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Obstetric Anesthesiology

Unwarranted Variability in Antibiotic Prophylaxis for Cesarean Section Delivery

A National Survey of Anesthesiologists

Raghunathan, Karthik MD, MPH*; Connelly, Neil Roy MD*; Friderici, Jennifer MS; Naglieri-Prescod, Deborah PhD; Joyce, Ryan MD*; Prasanna, Praveen MD*; Ponnusamy, Nandakumar MD*

Author Information
doi: 10.1213/ANE.0b013e318276cf72


Cesarean delivery is the most common major operation in the United States, with an annual volume of 1.3 million.1 This number is projected to increase to nearly 2 million cesarean deliveries by 2020.2 Postoperative infectious morbidity is the leading complication, primarily due to surgical site infections and endometritis. Prophylactic antibiotics reduce the rate of postcesarean delivery surgical site infections by 40%.3 Historically, prophylactic antibiotic administration for cesarean delivery was delayed until after clamping of the umbilical cord.4 In a meta-analysis of 3 randomized controlled trials, preincision prophylaxis was found to be superior to post–cord clamp prophylaxis in reducing maternal infectious morbidity without any observed adverse neonatal outcomes.5–8 The current American Congress of Obstetricians and Gynecologists guidelines, published in 2010, acknowledge and recommend preincision prophylaxis for cesarean delivery.9 Thus, the current understanding is that the optimal timing for antibiotic prophylaxis for scheduled and emergency cesarean delivery is before skin incision.6 We thus sought to assess the nationwide practice and opinion of anesthesiologists regarding obstetric prophylactic antibiotic administration. A survey questionnaire was sent to American Society of Anesthesiologists (ASA) members to measure adherence to the most current American Congress of Obstetricians and Gynecologists guidelines and to identify characteristics associated with their adoption.


After receiving IRB approval, a web-based survey was designed. The requirement for written informed consent was waived by the IRB.

Face validity was established internally. The survey (Web supplement, see Supplemental Digital Content 1, was sent by e-mail (containing a link to the survey) to a random sample of 10,000 ASA members. The random sample was chosen from the ASA membership directory by ASA member services. There were 2 rounds of surveys sent; each round was addressed to 5000 ASA members. Round 1 (April 30, 2010 to May 23, 2010) and round 2 (May 24, 2010 to June 8, 2010) surveys were open for 2 weeks each time. Nonresponders did not have a reminder sent, because the completed survey did not have a link to the responder. The target sample size was calculated based on the number necessary for sufficient power to estimate proportions within ±8 percentage points in subgroups as small as 150. The primary outcome, use of preincision prophylaxis for elective cesarean delivery, was examined as a function of various characteristics using χ2 tests (categorical variables) and nonparametric tests of trend (ordinal variables).

Means/SDs and proportions (95% confidence intervals) were calculated for summary analyses. To build multivariable models, a bivariable screening process was used, wherein any characteristic associated with preincision prophylaxis at P < 0.20 was included as a candidate covariate in the multivariable model. Candidate covariates were screened using unpaired t tests (2 means), 1-way analysis of variance (>2 means), and Fisher exact tests (2+ proportions). Case-mix index scores were calculated for each respondent’s hospital by summing Likert responses to the frequency with which cesarean delivery patients met criteria for obesity, diabetes, delayed prenatal care, and low socioeconomic status (“never” = 1, “rarely” = 2, “sometimes” = 3, “often” = 4, and “always” = 5; range of possible scores 4–20). Poisson regression with robust variance estimates10 was used to derive adjusted proportions and prevalence ratios (PRs), the appropriate point estimates for cross-sectional studies with common outcomes. The calculation and interpretation for the PR is similar to that of relative risk: a PR of 1.3 suggests the exposed group has a 30% greater likelihood than the referent group to experience the outcome of interest. Final models were derived using backward selection, with criterion P value for covariate retention set at <0.05 using the Wald test. Pairwise interactions among all final covariates were evaluated using likelihood ratio tests, with criterion P value set at <0.05.To examine the extent to which prophylaxis timing is influenced by belief about appropriate practice, we added this categorical variable to the final multivariable model. Each variable was removed one-by-one from the final model to quantify changes to its receiver operating characteristic curve. Only respondents with complete data were included and sample size was held constant for all analyses. Stata/MP 12.1 for Windows (©2011 StataCorp, College Station, TX) was used for all analyses.


The average response rate was 13.5% (members completing part of the survey). There were 1052 respondents (10.5%) with complete information for multivariable analysis (Fig. 1). Among all included respondents, 63.5% (95% confidence interval 60.6%, 66.4%) reported routine preincision prophylaxis for scheduled cesarean delivery. The characteristics of respondents and their practices are shown in Table 1. Most respondents (82.1%) reported practicing at least 5 years. More than one-third (38.9%) considered themselves “obstetric anesthesiologists”; 44.6% reported administering cesarean delivery anesthesia at least several times per week; and 44.8% reported a cesarean delivery rate of >500 per year at their primary practice institution. More than one-third of respondents (39.6%) did not think that current practice should be routine preincision prophylaxis; less than one-third (28.4%) thought that the anesthesia provider should take responsibility in this area.

