| 1. | Adenoma, Islet Cell (3 recruiting studies) |
| 2. | Anus Diseases (7 recruiting studies) |
| 3. | Anus Neoplasms (7 recruiting studies) |
| 4. | Barrett Esophagus (1 recruiting study) |
| 5. | Bile Duct Diseases (12 recruiting studies) |
| 6. | Bile Duct Neoplasms (7 recruiting studies) |
| 7. | Biliary Atresia (1 recruiting study) |
| 8. | Biliary Tract Diseases (13 recruiting studies) |
| 9. | Biliary Tract Neoplasms (8 recruiting studies) |
| 10. | Carcinoma, Hepatocellular (60 recruiting studies) |
| 11. | Carcinoma, Islet Cell (6 recruiting studies) |
| 12. | Caroli Disease (1 recruiting study) |
| 13. | Cholestasis (5 recruiting studies) |
| 14. | Cholestasis, Intrahepatic (1 recruiting study) |
| 15. | Chyloperitoneum (1 recruiting study) |
| 16. | Colitis (12 recruiting studies) |
| 17. | Colitis, Ulcerative (11 recruiting studies) |
| 18. | Colonic Diseases (123 recruiting studies) |
| 19. | Colonic Diseases, Functional (6 recruiting studies) |
| 20. | Colonic Neoplasms (78 recruiting studies) |
| 21. | Colorectal Neoplasms (125 recruiting studies) |
| 22. | Colorectal Neoplasms, Hereditary Nonpolyposis (2 recruiting studies) |
| 23. | Congenital Hepatic Fibrosis (1 recruiting study) |
| 24. | CREST Syndrome (1 recruiting study) |
| 25. | Crohn Disease (13 recruiting studies) |
| 26. | Cryptosporidiosis (3 recruiting studies) |
| 27. | Cystic Fibrosis (16 recruiting studies) |
| 28. | Deglutition Disorders (7 recruiting studies) |
| 29. | Digestive System Abnormalities (2 recruiting studies) |
| 30. | Digestive System Diseases (433 recruiting studies) |
| 31. | Digestive System Neoplasms (311 recruiting studies) |
| 32. | Duodenal Diseases (9 recruiting studies) |
| 33. | Duodenal Neoplasms (9 recruiting studies) |
| 34. | Enteritis (4 recruiting studies) |
| 35. | Enterocolitis (1 recruiting study) |
| 36. | Enterocolitis, Necrotizing (1 recruiting study) |
| 37. | Eosinophilic Gastroenteritis (1 recruiting study) |
| 38. | Esophageal Diseases (46 recruiting studies) |
| 39. | Esophageal Motility Disorders (7 recruiting studies) |
| 40. | Esophageal Neoplasms (37 recruiting studies) |
| 41. | Esophagitis (1 recruiting study) |
| 42. | Fatty Liver (4 recruiting studies) |
| 43. | Gallbladder Diseases (7 recruiting studies) |
| 44. | Gallbladder Neoplasms (7 recruiting studies) |
| 45. | Gastrinoma (5 recruiting studies) |
| 46. | Gastroenteritis (25 recruiting studies) |
| 47. | Gastroesophageal Reflux (2 recruiting studies) |
| 48. | Gastrointestinal Diseases (256 recruiting studies) |
| 49. | Gastrointestinal Neoplasms (207 recruiting studies) |
| 50. | Giardiasis (1 recruiting study) |
| 51. | Glucagonoma (2 recruiting studies) |
| 52. | Hepatitis (50 recruiting studies) |
| 53. | Hepatitis A (1 recruiting study) |
| 54. | Hepatitis B (10 recruiting studies) |
| 55. | Hepatitis B, Chronic (5 recruiting studies) |
| 56. | Hepatitis C (33 recruiting studies) |
| 57. | Hepatitis C, Chronic (13 recruiting studies) |
| 58. | Hepatitis D (1 recruiting study) |
| 59. | Hepatitis, Chronic (20 recruiting studies) |
| 60. | Hepatorenal Syndrome (1 recruiting study) |
| 61. | Hernia (3 recruiting studies) |
| 62. | Hypertension, Portal (1 recruiting study) |
| 63. | Ileal Diseases (10 recruiting studies) |
| 64. | Ileal Neoplasms (9 recruiting studies) |
| 65. | Ileitis (1 recruiting study) |
| 66. | Ileus (1 recruiting study) |
| 67. | Inflammatory Bowel Diseases (22 recruiting studies) |
| 68. | Insulinoma (5 recruiting studies) |
| 69. | Intestinal Diseases (175 recruiting studies) |
| 70. | Intestinal Diseases, Parasitic (3 recruiting studies) |
| 71. | Intestinal Neoplasms (134 recruiting studies) |
| 72. | Intestinal Obstruction (1 recruiting study) |
| 73. | Intestinal Volvulus (1 recruiting study) |
| 74. | Irritable Bowel Syndrome (6 recruiting studies) |
| 75. | Jejunal Diseases (9 recruiting studies) |
| 76. | Jejunal Neoplasms (9 recruiting studies) |
| 77. | Liver Cirrhosis (15 recruiting studies) |
| 78. | Liver Cirrhosis, Biliary (1 recruiting study) |
| 79. | Liver Diseases (119 recruiting studies) |
| 80. | Liver Failure (4 recruiting studies) |
| 81. | Liver Failure, Acute (2 recruiting studies) |
| 82. | Liver Neoplasms (67 recruiting studies) |
| 83. | Malabsorption Syndromes (3 recruiting studies) |
| 84. | Non-Alcoholic Steatohepatitis (3 recruiting studies) |
| 85. | Pancreatic Diseases (72 recruiting studies) |
| 86. | Pancreatic Insufficiency (1 recruiting study) |
| 87. | Pancreatic Neoplasms (54 recruiting studies) |
| 88. | Pancreatitis (3 recruiting studies) |
| 89. | Pancreatitis, Acute Necrotizing (2 recruiting studies) |
| 90. | Peptic Ulcer (7 recruiting studies) |
| 91. | Peritoneal Diseases (6 recruiting studies) |
| 92. | Peritoneal Neoplasms (5 recruiting studies) |
| 93. | Peritonitis (1 recruiting study) |
| 94. | Peutz-Jeghers Syndrome (1 recruiting study) |
| 95. | Pouchitis (1 recruiting study) |
| 96. | Rectal Diseases (110 recruiting studies) |
| 97. | Rectal Neoplasms (81 recruiting studies) |
| 98. | Short Bowel Syndrome (2 recruiting studies) |
| 99. | Sigmoid Diseases (2 recruiting studies) |
| 100. | Sigmoid Neoplasms (2 recruiting studies) |
| 101. | Somatostatinoma (3 recruiting studies) |
| 102. | Stomach Diseases (31 recruiting studies) |
| 103. | Stomach Neoplasms (26 recruiting studies) |
| 104. | Zellweger Syndrome (1 recruiting study) |
| 105. | Zollinger-Ellison Syndrome (5 recruiting studies) |
