmic sperm injection included husbands whose postoperative ejaculate remained azoospermic or severely oligospermic and wives who were approaching 40 years old. Only a limited number of couples (14.6% of the study group) have used the cryopreserved sperm but the delivered newborn rate (28.6%) was comparable to other intracytoplasmic sperm injection data. The natural pregnancy rate after vasectomy reversal was 43.7% but the time to pregnancy after surgery was lengthy (average 1 year). These findings may be helpful for counseling couples who are planning vasectomy reversal surgery and may be considering intraoperative sperm banking.  相似文献   

11.
OBJECTIVE: To determine the changing incidence of and mortality from cutaneous malignant melanoma in Scotland from 1979 to 1994. DESIGN: Detailed registration of clinical and pathological features, surgical and other treatment, and follow up of all cases of cutaneous malignant melanoma diagnosed from 1979 to 1994 and registered with specialist database for Scotland. SETTING: Scotland. SUBJECTS: 6288 patients with invasive primary cutaneous malignant melanoma diagnosed between 1 January 1979 and 31 December 1994. RESULTS: The annual age standardised incidence of cutaneous malignant melanoma rose significantly from 3.5 to 7.8 per 100,000 per year in men and from 6.8 to 12.3 per 100,000 per year in women (P < 0.001 for both). World standardised rates increased from 2.7 to 6.0 per 100,000 per year in men and 4.6 to 8.50 per 100,000 in women. The incidence of melanoma continued to increase significantly in men of all ages during the study, but the rate stabilised in women after 1986. Mortality from cutaneous malignant melanoma was 1.3 per million per annum in men in 1979, rising to 2.3 per million per annum in 1994 (P < 0.01); it was 2.4 per million per annum in women in 1979, falling to 1.9 per million per annum in 1994 (P = 0.09). The underlying mortality trends showed a continuing rise for men but a downward trend for women that was not significant (P = 0.09). In men, melanoma free survival was 69% at 5 years and 61% at 10 years; in women the corresponding rates were 82% and 75%. Younger patients had higher survival rates, which were not entirely explained by thinner tumours. Over the 15 year period, survival rates improved by 12% overall, only partly owing to thinner tumours. CONCLUSIONS: In Scotland the incidence of melanoma in women has stabilised, while mortality associated with melanoma in women shows a downward trend.  相似文献   

12.
During the period January 1, 1991 through December 31, 1995, 258 patients, in whom motile sperm counts for insemination (postwash, processed) were 10.0 million motile sperm or less were seen in the andrology unit for sperm washing and intrauterine insemination (IUI). No significant female factors were noted on history; all female partners had patent Fallopian tubes and were ovulatory spontaneously or were treated by the referring gynecologist with clomiphene citrate, human menopausal gonadotropin (hMG), or follicle-stimulating hormone (FSH) ovulation induction in both anovulatory or ovulatory women. Of the total of 258 patients, 15 achieved a pregnancy in 284 cycles of IUI in which the inseminating motile-count was < 1.0 million motile sperm, resulting in a monthly fecundity (f) of 5.3%. The mean (+/-SD) motile count for IUI in this group was 0.61 (+/-0.29) million sperm, with a range of 0.19-0.95 million motile sperm. The initial motile count was 2.97 (3.2) million sperm, with a range of 0.2-12.81 million sperm. With inseminating motile counts of 1.0-10.0 million motile sperm, there were 83 pregnancies after 467 cycles of IUI, resulting in a monthly f of 17.8%. The mean (+/-SD) motile count for IUI in this group was 4.9 (+/-2.7) million motile sperm with a range of 1.0-9.9 million motile sperm. The initial sperm count in this group was 10.9 million (+/-7.1), with a range of 1.1-23.7 million motile sperm. These data suggest that acceptable pregnancy rates can be achieved with IUI, even in severely oligozoospermic specimens. Intrauterine insemination is less invasive and less costly than other assisted reproductive techniques. These data are supportive of IUI prior to attempting other more invasive and potentially costly reproductive technologies.  相似文献   

