COMMENT
Several findings are notable from this retrospective, cohort study.
First, when cervical dilation 1-6 cm in twins, ECC performed with the
combined McDonald-Shirodkar procedure is of more benefit, with reduction
in the rates of sPTB at <28, <30, <32 and
<34 weeks, significantly prolongation of latency (8 weeks),
higher GA at delivery, higher birth weight and lower perinatal mortality
than with McDonald procedure. Second, when cervical dilation ≥ 3cm,
combined McDonald-Shirodkar procedure has more obvious advantages with
significantly reduction sPTB at <28 , <30 weeks, and
overall perinatal mortality, also with prolongation pregnancy (by more
than 6 weeks), greatly improved GA at birth, and higher birth weight
compared with McDonald technology.
Some previous studies suggested no difference in outcomes when women
receiving Shirodkar were compared with those receiving McDonald
cerclages27 .15 ,16 ,22 . Also some researches
indicated that Shirodkar superior to McDonald because of that the
advantage of Shirodkar cerclage placed higher on the
cervix.16 ,28 ,29 . However, all studies are
committed to singleton pregnancy with cervical incompetence,no
well-designed studies comparing the efficacy of these methods for ECC in
twin pregnancy have been published. Since the occurrence mechanism of
sPTB is different between twin and singleton
pregnancies24 ,30 ,31 , preventive measures should
be treated differently. In addition to the patient population, cerclage
position may effect the variability of cerclage efficacy, and higher
cerclage is associated with a lower incidence of sPTB. Recently, Alper
Basbug et al27 conducted a retrospective study compared the
efficacy of modified Shirodkar
and McDonald cerclage techniques in singleton pregnancy with cervical
dilation>1cm, although they found there had no differences
in rates of sPTB and GA at birth ,but the interval from cerclage to
delivery was significantly longer in Shirodkar
group than in McDonald group(83.8 ± 37.6 vs 63.7 ± 38.9 days, p=0.08)
.Therefore, we can assume that ECC performed Shirodkar technique had
longer pregnancy latency than McDonald technique, and in our study, we
underwent combined McDonald-Shirodkar technique which involves the
dissection of the bladder with suture placement as high as feasible
around the supravaginal. Our research had indicated that this technology
may reduce rates of sPTB and improve maternal and fetal outcomes when
compared with McDonald technology.
In our cohort research, we used a 1-0 non-absorbable sutures when
undergone McDonald’s technique and use a Mersilene tape when conducted
Shirodkar technique, and in a RCT research on cervix cerclage materials
suggested that monofilament suture did not reduce rate of pregnancy loss
when compared with a braided
suture32 . Zhi-
Min Xu et al33 conducted a retrospective case-control study compare the efficacy of two
stitches versus one stitch in women with ECC in singleton pregnancies
and indicated that the procedure with two stitches can prolong the
pregnancy and improve the neonatal prognosis more effectively, and it
was similar to our research that we also use two stitches in case group.
Resul Karakus et
al34 reported a
new a technique , using a combination of the Shirodkar and McDonald’s
techniques to trying to place the Mersilene tape as high as possible on
the uterine cervix for ECC and proposed this method is safe, effective,
and had better fetal and neonatal outcomes in singleton pregnancies
compared with McDonald method. But their study had a small sample size
and all the cases in the study were singleton pregnancies.
The efficacy of cerclage was reduced in cases which cervical dilatation
has begun and the fetal membranes have prolapsed into the vagina,
because the larger the cervical dilatation, the higher the difficulty of
operation and the higher the risk of
failure23 ,35 ,36 . The currently available
literature lack of evidence for cervical dilation of 4 cm or more, in
2019,SOGC10 suggested ECC
may be considered in women in whom the cervix has dilated to <
4 cm without contractions. The only published study comparing ECC in
twin pregnancies with cervical dilation 4-6cm showed an overall positive
effect on pregnancy and neonatal
outcomes37 ,
which indirectly supported a potential benefit of ECC in twin
pregnancies with cervical dilation ≥ 4cm.
In our study, the cervical dilation was 1-6cm and more than 50% of
cases with amniotic membranes prolapsed beyond the external os. And our
conclusions were consistent with Chanjuan
Zeng’s38 and we
believed that in the urgent situation of cervical dilation of 4-6cm and
bulging membranes, ECC may be the only salvage measure for prolonging
gestation and improving neonatal outcome. In addition, our study assume
that ECC performed with the combined McDonald- Shirodkar procedure is
the best option of surgical therapy in twin pregnancies with cervical
dilation of 3-6 cm and prolapsed membranes.
At present, most prior publications and guidelines on cervical cerclage
suggest GA at cervical cerclage placement is up to 24 weeks of
gestation. However, in clinical practice, prolongation of gestation can
significantly improve neonatal prognosis and reduce perinatal mortality
for women with asymptomatic cervical dilation≥ 1 cm or prolapsed
membranes up to the external os at 24-26 weeks of gestation. And ,in
2022 ,RCOG14 suggested that
ECC as a salvage measure in the case of premature cervical dilatation
with exposed fetal membranes in the vagina can be considered up to
27+6 weeks of gestation. Resently, some retrospective
cohort studies39 40 indicated that
Ultrasound-indicated cervical cerclage (UIC) placement in twins may
dilated to 26-28 week’s of gestation. And in our study, the GA of ECC
placement extended to 26 weeks. Due to the small sample size, more large
sample studies are needed to confirm this conclusion.