Discussion
It is a medical consensus that UFs
have adverse effects on fertility[12-14]. With the
global fertility decline, it is still a problem to be solved to
establish a minimally invasive, safe and effective treatment method that
can effectively improve the uterine pregnancy conditions and pregnancy
outcomes of the patients with UFs.
The MWA treatment for UFs is a new minimally invasive treatment
technology that has been applied to the clinic for more than ten years.
Research reports show that this method has the advantages of minimally
invasiveness, effectively making fibroids shrink or disappear on the
basis of preserving the uterus, and no damage to ovarian
function[6, 8]. Our previous study found that many
patients with symptomatic UFs had unplanned pregnancies and safe
production after MWA[9], suggesting that the MWA
treatment for UFs may have no negative impact on the patient’s
reproductive function and may even improve the patient’s reproductive
function. Therefore, this paper makes a further systematic and
prospective observational study.
Endometrial integrity and better receptivity are the basic conditions
for pregnancy. In order to effectively protect the endometrium from
thermal damage during MWA, for patients who already have sexual life, a
hysterosalpingography catheter was inserted into the uterine cavity
through the cervix 5 minutes before treatment, so as to identify the
endometrium compressed and deformed by UFs during treatment. During the
ablation of FIGO 0–4 UFs, cooling saline is injected into the uterine
cavity through the catheter to form water isolation on the surface of
the endometrium to protect the endometrium. The menstrual cycle and
menstrual period of patients were normal after treatment, indicating
that the protective measures were effective.
The subjects of this study were patients with fertility requirements,
seeking treatment due to large UFs, bleeding, compression and other
symptoms, which were in line with the clinical guidelines for the
treatment for UFs of the International Society of Obstetrics and
gynecology[15]. Because this cohort of patients
have fertility requirements after treatment, the follow-up observation
of fertility status after treatment can better reflect the impact of
this treatment technology on conception and continuous pregnancy.
In this study, the median follow-up time after treatment was 64 months
(1–124 months), and the pregnancy rate after treatment was 55.56%,
which was higher than the reported 38.3% after uterine artery
embolization (UAE)[16] and 53.6%~55.9% after
surgical
myomectomy[17].
Among continuing pregnancy patients, sustained pregnancy and safe
productivity were 96.2%(25/26), and the babies were all healthy,
indicating that US-guided MWA therapy can be used for symptomatic UFs
with fertility requirements. Among the 18 patients diagnosed as primary
infertility before treatment, the successful pregnancy rate after
treatment was 22.22%, and among the successful pregnancy patients, the
successful delivery rate was 50%, suggesting that the reason of primary
infertility could be UFs, the
shrinkage of fibroids after MWA
improved the fertility status of patients.
With respect to the appropriate pregnancy time after ablation treatment,
the results of this study showed that 6% of the 50 pregnancies of 45
patients were pregnant within 3 months after treatment, of which 1 case
became pregnant naturally 2 months after treatment and continued to
pregnancy smoothly until full-term delivery; 12% were pregnant 3
~ 6 months after treatment, and 82% were pregnant 6
months after MWA treatment. This data has certain guiding significance
for the preparation time of patients after MWA treatment. However, in
respect of when it is safer for specific patients to become pregnant
after treatment, personalized pregnancy guidance should be given
according to the type, size and treatment effect of the patient’s UFs.
It is recommended that the patient be rechecked 3 months after
treatment. If the shrinkage rate of UFs is ≥50%, the symptoms related
to fibroids disappear, and the menstruation is normal, then pregnancy
preparation can be considered. The average pregnancy preparation time of
patients after MWA treatment was shorter than that after surgical
myomectomy, and there was no uterine rupture in pregnancy cases,
suggesting local tissue necrosis of UFs after MWA. MWA will not increase
the risk of uterine rupture. Because the treatment was completed under
the US-guidance and monitoring. during the treatment, the microwave
thermal field can be effectively controlled in the UFs capsule, and the
damage to the tissues outside the adjacent UFs was small. Therefore,
there was no obvious damage to the elastic fibers and collagen fibers of
the myometrium. After treatment, the volume of the UFs is significantly
reduced[6, 7],but there is no scar formation in
the tissues of the myometrium outside the UFs. The risk of collagen
fiber hyperplasia is small, which can theoretically reduce the risk of
uterine rupture during pregnancy caused by scars caused by UFs surgical
myomectomy. For the elderly patients who urgently need to get pregnant
as soon as possible, this treatment may be a more appropriate treatment
option.
