Megarectum in Adults (MEGA-ORIGINE)

Megarectum in Adults: Congenital or Acquired Pathology?

Severe functional constipation associated with a pathological increase in rectal volume, with or without colonic dilation, is known as megarectum. In the absence of an organic cause, megarectum is called idiopathic. This condition can begin at birth, in childhood, or in adulthood. The exact incidence of idiopathic megarectum (IM) is unknown, but it is considered a rare condition. Clinically, IM is usually considered in the context of chronic constipation that is refractory to traditional treatments and accompanied by rectal distension, abdominal pain, encopresis, and recurrent fecal impaction. The pathophysiological basis of IM remains poorly understood. A study using a rectal barostat-a device that measures rectal capacity and compliance (the rectum's ability to distend) by controlled distension of a rectal balloon-identified two distinct subgroups of patients with MI: (1) those with increased rectal compliance, who can be described as having "physiological" megarectum, in which marked rectal hyposensitivity-characterized by the absence of perception of rectal distension-and hypocontractility lead to chronic fecal accumulation and progressive overdistension due to loss of rectal elasticity; and (2) those with normal rectal compliance, who can be considered to have anatomical megarectum. It is not yet known whether these subgroups reflect different underlying etiologies. Furthermore, in patients with physiological megarectum, it is unclear whether the condition is primary or secondary to long-term rectal distension.

Study Overview

• Status: Not yet recruiting
• Conditions: Idiopathic Megarectum
• Intervention / Treatment: Other: Idiopathic megarectum group; Other: Constipated patient group

Detailed Description

The aim of this study is to identify and characterize elements of the clinical history, particularly early ones, associated with the disease, in order to contribute to the understanding of its pathophysiology.

To this end, the project aims to analyze the personal and family histories of patients with idiopathic bowel dysfunction (BD) and compare them with a population of constipated patients without BD, in order to determine the chronology of the onset of the condition (from birth, childhood/adolescence, or later) and to evaluate the risk factors for BD. It is also planned to describe the population of patients with BD to confirm whether or not different subgroups exist.

A better understanding of the pathophysiology of BD should make it possible to prevent the condition (if secondary to dyssynergia present in childhood) and/or to provide earlier, more appropriate management, thus avoiding acute episodes of bowel obstruction.

• Study Type: Observational
• Enrollment (Estimated): 120

Contacts and Locations

• Study Contact: Name: Vincent VF FERRANTI, ARC; Phone Number: +33 02 32 88 82 65; Email: Vincent.Ferranti@chu-rouen.fr
• Study Contact Backup: Name: Nabila NL LAAJAIL, Director; Phone Number: +33 02 32 88 82 65; Email: Nabila.Laajail@chu-rouen.fr

Study Locations

• France
  • Rouen, France, 76031
    • Digestive Physiology Department

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Probability Sample

Study Population

• Patients with idiopathic Mega-Rectum (MI) treated in the Digestive Physiology Department between 2016 and 2026 for the performance of a rectal barostat to confirm the megarectum suspected by anorectal manometry.
• Constipated patients recruited consecutively during consultations by physicians in the Digestive Physiology department, and whose anorectal manometry, performed as part of routine care, ruled out the diagnosis of megarectum

Description

Inclusion Criteria:

• Idiopathic megarectum (IM) group:
• Adult patients presenting with chronic constipation according to the Rome criteria;
• Patients with megarectum suspected by anorectal manometry and confirmed by rectal barostat;
• Isolated, idiopathic megarectum (no known cause);

Constipated group:

• Constipated adult patients presenting consecutively with chronic functional constipation according to the Rome criteria;
• Patients without megarectum suspected by anorectal manometry.

Exclusion Criteria:

• Patients who are not constipated;
• Hirschsprung's disease;
• Patients with anorectal malformation;
• Patients with known neurological conditions;
• Patients with endocrine disorders that may cause constipation;
• Patients taking constipating medications such as morphine or neuroleptics;
• Patients with a potential organic and/or drug-induced cause of constipation;
• Constipation secondary to medication;
• Patients unable to complete a questionnaire;
• Patients deprived of their liberty, under guardianship, or curatorship

Study Plan

How is the study designed?

