The objective was to evaluate the relation between varicocele and sperm DNA fragmentation index (DFI) in infertile men. Materials and methods: A controlled observational study recruited 205 patients who sought medical consultation at Hanoi Medical University Hospital.
Trang 1THE RELATION BETWEEN VARICOCELE AND SPERM DNA
FRAGMENTATION INDEX IN INFERTILE MEN
1 Hanoi Medical University Hospital, 2 Hanoi Medical University The objective was to evaluate the relation between varicocele and sperm DNA fragmentation index (DFI) in infertile men Materials and methods: A controlled observational study recruited 205 patients who sought medical consultation at Hanoi Medical University Hospital One-hundred and forty-two men were diagnosed with male infertility who had unilateral varicocele belonged to the varicocele group and 63 men with normal reproductive health belonged to the control group Results: The mean DFI was significantly higher in the varicocele group compared with the control group (31.8 ± 18.8% compared with 22.6 ± 10.6%,with p < 0.01) The statistical difference in the percentage of severe DFI ( ≥ 30%) between the two groups was recognized in this study (45.8% in the varicocele group compared with 20.6% in the control group, with p < 0.03) Some factors which were found to increase the level of DFI were age and infertility duration in patients with varicocele However, there was no difference
in the level of DFI among the three groups of varicocele grade Conclusion: Varicocele has negative effects on sperm DFI Therefore, varicocele should be treated early in infertile men, disregarding the grade of varicocele.
I INTRODUCTION
Keywords: Varicocele, semen analysis, sperm DNA fragmentation, DFI
There are many causes leading to male
infertility including reproductive tract infections,
malignancies, endocrinal disorders, genetic
disorders, hypogonadism, varicocele, genital
abnormalities, etc Among them, varicocele
is one of a few causes that can be treated
Varicocele is found in 19 - 41% of primary
infertile men and up to 45 - 84% in secondary
infertile men [1] Varicocele is defined by the
dilation of the pampiniform venous plexus,
which is caused by the reflux of the blood flow
from the left renal vein on the left side and from
the inferior vena cava on the right side The
venous stasis leads to many consequences
that negatively affect the reproductive function
of men [2]
Recently, the sperm DNA fragmentation
index (DFI) has been used to evaluate the reproductive function of men in addition to conventional sperm analysis DFI provides more credibility because, unlike standard semen analysis, DFI exhibits low biological variability and has superior predictive value on reproductive outcomes [3] Varicocele has been proved to have associated with higher sperm DNA damage [4] The etiologies of sperm DNA damage are not completely understood but hypothesized to be the increased level
of reactive oxygen species and a significant reduction in the level of DNA polymerase in seminal fluid The highly damaged sperm DNA negatively affect spontaneous pregnancy and the success rate of assisted reproductive technique[5]
Many studies have assessed the correlation between varicocele and sperm DNA fragmentation index The majority of them were conducted on the European communities which have fundament differences in environment
Corresponding author: Nguyen Hoai Bac, Hanoi
Medical University Hospital
Email: drbac.uro@gmail.com
Received: 27/11/2018
Accepted: 12/03/2019
Nguyen Hoai Bac 1 , Nguyen Cao Thang 1 , Hoang Long 2
Trang 2compared with Asian communities in general
and Vietnamese communities in particular
In Vietnam, the researchers focused on
evaluating the impact of varicocele on standard
semen parameters Their studies commonly
had limited sample size and no control group
For the practical reasons mentioned above, the
objective of this study was to analyze the effect
of varicocele on sperm DNA fragmentation
index
II METHODS
1 Time and location
Our study was conducted from December
2013 to August 2018 at Hanoi Medical
University Hospital
2 Material and method
This was a controlled observational study
based on 205 men who had been examined
at Hanoi Medical University hospital, in which
142 infertile men with varicocele belonged to
