Approximately 60-90% of patients undergoing sphincter-sparing proctectomy complain of postoperative bowel dysfunction including incontinence, frequency, clustering, and urgency, collectively known as low anterior resection syndrome (LARS). Literatures and our previous data have demonstrated that diverting ileostomy is an independent risk factor for major LARS. This is a randomized, phase 2 trial in patients with rectal cancer who underwent sphincter-preserving proctectomy and ileostomy. This study will explore the effects of anal dilatation plus probiotics administered per anus in relieving the symptoms of LARS.