13.
PURPOSE: Because the effects of mitoxantrone on human male fertility were unknown, we determined prospectively the effects of three courses of mitoxantrone (Novantrone), vincristine (Oncovin), vinblastine, prednisone (NOVP) chemotherapy on the potential for fertility of men with Hodgkin's disease (HD). PATIENTS AND METHODS: Semen analyses were performed on 58 patients with stages I-III HD before, during, and after chemotherapy and after the sperm count recovered from the effects of abdominal radiotherapy that was given after chemotherapy. RESULTS: Before the initiation of treatment, 84% of the patients were normospermic. Sperm counts declined significantly within 1 month after the start of NOVP chemotherapy. In the month after chemotherapy, 38% of patients were azoospermic, 52% had counts < 1 million/ mL, and 10% had counts between 1 and 3 million/mL. Between 2.6 and 4.5 months after the completion of chemotherapy, sperm counts recovered rapidly to normospermic levels in 63% of patients. In the remaining patients who were followed up for at least 1 year after standard upper abdominal radiotherapy, counts also recovered to normospermic levels. CONCLUSION: NOVP chemotherapy, like most other regimens, produced marked temporary effects or spermatogenesis. However, sperm production recovered very rapidly, within 3 to 4 months after the end of NOVP chemotherapy. This pattern was caused by killing differentiating spermatogenic cells, but there was little cytotoxicity or inhibition of stem cells from mitoxantrone or the other drugs. After the combination of NOVP plus abdominal radiotherapy, sperm counts and motility were restored in most patients to pretreatment levels, which were compatible with normal fertility.  相似文献   

14.
OBJECTIVE: To assess the impact of the HIV epidemic on the demographic development of the Thai population. METHODS: A deterministic mathematical model was used to predict simultaneously epidemiological and demographic processes. Partial differential equations express the relationships between biological, behavioural and demographic variables. The model allows the evaluation of different sexual mixing patterns, variable transmission probabilities and incubation times. Validity analysis was performed by generating antecedent HIV prevalence patterns among military recruits and pregnant women. RESULTS: On the national level in Thailand we predict that the cumulative number of people in Thailand with HIV infection will exceed 1 million by 1999; the number of deaths from AIDS will be 555000 by the year 2000 but will not reach 1 million until after the year 2014. Without the HIV epidemic the population growth rate was estimated at 1.3% per annum until 1995, after which a decline to 0.9% by 2005 is predicted. The HIV epidemic started to affect the population growth rate by 0.026% per year in 1991, and the difference is predicted to rise to about 0.12% per year during the period 1995-2000, to decline to 0.06% in 2005 and then to disappear. In the mid-1990s HIV affected mainly the 15-35-year-old age group, but over time younger and older age groups have been affected as a result of perinatal transmission, and a decline in fertility as well as ageing of the 15-35-year-old birth cohort. Because of HIV, in 2000 there will be 612000 (1%) fewer people than expected and by 2010, 1140000 fewer (1.6%). We predict that the demographic impact of the HIV epidemic in the northern region will follow the same pattern, but with greater severity. Here, the effect on the population growth rate and the population age distribution is likely to be twice as high as at the national level. CONCLUSIONS: It is estimated that 1 million Thais will be infected with HIV by the year 2000 and an almost equal number will have died of AIDS by the year 2014. Although these numbers seem high, their direct and indirect effects on the demographic structure of the Thai population are small. However, at a regional level, for example in the northern region, the effect of the HIV epidemic may be more severe.  相似文献   

