Variability in cefazolin concentrations in amniotic fluid: the relevance of gestational age

Abstract number: P1245

Allegaert K., van Mieghem T., Verbesselt R., de Hoon J., Naulaers G., Deprest J., Devlieger R.

Objectives: Cefazolin is frequently administered for prophylaxis during foetal surgical interventions, but data on amniotic drug disposition and the determinants of its variability during pregnancy are still limited. We therefore wanted to document cefazolin disposition in the amniotic fluid and the determinants of its variability.

Methods: A first dose of cefazolin (2 g iv) was administered (time interval 30 min) one or two hours before foetal surgical intervention. Amniotic fluid sampling was performed when puncture of the amniotic cavity and subsequent sampling of amniotic fluid was part of the routine clinical care without addition burden for either mother or foetus. Time of sampling (min) was registered and gestational age (GA, weeks) at surgery was recorded. Cefazolin concentrations were determined based on High Performance Liquid Chromatography methodology (1). Data were reported by median and range, spearman rank correlation and multiple regression were used to assess the impact of time of sampling and GA at surgery on the variaibility in cefazolin concentrations observed in the amniotic fluid.

Results: 57 amniotic fluid samples were collected during foetal surgical interventions. The median cefazolin amniotic concentration was 0.82 (range 0.06–3.73) mg/L. Median GA was 26 (range 17–34) weeks, median time at collection was 100 (range 20–370) minutes. There is a significant increase in cefazolin concentration with time (r = 0.41, 95% CI 0.17–0.6) and with GA (r = 0.58, 95% CI 0.37–0.73). In a multiple regression model, both variables remained independent determinants of the amniotic cefazolin concentration (r adj = 0.35)

Conclusions: There is important variability in cefazolin concentrations in amniotic fluid during pregnancy. In addition to time of sampling after intravenous maternal administration, gestational age also contributes to this variability, suggesting the impact of maturational aspects (protein binding, placental transfer, foetal renal elimination) on cefazolin disposition during pregnancy.


1. Vella-Brincat JW, et al. Br J Clin Pharmacol 2007; 63: 753–7.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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