Small bowel (small intestine)

Author: Hanni Gulwani, M.D. (see Authors page)

Revised: 27 February 2018, last major update August 2012

Copyright: (c) 2003-2018,, Inc.

PubMed Search: Small bowel staging[TI]

Cite this page: Gulwani, H. Staging. website. Accessed July 18th, 2018.
Definition / general
  • Does not apply to carcinoid tumors, GIST, lymphoma or sarcoma OR tumors in ileocecal value, ampulla of Vater or Meckel diverticulum
Primary tumor (T)
  • TX: Primary tumor cannot be assessed
  • T0: No evidence of primary tumor
  • Tis: Carcinoma in situ
  • T1a: Tumor invades lamina propria
  • T1b: Tumor invades submucosa *
  • T2: Tumor invades muscularis propria
  • T3: Tumor invades through the muscularis propria into the subserosa or into the nonperitonealized perimuscular tissue (mesentery or retroperitoneum) with extension 2 cm or less *
  • T4: Tumor perforates the visceral peritoneum or directly invades other organs or structures (includes other loops of small intestine, mesentery or retroperitoneum more than 2 cm and abdominal wall by way of serosa; for duodenum only, invasion of pancreas or bile duct)

  • * Note: the nonperitonealized perimuscular tissue is, for jejunum and ileum, part of the mesentery and for duodenum in areas where serosa is lacking, part of the interface with the pancreas
Regional lymph nodes (N)
  • NX: Regional lymph nodes cannot be assessed
  • N0: No regional lymph node metastasis
  • N1: Metastasis in 1 - 3 regional lymph nodes
  • N2: Metastasis in four or more regional lymph nodes

  • Note: involvement of the celiac nodes is considered M1 disease for carcinomas of the duodenum, jejunum and ileum
Distant metastasis (M)
  • M0: No distant metastasis
  • M1: Distant metastasis
Stage grouping
  • Stage 0: Tis N0 M0
  • Stage I: T1 - 2 N0 M0
  • Stage IIA: T3 N0 M0
  • Stage IIB: T4a N0 M0
  • Stage IIIA: Any T N1 M0
  • Stage IIIB: Any T N2 M0
  • Stage IV: Any T any N M1