The determinants of delivery mode of pregnant women after MWA are not
only obstetric disease factors, but also social and patient
psychological factors. In this study, the cesarean section rate was
76%, which was only partly attributed to obstetric factors. Among the
19 cases of cesarean section, 1 case (5.3%) chose cesarean section
because of breech position; 7 cases (36.8%) had a history of cesarean
section;2 cases (10.5%) were conceived by ART, and the fetus was
precious, cesarean section was strongly required to complete delivery;1
case (5.3%) has a history of 2 artificial abortions; 1 case (5.3%)
refused to try vaginal delivery due to a history of ectopic pregnancy,
fear of pain during delivery and delivery complications; and 7 cases
(36.8%) opted for cesarean section because of the lack of confidence in
natural childbirth at the older age of pregnant women. Therefore, the
mode of delivery followed up in this study cannot accurately reflect the
obstetric delivery state formed by the treatment of UFs. No uterine
rupture occurred in all patients with continuous pregnancy and delivery,
suggesting that it is safe for patients with UFs to conceive and give
birth after microwave ablation treatment.
Although the relationship and mechanism between UFs and infertility are
not completely clear, studies have shown that UFs at different locations
have different effects on pregnancy. Submucosal fibroids of any size and
intramural fibroids >4cm significantly impair patient
fertility and in vitro fertilization results[1].
Among the 45 pregnant patients in this study, there were 7 cases of
submucosal fibroids, 15 cases of intramural fibroids, and 23 cases of
subserosal fibroids. The average maximum diameter of fibroids was
5.87±2.13cm (3–16.7cm), the ablation rate averaged 86.40±7.49%
(56.85–99.56%). After ablation of some submucosal or intramural UFs
close to the fibroids, the coagulated and necrotic
fibroids were discharged through
vagina, the fibroids disappeared completely, and the uterus returned to
normal size and shape, indicating that UFs were completely ablated, the
endometrium was effectively protected under real-time US-guidance, and
the pregnancy ability of patients can be unaffected or even effectively
improved.
In this study, 1 pregnant patient had placental abruption. Because there
are many factors related to the occurrence of placental abruption, even
pregnant women without UFs can also have placental abruption. At
present, there is no evidence that premature placental contractions are
caused by MWA treatment. It also needs to be verified by researches with
large sample sizes.
There are many factors affecting women’s fertility. The success of
pregnancy after MWA treatment of UFs is also related to many factors.
This study found that there were significant differences in age, history
of pregnancy, history of spontaneous abortion, history of infertility
and type of fibroids between the pregnant group and the non-pregnant
group after MWA treatment.
The OR value of the age of the pregnant group and the non-pregnant group
was 0.858, indicating that the older the patients, the lower the
pregnancy rate after MWA. The pregnancy rate of patients in the
group<35 years old was significantly higher than that in the
group≥35 years old. The pregnancy outcome analysis of pregnant patients
showed that after pregnancy, the spontaneous abortion rate was 22%, but
the spontaneous abortion rate was only 13.33% for
patients<35 years old,
and 23.33% for patients≥35 years old. This suggests that for patients
with UFs who have not given birth, interventions should be taken as soon
as possible. Previous studies believe that UFs that change the shape of
uterine cavity and make endometrial deformation and abnormal contour
have a greater impact on fertility, and surgery and other treatments can
improve and correct this damage [18].
This study found that the pregnancy rate after MWA for UFs close to the
serosal layer was higher than that close to the mucosal layer. This may
be due to the changes in the morphology of the uterine cavity caused by
submucosal fibroids, changes in
the receptivity of the endometrium, and the influence of the
intrauterine environment[2] , which also verifies
the previous study research that submucosal fibroids has a negative
impact on fertility, and the existence of
subseroal fibroids has little or
no impact on fertility[1]. Among patients with UFs
with a history of spontaneous abortion, the pregnancy rate after the MWA
treatment was higher than that without a history of spontaneous
abortion, and they could give birth smoothly and successfully. It is
suggested that these patients have their own fertility conditions and
ability, and the occurrence of spontaneous abortion might be closely
related to UFs. After MWA treatment, the fertility disorders related to
fibroids can be lifted or disappeared, which provides good conditions
for smooth conception and delivery. It is also consistent with the fact
that fibroids increase perinatal risks such as spontaneous
abortion[4]. Although this study showed more
optimistic results, the prospective comparation study of pregnancy
status of MWA and
UAE, as well as MWA and myomectomy
is still worthy of further research, in order to obtain objective
research data and guide doctors to give individualized and accurate
treatment suggestions according to the requirements and specific
conditions of the patients.
Conclusion
Patients with symptomatic UFs have a higher pregnancy rate after MWA
treatment, and the interval between preparations for pregnancy is
shorter than myomectomy. For patients who are infertile due to UFs and
plan to pregnant as soon as possible, the MWA therapy can be used as an
alternative safe minimally invasive treatment method. Vaginal delivery
appeared to be feasible and safe after MWA. For patients with
infertility and adverse pregnancy history caused by UFs, the MWA
treatment could improve the uterine conditions, and it is possible to
increase the natural conception rate and the ART conception rate. For
the patients with UFs and wanting to be pregnancy earlier treatment is
important.