Introduction

Caesarean Section (CS) occur in around 1 in 4 births in the UK1 and are classified as elective, or emergency, where the procedure is undertaken to prevent risk to the mother and unborn child. Amongst the risks associated with a CS procedure is the development of a surgical site infection (SSI); a serious surgical complication defined as ‘a type of healthcare-associated infection in which a wound infection occurs after an invasive (surgical) procedure ’. 2 The CDC 3 further define SSI as an infection that occurs after surgery in the part of the body where the surgery took place. Surgical site infections can sometimes be superficial infections involving the skin only. Other surgical site infections are more serious and can involve tissues under the skin, organs, or implanted material. The development of an SSI following CS can result in permanent injury to the bladder, uterus or rectum as well as scarring, increased pain, a reduction in mobility4 and extended hospital stays.5 A severe and potentially fatal complication of developing an SSI is necrotising fasciitis (NF), a rare bacterial infection affecting the soft tissue and fascia. 6
The World Health Organization [WHO] 7 recommended C-section rates should be between 10% and 15%. However, there has been a gradual international increase in the amount of CS being undertaken. In the United States, CS has been highlighted as a common procedure, increasing by 41% in a 13-year period to its current rate of about 32%8 Similarly, high rates are currently observed in the UK (26.5%) 9; in Australia (32.3%)10; and in China (41%). 11 In other countries both the current proportion and rate of increase are high: Zejnullahu et al. 12 report that in Kosovo, the rate of CS rose from 7.5% in 2000 to 27.3% in 2015 with 33.5% of deliveries in tertiary referral care services being C-sections.
The increase in CS risks an increase in SSI, with WHO13 warning that SSIs affect up to one-third of patients who have undergone a surgical procedure. Almost half of SSIs reported in the European Centres for Disease Prevention and Control surveillance system 14 were identified as superficial, with 30% being deep, and 20% extending to organ/space. However, Wilson et al. 15 reported that procedures associated with a very short post-operative stay, e.g. CS, only had infections recognised and reported following discharge from hospital. These are therefore likely to be underestimated given that approximately 50% of SSIs become evident after discharge. 16 Incidence rates for the development of SSI in CS have been reported globally, as 4.6%.17 However, Jenks et al. 18reporting on a multicentre English trial, concluded that SSI was estimated to be just under 10% and the readmission rate due to SSI following CS was 0.6%.
SSI represents a significant financial and patient burden, with costs estimated at over £2 billion to the UK healthcare system, with a median cost of £7,467 per SSI CS patient compared to £3,572 for non-SSI CS patients. 19 Annual costs exceed US$1.6 billion in the US 20 AU$268 million in Australia,21 and £930 million in the UK. 19Increased financial expenditure are mainly attributable to increased length of hospital stay 18 and excess cost per operation of £3,855, with an estimated excess cost of over £7,000,000 per hospital in the UK. 22 The pain and isolation concomitant with suffering an SSI also significantly impacts on patient quality of life and experiences of care. 23 Umscheid et al. 24 argue that 60% of SSIs may be preventable and their risk minimised by applying best practice in the perioperative period.
The international literature has identified several risk factors that predispose an individual developing an SSI following a CS procedure in general, including obesity and an increased BMI, increased age, pre-eclampsia, grade of surgeon and existing comorbidities. Indeed, obesity, age and pre-eclampsia have been linked to post-surgical complications, possibly compounding wound healing and increasing the risk of infection. 25, 26 Extended labour time and the complexities surrounding an emergency CS also impact the possibility of post-surgical infection. 27, 28 However, there are some inconsistences; in a multicentre study of 4107 women who underwent a CS at 14 NHS hospitals in England, Wloch et al.29 found obesity (defined as BMI>30 kg/m2), age <20 years and grade of surgeon to be significantly associated with developing an SSI. Obesity was also found to increase the risk of SSI within 30 days after CS in a case control study of 240 women at a hospital in Ireland.30 However, Najm and Majeed 31failed to find evidence to suggest that obesity was a contributing factor in SSI development in a sample of 200 women in a hospital in Iraq. Poor infection control monitoring and procedures may have limited the extent to which these findings are generalisable to the wider population.
Although there appears to be several patient level factors that make developing an SSI following a CS more likely, the extent to which the interaction between these elements increase the likelihood of infection, and the distinction between the predisposing factors associated with an elective versus emergency CS is less obvious. This is problematic, as a lack of evidence-based guidelines contributes to inconsistencies in SSI prevention, treatment and management in CS, increasing the economic burden 22 and obvious detrimental effect on patient outcomes and experiences of care. Whilst evidence-based guidelines emphasise the prevention and treatment of SSI 1 there is an obvious lack of guidance for the management of SSI in emergency CS. The study objective was to quantify the incidence of Surgical Site Infection (SSI) in patients who have had an emergency Caesarean Section (CS), identifying the risk and associated factors that contribute to the development of SSI in order to develop a better understanding of the potential mechanisms that may increase the likelihood of infection and the distinction between the predisposing factors associated with an elective versus emergency CS.