From the Guidelines
A mega rectum is an abnormally enlarged rectum, typically resulting from chronic constipation or other conditions that cause the rectum to stretch beyond its normal size, and is often associated with conditions like megacolon, which can lead to increased recurrence of sigmoid volvulus if not adequately treated. This condition develops when the rectum repeatedly holds large amounts of stool for extended periods, causing the rectal walls to lose tone and elasticity. Mega rectum can occur in both children and adults, often associated with conditions like Hirschsprung's disease, chronic laxative use, spinal cord injuries, or neurological disorders that affect bowel function. Patients typically experience symptoms such as severe constipation, fecal incontinence, abdominal discomfort, and sometimes paradoxical diarrhea (where liquid stool leaks around impacted feces) 1.
Key Characteristics of Mega Rectum
- Abnormally enlarged rectum
- Often associated with megacolon
- Increased recurrence of sigmoid volvulus if not adequately treated
- Symptoms include severe constipation, fecal incontinence, abdominal discomfort, and paradoxical diarrhea
Diagnosis and Treatment
Treatment usually involves addressing the underlying cause, implementing bowel management programs, and in severe cases, surgical intervention may be necessary, such as subtotal colectomy for patients with concomitant megacolon and sigmoid volvulus 1. Regular bowel habits, adequate fluid intake, and proper dietary fiber can help prevent the development of mega rectum in susceptible individuals. The condition is diagnosed through physical examination, imaging studies like X-rays or CT scans, and sometimes anorectal manometry to assess rectal function.
Important Considerations
- In patients with megacolon treated by subtotal colectomy, no recurrences were documented 1
- Sigmoid colectomy alone is insufficient as the volvulus tends to recur in the remnant segments of colon 1
- The correlation between symptoms and rectocele size is weak, and the correlation between improvement in symptoms and anatomy after surgical procedures is also weak 1
From the Research
Definition of Mega Rectum
- A mega rectum refers to an abnormal and permanent dilatation of the rectum, often associated with chronic constipation, fecal impaction, and other gastrointestinal symptoms 2, 3, 4, 5.
- The condition is characterized by a rectal diameter greater than 6.5 cm, with some cases presenting with a massively dilated rectum filled with a large amount of fecal matter 2, 5.
Clinical Features and Diagnosis
- Patients with idiopathic megarectum (IMR) often present with symptoms such as soiling, impaction, and fecal incontinence, whereas those with idiopathic megacolon (IMC) may experience constipation, increased bowel frequency, pain, and variable need for laxatives 2.
- Diagnostic evaluation may include contrast studies of the upper and lower intestine, spine x-rays to exclude spinal dysraphism, anorectal physiological studies, and assessment of clinical outcome 2.
- The presence of ganglion cells in a full-thickness rectal biopsy can help rule out Hirschsprung's disease and establish the diagnosis of IMR or IMC 4, 5.
Treatment and Management
- Treatment options for idiopathic megarectum and megacolon may include medical measures such as colonic evacuation with enemas, fiber supplementation, and laxatives, as well as behavioral retraining including biofeedback 3.
- In some cases, surgical intervention may be necessary, such as a laparoscopic modified Duhamel procedure or a two-stage surgical intervention including a Hartmann's procedure with sigmoid colectomy and a subsequent completion proctectomy with coloanal anastomosis 4, 5.
- The goal of treatment is to alleviate symptoms, prevent complications, and improve quality of life, with individualized approaches often required due to the complexity and variability of the condition 2, 4, 5.