Abstract
Transperineal ultrasound (TPU) started to be used in the 1970-80s for assisting biopsies of the prostate. Only in the mid to late 1990s did it become a tool used by both urogynecologists and obstetricians. Different from invasive urodynamic tests, and digital vaginal or digital rectal examination, this approach is noninvasive and well tolerated by patients. While MRI or CT examination requires expensive equipment and highly trained personnel, TPU is easy to perform and can be done in real time to answer the clinical question being investigated. Furthermore, cine loop clips are easily acquired and stored for later evaluation and for educational purposes. In urogynecology, TPU can be used to visualize the urethra and its hypermobility, being useful for diagnosis of stress urinary incontinence. During labor, TPU allows an objective assessment of fetal head descent in the birth canal. Many other measurements have been proposed by different scientists: the angle of progression, the head direction, the progression distance, and the head-perineum distance. The angle of progression is the most widely used parameter. TPU is also used to assess fetal head rotation, with both 2D and 3D images. The latter helps with the visualization of fetal sagittal suture in real time. It is clear that with all these potentialities, TPU can become the most objective way to help in making a key decision at time of delivery: perform an operative vaginal or potentially difficult cesarean delivery. In postpartum, TPU can be used to visualize the rectal sphincter, and it is being used to identify patients at high risk for fecal incontinence. Nowadays, TPU is becoming the most advanced and objective tool used in many labor and delivery units around the world during the first and second stage of labor to assess fetal position and fetal station, and in puerperium to visualize the rectal sphincter.
