Assessment of defecation disorders using high-resolution MRI-defecography

Aims. The aim of this retrospective study was to try to find correlations between different diagnoses established by clinical examination, anorectal manometry and MRI-defecography and, the association with psychiatric disorders. Methods. 44 patients (median age 53.81 years) presenting with intestinal motility disorders and who underwent clinical, biological and psychiatric examination, dynamic defecographic-MRI (resting, squeezing, straining, defecation and evacuation phases), anorectal manometry, colonoscopy. MRI was performed using the 1,5 T. Results. MRI-defecography revealed the following changes: anismus (16), rectocele (12), pelvic floor dysfunction (6), peritoneocele (2), cervical-cystic-ptosis (1), rectal prolapse (6), and in 1 case the examination was normal. Hypertonic anal sphincter (16) and lack of defecation reflex (12) at anorectal manometry correlated with anismus in all patients at MRI-defecography. Lack of inhibitor anal reflex (6) was associated with rectocele (4), cervix-cysto-ptosis (1) and peritoneocele (2). Anxiety (11), depression (6) and anxiety-depressive disorders (10) were found in 27/44, somatization disorders in 9/44 and no psychiatric changes in 8/44 cases. Conclusion. As multiparous women are at risk for outlet obstruction constipation, MRI-defecography is suggested in this category. There is good correlation between diagnosis using anorectal manometry and MRI-defecography in patients with terminal constipation and anismus. Lower defecation dysfunction is often associated with psychiatric disorders.


INTRODUCTION
Pelvic floor prolapse (PFP), representing the herniation of the pelvic organs through the perineum, can be classified as: anterior (cystocele-urinary bladder), middle (uterus, vagina) and posterior (small bowel-enterocele and rectum-rectocele); all these have at magnetic resonance imaging (MRI)-defecography a prolapsing pattern 1 . Dyssynergic defecation and PFP often coexist in functional defecation disorders in females, clinical examination being inadequate 2 . Mild cases with involvement of a single compartment are poorly evaluated by imaging methods, but complex cases with multiple organic involvement are best evaluated by translabial ultrasound and dynamic pelvic MRI-defecography 3 .
Among the advantages of MRI-defecography are: lack of ionizing radiation, good soft tissue resolution, ability to display the entire pelvic floor, guiding the pre/postoperatory management.
The aim of this study was to try to find correlations between different diagnosis established by clinical examination, anorectal manometry and MRI-defecography and also the degree of association with psychiatric disorders.

MATERIALS AND METHODS
A retrospective study was conducted among patients with symptomatic pelvic floor dysfunction (PFD), subjects that presented at our unit between 01.01.2019-31.12.2020.
MRI was performed using the 1,5 T (MAGNETOM Avanto, Siemens, Germany) with 18 channel phase array body coils. Defecographic algorithm consists in views in sagittal and coronal planes, and images were obtained during the resting, squeezing and straining (Valsalva maneuver), defecation and evacuation phases. Defecation phase is demonstrating best the anterior/middle organic descent in dyssynergic defecation. MRI images were analyzed by 2 experienced radiologists independently. Patients were positioned in the supine position within the MRI scanner, initial T2 weighted images were acquired through the pelvis in sagittal, coronal and axial directions.  During dynamic MRI-defecography, the anal-rectal angle (ARA) was measured between the pubococcygeal line and anorectal junction. Dyssynergic defecation was defined if abnormal ARA-change was found. The dynamic phases of squeezing and straining required breath holding for maximum of 20 seconds each. Prior to MRI, the patient's rectum was filled with a synthetic stool of potato starch and Gadolinium (Gd) based contrast liquor (2-3 ml/potato starch box) named Gadovist 1mmol/ml. 50-60 ml of the enema with potato and Gd was administrated via a rectal tube with the patient on the MRI table in the lateral position. Patients were asked to produce Valsalva maneuver with contracted sphincter for 10 seconds and then to eliminate the rectal content; the limitation was impossible or possible after one or several attempts, depending on the underlying pathology.
Diagnostic MRI-defecography criteria was considered for: anismus-the lack of normal puborectal muscle relaxation during defecation, rectocele-bulge of anterior rectal wall >2 cm during straining, cystocele-bladder descent below pubic symphysis, vaginal prolapse-descent of cervix below pubococcigeal line during straining, enterocele-herniation of pelvic peritoneal sac into rectogenital space, intussusception circular invagination of proximal rectum (mucosa and muscular layer) during defecation.
Assessments included also a validated constipation questionnaire, and psychiatric disorders were evaluated by Hospital Anxiety and Depression scale (HADS), GAD-7 (Generalized Anxiety Disorder-7).
All patients included signed the informed consent and also the approval for participating in medical teaching, in accordance with the Declaration of Helsinki.

