Introduction
Preterm birth (PTB) is responsible for an estimated one million neonatal
deaths per year, making it the leading cause of mortality in children
under five years(1). Despite increasing international research, PTB
remains an unresolved obstetric complication of pregnancy, affecting
5-13% of pregnant women(2). Children born preterm are at a higher risk
of respiratory distress syndrome (RDS), intraventricular haemorrhage,
necrotising enterocolitis and retinopathy of prematurity(3). Preterm
Birth is also associated with increased maternal morbidity with higher
rates of obstetric haemorrhage, infection and intensive care unit
admission, likely related to increased operative delivery(4).
A short cervical length (<25mm) is a good predictor of PTB,
with a 31.2% to 41.3% risk of PTB, if present between 18 and 24
weeks(5, 6). In these women, management options include vaginal
progesterone(7) or cervical cerclage(5, 8). Cervical cerclage has been
used since the 1950’s and two methods are in common use. The McDonald
technique is a simpler purse-string suture around the cervix whereas the
Shirodkar technique involves colpotomy and bladder dissection with the
aim of a higher suture placement.
There is currently a lack of consensus on the superiority of the
McDonald or Shirodkar technique of cervical cerclages and there are no
current guidelines or agreement on which technique is recommended. In
the absence of emerging therapies to prevent PTB, combined with the
increasing rate of PTB worldwide and in Australia, there is a great need
to maximise the effect of the currently available treatments. This
review aims to determine if one technique provides a greater reduction
in preterm birth rates.
Aim
To synthesise existing quantitative evidence comparing McDonald with
Shirodkar cervical cerclage techniques to determine which correlates to
better maternal and neonatal outcomes. This systematic review will
answer the following question regarding women requiring prophylactic
cervical cerclage in singleton pregnancy: Is there a difference between
the McDonald and the Shirodkar cerclage techniques in the prevention of
PTB and other significant maternal or neonatal outcomes?