Participants:
The review considered all studies that included pregnant women
undergoing McDonald or Shirodkar cervical cerclage for prevention of
PTB. Studies were excluded if they included women with multiple
gestation pregnancies.
Intervention :
Studies which compared the McDonald and Shirodkar techniques of cervical
cerclage as a prophylactic procedure.
McDonald Cerclage
In the McDonald approach a suture is placed around the cervix in
purse-string fashion and securely tied anteriorly. The McDonald approach
requires no dissection into para-cervical tissues(13, 14).
Shirodkar Cerclage
The Shirodkar technique involves a transverse anterior colpotomy,
dissection of the bladder up to the internal cervical os and a posterior
colpotomy with dissection of areola and peritoneum upwards to the
internal os. The suture is placed subcutaneously and the knot tied in
the posterior defect and buried under the vaginal epithelium(13, 15,
16). Later modifications do not require a posterior colpotomy and place
the knot exterior to the vaginal mucosal for ease of removal(17). Whilst
technically more challenging, the rationale of this technique is to
allow more proximal placement of cerclage closer to the internal os. A
number of other modifications have been reported which simplify the
Shirodkar technique by utilising a clamp on the paracervical tissues for
more accurate suture needle placement(18) or avoiding a posterior
colpotomy and suture burial(17). For the purpose of this study both the
original technique described by Shirodkar and the modified techniques
were included.
Types of studies:
This review accepted randomised control trials, pseudo-randomised
control trials, non-randomised experimental control trials and cohort
studies. All papers included had to compare the co-interventions,
McDonald and Shirodkar cerclage.
Search Strategy:
Six electronic bibliographic databases were searched for eligible,
peer-reviewed literature: Medline (Ovid), EMBASE (Ovid), PsycINFO
(Ovid), Scopus, CINAHL (EBSCOhost), and Cochrane Library (Wiley).
Reference lists of included studies were screened and references in
academic textbooks were also reviewed. Where studies were unable to be
sourced contact was attempted with the corresponding author. A more
detailed database search strategy is described in Appendix S1.
Data collection and analysis
Study Selection
The titles and abstracts were reviewed using Endnote(19) and
Covidence(20). Studies that did not meet the criteria based on abstracts
were excluded (authors A-M.A and L.M.) and full texts of remaining
articles were sourced and screened (A-M.A and R.D.). No language
restriction was set, all non-English included studies were translated.
Included studies were critically appraised (by L.M and A.I.) and data
extracted using a standardised electronic form (by R.D. and K.P.W.). At
all levels of screening, any discrepancies were moderated by a third
senior reviewer (C.E.P.).
Assessment of risk of bias
To facilitate the assessment of possible risk of bias for each study,
two independent reviewers (A.I and L.M) assessed each paper using the
Cochrane Collaboration tool for assessing the risk of bias (ROBINS-I &
RoB 2)(21, 22) for non-randomised and randomised studies
respectively(12).
Cochrane GRADE Assessment
Quality of evidence for our primary outcome was judged using the GRADE
tool by two independent reviewers (A-M.A. and K.P.W.)(23).