This chapter examines the use of ultrasound scanning in the intrapartum assessment of patients in labor and its invaluable utility to guide invasive procedures. It reviews several of these recent advances: cervical length evaluation as a predictor of preterm delivery and for the selection of appropriate induction of labor candidates; the evaluation of uterine bleeding; the monitoring of intrapartum fetal weight, and fetal well-being. Evaluation of fetal amniotic fluid quantity is an essential fetal assessment tool for the obstetrician. Fetal blood sampling is a practice used to gain access to the fetal blood for various indications; classically, obtaining a fetal blood sample can assist in the diagnosis of genetic disorders using a technique of rapid karyotyping, as well as to diagnose fetal infection and determine fetal blood type. Ultrasonography has proved to be helpful in the diagnosis of failed placental separation, allowing for expeditious surgical management prior to severe hemorrhage.

The process of placental delivery and the subsequent involution of the uterus during the puerperium are often described as the third and fourth stages of labor. This chapter presents a brief historical review concerning third- and fourth-stage events, followed by a discussion of the physiology of placental separation and uterine involution. The diagnosis and treatment of retained placenta and membranes (secundines), uterine inversion, postpartum hemorrhage and atony, and hematomas are considered. Important cultural and historical events in world history have been directly influenced by complications of involving the third stage of labor. Active management of the third stage of labor consists of the immediate administration of oxytocin after delivery of the infant, early cord clamping, and gentle traction on the cord, combined with gentle uterine massage to prompt placental separation. Periurethral lacerations, which often bleed freely, appear in the thin tissues on either side of the clitoris or urethra.