Objective
The objective of the study was to determine whether genital hiatus (gh) and perineal body (pb), measured using the pelvic organ prolapse quantification system of the International Continence Society, are predictive of an abnormally distensible levator hiatus on ultrasound and of objective prolapse and/or prolapse symptoms.
Study Design
The design of the study included datasets of 188 urogynecology patients assessed in a cross-sectional retrospective study.
Results
Gh and pb, as well as gh plus pb, were strongly associated with symptoms and signs of prolapse and with hiatal area on ultrasound. The sum of gh and pb was superior in predictive performance to individual measures for symptoms ( P < .001) and signs of prolapse ( P < .001). Gh plus pb equaled the hiatal area on ultrasound (area under the curve, 0.886; 95% confidence interval, 0.828–0.945 vs 0.867; 95% confidence interval, 0.808–0.926) for predicting objective prolapse. Optimal sensitivity (80%) and specificity (81%) was reached with a cutoff of 7 cm for gh plus pb.
Conclusion
A cutoff of 7 cm for gh plus pb measured on Valsalva is proposed as a clinical definition of excessive levator hiatal distensibility.
The dimensions of the levator hiatus, that is, the space enclosed by the levator ani muscle, are strongly associated with prolapse. This is not surprising if one considers the levator hiatus as a hernial portal, the largest potential hernial portal in the abdominal envelope. Excessive distensibility of the levator hiatus may be congenital or acquired, due to avulsion of the puborectalis muscle or due to overdistension of a macroscopically intact muscle and is independently associated with prolapse and prolapse symptoms. It is plausible that the size of the levator hiatus may play a role in the etiology of female pelvic organ prolapse, which implies that there may be substantial benefit, both for research and clinical practice, in measuring hiatal dimensions.
To determine the size of the levator hiatus, it is necessary to use magnetic resonance or 4-dimensional (4D) ultrasound imaging, modalities that are neither cheap nor universally available. If it were possible to diagnose excessive distensibility of the hiatus clinically, this would allow clinicians to avoid more expensive imaging investigations and open up new opportunities for research and therapy.
The closest equivalent to the levator hiatus that can be measured clinically is the genital (or urogenital) hiatus, that is, the distance from the center of the external urethral meatus to the center of the fourchette. DeLancey and Hurd measured the urogenital hiatus using a ruler and found that pelvic organ prolapse was associated with the anteroposterior diameter of the urogenital hiatus and that this parameter was associated with surgical failure. The former finding has been confirmed independently by authors measuring the genital hiatus on pelvic floor muscle contraction. The genital hiatus, together with determination of the length of the perineal body, forms part of the pelvic organ prolapse quantification (POPQ) of the International Continence Society (ICS) and has been shown to be highly repeatable. Correlations for interobserver reliability were 0.913 and 0.514 for genital hiatus (gh) and perineal body (pb). The intraobservor reliability correlations for 25 subjects were 0.812 and 0.659 for gh and pb.
In this study we aimed to determine whether clinical estimation of the genital hiatus and perineal body on Valsalva, recorded as part of a routine clinical pelvic floor assessment using the ICS POP-Q, is predictive of an abnormally distensible hiatus (ballooning) as documented on pelvic floor ultrasound and prolapse/prolapse symptoms.
Materials and Methods
This is a retrospective cross-sectional analysis of datasets of 188 patients seen at a tertiary urogynecology center for lower urinary tract symptoms and/or symptoms of pelvic organ prolapse between September 2010 and February 2011.
All patients had undergone an interview and a clinical examination using the ICS POP-Q, including measurement of the genital hiatus and perineal body at maximal Valsalva using a wooden, disposable, calibrated ruler (PopStix; Endoventure, Auckland, New Zealand). Translabial 3-dimensional (3D)/4D pelvic floor ultrasound was performed using GE Kretz Voluson 730 expert systems (GE Kretz Medizintechnik, Zipf, Austria) with RAB 8-4 MHz abdominal volume transducer as described previously.
Symptoms of pelvic organ prolapse were solicited from every study participant using the same standardized wording, which defined symptoms as “the sensation of a lump in the vagina and/or a dragging sensation in the vagina.” Archived 4D translabial ultrasound datasets were analyzed offline at a later date using software (GE Kretz 4D View, version 5.0; GE Kretz Medizintechnik) by A.K., who was blinded to all other data.
Hiatal dimensions were determined according to a previously published methodology, which has been shown by several authors to be highly repeatable. Anterior-posterior diameter and hiatal area were measured on maximal Valsalva in the plane of minimal hiatal dimensions. Great care was taken to avoid levator coactivation. Mean genital hiatus and mean genital hiatus plus perineal body were tested against measurements of hiatal dimensions.
Both ultrasound and clinical measurements were then tested for their predictive value for symptoms and signs of prolapse. We did not perform formal power calculations because of an absence of pilot data in the literature. Statistical analysis was undertaken using SPSS, version 14 (SPSS Inc, Chicago, IL) and Minitab version 13 (Minitab Inc, State College, PA).
All quantitative data were found to be normally distributed on Kolmogorov-Smirnov testing. Pearson’s correlation was used to compare clinical examination measurements and 3D/4D ultrasound measurements. Receiver operator characteristics (ROCs) curve analysis was used to examine the relationship between gh, pb, and signs (prolapse stage 2 POPQ or greater) and symptoms of prolapse.
The Human Research Ethics Committee of the Sydney West Area Health Service approved this research project (IRB code, NBMLHN 11/13). Because this was a retrospective analysis of data obtained during normal clinical practice, informed consent was not required. The manufacturer donated the PopStix (Endoventure).
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