Intro
The demand for infertility treatment has grown exponentially in Brazil. Intrauterine
insemination (IUI) is a low complexity fertility treatment that is much less
invasive and inexpensive when compared to in vitro fertilization (IVF) ( Isa et al ., 2014a ). Pregnancy
rates after IUI vary widely due to multiple patient-related factors ( Isa et al ., 2014a ; 2014b ; Allen
et al ., 1985 ; Asante
et al ., 2013 ; Nuojua-Huttunen et al ., 1999 ; Schuffner et al ., 2009 ). IUI can be indicated
for patients with different causes of infertility, including cervical factor
infertility, ovulatory dysfunction, endometriosis, infertility for immunological
causes, and idiopathic infertility ( Duran et
al ., 2003 ).
Some factors may have a decisive role in the outcome of IUI, such as age, ovarian
reserve, endometrial thickness, types and doses of gonadotropin, and sperm quality.
Although several studies have searched for markers of success in IUI, age remains as
the best parameter to assess ovarian function and consequently the response to
assisted reproductive technologies ( Deatsman
et al ., 2016 ). Although some authors have linked
higher levels of AMH to higher pregnancy rates ( Bakas
et al ., 2015 ), the predictive value of AMH remains
questionable in scientific literature ( Tremellen
& Kolo, 2010 ).
Endometrial thickness has been associated with higher embryo implantation and IUI
success rates. There is no consensus in the literature over an ideal cutoff value,
although most studies agree on endometrial thickness greater than 7 mm ( Biswas et al ., 2016 ; Caetano et al ., 2005 ).
IUI without controlled ovarian stimulation is not recommended, as natural cycles
offer no clinical advantage. Fertility rates are higher in stimulated cycles ( Rashidi et al ., 2013 ; Fritz & Speroff, 2011 ). In several
countries, it is mandatory to register IUI procedures. In Denmark, for example, IUI
treatments have been registered since 2007 ( Malchau
et al ., 2014 ). REDLARA, the Latin American Network
of Assisted Reproduction, reported 6,250 cycles of IUI in 2013 with a birth rate per
cycle of 14.9% ( Zegers-Hochschild et
al ., 2016 ). In Brazil, outcomes and indications of IUI are
scarce.
The aim of the study was to identify which parameters positively affected the
clinical pregnancy rates of IUI cycles in a private assisted reproduction center and
evaluate which couples should opt for IUI.
Results
Idiopathic infertility was identified in 35.9% of the cases, followed by ovulatory
dysfunction with 26.2% and endometriosis with 15.2%. Other less frequent causes were
cervical factor, tubal factor, male factor and multiple factor infertility. There
was no statistical difference regarding the cause of infertility and the number of
pregnancies ( p =0.8). Fifty-six (14.6%) of the 381 cycles analyzed
resulted in clinical pregnancy.
Patients younger than 40 years accounted for 87.9% (335) of the sample and achieved
54 clinical pregnancies (16.1%). The clinical pregnancy rate was five times higher
in younger patients (40 years)
( p =0.043). Among the patients with positive clinical
pregnancies, only two were older than 40 years ( Table 1 ). When the patients were split by age (≤29, 30-34, 35-39,
and ≥40 years), most pregnancies - 26 (6.8%) - occurred between 35 and 39
years of age ( Table 2 ), but the groups were
not statistically different ( p =0.156).
Pregnancy rates and patient characteristics
Pregnancy rates according to maternal age
Endometrial thickness >8mm was found in 76.6% (292) of the patients. Patients with
an endometrial thickness greater than 8 mm were three times more likely to achieve
clinical pregnancies than the individuals with an endometrial thickness <8mm
( p =0.016). Of the 89 patients with endometrial thickness
<8mm, only six (6.7%) achieved clinical pregnancies ( Table 1 ).
Fresh semen samples were more frequent (97.1%), and sperm concentration ranged from 2
to 300 million per mL, while sperm motility ranged from 8.1% to 95% after
processing. Cryopreserved semen was used in 11 procedures, and only one patient
achieved clinical pregnancy. Motility above 55% had higher rates of clinical
pregnancy ( p =0.002).
Of the 381 cycles analyzed, 328 (86.0%) were from Group 1 (injectables) ( Table 3 ), and 42 (11.0%) were from Group 2
(injectables plus oral medication). Nine patients (2.3%) took only oral drugs and
two (0.52%) did not use medication. The group given oral medication alone and the
individuals undergoing medication-free natural cycles did not achieve clinical
pregnancy.
