Understanding Abdominal Pain

When I was a surgical registrant, one of the local GPs could diagnose an acute appendix over the telephone with the instruction; ‘Stand on your right leg and hop’. If the mild gymnastics exacerbated the pain, he would contact the hospital and announce that he was sending in a patients with appendicitis and a ‘positive hop test.’

I know it sounds strange, but he was so uncannily accurate that for a time, hopping on one leg because a popular test among juniors in the A&E department.

The GP presumably has long since restored and his eccentric method of diagnosis seems to have been forgotten, but in retrospect, I now realize that he unwittingly taught me a great deal about abdominal pain, in particular, the simplicity of diagnosis. There are in fact only two types.

  • Colic is griping, rolling-about pain that comes in waves. It is produced by abnormally strong peristalsis of a hollow virus due to either obstruction, such as stone, tumour or hernia, or irritation, perhaps associated with enteritis, chicken vindaloo or laxatives.
  • Continuous. Persistent, lying still pain that is mad worse by movement is produced by inflammation due to infection, peritonitis or ulceration, or ischaemia associated with infraction or mesenteric embolus.

Forget all about burning, stabbing, excruciating, terrible and any other adjective that may be used. Your ears and your eyes will tell you whether or not the patient is describing colikly or continuous pain. Or perhaps you could ask if it makes them roll about or lie still. Either way, it has to be colic or constant and once this is established you are halfway there-you know whether the pain is due to obstruction or irritation, or inflammation. There is nothing else to consider.

Next is where exactly is the pain felt? For this, a liitle embryological knowledges is required.

No! please don’t give up at this point just because I have mentioned embryology. To keep up your interest, I want you think back to that time when you last suffered from ‘gastroenteritis’, or in some cases, an overdose of beer and curry. Those tooth marks you made on the toilet door-handle were the result of the suprapubic colic you felt as your bowels exploded the following morning.

The point is that afferent visceral impulses reach the brain via the bags and splanchnic nerves, and are perceived simply as foregut (epigastric), midgut (periumbilical) or hindgut (suprapubic) pain felt in the midline. Usually, a patient will place hand on the appropriate are when describing their viscelal pain or will do so when prompted.

So, at the risk of being boring, let’s restate the facts. Foregut, midgut and hindgut, coupled with colic or continuous, gets the diagnosis almost every time. All we need to know now is which bits are which:

  • Foregut: Stomach, first and second oarts of the duodenum, gallbladder, billiary tree and pancreas.
  • Midgut: Third and fourth parts of the duodenum to two thirds across the transverse colon.
  • Hindgut: Last third of the transverse colon, descending colon, rectum and the gynaecological areas (the last derived from the cloacal sac).

Let’s use an example encountered frequently in the clinic or on wars rounds- an anemic 60 years old with weight loss and a few months history of periumbilical (midgut) colicky abdominal pain.

On the history alone it just has to be aright or tranverse colon cancer, and, with luck, a hand on the abdomen will feel a right sided mass. Easy.