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
To determine if patients with Idiopathic MegaRectum (MI) have a history of earlier constipation in childhood than constipated patients without megarectum	This involves comparing the history of constipation that may reveal anorectal dysfunction in childhood in constipated adults with MI and in constipated control subjects without megarectum through clinical questioning.	1 day
To determine if patients with Idiopathic MegaRectum (MI) have a history of more digestive symptoms in childhood than constipated patients without megarectum	This involves comparing the history of digestive symptoms that may reveal anorectal dysfunction in childhood in constipated adults with MI and in constipated control subjects without megarectum through clinical questioning.	1 day

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Comparison of environmental factors in constipated adults with MI and in constipated control subjects without megarectum	Determination of the presence of environmental factors in childhood: breastfeeding, repeated early antibiotic therapy, drug treatment in childhood and indication (antibiotics, anticholinergic treatments, opiates, morphine, etc.) through clinical questioning	1 day
Comparison of environmental factors in constipated adults with MI and in constipated control subjects without megarectum	Presence of psychosocial factors in childhood: psychosocial or school-related stress, anxiety and depressive disorders as revealed by clinical questioning	1 day
megarectum phenotyping	The aim is to phenotype the megarectum using anorectal manometry to distinguish an "acquired" profile from a "congenital" profile. The measured indicators will be anal tone, amplitude and duration of voluntary contraction, the presence of the rectoanal inhibitory reflex; the amplitude of the rectoanal inhibitory reflex at 30 ml of rectal distension; the presence of rectosphincter dyssynergia; the amplitude of rectal contraction during straining; the percentage of anal relaxation during straining; the residual pressure during straining; the threshold volume for perceiving rectal distension; the constant perceiving volume; the maximum tolerable volume; and rectal compliance.	1 day
megarectum phenotyping	The aim is to phenotype the megarectum using Balloon evacuation test is to assess a patient's ability to evacuate stools, particularly in cases of constipation or suspected defecation disorder. This test is based on the concept of success or failure. Success: The patient manages to expel the balloon within a timeframe considered normal (often < 1 to 2 minutes, according to protocols). This suggests that the recto-anal evacuation mechanism is generally functioning correctly. Failure: The patient is unable to expel the balloon or takes an abnormally long time. This may indicate a defecation disorder, for example: anorectal dyssynergia (poor muscle coordination), rectal hypocontractility, or a functional obstruction to evacuation.	1 day
megarectum phenotyping	The aim is to phenotype the megarectum using rectal Barostat is to allow the measurement of rectal distension volumes to obtain the desired rectal pressure	1 day
megarectum phenotyping	The aim is to phenotype the megarectum using rectal Barostat is to allow the measurement of rectal distension volumes to obtain the rectal compliance	1 day
megarectum phenotyping	The aim is to phenotype the megarectum using rectal Barostat is to allow the measurement of rectal distension volumes to obtain the maximum tolerable volume;	1 day
megarectum phenotyping	The aim is to phenotype the megarectum using imagery is to assess rectal size in diameter	1 day
megarectum phenotyping	The aim is to phenotype the megarectum using imagery is to assess colon size in diameter	1 day
Constipation Severity Score Evaluation	This assessment is carried out using the Kess scores. The KESS score (KESS score = Knowles-Eccersley-Scott Symptom score) is intended to assess the severity of chronic constipation. It takes into account: frequency of bowel movements; difficulty passing stool; feeling of incomplete evacuation; use of laxatives; pain or straining; duration of the problem. The higher the score, the more severe the constipation.	1 day
Constipation Severity Score Evaluation	This assessment is carried out using the Francis scores. The Francis score (or IBS-SSS: Irritable Bowel Syndrome Severity Scoring System) is used to measure the severity of Irritable Bowel Syndrome. It assesses: intensity of abdominal pain; frequency of pain; bloating/distension; bowel movement irregularities; and impact on quality of life. The total score ranges from 0 to 500: < 75: no or very mild symptoms; 75-175: mild; 175-300: moderate; 300: severe.	1 day
fecal incontinence severity score	The Cleveland Clinic score will be used to assess the severity of chronic constipation. This score assesses several factors: frequency of bowel movements; difficulty of defecation; straining; feeling of incomplete evacuation; abdominal pain; time spent on the toilet; need for assistance (laxatives, enemas, digital defecation); duration of constipation. Each item is assigned a number of points. In practice: < 8: mild constipation; 8-15: moderate constipation; > 5: severe constipation	1 day