Stimulation protocols and pregnancy
In the group taking only injectables, 159 patients (48.4%) took rFSH, 127 (38.7%)
were on hMG, and 42 (12.8%) on uFSH, yielding clinical pregnancy rates of 21.3%,
10.4%, and 10.5%, respectively. Patients on rFSH achieved clinical pregnancy rates
2.5 times higher than the individuals on hMG ( p =0.02) ( Table 4 ). Six (14.2%) of the 42 patients in
Group 2 achieved clinical pregnancies, three with clomiphene citrate and rFSH and
three with clomiphene citrate and hMG.
Pregnancy outcomes for each injectable drug used
Discussion
It is important to point out that even in patients diagnosed with idiopathic
infertility, fertility rates may decline due to lower oocyte quality, fertilization
failure or embryo implantation abnormalities ( Wolff
et al ., 2013 ). Advanced maternal age is an
established independent negative prognostic factor for live births and clinical
pregnancy associated with lower chances of spontaneous or assisted pregnancy ( Geisler et al ., 2017 ). In the
present study, a clear relationship was observed between lower clinical pregnancy
rates and advanced maternal age. IUI procedures do not achieve high pregnancy rates
in this group. In another similar study carried out in Brazil, advanced maternal age
was the only variable significantly correlated with success rates of IUI ( Sicchieri et al ., 2018 ).
Adequate endometrial thickness is widely considered a decisive factor in the
outcomes of ART treatments ( Wolff et al.,
2013 ). The finding in our study that more than 93% of the patients with
endometrium thickness >8 mm did not achieve pregnancy corroborates other studies.
In a large study enrolling 2,929 patients submitted to IUI with idiopathic
infertility factor, the results plateaued at an endometrial thickness of 10 mm . The
literature is still controversial in relation to very thick endometria (>14mm),
and some studies suggested that there might be less favorable endometrial
characteristics in this group, as well as lower implantation rates ( Dietterich et al ., 2002 ; Weissman et al ., 1999 ). Some
studies suggested that the ultrasound aspect of the endometrium (echogenicity) might
be linked to higher implantation rates. This was not analyzed in the present study
( Alborzi et al .,
2005 ).
The link between increased pregnancy rates and increased sperm motility is in
agreement with the literature ( Duran et
al ., 2003 ). Few studies have looked into the outcomes of IUI
with frozen semen. Our study corroborated the literature, suggesting lower pregnancy
rates when frozen semen samples were used in IUI ( Dinelli et al ., 2014 ). Since our study featured a
limited number of patients using frozen semen, more studies are needed to determine
whether IUI should be carried out with frozen semen. Since motility is very
important to achieving successful outcomes, it has been suggested that the causes of
low sperm motility after semen processing, such as varicocele, should be corrected
prior to assisted reproduction procedures ( Hendin
et al ., 2000 ).
Although only a few patients did not take injectables in our study, cycles stimulated
with injectable or oral medications and injectables only have reportedly greater
chances of success. In a study by Malchau et
al . (2014) , 76% of the children born after IUI resulted from
controlled ovarian stimulation with CC, FSH or both ( Rashidi et al ., 2013 ).
A trend toward higher pregnancy rates was observed with rFSH ( Demirol & Gurgan, 2007 ), but the cost-effectiveness of this
drug compared to hMG is questionable, since rFSH is more expensive than hMG ( Gerli et al ., 2008 ). In
addition to providing better ovarian response, cycles with rFSH reportedly yield
better quality oocytes ( Cheon et
al ., 2004 ). Our study showed better results in stimulated cycles
using rFSH, but the medication is not affordable by the standards of most of our
patients. Moreover, positive pregnancy outcomes may also be achieved through other
stimulation protocols.
Conclusions
IUI is a viable procedure and a good option for the initial treatment of infertile
couples, since high pregnancy rates may be achieved when patients are adequately
selected.
In this study, IUI patients younger than 40 years with endometrial thickness greater
than 8mm had higher clinical pregnancy rates. Endometrial thickness may be an
important parameter to be assessed in future research. Sperm motility also had a
significant impact on the success of IUI cycles. Further studies are needed to
evaluate whether frozen sperm negatively affects pregnancy rates.
Our results suggest that rFSH produces better outcomes than hMG, but more prospective
controlled studies are needed to confirm the efficiency of these drugs in IUI.
