The proportion of births delivered by caesarean section in England has risen substantially over the past 30 years from 9% in 1980 to 25% in 2009-10. This new study estimates that one in ten women develop a post-surgical infection following the procedure, with between 1.2 and 5% of women developing the infection during their inpatient stay.
A total of 4107 operations were included in this study and women were followed up during their inpatient stay, on readmission to hospital, on day visits to hospital, by community midwives up to the last visit and through a self-completed questionnaire. The volunteers were from 14 hospitals already participating in the Health Protection Agency’s (HPA) Surgical Site Infection Surveillance Scheme.
The average age of the women was 31 years (range 14-56) and the average BMI was 25.3 (interdecile range 20.4-35.0).
In total 394 surgical site infections were identified from 4107 operations representing a risk of 9.6%. Of the 394 infections, 348 (88.3%) were superficial incisional affecting the skin and surface layers, 19 (4.8%) deep incisional (affecting deeper tissues) and 27 (6.9%) organ/space infections (affecting internal organs) including endometritis (infection of the womb lining) and reproductive tract infections.
The average time to developing an infection for all surgical site infections was 10 days and for deep and organ/space infections 8 days. Of the 4107 women, 23 (0.6%) were readmitted to hospital for treatment of their infection.
After adjustment for other patient and operation risk factors, the study found that obesity and young age (under 20 years old) were associated with the development of an infection after a caesarean.
Obesity was strongly associated with development of a surgical site infection, with risk increasing with each successive category of BMI. Compared to women with a normal BMI (18.5 to 25) overweight women (BMI 25-30) were found to have a 1.6 times greater risk of infection than normal weight women, and obese women (BMI more than 30) 2.4 times greater risk.
There was some evidence of an increased likelihood of infection in women aged less than 20 who had a 1.9 times greater risk compared to women 25-30 years following adjustment for other patient and operation risk factors.
The study also looked at the grade of doctor performing the operation. It found that for operations where the lead surgeon was an associate specialist or staff grade there was weak evidence of a higher likelihood of infection in comparison to consultants (1.6 times greater risk). Most procedures (61%) were performed by specialist registrars.
Dr Catherine Wloch, Department of Healthcare Associated Infection and Antimicrobial Resistance, Health Protection Agency and lead author of the paper said:
“This study has identified high rates of surgical infection following a caesarean with one in ten women developing an infection. Whilst our study didn’t measure this, these infections are likely to have an impact on a woman’s experience and quality of life.
“Although most caesarean section wound infections are not serious, they do represent a substantial burden to the health system, given the high number of women undergoing this type of surgery. Minor infections can still result in pain and discomfort for the woman and may spread to affect deeper tissues. The more serious infections will require extended hospital stays or readmission to hospital.
“Prevention of these infections should be a clinical and public health priority.”
John Thorp, BJOG Deputy-Editor-in-Chief added:
“With the rise in numbers of women having a caesarean section and the rise in obesity rates, this issue is an important one. Post-surgical infection can seriously affect a woman’s quality of life at a critical time when she is recovering from an operation and has a new born baby to look after. More needs to be done to look into this and address ways of reducing infection.”
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Wloch C, Wilson J, Lamagni T, Harrington P, Charlett A, Sheridan E. Risk factors for surgical site infection following caesarean section in England: results from a multicentre cohort study. BJOG 2012; DOI: 10.1111/j.1471-0528.2012.03452.x.