“When the Fetus is Strong...”

UCH Ob/Gyn Grand Rounds

Sasha E. Andrews, MD

June 5, 2013

ANTIMICROBIAL PROPHYLAXIS FOR CESAREAN SECTION

Learning Objectives

Review the morbidity and mortality of early

techniques for cesarean section

Understand data supporting the use of

prophylactic antibiotics for cesarean section

Discuss specific ACOG recommendations for

prophylaxis

Evaluate adherence to these recommendations

at University of Colorado Hospital

1972

2010

Antib iotic regimens for cesarean prophylaxis

Over 20 different regimens have been compared, with

different spectrums of coverage.

The cephalosporins have emerged as the drugs of

choice because of their broad antimicrobial spectrum

and the low incidence of allergic reactions and side

effects.

Cefazolin is the most commonly used agent because

of its reasonably long half-life (1.8 hours) and low cost.

ACOG Recommendations

Antibiotics within 1 hour before skin incision

Doubling of standard cefazolin dose to 2 grams for

morbidly obese patients (>100 kg or BMI > 35)

For cefazolin, 2nd dose given as duration of surgery

approaches 3 hours

A second dose of antibiotic if blood loss exceeds 1500 mL

Practice Bulletin Recommendations

Data support antimicrobial prophylaxis, “ideally within 30

minutes, and certainly within 2 hours” before skin incision

Prophylaxis should be given for all cesarean deliveries unless

the patient is already receiving appropriate antibiotics (eg, for

chorioamnionitis)

Larger dose may be indicated if the woman is obese

For a 1 gram intravenous dose of cefazolin, a therapeutic level is

maintained for 3 - 4 hours

If a significant allergy to B-lactam antibiotics exists, clindamycin

with gentamicin is a reasonable alternative

Committee Opinion Recommendations

Data to Support Recommendations

Effect of morbid obesity on dose

Timing of administration

Effect of operative time

Effect of intraoperative blood loss

Effect of Morbid Obesity

Forse et al., 1989:

Compared 1 gram cefazolin SC, IM, & IV to 2 grams IV in

morbidly obese pts undergoing gastroplasty (mean BMI 46)

Also compared to a control group w/ normal BMI undergoing

abdominal surgery (mean BMI 22)

Collected blood & subcutaneous fat tissue samples at

incision and wound closure, analyzed antibiotic levels

Operative times were not significantly different between

groups

Effect of Morbid Obesity

Forse et al., 1989:

Serum and tissue levels at incision and closure

were similar to control only in the obese patient

group that received 2 grams IV cefazolin.

After changing surgical protocol accordingly, they

noted a decrease in wound infection rate from

16.5% to 5.6%.

Timing of Prophylactic Dosing

Costantine et al., 2008:

A meta-analysis of 5 randomized controlled trials comparing

administration preoperatively versus at umbilical cord clamping

Preoperative administration (15-60 minutes prior to skin incision)

significantly reduced the risk of postpartum endometritis (4% vs

8.8%)

There was a trend towards decreased wound infection (RR, 0.60;

95% CI, 0.30-1.21; P = .151)

No significant effect on suspected neonatal sepsis, proven sepsis,

or neonatal intensive care unit admissions.

van Kasteren et al., 2007

Timing of Prophylactic Dosing

Effect of Operative Time

Coppa et al., 1988:

350 pts undergoing colorectal surgery, received preoperative IV

cefoxitin

Operative time > 215 minutes significantly associated with

wound infection

Shapiro et al., 1982

Double-blind RCT comparing preoperative cefazolin to placebo

in patients undergoing total abdominal or vaginal hysterectomy

Benefit of cefazolin decreased with increased operative time

beyond 2.75 hours

Half-Lives of Commonly Used Antib iotics

Cefazolin: 1.8 hours

Gentamicin: 2.4 - 4 hours

Clindamycin: 2.4 - 3 hours

Metronidazole: 8 hours

Vancomycin: 4-6 hours

Swoboda et al., 1996:

11 adult patients undergoing spinal procedures

Surgical length 3 - 8 hours

Cefazolin & gentamicin given 15-30 min before

incision

Serum & tissue samples taken every hour during

procedure

Effect of In traoperative Loss

Serum & tissue concentrations @ 1 hour

Swoboda et al., 1996

Effect of In traoperative Loss

Quality Review of

Performance Measures

100 consecutive cesarean deliveries

Oct 17, 2012 - Dec 13, 2012

Complicated cases over the last 6 months, identified

from Morbidity and Mortality reports:

EBL > 1500 mL

Duration > 3 hours

Total 105 cases reviewed (including 2 cesarean

hysterectomies)

Methods

Data Collection

`

Endometritis?

Wound infection?

Data Collection

Results

Patient Weight

Average weight: 83 kg (183 lb), range 55 to 158 kg

Average BMI: 33.2, range 20.5 to 62

25 patients with a BMI > 35 (24%)

4 patients with a BMI > 50 (3.8%)

Antibiotic Choice & Dose

88.6% (93/105): Ancef 2 grams IV x 1

Standard dose, given average BMI

1.9% (2/105): Ancef 1 gram IV x 1 (appropriate for weight)

3.8% (4/105): Ampicillin & gentamicin for chorioamnionitis

3.8% (4/105): Gentamicin & clindamycin for penicillin allergy

1.9% (2/105): Antibiotics not recorded

Timing of Antib iotic Prophylaxis

Average: 25 minutes before incision

Range: 1 hr 45 min before to 8 min after skin incision

26% (27/105): 30-60 minutes before skin incision

~2% (2/105): >1 hour before skin incision

Both were scheduled cases

~3% (3/105): After skin incision

All emergent cases

~2% (2/105): Preoperative antibiotics not recorded

Length of Surgery

Average: 53 minutes

Range: 23 minutes to 4 hrs 5 minutes (cesarean hyst)

One case > 3 hrs, antibiotics appropriately redosed

Estimated Blood Loss

Average: 840 mL (350 - 4000 mL)

9 cases > 1500 mL

5 cases (55%) given a 2nd dose of antibiotics

ACOG Recommendations/

Performance Measures UCH Compliance

Prophylactic antibiotics

documented 98% (103/105)

Prophylactic antibiotic dose

appropriate for weight 100%

Dose given within 60 minutes

before incision 93% (98/105)

Dose given within 30 minutes

before incision 68% (71/105)

Repeat dose if case duration

> 3 hrs (for Ancef) 100% (1/1)

Repeat dose if EBL > 1500 mL 55% (5/9)

3.8% 2.8% UCH

Conroy et al., 2012

Conclusions

For routine use of prophylactic antibiotics, antibiotic selection

& dosing, UCH quality performance is 98-100%.

For dosing intervals, UCH compliance was 91%, with

exceptions being too much time before scheduled

procedures and too little time before emergent procedures.

Based on a sample size of only 9, with EBL > 1500 mL, our

compliance for repeat dosing was 55% (5/9).

There was only one case > 3 hours, and antibiotics were

appropriately redosed.

Recommendations

Congratulations to the Ob/Gyns, anesthesiologists,

and nursing staff!

Areas for improvement:

Timing of prophylaxis within 30 minutes before

incision

Repeat antibiotic dose for EBL > 1500 mL