Internal monitoring

Harper LM, Shanks AL, Tuuli MG, et al. The Risks and Benefits of Internal Monitors in Laboring Patients. Am J Obstet Gynecol 2013; 209:38. e1-6

“Intrauterine pressure catheters (IUPC) and fetal scalp electrodes (FSE) are commonly used devices for intrapartum monitoring and management. Although the internal monitors used are sterilely packaged, they travel through the vaginal canal into the uterine cavity, providing a potential pathway for contamination and ascending infections. Studies are conflicting on whether or not internal monitors are associated with maternal and neonatal infections, but amniotic fluid specimens collected after IUPC insertion have been found to be contaminated with bacteria in 50% of subjects. Additionally, numerous case reports exist of scalp abscesses after monitoring with FSE, and one case control study of infants with GBS sepsis suggest that monitoring with FSE may be associated with a greater risk of death.

Because the IUPC can be used to calculate Montevideo units and adequacy of contractions, they are frequently placed when labor dystocia is a concern. However, randomized control trials comparing the use of internal and external monitors for labor management have not demonstrated a decrease in the risk of cesarean when internal monitors are used, although they also do not demonstrate an increased risk of infectious morbidities.

In spite of this, the use of internal monitors is widespread. At some institutions, it is routine to place internal monitors at the time of membrane rupture.”