RESULTS
The following risk factors were found in our study- Colonoscopy detected internal hemorrhoids in 26 patients, without other lesions. Hypertonic anal sphincter (16) and lack of defecation reflex (12) at anorectal manometry correlated with anismus in all patients at MRI-defecography. Lack of inhibitor anal reflex (6) was associated with rectocele (4), cervix-cysto-ptosis (1) and gastroenterologist, an internist and a radiologist after reviewing the medical history, anorectal manometry and MRI-defecography.

DISCUSSION
Functional PFD can be present, clinically and radiologically, independent from pelvic organ prolapse 4 . The most frequent finding for the spastic pelvic floor syndrome is the prolonged and incomplete evacuation 5 . Mean evacuation time was considered longer (mean time 60 seconds) compared to the results of Halligan et al. 6 possible due to the bigger volume of enema. Paradoxical sphincter contraction is a useful indicator for anismus.
Hard and small volume feces, excessive strain at stool, tenesmus and fecaloma are the most frequent symptoms described by anismus patients with dyskinetic pattern at MRI-defecography 1 . The anorectal group had anismus as the most common clinical feature (16/24, 66.66%), while rectocele (12/20, 60%) and rectal prolapse (6/20, 30%) were predominant in the multi-compartment pelvic group. Rectocele occured in most of the patients with outlet obstructive constipation with anorectal and pelvic floor dysfunction 11 . Reiner et al. 12 found in 100% patients with dyssynergic defecation (anismus/PFD) an impaired evacuation, the most frequent finding here being rectal descent (78%); his results suggest that impaired evacuation can be also found in other causes of functional constipation due to pelvic floor abnormalities (other than anismus). 95% of the patients with PFD have abnormalities in all 3 pelvic compartments 13 .
Regarding the contrast agent used for the rectal enema at MRI-defecography in literature, ultrasound gel mixed with Gd proved to underestimate the size and degree of anterior rectocele and intussusception size, compared to potato starch mixed with gadolinium 14 . peritoneocele (2). Anxious-depressive disorders (anxiety in 11, depression in 6 and combined anxious-depressive disorder in 10 patients) were found in 27/44, somatization disorders in 9/44 and no psychiatric changes in 8/44cases. Evaluation by means of Hospital Anxiety and Depression scale (HADS) greater than 8 and GAD-7 (Generalized Anxiety Disorder-7) over 7 was found in 28/36, respectively in 30/36 patients.
The final diagnosis of dyssynergic defecation was established by an interdisciplinary group, including a Poncelet et al. 15 revealed no significant difference between dynamic MRI-defecography and X-ray defecography while investigating abnormalities of the posterior compartment of the pelvic floor, while Van Iersel 16 found an inferior accuracy in diagnosing rectocele and enterocele, but a superior value for intussusception. Salvador et al. 6 found the superiority of MRI-defecography for evaluating the posterior compartment disorders, and similar to fluoroscopy in pelvic organ prolapses [17][18][19] . In older times, colpocystodefecography was even considered the gold standard method among the imaging investigation methods, and MRI-defecography was considered unreliable for the anterior and middle compartment 20 .
Recent studies involving women with pelvic organ prolapse showed no significant association with depression and anxiety symptoms both in preoperative and postoperative patients 21 . Other studies, like Ai et al. 22 revealed generalized anxiety disorders in 20.6% of women with pelvic organ prolapse, being present in almost 1/5 of postmenopausal women, and associated with higher scores in those with bowel and urinary dysfunction (22). Vrijens et al. 23 showed a prevalence of 20.3% depression among females with pelvic organ prolapse and Mazi et al. 24 even higher, of 43% among patients with pelvic floor dysfunction. Our group showed even a higher rate of anxiety alone or in combination with depression (21/44, 47.72%) compared to the literature; even if general recommendations 25 show higher values of the scales of assessing anxiety and depression, 77.7% of our patients had the HADS score above 8 and 83.33% GAD-7 above 7. On the other hand, strong correlation between the severity of these psychiatric symptoms and the severity of the pelvic floor dysfunction was shown by Khan et al. 26 . Merkel et al. 27 demonstrated a higher incidence of depression, somatization and anxiety in chronic constipated patients. Limer et al. 28 described a higher rate of anxiety in patients with mixed urinary incontinence.

CONCLUSION
As multiparous women, especially those ones with vaginal delivery, are at risk for outlet obstruction constipation, MRI-defecography is suggested in this category. There is a good correlation between diagnosis using anorectal manometry and MRI-defecography in patients with terminal constipation and anismus. Lower functional digestive disorders generating defecation dysfunction is often associated with psychiatric disorders.