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857 Antibiotics Prophylaxis for Lower Segment Caesarean Sections: A Multi-centered Prospective Study in Public Hospitals in Hong Kong

Sunday, March 21, 2010
Grand Hall (Hyatt Regency Atlanta)
Hong Chen, MBBS, MPH , Infection Control Branch, Centre for Health Protection, Kowloon, Hong Kong
Carole SK Tam*, MBChB, MMed(PH) , Infection Control Branch, Centre for Health Protection, Kowloon, Hong Kong
Carol HY Fong, BSc , Infection Control Branch, Centre for Health Protection, Kowloon, Hong Kong
Iris HL Tsang, BSc(Hons), MStat , Infection Control Branch, Centre for Health Protection, Kowloon, Hong Kong
Raymond WH Yung, MBBS, MPH , Chinese University of Hong Kong, Shatin, Hong Kong
Patricia TY Ching, RN, DNA, CPHQ , Chief Infection Control Officer Office, Hospital Authority, Kowloon, Hong Kong
WH Seto, MBBSFRCPathCPHQ , Chief Infection Control Officer Office, Hospital Authority, Kowloon, Hong Kong
Andrew TY Wong, MBBS, MSc, CIC , Infection Control Branch, Centre for Health Protection, Kowloon, Hong Kong
Background: Surgical site infection (SSI) following lower segment caesarean section (LSCS) is a common cause of morbidity.  Prophylactic antibiotics are usually given within 30 minutes before surgical incision (ie on induction of anaesthesia) to achieve adequate tissue concentration.  For LSCS, to reduce antibiotic exposure to the infant, prophylactic antibiotics should be administered immediately after cord clamping to prevent SSI as recommended by the Scientific Committee on Infection Control in Hong Kong.

Objective: To identify risk factors for SSI after LSCS and to determine the effect of prophylactic antibiotics on wound infection by a prospective multi-centered observational study.

Methods: Through 2006 to 2008, 13724 women who underwent LSCS in 5 hospitals were observed prospectively for the development of SSI using CDC/NHSN surveillance definition.  Apart from NNIS risk factors (duration of operation, wound class and ASA score, parameters as age, urgency of operation and use of antibiotics were analyzed.
Results: The overall SSI rate for LSCS was 2.44% (95% CI 2.18-2.70%).  SSI rates for operations with different risk index were shown in table 1. 

Risk Index

No. of Procedures
No. of SSI
Pooled Mean Rate (95%CI)
0
8905
194
2.18 (1.87-2.47)
1,2,3
4819
141
2.93 (2.45-3.40)
Table 1. SSI Rates for LCSC with Different Risk Index

Risk index was significantly associated with SSI (OR 1.35; 95%CI 1.09-1.69 for risk index 1, 2, 3 vs 0). Wound class, comparing with ASA score and duration of operation, was the only independent predictor for SSI (OR 1.31; 95%CI 1.02-1.61 for wound class 3, 4 vs class 2). This association remained statistically significant after adjustment for the use of prophylactic antibiotics (adjusted OR 1.51; 95%CI 1.16-1.95).  
51.6% women were given prophylactic antibiotics.  Among them, 47.1% were given on induction of anaesthesia; 51.6% were given at cord clamping and 1.5% were given both on induction of anaesthesia and at cord clamping. Prophylactic antibiotics can reduce SSI (RR 0.73; 95%CI 0.59-0.91).  Effect of prophylactic antibiotics was more prominent for advanced wound class (RR 0.53; 95%CI 0.34-0.83) and emergency operation (RR 0.64; 95%CI 0.48-0.85). There is no difference with regards to the timing of antibiotics  (p=0.994) for wound infection. The frequency of other maternal infections such as urinary tract infection was not affected by timing of prophylactic antibiotics.

Conclusions: Wound class was the most important risk factor associated with SSI after LSCS comparing with ASA score or duration of operation. Prophylactic antibiotics can reduce SSI. There was no difference in maternal infectious morbidity whether antibiotics were given before skin incision or at cord clamping. Evidence-based prophylactic antibiotics recommendation should be promulgated to individual hospital.


 *co-author with equal contribution as first author