Patients presenting with megacolon and megarectum require extensive specialized testing to distinguish underlying Hirschsprung's disease from other secondary causes. Diagnostic testing and long-term treatment are best initiated after disimpaction has been achieved, by large-volume tap water enemas and/or oral colonic lavage with polyethylene glycol. With intensive treatment (including biofeedback if pelvic floor dysfunction is present), at lease one half of patients can avoid surgery. Maintenance therapy relies on daily use of osmotic laxatives. Stimulant laxatives are used intermittently as rescue treatments if there has not been a satisfactory bowel movement in 3 days. Patients with idiopathic megacolon or megarectum may require surgery if they have refractory symptoms. Depending on age, pelvic floor, and anal sphincter function, patients who have isolated megacolon can be treated with either subtotal colectomy with ileorectostomy or diverting loop ileostomy. Patients with isolated megarectum can be treated with either proctectomy and coloanal anastomosis or vertical reduction rectoplasty. Patients who have combined megacolon and megarectum can be offered diverting loop ileostomy or, if pelvic floor function is normal and they wish to avoid stoma, total proctocolectomy with ileal pouch-anal anastomosis.
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