**2.5 Surgical plane for very low-lying rectal cancer**

In case of very low-lying rectal cancer, several surgical options can be considered (**Figure 11**). If the tumor did not invade the anal sphincter complex, the ultra-low anterior resection with coloanal anastomosis could be considered. If the tumors are located close to the dentate line, the intersphincteric resection (ISR) could be considered. The ISR is the partial or complete resection of the internal anal sphincter along the intersphincteric plane. However, if the tumor invades the external sphincter complex, the abdominoperineal resection (APR) should be performed. For invasive low rectal cancer which invades the levator ani muscle, extralevator APR (ELAPE) should be considered to achieve adequate resection margin. The ELAPE is the cylindrical anorectal excision and removes more tissue around the tumor including levator ani muscle (**Figure 12**). This procedure has the advantage of reducing the risk of tumor perforation during operation and acquiring sufficient

#### **Figure 10.**

*Anococcygeal ligament. (a) Anococcygeal ligament and pelvic floor. During posterior dissection of the rectum. (b) Anococcygeal ligament during cadeveric dissection. Lt. hemipelvis.*

*Pelvic Anatomy for Distal Rectal Cancer Surgery DOI: http://dx.doi.org/10.5772/intechopen.99120*

#### **Figure 11.**

*Low-lying rectal cancer. (a) T2 weighted image on MRI. Coronal view. The low-lying rectal cancer invades internal anal sphincter. (b) T2 weighted image on MRI. Sagittal view.*

#### **Figure 12.**

*Sugical plane for low-lying rectal cancer. (a) Low anterior resection (LAR). (b) Intersphincteric resection (ISR). (c) Abdominoperineal resection (APR). (d) Extralevator APR.*

safety resection margin, but there is still controversy about the long-term oncologic outcome [29]. In addition, the postoperative complications can be increased due to the wide resection range.
