If sentinel loop, mid-left, is evident on one of two abdominal x-rays due to severe constipation, can this indicate intermittent bowel obstruction or intermittent pancreatic inflammation, or other?

Possibly: A sentinel loop refers to a sign on an x-ray of the abdomen in which a loop of colon or small intestine is dilated and enlarged with gas. It often indicates that there is an area of inflammation in a nearby organ. It may indicate bowel ileus, pancreatic, appendix or gall bladder inflammation (mid-left may be pancreas). However it is only a sign and needs to be part of the whole picture to make dx.

Constipation/blocked: Your bowel habits, ie chronic constipation can lead to partial bowel obstruction. Your plain film xrays show evidence of this. If you have pain lasting more a few hours, fever, vomiting then go directly to er. Treating constipation is important. You may benefit from a colonoscopy and a bowel regimen. Be well and avoid urgent interventions, goal is twice daily bowel movements.

Indicative of: Localized reaction , ( inflammation ) , more likely due to your pancreatitis , intermittent bowel obstruction than chronic constipation , speak to your doctor