NEW YORK (Reuters Health) – It makes no difference whether internal tocodynamometry or external monitoring is used during induced or augmented labor – either way, the rate of operative deliveries is similar.
That’s according to a large randomized, controlled trial conducted at 6 hospitals in the Netherlands and reported in the New England Journal of Medicine January 28.
Internal tocodynamometry is believed to be more accurate in quantifying the frequency, duration, and magnitude of uterine activity, the authors explain. Theoretically, this information could improve oxytocin dosing, thus helping to prevent uterine hyperstimulation and fetal hypoxia, and it might also improve the interpretation of abnormal fetal heart-rate patterns.
Because data to support these theories are limited, Dr. Joris A. M. van der Post, at Amsterdam’s Academic Medical Center, and colleagues compared external monitoring and internal tocodynamometry in a randomized trial. Inclusion criteria were a singleton pregnancy, gestational age > 36 weeks, fetus in the cephalic position, and IV oxytocin required for induction (66%) or augmented labor (34%).
After randomization, 734 women were assigned to internal tocodynamometry and 722 to external monitoring.
Spontaneous vaginal delivery was achieved by 68.7% of patients in the internal monitoring group and 70.4% in the external monitoring group. Cesarean section was required by 16.3% and 15.7%, respectively, and instrument delivery by 14.9% and 14.0%, respectively. None of these differences was statistically significant.
The frequency of secondary outcomes — complications from use of the intrauterine pressure catheter, use of analgesia or antibiotics, amount of oxytocin, time to delivery and adverse neonatal outcomes — was also similar between groups.
Post hoc analyses showed no significant interactions between treatment and type of labor, parity, or body mass index.
The authors point out that internal tocodynamometry “has serious risks, including placental or fetal-vessel damage, infection, and anaphylactic reaction.”
They conclude, “The results of our trial do not support the routine use of internal tocodynamometry for monitoring contractions in women with induced or augmented labor.”
Reference:
N Engl J Med 2010;362:306-313.
