Treatment of megacolon and megarectum

Clinical features and outcomes of adult idiopathic megarectum

OBJECTIVE

Idiopathic megarectum is characterized by abnormal, pronounced rectal dilatation in the absence of identifiable organic pathology. Idiopathic megarectum is uncommon and under-recognized. This study aims to describe the clinical features and management of idiopathic megarectum.

METHODS

A retrospective review was undertaken on patients diagnosed with idiopathic megarectum with or without idiopathic megacolon over a 14-year period until 2021. Patients were identified from the hospital's International Classification of Diseases codes, and pre-existing clinic patient databases. Patient demographics, disease characteristics, healthcare utilization and treatment history data were collected.

RESULTS

Eight patients with idiopathic megarectum were identified; half of the patients were female, with the median age of symptom onset being 14 years (interquartile range [IQR] 9-24). The median rectal diameter measured was 11.5 cm (IQR 9.4-12.1). The most common presenting symptom was constipation, bloating and faecal incontinence. All patients required prior sustained periods of regular phosphate enemas and 88% were using ongoing oral aperients. Concomitant anxiety and or depression were found in 63% of patients and 25% were diagnosed with an intellectual disability. Healthcare utilization was high with a median of three emergency department presentations or ward admissions related to idiopathic megarectum per patient over the follow-up period; 38% of patients required surgical intervention during the period of follow-up.

CONCLUSION

Idiopathic megarectum is uncommon and associated with significant physical and psychiatric morbidity and high healthcare utilization.

Idiopathic Megacolon-Short Review

INTRODUCTION

Idiopathic megacolon (IM) is a rare condition with a more or less known etiology, which involves management challenges, especially therapeutic, and both gastroenterology and surgery services. With insufficiently drawn out protocols, but with occasionally formidable complications, the condition management can be difficult for any general surgery team, either as a failure of drug therapy (in the context of a known case, initially managed by a gastroenterologist) or as a surgical emergency (in which the diagnostic surprise leads additional difficulties to the tactical decision), when the speed imposed by the severity of the case can lead to inadequate strategies, with possibly critical consequences.

METHOD

With such a motivation, and having available experience limited by the small number of cases (described by all medical teams concerned with this pathology), the revision of the literature with the update of management landmarks from the surgical perspective of the pathology appears as justified by this article.

RESULTS

If the diagnosis of megacolon is made relatively easily by imaging the colorectal dilation (which is associated with initial and/or consecutive clinical aspects), the establishing of the diagnosis of idiopathic megacolon is based in practice almost exclusively on a principle of exclusion, and after evaluating the absence of some known causes that can lead to the occurrence of these anatomic and clinical changes, mimetically, clinically, and paraclinically, with IM (intramural aganglionosis, distal obstructions, intoxications, etc.). If the etiopathogenic theories, based on an increase in the performance of the arsenal of investigations of the disease, have registered a continuous improvement and an increase of objectivity, unfortunately, the curative surgical treatment options still revolve around the same resection techniques. Moreover, the possibility of developing a form of etiopathogenic treatment seems as remote as ever.

Acute and chronic megacolon

Megacolon, defined as dilation of the abdominal colon, may occur acutely or in a chronic form. Acute megacolon that occurs in association with severe inflammation of the colon is known as toxic megacolon, whereas acute megacolon without obvious colonic disease is known as Ogilvie's syndrome. The pathophysiology and management of toxic megacolon, Ogilvie's syndrome, and chronic megacolon in adults differ significantly, and it is critically important to distinguish among these entities. Toxic megacolon is a medical emergency that requires coordinated intensive medical and surgical management. In addition to vigorous resuscitation with fluids, electrolytes, and blood products, medical treatment consists of parenteral corticosteroids, broad-spectrum antibiotics, and close monitoring of the patient. Surgical intervention is required if there is no improvement, or deterioration after 12 to 24 hours of intensive medical management, or if there is evidence of colon perforation. Ogilvie's syndrome usually occurs in hospitalized patients with serious underlying medical or surgical illnesses. Management is directed at preventing ischemia and perforation of the distended colon. Supportive therapy includes nasogastric suction, correction of fluid and electrolyte imbalances, stopping potentially aggravating medications, and decompressing the colon with a rectal tube and positional changes. Intravenous neostigmine is the only pharmacologic agent of proven efficacy; colonoscopic decompression is an alternative in patients who do not respond to neostigmine or who have conditions that contraindicate its use. Daily oral administration of polyethylene glycol electrolyte solutions appears to decrease the relapse rate after initial decompression is achieved. Chronic megacolon in adults represents advanced colon failure that does not respond to pharmacologic stimulation. Goals of therapy are to cleanse the colon, prevent impaction, and minimize stool volume and gas buildup. For patients with disabling symptoms, surgical exclusion of the colon, decompression and antegrade enemas via cecostomy, or subtotal or segmental resection may be palliative.

Current management strategies and therapeutic targets in chronic constipation

Constipated patients who are refractory to simple lifestyle interventions will usually resort to laxatives, whether prescribed or over the counter. Clinical trial evidence is scarce for older medications such as laxatives, especially with a condition as chronic and subjective as constipation. Newer polyethylene glycol-based laxatives have been investigated under rigorous clinical trial settings, but comparisons between different laxatives are not available. Newer prokinetic agents, targeting peristalsis, intestinal secretion and the colonic flora, have been developed for laxative refractory constipation. This review focuses on the evidence for each of these agents, and the relative indications for each of them.

Pharmacological management of constipation

The approach of this review is to give a pragmatic approach to using laxatives, based on a combination of what is known about mechanism of action and the available literature on evidence.