the varicocele group and 63 men with normal
reproductive health belonged to the control
group
Inclusion criteria of the varicocele group
- Diagnosed with infertility according to the
WHO manual 2010
- Diagnosed with unilateral varicocele
confirmed on clinical examination and ultrasound
- Had sufficient laboratory tests
- Exclusion criteria of the varicocele group Had subclinical varicocele (grade 0) or had clinical varicocele with normal ultrasonography
- Laboratory tests were not performed at Hanoi Medical University’s lab
Inclusion criteria of the control group
- Having good health determining via periodical examination
- Their partner having pregnancy
- Without varicocele by clinical examination and ultrasonography
3 Variables
Sperm DNA fragmentation index (DFI) is based on the evaluation of the SCD technique which was generated with Halosperm kit
4 Data analysis
Collected data was processed and analyzed
by STATA 13
All results were expressed as the mean
± SD Difference between 2 groups was estimated by the paired sample T - student test for normal distribution and Mann Whitney test for non-normal distribution
All hypothesis testing was considered statistically significant if p < 0.05
III RESULTS
1 General features of the patients
Table 1 General features of the varicocele group and the control group
Variables
Varicocele group (n = 142)
Control group
n (%) (Mean ± SD)
n (%) (Mean ± SD)
26.6 ± 2.7
42 (66.7)
> 30 55 (38.7)
34.9 ± 4.5
21 (33.3) 33.6 ± 2.7
Trang 3Varicocele group (n = 142)
Control group
n (%) (Mean ± SD)
n (%) (Mean ± SD) BMI (kg/m 2 ) 21.9 ± 2.4142 22.5 ± 2.563 0.07
Avg testicular
The mean age of the varicocele group and the control group were 29.8 ± 5.4 and 28.9 ± 4.2, respectively The mean BMI of the two groups were also similar The average testicular volume of the two groups was similar and within normal range
2 Clinical findings of varicocele group
Chart 1 Clinical findings of the varicocele group
Grade III varicocele occupied the highest proportion with 64.9%; grade I and grade II varicocele took over 18.2% and 16.9%, respectively The majority of patients had left side varicocele (98.6%), only two cases had right side varicocele (1.4%) Primary infertility occupied the major proportion with 73.7% Most men had duration of infertility under 24 months
3 Measuring DFI of the varicocele group and the control group
Table 2 DFI of the varicocele group and the control group
n (%) Mean ± SD n (%) Mean ± SD
Trang 4Variables Varicocelegroup Control group p
n (%) Mean ± SD n (%) Mean ± SD
< 15 22 (15.5) 11.1 ± 2.3 16 (25.4) 11.8 ± 2.2 0.16
15 - 30 55 (38.7) 21.6 ± 4.2 34 (53.9) 21.3 ± 4.8 0.35
≥ 30 65 (45.8) 47.4 ± 16.8 13 (20.6) 39.5 ± 6.4 0.05
The mean DFI of the varicoecele group was significantly higher than the controls (31.8% ± 18.8% and 22.6 ± 10.6%, respectively, with p = 0.0002)
Chart 2 Ratio of DFI in both groups
In the varicocele group, the ratio of severely damaged DFI was the highest at 45.8% This ratio was only 20.6% in the control group
4 Correlation of some clinical factors and DFI
Table 4 Correlation of DFI and some clinical facors Variables
Varicocele group
p
(Mean ± SD) BMI (kg/m 2 )
Trang 5Varicocele group
p
n (%) (Mean ± SD) DFI
Age (year)
Varicocele grade
Type of infertility
Secondary infertility 37 (26) 33.4 ± 20.5
Duration of infertility (month)
Age and duration of infertility are two risk factors that can affect DFI in varicocele men with
p = 0.03 and p = 0.02, respectively
IV DISCUSSION
This study involved 142 infertile men
with clinical varicocele with the mean age of
29.9 ± 5.5 and 63 men of the control group
with the mean age of 28.8 ± 4.3 (Table 1) It
was appropriate to determine the effect of
varicocele on semen quality due to the fact that
the majority of patients were in reproductive
age Previous authors also studied a group
of patients similar to this study (Abdel-Meguid
et al and Ghazi et al) [6, 7] The mean BMI
of the varicocele group and the control group
were also identical (Table 1) This was the
basis to assess the impact of varicocele on the
sperm DNA integrity on the varicocele group compared with normal fertile men
In this study, 140 of 142 patients (98.6%) had left side varicocele and the two patients left had right side (Chart 1) As the spermatic veins dilated, the obstruction of the blood flow hinders the heat-exchange process of the pampiniform plexus and consequently leads to discomfort or pain in the scrotum and testicular over-heat
