From the FDA Drug Label
After subcutaneous administration of 0.25 mg of terbutaline sulfate injection, a measurable change in expiratory flow rate usually occurs within 5 minutes, and a clinically significant increase in FEV1 occurs within 15 minutes. The maximum effect usually occurs within 30 to 60 minutes,
The waiting time for terbutaline to work before attempting external cephalic version (ECV) bedside is at least 15 minutes to allow for a clinically significant effect, but ideally 30 to 60 minutes for the maximum effect to occur, based on its bronchodilator activity 1.
- Key consideration: The effect of terbutaline on uterine relaxation may not be directly equivalent to its bronchodilator effect.
- Clinical decision: Wait at least 15 minutes to 30-60 minutes after administering terbutaline before attempting ECV bedside.
From the Research
After administering terbutaline for external cephalic version (ECV), wait approximately 15-30 minutes before attempting the procedure. This recommendation is based on the most recent and highest quality study available, which is from 2020 2. Typically, terbutaline is given as a 0.25 mg subcutaneous injection, and its uterine relaxation effects begin within 5-10 minutes, with peak effects occurring around 15-30 minutes after administration. This waiting period allows the medication to achieve optimal uterine relaxation, which increases the likelihood of successful version by reducing uterine tone and making the fetus easier to manipulate.
The relaxation effect generally lasts about 2-4 hours, so the procedure should be performed within this window. Be aware that terbutaline may cause maternal side effects including tachycardia, palpitations, tremors, and anxiety due to its beta-adrenergic properties. Continuous maternal and fetal monitoring should be maintained throughout the procedure, and the patient should be observed for at least 1-2 hours afterward to ensure no complications develop from either the medication or the version attempt.
Some key points to consider when performing ECV with terbutaline include:
- The success rate of ECV is associated with maternal Body Mass Index (BMI) and previous vaginal delivery, as shown in the 2020 study 2.
- The procedure is generally safe, with a low complication rate, as reported in the 2020 study 2 and other studies such as the 1997 study 3 and the 2009 study 4.
- The use of terbutaline for ECV has been shown to increase the success rate of the procedure, as demonstrated in the 1997 study 3 and the 2009 study 4.
Overall, waiting 15-30 minutes after administering terbutaline before attempting ECV is a reasonable approach, based on the available evidence and considering the potential benefits and risks of the procedure.