Intrapartum ultrasound

Throughout the last decade, robust, compact, mobile, high-resolution real-time ultrasound machines, often capable of duplex and color Doppler imaging and designed to enable service at the patient's bedside, have become increasingly available. As a result, most labor and delivery services can (and many do) provide continuous 24-h, on-site, on-demand, ultrasound capability. This technology has become so user friendly that non-ultrasound-trained professionals, including attending physicians, residents, nurses and physician assistants, routinely provide high-quality basic ultrasound services. Undoubtedly, the availability of immediate and convenient diagnostic and intervention-guided ultrasound support has enhanced medical care in the demanding labor and delivery environment. Although, overall, most obstetric ultrasound examinations will clearly remain in the antepartum arena, it is essential to understand current applications of ultrasound in the setting of labor and delivery. Accordingly, in 2002 the Journal dedicated an opinion article to the role of ultrasound scanning on the labor ward1. A growing body of knowledge is accumulating regarding true intrapartum ultrasound, a relatively new application of ultrasound. Accordingly, currently available data on intrapartum ultrasound assessment of active labor, limitations, recent developments and future possibilities, as well as other pertinent intrapartum applications of ultrasound examination as an adjunct to the overall management of the patient in labor (intrapartum ultrasound-assisted identification of the epidural space, maternal postvoid residual and total bladder volume measurements) and investigative data (uterine contractions, intrapartum myometrial contractility, the third stage of labor, intrapartum maternal and fetal hemodynamics and fetal behavior), are presented in this Editorial. By virtue of its safety and non-invasive nature, given appropriate circumstances, intrapartum ultrasound examination is applicable for most (if not all) indications currently practiced in the antepartum arena. These include fetal biometry and weight assessment, fetal presentation(s), assessment of the breech-presenting fetus, multiple gestations, placental positioning, anatomy, preinduction cervical assessment, preinduction transvaginal ultrasonographic prediction of successful induction or operative delivery, fetal testing (amniotic fluid volume, biophysical profile, Doppler flow velocimetry), assessment of the size and location of (possibly obstructing) uterine leiomyomata, assessment of amniotic fluid volume following amnioinfusion, and procedure guidance (transabdominal and transvaginal cephalocentesis, thoracocentesis, drainage of fluid-filled fetal tumors, external cephalic and internal podalic version, manual removal of the placenta and placement of central intravenous lines)2-36. Similarly, intrapartum ultrasound has been used in the diagnosis of esoteric conditions such as uterine rupture and vasa previa37-39. Overall, few data are available regarding utilization of ultrasound imaging in labor and delivery services, which may vary according to various practices and clinical settings (academic teaching institutions, community hospitals, birthing centers). Indications for ultrasound examination in labor and delivery suites in an active academic teaching institution in the USA were assessed over a 4-month period40. Not surprisingly, this study demonstrated that 68% of all ultrasound examinations in this service were performed on non-laboring patients (who were ultimately discharged undelivered following that examination), compared with 32% of studies performed on patients in labor. 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