Abstract
Objective To quantify the effects of operative blood loss during cesarean on tissue and plasma
cefazolin concentrations.
Study Design This was a prospective observational study of singleton pregnancies undergoing scheduled
cesarean between 34 and 40 weeks. Cefazolin administered prior to skin incision. Maternal
plasma samples were obtained (Time 1[T1]: immediately, T2: 20 minutes, T3: 40 minutes,
and T4: 60 minutes after cefazolin infusion). Subcutaneous adipose tissue sampled
before and after fascia. Primary outcome was subcutaneous adipose cefazolin level
after fascial closure. Formal quantitative blood loss (QBL) performed. Women with
higher QBL, those at/above 75% of QBL in this population, were compared with those
with lower QBL (QBL below 75%). Data analyzed using bivariable statistics.
Results Ninety-two women were screened, 32 were eligible, and 20 enrolled. Median QBL was
630 mL (interquartile range [IQR]: 473–818) and 1,160 mL (IQR: 1,000–1,560) in the
low and high QBL groups, respectively. Demographics and operative characteristics
were similar. Median adipose cefazolin level after fascial closure did not differ
between the groups (3.5 vs. 3.9 μg/g, p = 0.75). No differences in maternal plasma cefazolin concentrations between the groups
at any time point or in pharmacokinetic parameters were seen.
Conclusion Intraoperative maternal plasma concentrations and adipose levels of cefazolin are
similar between women with high and low blood loss at the time of cesarean delivery.
Keywords
cefazolin - blood loss - surgical site infection - antibiotics - prophylaxis
