Megarectum in Adults

Official title

Megarectum in Adults: Congenital or Acquired Pathology?

Overview

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.

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.

Interventions

• Other Idiopathic megarectum group
  questionnaires documented by patients with suspected megarectum on anorectal manometry and confirmed by rectal barostat
• Other Constipated patient group
  questionnaires completed by adult patients consulting for functional constipation without suspected megarectum on anorectal manometry

Primary outcome measures

• To determine if patients with Idiopathic MegaRectum (MI) have a history of earlier constipation in childhood than constipated patients without megarectum [Time frame: 1 day]
• To determine if patients with Idiopathic MegaRectum (MI) have a history of more digestive symptoms in childhood than constipated patients without megarectum [Time frame: 1 day]

Secondary outcome measures (12)

• Comparison of environmental factors in constipated adults with MI and in constipated control subjects without megarectum [Time frame: 1 day]
• Comparison of environmental factors in constipated adults with MI and in constipated control subjects without megarectum [Time frame: 1 day]
• megarectum phenotyping [Time frame: 1 day]
• megarectum phenotyping [Time frame: 1 day]
• megarectum phenotyping [Time frame: 1 day]
• megarectum phenotyping [Time frame: 1 day]
• megarectum phenotyping [Time frame: 1 day]
• megarectum phenotyping [Time frame: 1 day]
• megarectum phenotyping [Time frame: 1 day]
• Constipation Severity Score Evaluation [Time frame: 1 day]
• Constipation Severity Score Evaluation [Time frame: 1 day]
• fecal incontinence severity score [Time frame: 1 day]

Eligibility criteria

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

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Observational model

Case-control

Study locations

France · 1 center

• Digestive Physiology Department — Rouen

Identifiers

NCT: NCT07599527 · 2026/0116/OB · 2026-A00636-45

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