15.
OBJECTIVES: To describe the experience of two male fertility programs using electroejaculation (EEJ) in the management of men with ejaculatory failure secondary to diabetes mellitus. METHODS: Twenty-nine EEJ procedures were performed in 7 diabetic men with ejaculatory failure. Results were reviewed with attention paid to sperm characteristics in both antegrade and retrograde specimens as well as pregnancy rates. RESULTS: Retrograde semen specimens retrieved from the bladder following EEJ contained a mean of 3444.5 million sperm (range 269.2 to 4996 million). Antegrade specimens contained a mean of 698.8 million sperm (range 226.8 to 1961 million). Mean sperm motility was 4% for retrograde specimens (range 0% to 11%) and 7% for antegrade specimens (1% to 15%). In all but 1 case, semen specimens were used for intrauterine insemination. The total number of motile sperm contained in the processed, inseminated specimens ranged from 1 to 87.2 million. In 1 case, the sperm obtained through EEJ was used in an in vitro fertilization procedure. CONCLUSIONS: EEJ can be successfully used to obtain sperm from men with ejaculatory failure due to diabetes mellitus. The procedure requires general anesthesia, and pregnancy rates after intrauterine insemination with the processed sperm are low. Advanced reproductive technologies may offer a feasible alternative, providing higher success rates with fewer procedures.  相似文献   

16.
Paleodemographers must work to understand how representative any archaeologically recovered skeletal series is and the potential effects of series bias on their demographic reconstructions. We examine two forms of bias: 1) infant underenumeration caused by differential preservation or incomplete archaeological recovery and 2) the underenumeration of individuals over age 45 related to methodological bias. We generated 60 simulated skeletal series of 250 individuals each based on the Brass ([1971] Biological Aspects of Demography (London: Taylor and Francis), pp. 69-110) logit models. In the first test, age bias was introduced deterministically for all individuals with age at death over 40 years using the Lovejoy et al. ([1985] Am. J. Phys. Anthropol. 68:1-14) bias estimates. In the second test, 50% of all individuals under 5 years old were removed from each simulated distribution. The simulated series were analyzed using the model life table fitting procedure developed by the authors (Milner et al. [1989] Am. J. Phys. Anthropol. 80:49-58; Paine [1989] Am. J. Phys. Anthropol. 79:51-62). Forms of adult age estimation bias described by Lovejoy and coworkers inflate estimates by 10-20% of the true crude birth rate (CBR) (the number of births per year per 1,000 population). Overestimation of fertility and birth rates increases both absolutely and as a percentage of the true rate as population growth increases. This bias is very consistent. Because Lovejoy and colleagues have estimated the methodological bias itself, its effects can be estimated. Infant underenumeration is a more serious obstacle. It is not presently possible to estimate infant underenumeration reliably without prior knowledge of fertility rates. This reduces fertility reconstructions based on infant-biased samples to minimum fertility estimates.  相似文献   

17.
Five hundred and thirty families with at least 1 child who had been referred to a dermatologist with atopic dermatitis were interviewed in an effort to determine whether factors such as the age of the mother when a child is born and/or birth rank can contribute to the development of atopic dermatitis. The families interviewed had a total of 1,084 children, or an average of 2 children per family. Sixty per cent of the children with atopic dermatitis were under 5 years of age. Ninety-one per cent of them had developed the disease before the age of 3; those most severely affected had developed the disease during the first year of life. In families with 2 children, but only 1 child with atopic dermatitis, the odds ratio for the second child to develop atopic dermatitis was 1.379 (0.025 < p < 0.05). The average maternal age was 24.8 to 25.2 years when giving birth to the first child and 28 years when giving birth to the second child, irrespective of the status of the child. Thus, atopic dermatitis can be related to birth rank or to the age of the mother.  相似文献   

18.
OBJECTIVE: To determine the incidence of acute symptomatic toxoplasma retinochoroiditis presenting to ophthalmologists for patients born in Britain and elsewhere. DESIGN: Population based, cross sectional study. SETTING: 11 districts in south Greater London. SUBJECTS: All patients presenting to NHS ophthalmologists with symptoms due to acute toxoplasma retinochoroiditis in 1992-3. MAIN OUTCOME MEASURE: Intraocular inflammation in association with a retinochoroidal scar, active adjoining retinitis, and IgG serum antibodies to toxoplasma. RESULTS: The estimated incidence of acute symptomatic retinochoroiditis for all people born in Britain was 0.4/100,000/year. If a mean of two symptomatic episodes per lifetime is assumed, 100 people born in Britain may be affected each year, about a fifth of the estimated 500-600 congenitally infected people born each year. CONCLUSIONS: A substantial proportion of people with acute symptomatic toxoplasma retinochoroiditis were born outside the country, and the number born in Britain was smaller than the number previously estimated to develop retinochoroidal lesions due to congenital toxoplasmosis. These findings suggest that prenatal screening for toxoplasmosis in Britain may be of limited benefit.  相似文献   

