title: Midtrimester amniocentesis. Influence of operator caseload on sampling efficiency.
abstract: OBJECTIVE
  To evaluate the impact of operator caseload on the sampling efficiency for early and standard, midtrimester amniocentesis.
  
  
  METHODS
  Prospective ascertainment of genetic amniocenteses performed during 36 months, grouped into early (13-14 weeks' gestation) and standard procedures (15-20 weeks' gestation). Details of each amniocentesis were recorded immediately after sampling, and pregnancy outcomes were retrieved via questionnaires completed by the delivering physician. Sampling efficiency was evaluated separately in the early and standard cohorts in relation to operator caseload.
  
  
  RESULTS
  In total, 193 and 707 patients underwent early and standard amniocentesis, respectively. Forty of 46 physician-operators performed < 50 total procedures during the study interval (group A). When compared to operators performing > or = 50 cases (group B, n = 6), a higher rate of single-pass success was noted among group B physicians for both early and standard procedures (A vs. B, early: 40/45 vs. 145/148, P = .018; standard: 243/295 vs. 384/412, P < .0001). Logistic regression confirmed an independent effect of physician caseload on sampling efficiency and a significant interaction between physician caseload and simultaneous ultrasound guidance in predicting single-attempt success.
  
  
  CONCLUSIONS
  Operator caseload directly influenced sampling efficiency for both early and standard, midtrimester amniocentesis.
authors.affiliation: Division of Maternal-Fetal Medicine, Evanston Hospital, Illinois 60201, USA. r-silver@nwu.edu
authors.forename: R K
authors.initials: RK
authors.lastname: Silver
authors.forename: T L
authors.initials: TL
authors.lastname: Russell
authors.forename: M P
authors.initials: MP
authors.lastname: Kambich
authors.forename: E A
authors.initials: EA
authors.lastname: Leeth
authors.forename: S N
authors.initials: SN
authors.lastname: MacGregor
authors.forename: J S
authors.initials: JS
authors.lastname: Sholl
mesh_terms: D000328:Adult; D000649:Amniocentesis / Q000592:standards*; D005260:Female; D006801:Humans; D010820:Physicians / Q000592:standards*; D011247:Pregnancy; D011256:Pregnancy Outcome; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D011446:Prospective Studies; D015203:Reproducibility of Results; D016216:Ultrasonography, Prenatal; D016526:Workload