Assessment of pelvic floor structural abnormalities in patients with functional constipation through ecodefecography and transperineal ultrasonography, simultaneous with high resolution anal manometry. 
Correlate the findings with the presence or absence of dyssynergic defecation.

40 female patients referred to the anorectal physiology unit from January 2017 to December 2018, under the diagnosis of chronic functional constipation refractory to medical treatment, were included. The protocol used by our unit for the study of chronic constipation involves proctologic and gynecologic clinical evaluation, high resolution anal manometry, and transperineal ultrasonography. The data gathered included demographic information and clinical history of each patient obtained by direct interview. For constipation the Kess questionnaire was applied.
Statistical analysis was carried out with the statistical package SPSS version 25 (IBM Corp Armonk, NY). The quantitative variables were reported in mean ± standard deviation and qualitative variables in frequencies and percentages. Variables distribution was determined by the Kologorov Smirnov test. For variables comparison the t student test was applied. Qualitative/dichotomous variables were analyzed using chi square test. The risks were established through odds ratios. The value of p was considered statistically significant when it was lower than 0.05.

All of our patients were female. Mean age was 52.82 (±14.10) years. 85% (34 patients) were otherwise healthy, and the rest presented some kind of comorbidity: type 2 diabetes (2.5%), systemic arterial hypertension (2.5%), Crohn disease (2.5%), among others. 55% (22 patients) did not have previous surgical interventions, and in those who had the most frequent procedures were: hysterectomy (10%), cystocele mesh repair (5%). 60% of patients (24) had some type of dyssynergic defecation documented by high resolution anal manometry. 95% of patients had an anorectal structural abnormality identified through transperineal ultrasonography, the most frequent diagnosis were: rectocele (37.5%), rectocele and cystocele (15%), cystocele (10%). 
The mean Kess global score was 19.25 (6.53) points. We did not observed statistically significant differences in the Kess score between patients with structural abnormalities documented by transperineal ultrasonography and those without them (19.4 versus 15.5; p=0.40).
The Kess score was not different in patients with dyssynergic defecation compared to those who did not presented it in high resolution anal manometry studies (20.9 versus 16.7; p= 0.73). However a Kess score higher than 16 points represented a risk factor for presenting dyssynergic defecation (OR 1.46 [0.98 – 2.18]; p=0.03). In these kind of patients Kess score higher or lower than 16 points served to determine the presence or absence of dyssynergic defecation, respectively, with a sensitivity of 68.5% and a specificity of a 100%, positive predictive value of 100% and negative predictive value of 31.3%. 91.7% of patients with dyssynergic defecation presented an anorectal structural abnormality, documented through transperineal ultrasonography.

Functional constipation (FC) is a  functional disorder,  characterized by a persistent difficulty in defecation or incomplete defecation, that does not have a physical (anatomical) or physiological cause. (1,2) It is said that it cannot be adequately distinguished upon symptom criteria or physiologic tests, however biofeedback has been proven effective for the treatment of FC. (1) We have seen as part of our study protocol in these patients (that ordinarily consist of performing   proctologic and gynecologic clinical evaluation, high resolution anal manometry, and transperineal ultrasonography), specifically in those who do not respond to medical treatment  that the vast majority 95% have  anorectal structural abnormalities associated with some type of dyssynergic defecation (60%). Therefore the main cause of failure with medical treatment can be associated with the lack of treatment for the structural abnormality that lies underneath the functional disorder. We also established a correlation with the kess score as a predictive  factor for the presence of dyssynergic defecation, with a sensitivity of 68.5% and a specificity of a 100%.

More than half of patients with chronic functional constipation refractory to medical treatment present dyssynergic defecation. The majority present as well some kind of pelvic floor structural abnormality.  Kess questionnaire can aid to identify from the first interview patients who have dyssynergic defecation.

Chen, Hung-Da, et al. "Similarities and Differences Between IBS-C and FC With Regards to Symptomatology, Sleep Quality and Psychological Attributes." Journal of the Formosan Medical Association = Taiwan Yi Zhi, 2019.
Americal College of Gastroenterology: Functional Bowel Disorders