Fetal heart rate changes after accidental intrauterine lidocaine.

Fetal heart rate (FHR) decelerations resembling post-paracervical block (PCB) bradycardia were observed immediately after the inadvertent intrauterine injection of lidocaine hydrochloride. A review of the pathophysiology of post-PCB bradycardia is presented. The administration of a local anesthetic, either into the paracervical tissues or directly into the uterine cavity, may precipitate FHR decelerations principally, through arterial vasoconstriction with subsequent reflex responses and/or hypoxia in the fetus.