Anal canal to pubis angle: a novel clinical ultrasound technique for the assessment of the anorectal region.

INTRODUCTION AND HYPOTHESIS: Posterior compartment prolapse is associated with severe morbidity including faecal incontinence and defaecation dysfunction. The aim of this study was to develop and validate a novel ultrasound marker (anal canal to pubis angle) for the assessment of the anal axis in the context of posterior compartment prolapse in women and in controls (healthy, nulliparous, non-pregnant volunteers). METHODS: Anal canal to pubis (AC/Pubis) angle is measured with 2D transperineal ultrasound in precisely the midsagittal plane. The image was inverted and zoomed out and the angle opened to 107° (maximum). The image includes the pubis, urethra and anal canal. The angle measurement starts from the anal canal, pivots on the anorectal junction and ends at the shadow of the pubis. Inter- and intra-observer agreement in AC/Pubis angle measurement was assessed and the angles measured in the two groups compared. RESULTS: Forty women with posterior prolapse and 17 controls were included. Close agreement was observed in inter- and intra-observer AC/Pubis angle measurements assessed with Bland-Altman analysis. AC/Pubis angle is significantly wider in prolapse patients compared to controls (t-test, p < 0.001), with mean AC/Pubis angle in prolapse patients 122.9° (SD 15.6°) and controls 98.2° (SD 15.9°). CONCLUSION: The AC/Pubis angle is a novel validated 2D ultrasound technique for the assessment of the anorectal axis that potentially can be performed using equipment that is widely available in routine clinical practice. The AC/Pubis angle is significantly wider in prolapse patients compared to controls.

Ultrasound technique for the assessment of urethral descent assessment technique (UDAT) in healthy volunteers.

Bladder neck descent (BND) has been implicated in the pathophysiology of stress incontinence and prolapse. The aim of this study was to evaluate a novel 2D technique for the evaluation of BND, the Urethral Descent Assessment Technique (UDAT). UDAT involves measuring BND during dynamic manoeuvres in live 2D ultrasound, by using the geometrical properties of parallel lines. The internal urethral meatus and distal end of the urethra are used as reference points. Y1 is the urethral height at rest (also the urethral length when the urethra is straight). Y2 is the urethral height on Valsalva. Y1 and Y2 are parallel lines. Y1-Y2 = BND. A horizontal line (X) connecting Y1 and Y2 is the forward movement of the bladder neck.Y1 mean 30.4 mm (95% CI ± 1.36 mm). Y2 mean 24.2 mm (95% CI ± 2.58 mm). X mean 12.1 mm (95% CI ± 1.66 mm). BND mean 6.2 mm (95% CI ± 1.47 mm). Bland-Altman plots and linear regression showed that UDAT is repeatable and reliable.Impact statementWhat is already known on this subject? Bladder neck descent (BND) has been associated with stress incontinence and prolapse nearly a century. In 1975, Green introduced a classification based on X-ray cysto-urethrograms. Between 1989 and 1995, a 2D technique was described that had several limitations.What do the results of this study add? This study validates a novel technique for the assessment of bladder neck descent using 2D ultrasound and provides a reference range of BND for normal nulliparous women.What are the implications of these findings for clinical practice and/or further research? This is a simple and quick technique that could be adopted in research and clinical practice in the future to assess stress incontinence and anterior compartment prolapse.

Validation study of ultrasound bladder wall thickness measurements.

INTRODUCTION AND HYPOTHESIS: The aim was to validate ultrasound bladder wall thickness measurements. We scanned at three frequencies (5 MHz, 7 MHz and 9 MHz), using two techniques described in clinical practice and compared them with direct micrometre calliper measurements. METHODS: Bladder dome cadaver specimens were dissected from male and female cadavers. The direct micrometre calliper measurement under direct vision was used as the gold standard. We imaged using a Voluson E8 ultrasound scanner at three frequencies, using three probes: AB27D (2-7 MHz), RAB25D (2-5 MHz) and RIC50D (5-9 MHz). The specimens were scanned on two different occasions for intra-observer variability. A second operator, measured the samples again independently for the interobserver agreement. The specimens were gently placed onto a sheathed and gelled probe to avoid deformation. The method of scanning was the same for all the specimens, probes and operators. RESULTS: Twenty-five bladder dome specimens were assessed. The correlation of the ultrasound measurement to the direct measurement improved at higher ultrasound frequencies. Measuring from the inside of the serosal hyperechogenicity also increased the accuracy correlation with the direct measurement for all the frequencies tested. CONCLUSIONS: This is the first study validating BWT ultrasound measurements against cadaveric bladder wall calliper measurements. Technology and technique affect accuracy, which is important in clinical practice. The use of 5-MHz probes is not recommended. The most accurate measurement was obtained using high-frequency ultrasound, where the measurement did not include the serosal brightness. These data suggest that high-frequency ultrasound should be used to assess BWT.