Increased perinatal loss after intrauterine transfusion for alloimmune anaemia before 20 weeks of gestation.

Objectives: To evaluate and compare perinatal outcome after intrauterine transfusions (IUT) performed before and after 20 weeks of gestation. To analyse contributing factors.
Design: Retrospective analysis.
Setting: The Dutch referral centre for fetal therapy.
Population: IUTs for fetal alloimmune anaemia.
Methods: Fetuses were divided into two groups: fetuses requiring the first IUT before 20 weeks of gestation (Group 1) and those in which the IUTs started after 20 weeks (Group 2). The cause of perinatal loss was classified as procedure-related (PR) or not procedure-related (NPR). The cohort was divided into two periods to describe the change of perinatal loss over time.
Main Outcome Measures: Perinatal loss of fetuses requiring the first IUT before 20 weeks of gestation, compared with perinatal loss later in gestation.
Results: A total of 1422 IUTs were performed in 491 fetuses. Perinatal loss rate in Group 1 was higher (7/29 24% versus 35/462 8%, P = 0.002). Especially NPR was higher for IUTs performed before 20 weeks (4/37 11% versus 19/1385 1%, P < 0.001). Kell alloimmunisation was overrepresented in Group 1 (7/29 24% versus 52/462 11%, P = 0.04). In a multivariate regression analysis, only hydrops was independently associated with perinatal loss (P = 0.001). In recent years, a decline in total perinatal loss was found (36/224 16% versus 6/267 2%, P < 0.001), but perinatal loss in Group 1 did not decline (4/224 1.8% versus 3/267 1.1%, P = 0.5).
Conclusions: Perinatal loss after IUT performed before 20 weeks of gestation is increased compared with loss after IUT performed later in gestation. In addition, we confirmed earlier observations that hydrops is a major contributor to adverse outcome. Early and timely detection and treatment may prevent hydrops and improve outcome.
(© 2013 The Authors BJOG An International Journal of Obstetrics and Gynaecology © 2013 RCOG.)