19.
BACKGROUND: The incidence of classic Kaposi's sarcoma (CKS) has been reported to be high in Jewish populations, mostly born in Eastern Europe. OBJECTIVE: To describe the incidence on CKS in Israeli Jews and to determine differences in incidence according to their geography origin. DESIGN: We analysed data on 1098 incident CKS cases with known country of origin occurring between 1961 and 1989 in the Jewish Israeli population. Reporting systems were the Israel Cancer Registry, the medical documentation of all-Kaposi's sarcoma cases and the registry of HIV-seropositive patients. Patients who were seropositive for HIV were excluded from the study population. Population figures for groups of migrants and natives were derived from census surveys (1961, 1972, 1983) and inter-census estimates based on the population registry. RESULTS: The overall age-standardized rate of CKS was 16.9 per million in men and 6.3 per million in women. The ratio between genders remained stable during the study period. In both genders, there was a steep increase in CKS incidence between the late 1960s (age-standardized rates per million: 8.0 in men and 2.2 in women) and the early 1970s (17.9 in men and 6.7 in women). No further increase was present after 1971. Overall, immigrants experienced a relative risk (RR) of 1.17 [95% confidence interval (CI) 0.90-1.521 compared with Jews born in Israel. Immigrants from Morocco, Algeria and Tunisia had the highest incidence (RR 2.01; 95% CI 1.52-2.65) compared with Jews born in Israel, followed by those born in Iraq (RR 1.74; CI 95% 1.27-2.37). The lowest incidence was experienced by immigrants from Iran (RR 0.37; CI 95% 0.18-0.77) and from Central European countries (RR 0.45; CI 95% 0.30-0.66). Immigrants from other countries in Asia, Africa, the Americas and Europe had similar rates as Jews born in Israel. CONCLUSIONS: Israeli Jews present one of the highest incidences of CKS reported from developed countries. The incidence varies according to geographical origin. Countries surrounding the Mediterranean sea represent the area of highest CKS incidence.  相似文献   

20.
PURPOSE: We evaluated the safety and efficacy of percutaneous sperm aspiration from the epididymis or testicle as a diagnostic technique to confirm sperm production and as a therapeutic technique to harvest sperm for use in intracytoplasmic sperm injection. MATERIALS AND METHODS: We present our experience with 69 sperm aspiration procedures in men considered to have nonreconstructible obstructive azoospermia. This short outpatient procedure was performed using a butterfly needle with the patient under intravenous sedation and local anesthesia. RESULTS: Of the 32 diagnostic aspirations 20 demonstrated mature and motile sperm, 9 maturation arrest and 3 germ cell aplasia. In 35 of 37 therapeutic sperm aspirations (95%) adequate samples of sperm after processing (mean of 5.4 million) were obtained. Of 24 epididymal aspirations 13 (54%) had sufficient residual sperm for cryopreservation of 1 to 5 vials (mean 2.5) containing an average of 170,000 sperm per vial. In the 32 intracytoplasmic sperm injection cycles 221 of 392 eggs (56.3%) fertilized (2PN) and 6 resulted in ongoing pregnancies (21.4% per transfer). There have been no acute or chronic complications in this patient population. Ten men underwent a second successful aspiration procedure for intracytoplasmic sperm injection and 3 underwent a third aspiration without added difficulty. CONCLUSIONS: Percutaneous epididymal or testis sperm aspiration is a minimally invasive sperm retrieval technique and appears to be an effective alternative to microsurgical epididymal sperm aspiration, which is more invasive, costly and technically difficult.  相似文献   

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