The decision to perform the most appropriate treatment for each patient should be a
priority in ART centers. It is important to carry out studies in each service and
compare the findings with data from the literature.
Materials|Methods
This retrospective observational study included 261 patients submitted to 381 IUI
cycles with fresh or cryopreserved partner semen (IU-H) from January 2012 to
February 2017 in a private center in Curitiba-PR, Brazil. Heterologous
intrauterine insemination procedures were not included, so as not to affect
pregnancy rates.
The local institutional review board approved the study. Patients were not
required to give consent due to the retrospective nature of the study.
The included subjects were split into groups based on the cause of infertility,
age, endometrial thickness (measured two days before IUI), and
anti-Müllerian hormone (AMH) levels. AMH levels were measured in 125
patients, and test results were not considered for IUI. The groups were further
divided between fresh vs. frozen semen and levels of sperm
concentration and motility.
Controlled ovarian stimulation was achieved by three different protocols: 1)
Injectables, 2) Oral medication + injectables, 3) Oral medication. Group 1 was
divided into three subgroups: A) human menopausal gonadotropin (hMG) -
Menopur ® , B) recombinant follicle stimulating hormone
(rFSH) - Gonal ® or Pergoveris ® , and C)
urinary follicle stimulating hormone (uFSH) Fostimon ® . Group 2
took clomiphene citrate (CC) followed by the injectable medications cited above.
Group 3 took CC or Letrozole ® . The final outcome considered
for all variables was clinical pregnancy.
Serial transvaginal ultrasound examination was performed on the second or third
day of the cycle and on the sixth day after the start of controlled ovarian
stimulation. The remaining tests varied according to the response each patient
had to the stimulation protocol. hCG (Choriomon ® or
Ovidrel ® ) was administered when the mean diameter of the
dominant follicle reached at least 18mm. IUI was scheduled 36h to 40h
thereafter. Endometrial thickness was evaluated 48h before IUI, without later
analysis. Supplementation of the luteal phase with Utrogestan ®
or Duphaston ® was also performed.
Semen samples were processed by density gradient centrifugation or sperm wash
according to the 2010 guidelines of the World Health Organization (WHO) for
semen processing ( WHO, 2010 ). Sperm wash
was performed in samples meeting the following criteria: increased viscosity,
concentration <15 million per ml, and motility <32%. Other samples
underwent density gradient centrifugation. In both procedures, the volume was
measured after collection and concentration and motility were evaluated on
Makler chambers with the aid of a light microscope.
After complete liquefaction in density gradient centrifugation, the semen samples
were processed with density gradient medium (Isolate, Irvine Scientific,
California) and sperm washing medium (Modified HTF Medium HEPES with Gentamicin,
Irvine Scientific, California). In the processing technique, 90% and 45%
colloidal gradient were used. One mL of the lower phase gradient was transferred
into a sterile disposable conical-bottom centrifuge tube using a Pasteur
pipette. A second 1 mL layer of the upper phase was gently placed on top of the
lower phase. Liquefied semen was gently placed onto the upper phase. The sample
was centrifuged for 20 minutes at 516G. The supernatant was discarded, and the
pellet was resuspended with a Pasteur pipette in 2.5 mL of HTF. Sperm wash was
performed with centrifugation for eight minutes at 516G. Then the supernatant
was discarded and the pellet resuspended with a Pasteur pipette in 0.5 mL of
HTF. Sperm parameters were then evaluated according to the WHO criteria for
IUI.
Data were organized on Microsoft Office Excel 2007 ® and
analyzed on SPSS Statistics 22.0 ® . The results were expressed
as frequencies and proportions for categorical and qualitative variables, and as
measures of dispersion and central tendency for quantitative variables.
The Mann-Whitney test for quantitative variables was used to assess the
relationship between clinical/biological variables and pregnancy success. The
non-parametric Shapiro-Wilk test was chosen to test the normality of
quantitative variables. The Chi-square or Fisher's exact test was used to test
the association between qualitative variables and the outcome of treatment.
Statistical significance was attributed to comparisons with a
p -value <0.05.
Linear logistic regression models were used to determine the relationship between
outcomes and the clinical/biological variables. Explanatory variables with a
significance level of up to 20% in univariate analysis were included in the
logistic regression model. The results were expressed as odds ratios (OR).
Statistical power analysis was performed to verify the ability of tests to reject
a false null hypothesis. Software program GPower 3.1 was used in the analysis of
statistical power from univariate and multivariate analysis.
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