Furthermore, an increased hydrostatic pressure in the spermatic veins obstructs the arterial blood flow of the testis and restricts
Trang 6normal testicular growth
In our study, however, the testicular volume
of the affected group was 12.8 ± 3.8 ml, similar
to the control group which was 13.7 ± 3.7 ml
(Table 1) These results were also observed
in a study by Mohammed et al which was
12.7±1.02 ml [8] The percentage of grade I,
grade II and grade III varicocele were 18.3%,
17.6% and 64.1 %, respectively The majority
of varicocele patients were primary infertile
(73.7%) (Chart 1)
Recent evidence have shown that only
clinical varicocele would have a negative effect
on male reproductive health [9] The deleterious
effects of varicocele are manifested in the
decline in quality and the quantity of sperm
Conventional semen analysis is generally
used to evaluate male fertility However, these
parameters exhibit many limitations such as
high degree of biological variability and can
be affected by the patient’s duration of sexual
abstinence and mental state
In recent years, with the development of
genetics and molecular biology, sperm DNA
damage has been evaluated and considered
a promising biomarker for infertility Sperm
DNA fragmentation index (DFI) has been
proved to be superior to the conventional
semen analysis that it exhibits a lower degree
of biological variability and has more predictive
value in pregnancy rate [4] When DFI < 15%,
the sperm has a low level of DNA damage, the
couple can achieve spontaneous pregnancy
The fertilization capacity of sperm significantly
decreases when DFI reaches 15 - 30% DFI
higher than 30% results in poor pregnancy rate
even with assisted reproductive technique [10]
The correlation between increased sperm
DNA fragmentation and varicocele has
been proved in many previous studies In a
prospective controlled trial on infertile men with varicocele, there was a considerable elevation in sperm mean DFI in the varicocele group compared with the control group (25%
in varicocele group compared with 15% in control group), the difference was statistically significant [5]
In another meta-analysis which was conducted to evaluate the alteration of sperm DNA damage in varicocele patients and to determine the efficacy of varicocelectomy, Wang et al have shown that the sperm DNA damage is significantly higher in varicocele patient and the mean difference was 9.84% (95% CI; 9.19 - 10.49; p < 0.00001) [11]
In our study, the mean DFI of the varicocele patients was remarkably higher comparing with the control group (32.8 ± 19.2% and 21.4
± 8.7% with p = 0.001) (Table 2) When sperm DNA damage is categorized into severe, moderate and mild degree, it was also apparent that the proportion of severely damaged sperm DNA in varicocele group was higher than the control group (45.8% compared with 20.6%,
p = 0.003) (Chart 2) Our results once again confirmed the negative effect of varicocele on the integrity of sperm DNA
Besides the direct effect of varicocele, some risk factors which contribute to the damage of sperm DNA are age, BMI, grade of varicocele, duration of infertility, etc [12]
In our study, the level of DNA fragmentation had a relation with age and the duration of infertility Men aged over 30 or men with duration of infertility above 24 months had increased level of DFI (p = 0.02 with age and
p = 0.03 with duration of infertility) However, there was no correlation between DFI and BMI
or different varicocele grades These results indicated that varicocele could damage sperm DNA even in early grade and the damage was
Trang 7more severe in elder men or men with longer
duration of infertility Therefore, in clinical
practices, it is important to advise patients with
varicocele to have early intervention which
would prevent further adverse effects
V CONCLUSIONS
Varicocele has a negative effect on sperm
quality which is demonstrated by the increase
in sperm DNA fragmentation index
Infertile patients with varicocele need to
have early intervention even with low grade
varicocele to prevent that negative effect
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