Transperineal Pelvic Floor Ultrasound

Transperineal Pelvic Floor Ultrasound

 

Introduction and Historical Background

Ultrasound has been a dominant diagnostic tool in obstetrics and gynecology for generations, but its application in urogynecology (pelvic floor medicine) remained a relatively marginal topic for many years. The transition to the use of ultrasound for pelvic floor assessment began in the mid-1980s as an alternative to invasive radiological methods (such as cystourethrography) for diagnosing urinary incontinence. The main advantages of the transperineal (or translabial) approach are its non-invasiveness, lack of ionizing radiation, and excellent soft tissue imaging capability.

 

The Technological Revolution: From 2D to 3D/4D

For the first two decades, use focused on B-mode (2D) for the assessment of the bladder neck, urethra, and prolapse. The real revolution came with the introduction of Voluson technology (around 2002), which allowed axial plane imaging. This capability is essential for assessing the levator ani muscle, as defects in this muscle are almost undetectable in other planes.

 

Obstetric Trauma and Levator Avulsion

One of the most significant findings in the 3D/4D era is the "avulsion" or traumatic separation of the puborectalis muscle from the inferior ramus of the pubic bone or more precisely from the "linea alba" a line of connective tissue where the levator ani converges, the arcus tendineous facia pelvis.

Risk factors: The use of forceps has been identified as the most significant risk factor for avulsion. Other factors include advanced maternal age at first birth, a prolonged second stage of labor, and performing a Christler.
Clinical implications: Ablation is a major etiological factor in the pathogenesis of pelvic organ prolapse (POP) and is a significant risk factor for recurrence of prolapse after repair surgery.
Ballooning: A phenomenon of over-dilation of the levator hiatus during Valsalva, which is another marker of pelvic floor injury and is associated with prolapse symptoms.

 

Anal sphincter assessment (OASIS)

While endo-anal ultrasound is considered the classic method, transperineal imaging ("Exo-anal") has become more common in recent years due to the availability of equipment and patient convenience.

The use of tomographic imaging (Multislice) allows the identification of residual defects after repair of grade 3 and 4 tears.
A significant defect in the external anal sphincter (EAS) can be defined based on the angle of the defect and the number of tomographic slices involved.
New studies even allow the visualization of episiotomy scars and second-degree tears.

 

Urogynecological implants and urethral function

Ultrasound is the only tool that allows the visualization of suburethral slings and polypropylene meshes, which are not visible on X-ray, CT or MRI.

It is used for postoperative review to assess the position of the sling and its function/performance during Valsalva.

3D/4D imaging helps in the diagnosis of complex pathologies such as urethral diverticulum.

 

The Future: Artificial Intelligence (AI) in Urogynecology

The latest development includes the use of machine learning algorithms for automated measurement:

Measurement of the dimensions of the hiatus: There are currently systems that automatically measure the area of ​​the levator ani opening during the Valsalva maneuver, which shortens the examination time and improves standardization.

Automatic diagnosis of avulsion: Technological developments are working to automatically generate tomographic series of slices for diagnosing the integrity of the levator ani muscle.

 

Summary and clinical recommendations

For the resident, understanding pelvic floor ultrasound is essential not only for diagnosis, but also for improving obstetric practice. There is a thought to introduce the sonographic diagnosis of maternal trauma during childbirth as a quality indicator in obstetrics. The growing awareness of the physical harm caused by instrumental births, especially forceps, may lead to a significant change in birth management with the aim of reducing rates of long-term maternal trauma.