Meta-analysis reports lowest fetal asystole failure rate with intracardiac potassium chloride

A systematic review and meta-analysis published in Ultrasound in Obstetrics & Gynecology evaluated pharmacological and non-pharmacological methods of inducing fetal asystole before second- or third-trimester termination of pregnancy. Searches covered January 1991 through June 2025 and identified 25 studies involving 10,683 cases. Eligible designs included observational and randomized studies. The primary outcome was failure to achieve fetal asystole before termination; secondary outcomes included agent dose, maternal complications and effects on postmortem evaluation.

Pooled failure proportions were 0.4% (95% CI, 0.1–2.4%) for intracardiac potassium chloride, 3.2% (1.2–8.2%) for intrafunic potassium chloride, 4.8% (3.9–5.9%) for intrafetal digoxin and 10.6% (6.4–17.1%) for intra-amniotic digoxin. Doses varied across agents and injection routes. Four cases of postprocedure chorioamnionitis were reported across the studies, with no other significant adverse events reported as directly related to the procedures.

Intracardiac potassium chloride had the lowest failure point estimate, but these pooled proportions should not be interpreted as establishing comparative superiority. The authors emphasized considering safety and feasibility alongside effectiveness. Assessment of postmortem effects was limited, although fetal intravascular lidocaine and potassium chloride were consistently associated with cell lysis. Full text was unavailable for this update, limiting appraisal of study-level bias and safety reporting.