Hypothesis / aims of study
Suburethral tapes is the most commonly performed procedure to treat stress urinary incontinence. Complications such as voiding dysfunction, overactive bladder, tape erosion or recurrent stress incontinence may arise. Translabial ultrasound is a non-invasive procedure capable of evaluating sling implants with ease. Palpation of the sling, on the other hand, is not always possible and determining tape position when complications arise is important in deciding patient treatment and follow-up.
Our aim was to determine the correlation between tape position determined by ultrasound with clinical palpation after transobturator suburethral tape (TVT-O) placement.
Study design, materials and methods
This retrospective study included women who underwent TVT-O placement during 2014 and 2016 at a pelvic floor unit of a tertiary hospital. Patients with more than one suburethral tape were excluded. All patients had a medical history taken, physical examination and 4D translabial ultrasound. Position of the sling by clinical palpation was recorded before the translabial ultrasound was performed. 4D TLUS volumes were stored and analysed at a later date by one of the authors blinded to all clinical data.
Position of the tape by ultrasound was assessed by determining the tape relative to the urethra by calculating the percentile of the urethra where the tape was located. The urethra was divided into distal urethra if >70th percentile of the urethral length, midurethra if between 40-70th percentile and proximal urethra if <40th percentile. The urethra length was measured along the urethral longitudinal axis in the mid sagittal plane from the bladder neck to the external meatus. The distance from the midpoint of the tape to the bladder neck was then measured.
On clinical examination, tape palpability was recorded if possible and location of the tape along the length of the urethra: distal, mid or proximal urethra. Chi-squared test was performed to evaluate tape palpation/visualization by ultrasound. Intraclass correlation coefficient was calculated to determine the agreement between tape percentile by palpation and ultrasound.
Interpretation of results
In 15.9 % (n=10) of patients the suburethral tape could not be palpated on clinical examination however there was no statistical differences when compared to ultrasound finding of the tape. Palpation underestimated the number of tapes located at the proximal urethra. Tape location has been reported to be an important factor for surgical outcome. The ideal position of TVT-O is at mid urethra but distal location has also been described as a target, however the tape located under the proximal third of the urethra as shown to have a higer failure rate.
Palpation dificulty of the tape will depend on the mucosa thickness and how deep the tape is located beneath the vaginal mucosa.