Table 1
Table 1:
Respondent and Hospital Characteristics
Figure 1
Figure 1:
Chart representation of the exclusion criteria and creation of the analytic sample from the total respondent population.

Bivariate correlates of preincision prophylaxis are shown in Table 2. In the multivariable model (Table 3), anesthesiologists who used preincision prophylaxis for scheduled cesarean delivery were significantly more likely to work in teaching hospitals versus community hospitals; to practice in the West versus Southeast or Southwest; and to believe that current practice should be preincision prophylaxis (versus post–cord clamping, at the discretion of the obstetrician, or belief that more information is needed) (Fig. 2). Of all variables in the model, respondents’ belief in appropriate practice was best able to discriminate those who reported preincision prophylaxis from those who did not (change in area under the receiver operating characteristic curve, 0.66–0.79). No other predictor had this impact.

Table 3
Table 3:
Multivariable-Adjusted Proportions for the Likelihood of Preincisional Prophylaxis
Table 2
Table 2:
Bivariate Associations with Preincision Prophylaxis
Figure 2
Figure 2:
Graphical analysis depicting the comparison of respondents who do not give preincision and their beliefs on how antibiotics should be administered for cesarean delivery. The respondents are further subdivided into the separate major geographical regions. A significant finding is that the majority of those providers in the Southeast and Southwest who believe antibiotics should be given post–cord clamp actually dose their antibiotics after cord clamping. Conversely, the majority of the providers in the Northeast and West who administer antibiotics post–cord clamping actually believe they should be administered preincisionally. CI = confidence interval.


Historically, the prevailing consensus regarding antibiotic prophylaxis for cesarean delivery was that fetal exposure to the maternally administered antibiotic could mask signs of neonatal sepsis.4 There was also concern of antimicrobial resistance and anaphylaxis in the neonate.11 Maternal preincisional antibiotic administration results in an immediate increase in neonatal serum concentrations12,13; thus, signs of neonatal sepsis might be masked. Current recommendations are that prophylaxis should be given preincisionally.

Less than two-thirds of anesthesiologists completing the survey nationwide were routinely administering preincision antibiotic prophylaxis for the most common operation in the country. Belief regarding “what current practice should be” was the strongest independent correlate of prophylaxis timing. Cost-effective reduction in infectious morbidity may be possible, especially in community hospitals and in hospitals located in the Southeast and Southwest. We found that the majority of anesthesiologists who responded to our survey are adherent with current guidelines, that is, reporting that they routinely administer preincision prophylaxis for cesarean delivery. However, we found that 41% did not believe that current practice should include preincision prophylaxis. Furthermore, only 28% agreed that the anesthesia provider should take responsibility in this area. A systematic review of the literature suggests that important barriers to adherence with clinical guidelines regarding preincision antibiotic administration during scheduled cesarean delivery seem to be, in order of importance, inertia of previous practice, lack of familiarity/awareness, lack of agreement, and lack of outcome expectancy.14 These findings may help to explain the variability in practice of preincision antibiotic administration during scheduled cesarean delivery in our study.

Clinical care is a result of many competing beliefs, dogmas, and scientific evidence, provided in a complex system. There are many barriers to providing good, consistent, and ever-improving care. We believe there are 2 potential barriers to improved anesthesiologists’ adherence with preincision prophylaxis: anesthesiologists may believe that it is not the right approach (lack of knowledge) and/or they may believe that they are not responsible (lack of motivation/practice inertia).The finding that adherence with preincision prophylaxis did not improve when anesthesiologists defer the decision to obstetricians suggests that this issue should be addressed from different vantage points: working on educational initiatives directed toward anesthesiologists and obstetricians to address “lack of knowledge,” and designing regulatory and quality improvement interventions to address the “lack of motivation.”

There are several inherent limitations with using an online survey research tool, including concern with sampling issues and validity of the data.15 As with all convenience samples, findings should be interpreted with the caution that subjects who respond might not be representative of the target population. For example, individuals who have access to a computer and those with a high comfort level with computer use or online surveying may be overrepresented. Furthermore, we only sampled ASA members who may in fact “perform” better than a broader sample of all anesthesiologists. Second, we were not able to track respondents to prevent an individual from taking the survey more than once. It is also possible that a proportion of the 10,000 target respondents either did not have working e-mail addresses, or may have quarantined our e-mail as spam. Because these issues limit our ability to make generalizations, additional studies using more rigorous sampling schemes may be needed to corroborate our findings.

In conclusion, we have shown that there are significant variations in practices and beliefs regarding timing of antibiotic prophylaxis among anesthesiologists who provide care to women undergoing cesarean delivery. Most do not believe that it is primarily the anesthesiologist’s responsibility. Approximately one-third of all anesthesiologists who practice post–cord clamp prophylactic antibiotic administration stated that prophylaxis should in fact be given preincision.

