Chronic abdominal and gastrointestinal visceral pain

Most chronic abdominal pain with a negative workup is a disorder of gut–brain interaction treated by positive diagnosis and targeted therapy, but porphyria and mesenteric ischemia must not be missed, and post-cholecystectomy pain does not need sphincterotomy.

1. Diagnose IBS positively, not by exclusion. The ACG suggests a positive diagnostic strategy to shorten time to therapy; it recommends chloride channel and guanylate cyclase activators for IBS with constipation and rifaximin for IBS with diarrhea ¹.
2. Several drug classes help diarrhea-predominant IBS. AGA 2022 makes conditional recommendations for eluxadoline, rifaximin, alosetron, loperamide, tricyclic antidepressants and antispasmodics, and against SSRIs ².
3. Sphincterotomy does not help post-cholecystectomy pain. In a sham-controlled trial of 214 patients, success occurred in 23% after sphincterotomy versus 37% after sham, and manometry did not predict outcome ³.
4. Consider porphyria in recurrent unexplained pain. Acute hepatic porphyria should be considered in women aged 15 to 50 with recurrent severe abdominal pain after an unrevealing workup, typically without peritoneal signs ⁴.
5. Chronic pancreatitis pain is multidimensional. Mechanisms are inflammatory, structural and neurogenic; endoscopy treats ductal obstruction, behavioral care belongs in a multidisciplinary plan, and neurolysis is for difficult cases ⁵.
6. Pain after meals with weight loss suggests ischemia. Chronic mesenteric ischemia worsens after eating because perfusion cannot meet demand; patients avoid large meals and lose weight, and atherosclerosis is the usual cause ⁶.

CT angiography of the abdomen and pelvis is the most appropriate initial imaging for suspected acute or chronic mesenteric ischemia; exclude it before attributing postprandial pain to a functional disorder ⁷.

• During porphyria attacks, urinary aminolevulinic acid and porphobilinogen rise at least 5-fold, so a random urine sample suffices ⁴.
• Urine porphyrins alone should not be used to screen for acute hepatic porphyria ⁴.
• Fasting induces the heme enzyme ALAS1, so carbohydrate loading is used early in attacks; hyponatremia can accompany them ⁴.
• Chronic mesenteric ischemia usually reflects occlusion or severe stenosis of at least two main mesenteric vessels ⁷.
• Post-ERCP pancreatitis occurred in 11% after sphincterotomy and 15% after sham in the post-cholecystectomy trial ³.
• For global IBS symptoms the ACG recommends a limited low-FODMAP diet trial and suggests gut-directed psychotherapy ¹.
• After biochemical diagnosis, the porphyria type is confirmed by genetic testing of HMBS, CPOX, PPOX and ALAD ⁴.
• Median arcuate ligament syndrome is another cause of chronic mesenteric ischemia, especially in younger patients ⁶.

• Referring post-cholecystectomy pain without objective abnormalities for manometry and sphincterotomy ³.
• Screening for porphyria with urine porphyrins alone ⁴.
• Treating IBS as a diagnosis reached only after exhaustive testing ¹.