Quality of life score assessment	The quality of life score will be assessed using the GIQLI questionnaires. The GIQLI (Gastrointestinal Quality of Life Index) is a questionnaire used to measure quality of life related to digestive diseases. The questionnaire comprises 36 questions. Each question is scored from 0 to 4 on the following scale: 0 = very poor condition / significant symptoms 4 = no problems The maximum score is 144. A high score indicates good digestive health. A low score indicates significant impact of digestive disease.	1 day
Quality of life score assessment	The quality of life score will be assessed using the PAC-QOL questionnaire. The PAC-QOL (Patient Assessment of Constipation - Quality Of Life) is a specific questionnaire used to assess the impact of chronic constipation on quality of life.The questionnaire typically contains 28 questions divided into several areas: 1) physical discomfort; 2) psychosocial discomfort; 3) worries/concerns; 4) satisfaction. Each item is rated on a scale of 0 to 4. A low score indicates a good quality of life; A high score indicates a significant impact of constipation.	1 day
Quality of life score assessment	The quality of life score will be assessed using the FIQL questionnaires. The FIQL (Fecal Incontinence Quality of Life Scale) is a questionnaire designed to assess the impact of fecal incontinence on quality of life. The FIQL measures the psychological, social, and emotional impact of fecal incontinence, going beyond simply the frequency of leakage. It explores, in particular: social discomfort; anxiety; self-image; limitations in daily activities; emotional impact. The FIQL comprises 29 questions divided into 4 domains: 1) Lifestyle; 2) Behavior; 3) Depression/Self-Perception; 4) Embarrassment. Each question is scored on a scale of 0 to 4. A high FIQL indicates a better quality of life. A low FIQL indicates a significant impact of incontinence.	1 day
Predictive factors for each of these profiles in terms of medical history	Identify predictive factors for each of these profiles in terms of family history during the clinical interview with the patient (severe constipation leading to surgery (and type of surgery) or difficult to treat medically, onset of constipation in childhood or adulthood, Hirschsprung's disease, colonic inertia, chronic intestinal pseudo-obstruction, gastroparesis, stoma, gastrostomy, enteral or parenteral nutrition, anorectal malformation, neurological malformation)	1 day
Predictive factors for each of these profiles in terms of medical history	Identify the predictive factors of each of these profiles in terms of personal history during the clinical interview with the patient (severe constipation requiring surgical intervention (and type of intervention) or difficult to treat medically, onset of constipation in childhood or adulthood, Hirschsprung's disease, colonic inertia, chronic intestinal pseudo-obstruction, gastroparesis, stoma, gastrostomy, enteral or parenteral nutrition, anorectal malformation, neurological malformation).	1 day
Current symptoms	Identify current symptoms: encopresis, fecal incontinence, dyschezia, abdominal bloating, abdominal pain, number of bowel movements per week, stool consistency according to the Bristol Stool Scale	1 day
Predictive factors for each of these profiles in terms of medical history	information search regarding the age of toilet training in childhood during the clinical interview with the patient.	1 day
Predictive factors for each of these profiles in terms of medical history	information search regarding childhood digestive symptoms during the clinical interview with the patient.	1 day
Predictive factors for each of these profiles in terms of medical history	information regarding stool frequency in childhood and stool consistency in childhood during the clinical interview with the patient.	1 day
Predictive factors for each of these profiles in terms of medical history	research for information regarding the factors identified as triggers of constipation during the clinical interview with the patient.	1 day
Predictive factors for each of these profiles in terms of medical history	information search regarding possible pain during defecation during the clinical interview with the patient.	1 day

Collaborators and Investigators

• Sponsor: University Hospital, Rouen
• Investigators: Study Director: Anne-Marie AL LEROI, Professor, University Rouen Hospital

Study record dates

Study Major Dates

• Study Start (Estimated): June 1, 2026
• Primary Completion (Estimated): June 2, 2028
• Study Completion (Estimated): December 1, 2028

Study Registration Dates

• First Submitted: May 13, 2026
• First Submitted That Met QC Criteria: May 13, 2026
• First Posted (Actual): May 20, 2026

Study Record Updates

• Last Update Posted (Actual): May 20, 2026
• Last Update Submitted That Met QC Criteria: May 13, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: severe functional constipation; understanding pathophysiology.
• Other Study ID Numbers: 2026/0116/OB; 2026-A00636-45 (Other Identifier: ANSM)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No