We believe that all caregivers must work together to serve the patients’ needs. It should be all the “caregivers’ antibiotic” issue (surgeons, nurses, anesthesiologists, and nurse anesthetists). Anesthesiologists leaving prophylaxis timing decisions to the obstetrician must remain actively engaged in the process. It has been shown that preincision timing of antibiotic administration has benefit for the cesarean delivery patient, and anesthesiologists should advocate within the team for this practice to be adopted as soon as feasible.


Name: Karthik Raghunathan, MD, MPH.

Contribution: This author helped design the study, conduct the study, analyze the data, and write the manuscript.

Attestation: Karthik Raghunathan has seen the original study data, reviewed the analysis of the data, approved the final manuscript, and is the author responsible for archiving the study files.

Name: Neil Roy Connelly, MD.

Contribution: This author helped design the study and write the manuscript.

Attestation: Neil Roy Connelly has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.

Name: Jennifer Friderici, MS.

Contribution: This author helped analyze the data and write the manuscript.

Attestation: Jennifer Friderici has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.

Name: Deborah Naglieri-Prescod, PhD.

Contribution: This author helped analyze the data and write the manuscript.

Attestation: Deborah Naglieri-Prescod has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.

Name: Ryan Joyce, MD.

Contribution: This author helped write the manuscript.

Attestation: Ryan Joyce has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.

Name: Praveen Prasanna, MD.

Contribution: This author helped write the manuscript.

Attestation: Praveen Prasanna has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.

Name: Nandakumar Ponnusamy, MD.

Contribution: This author helped write the manuscript.

Attestation: Nandakumar Ponnusamy has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.

This manuscript was handled by: Cynthia A. Wong, MD.


1. Hamilton BE, Martin JA, Ventura SJ. Births: preliminary data for 2007. Natl Vital Stat Rep. 2007;57:1–23
2. Tita AT, Rouse DJ, Blackwell S, Saade GR, Spong CY, Andrews WW. Emerging concepts in antibiotic prophylaxis for cesarean delivery: a systematic review. Obstet Gynecol. 2009;113:675–82
3. Smaill F, Hofmeyr GJ. Antibiotic prophylaxis for cesarean section. Cochrane Database Syst Rev. 2002;2
4. Hopkins L, Smaill F. Antibiotic prophylaxis regimens and drugs for cesarean section. Cochrane Database Syst Rev. 2000;2
5. Costantine MM, Rahman M, Ghulmiyah L, Byers BD, Longo M, Wen T, Hankins GD, Saade GR. Timing of perioperative antibiotics for cesarean delivery: a metaanalysis. Am J Obstet Gynecol. 2008;199:301.e1–6
6. Sullivan SA, Smith T, Chang E, Hulsey T, Vandorsten JP, Soper D. Administration of cefazolin prior to skin incision is superior to cefazolin at cord clamping in preventing postcesarean infectious morbidity: a randomized, controlled trial. Am J Obstet Gynecol. 2007;196:455.e1–5
7. Thigpen BD, Hood WA, Chauhan S, Bufkin L, Bofill J, Magann E, Morrison JC. Timing of prophylactic antibiotic administration in the uninfected laboring gravida: a randomized clinical trial. Am J Obstet Gynecol. 2005;192:1864–8
8. Wax JR, Hersey K, Philput C, Wright MS, Nichols KV, Eggleston MK, Smith JF. Single dose cefazolin prophylaxis for postcesarean infections: before vs. after cord clamping. J Matern Fetal Med. 1997;6:61–5
9. . American College of Obstetricians and Gynecologists. ACOG committee opinion no. 465: antimicrobial prophylaxis for cesarean delivery—timing of administration. Obstet Gynecol. 2010;116:791–2
10. Barros AJ, Hirakata VN. Alternatives for logistic regression in cross-sectional studies: an empirical comparison of models that directly estimate the prevalence ratio. BMC Med Res Methodol. 2003;3:21
11. Edwards RK, Clark P, Sistrom CL, Duff P. Intrapartum antibiotic prophylaxis I: relative effects of recommended antibiotics on gram negative pathogens. Obstet Gynecol. 2002;100:534–9
12. Bloom SL, Cox SM, Bawdon RE, Gilstrap LC. Ampicillin for neonatal group B streptococcal prophylaxis: how rapidly can bactericidal concentrations be achieved? Am J Obstet Gynecol. 1996;175:974–6
13. Fiore Mitchell T, Pearlman MD, Chapman RL, Bhatt-Mehta V, Faix RG. Maternal and transplacental pharmacokinetics of cefazolin. Obstet Gynecol. 2001;98:1075–9
14. Cabana MD, Rand CS, Powe NR, Wu AW, Wilson MH, Abboud PA, Rubin HR. Why don’t physicians follow clinical practice guidelines? A framework for improvement. JAMA. 1999;282:1458–65
15. Kaplowitz MD, Hadlock TD, Levine R. A comparison of web and mail survey response rates. Pub Opin Q. 2004;68:98–101

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© 2013 International Anesthesia Research Society