An evaluation of the chorionic villus sampling learning curve.
Prior studies have identified a correlation between the rate of fetal loss (subsequent to chorionic villus sampling) and the operator's level of experience. However, centers performing only modest numbers of procedures during the initial phase of their programs have reported loss rates similar to those of the more active diagnostic units. Our personal experience would suggest that a "learning curve" for chorionic villus sampling does exist but that fetal loss may be an insensitive end point with which to evaluate the impact of cumulative performance. In an attempt to quantify the learning curve that we have appreciated subjectively, a detailed analysis of our initial experience with chorionic villus sampling was undertaken. Between May 1988 and August 1989, a total of 185 procedures were accomplished consecutively by one operator and form the basis for this analysis. Transcervical (n = 82) and transabdominal (n = 103) techniques were used for posterior and anterior-fundal placental locations, respectively. Three pregnancy losses occurred and insufficient material for analysis was retrieved in five patients. We observed a significant reduction in the required number of placental aspirations during the study interval (p less than 0.001). When analyzed separately, consecutive performances of the transabdominal technique demonstrated a significant reduction in the mean number of placental passes (p less than 0.00001) along with more efficient sampling (increased sample weight/aspiration attempt; p less than 0.01). Although the fetal loss rate is a critical measure of safety and may directly be related to operator experience, other measures of expertise (e.g., single-pass success rate) may be more appropriate indicators of competence and may be useful to centers wishing to initiate their own chorionic villus sampling programs.
Silver
R K
RK
Division of Maternal-Fetal Medicine, Evanston Hospital, IL 60201.
MacGregor
S N
SN
Sholl
J S
JS
Hobart
E D
ED
Waldee
J K
JK
D000022:Abortion, Spontaneous / Q000209:etiology; D000704:Analysis of Variance; D015193:Chorionic Villi Sampling / Q000009:adverse effects / Q000379:methods*; D002983:Clinical Competence; D005260:Female; D006801:Humans; D011247:Pregnancy