Operator experience reduces the risk of second trimester amniocentesis-related adverse outcomes

Abstract

Objective

To investigate the impact of operator experience on amniocentesis-related adverse outcomes.

Study design

Retrospective study of mid-trimester amniocenteses performed by the same operator on singleton pregnancies in a single private institution during 1994–2007. Outcomes were hemorrhagic or dark amniotic fluid aspiration, insufficient volume aspiration, repeated puncture and fetal loss. Rates were estimated annually, as well as for every 10% of procedures up to the total number. The association of each outcome with epidemiological aspects was also examined.

Results

In total, 5913 amniocenteses were performed. The overall rate of adverse outcomes was 5.4%. The total adverse outcome rate reduced from 10.2% in the first 10% of cases to 3.0% in the last 10% (P = .001). The rate of hemorrhagic fluid gradually decreased from 4.4% to 1.5% (P = .05) over the same intervals. The fetal loss rate was also reduced from 0.5% during the first half to 0.3% in the second half of the study period (P = NS). Logistic regression analysis indicated no significant correlations between adverse outcomes with any of epidemiological parameters of women undergoing amniocentesis.

Conclusion

Operator experience has a beneficial impact on preventing procedure-related adverse outcomes.

Introduction

Mid-trimester amniocentesis remains the most common invasive procedure for prenatal diagnosis of chromosomal abnormalities, followed by chorionic villus sampling. Initially, the amniocentesis procedure was associated with a high risk of fetal loss, up to 1% [1], [2], [3], [4]. Nowadays new techniques, higher resolution ultrasound devices and more experienced operators have rendered amniocentesis a less precarious invasive method for prenatal diagnosis [5], [6].

In the 2001 American College of Obstetricians and Gynecologists (ACOG) guidelines, the fetal loss rate attributed to mid-trimester amniocentesis was described as one in every 200 procedures, whereas the same rate in 2007 was evaluated as almost one in 500 cases in singleton pregnancies [5], [6]. At the same time, a comparison of 3096 unselected women undergoing amniocentesis with 31,907 control women who did not, during the First and Second Trimester Evaluation of Risk (FASTER) Trial, showed that the amniocentesis-related fetal loss rate was only 0.06% (1/1600) [7]. Subsequent studies also reported low rates of miscarriage (0.16% and 0.13%) [8], [9].

Operator experience seems to be the most important factor affecting not only the risk of fetal loss but also of other adverse outcomes such as haemorrhagic fluid aspiration and the need for repeated puncture. It has been repeatedly shown that the learning curve for performing amniocentesis is significantly associated with procedure-related outcomes, as higher miscarriage and complication rates are recorded when amniocentesis is performed by less experienced physicians [10], [11], [12], [13], [14], [15]. Therefore, although competence is difficult to evaluate, performance quality should be monitored, adverse outcomes should be audited and a minimum number of invasive procedures per year must be also established [16], [17].

The aim of the present study was to investigate whether operator experience may have an actual impact on the risk of amniocentesis-related adverse outcomes.