Fetal heart rate patterns of pregnancies with vasa previa and velamentous cord insertion.

Objective: To investigate the fetal heart rate (FHR) patterns in pregnancies complicated with vasa previa and velamentous cord insertion (VCI).

Methods: A retrospective study comparing FHR patterns in pregnancies and subsequent pregnancies with/without VCI and in pregnancies with/without vasa previa was conducted. For each patient, FHR patterns were compared to the subsequent pregnancy. Deliveries occurred between the years 1988 and 2012 in a tertiary medical center. FHR patterns were evaluated according to the ACOG guidelines.

Results: During the study period, there were 184 pregnancies with VCI and 37 pregnancies with vasa previa, undetected during pregnancy. FHR patterns of the VCI group included more cases of abnormal baseline (7 vs. 2 %, p < 0.05), out of which 7 % were fetal tachycardia (vs. 2 %) and 4 % were bradycardia (vs. 1 %). There were also more cases of abnormal baseline and abnormal variability (7 vs. 2 % and 32 vs. 22 %, respectively, p < 0.05) in the VCI group. FHR categories also differed between the velamentous cord insertion pregnancies and subsequent ones. VCI pregnancies had more category 2 patterns, not statistically significant (64 vs. 55 %, p = 0.11). FHR patterns of the vasa previa group included more cases of abnormal baseline (27 vs. 7 %, p < 0.05), out of which 18 % were tachycardia and 9 % were bradycardia. Decelerations were recorded in a total of 61 % of the vasa previa cases (61 vs. 31 %, p = 0.02), most of which were variable decelerations (48 vs. 17 %). Vasa previa pregnancies had more category 2 patterns (64 vs. 52 %).

Conclusions: Fetal heart rate patterns in pregnancies complicated with VCI or vasa previa have several non-specific pathological characteristics; none can be used for early detection of these conditions.