Further investigations

Histology:

• duodenal, jejunal or ileal mucosal biopsy
• area from mid-jejunum to distal ileum is difficult to reach endoscopically. If definitive abnormalities are identified radiologically, further investigation may necessitate laparotomy

Anatomy:

• barium follow through or small bowel enema; the latter provides better anatomical definition
• abdominal CT - good for demonstrating abdominal lymphadenopathy, hepatic metastases, pancreatic anatomy
• ERCP - better than CT for diagnosing chronic pancreatitis

Function:

• specific carbohydrate absorption - most commonly, lactose breath hydrogen test
• pancreatic function - particularly, NBT-PABA and fluorescein dilaurate indirect methods
• ileal function:
  • Schilling's test - vitamin B12, intrinsic factor
  • SeHCAT - bile salt absorption

Small bowel contamination:

• see investigation of bacterial overgrowth