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?