UPDATE: INFECTIOUS DISEASE

REFERENCES

1. Schrag S, Gorwitz R, Fultz-Butts K, Schuchat A. Prevention of perinatal group B streptococcal disease. Revised guidelines from CDC. MMWR Recomm Rep. 2002;51:1-24

2. Edwards RK, Clark P, Sistrom CL, Duff P. Intrapartum antibiotic prophylaxis 1: relative effects of recommended antibiotics on gram-negative pathogens. Obstet Gynecol. 2002;100:534-539

New data suggest that preincision prophylaxis is best for C-section

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.e1–455.e5.

Is preoperative antibiotic prophylaxis superior to intraoperative prophylaxis in preventing postcesarean infection? Sullivan and colleagues set out to answer this question in a prospective, randomized, double-blinded, placebo-controlled study at the Medical University of South Carolina.

In the study group, 175 women undergoing cesarean delivery were randomized to receive 1 g of IV cefazolin 15 to 60 minutes before surgery, followed by a placebo infusion immediately after the umbilical cord was clamped. In the control group, 182 women received preoperative placebo, followed by 1 g of cefazolin immediately after cord clamping.

Two patients in the study group developed endomyometritis, compared with 10 in the control group (relative risk [RR], 0.2; 95% CI, 0.15–0.94). Five patients in the study group developed a wound infection, compared with 10 in the control group (RR, 0.52; 95% CI, 0.18–1.5, not significant). Overall, eight women in the study group and 21 women in the control group met the criteria for infectious morbidity (RR, 0.4; 95% CI, 0.18–0.87).

There were no differences between the groups in the frequency of neonatal sepsis, neonatal intensive care unit (NICU) admission, total length of hospital stay, metabolic acidosis, or sepsis evaluation. Infants in the study group had significantly fewer days in the NICU (P<.01).

How this study differs from earlier investigations

The classic studies of antibiotic prophylaxis were performed in an animal model by Burke.¹ He demonstrated that prophylaxis had its greatest effect when the antibiotic was administered before the surgical incision. Essentially, no effect of prophylaxis was evident when antibiotic administration was delayed more than 4 hours beyond the start of surgery.

Early studies of antibiotic prophylaxis for cesarean delivery, conducted in the 1970s, administered antibiotics preoperatively and continued administration for several days after surgery. In 1979, Gordon and colleagues published an important investigation demonstrating that delay in administration of antibiotics until after the umbilical cord was clamped did not compromise the effectiveness of prophylaxis and significantly decreased the number of infants who required sepsis evaluations.²

This latter effect presumably occurred because infants were not exposed to antibiotics before delivery. Gordon’s investigation and subsequent reports also demonstrated that effective prophylaxis could be achieved with one to three doses of antibiotics.³

Why this new study may alter practice

Before Sullivan and colleagues published their findings, I believe that the best available evidence supported the use of a single dose of antibiotic, such as cefazolin, immediately after cord clamping. There are no convincing data that demonstrate an advantage for extended-spectrum agents (second- and third-generation cephalosporins, broad-spectrum penicillins, or carbapenems) over cefazolin.³

However, if the findings of Sullivan and coworkers are confirmed by other investigations in different patient populations, they definitely should lead to a change in the standard of care for prophylaxis. This investigation was exceptionally well designed and executed. The reduction in the frequency of endomyometritis and overall rate of infectious morbidity was impressive. This advantage was achieved without increasing the rate of neonatal sepsis evaluation.

REFERENCES

1. Burke JF. The effective period of preventive antibiotic action in experimental incisions and dermal lesions. Surgery. 1961;50:161-168

2. Gordon HR, Phelps D. Blanchard K. Prophylactic cesarean section antibiotics: maternal and neonatal morbidity before or after cord clamping. Surgery. 1979;53:151-156

3. Duff P. Prophylactic antibiotics for cesarean delivery: a simple cost-effective strategy for prevention of postoperative morbidity. Am J Obstet Gynecol. 1987;157:794-798

Expect to see more women with diverticulitis as the population ages

Jacobs DO. Diverticulitis. N Engl J Med. 2007;357:2057–2066.

ObGyns continue to play a major role in providing primary care to women. With the steady aging of the American population, practitioners certainly can expect to care for more and more women who are 50 years of age or older, and diverticulitis is likely to turn up in an increasing number of these patients.

Diverticulitis is a relatively common condition in older patients and must consistently be considered in the differential diagnosis of women with acute abdominal pain—particularly left-sided pain.

It is present in approximately 10% of adults younger than 40 years of age and in 40 to 70% of people 80 years of age or older. It primarily affects the sigmoid and descending colon and is associated with diets that are low in fiber and high in refined carbohydrates.