Non-surgical causes of abdominal pain

Abdominal pain often arises from surgical pathology, and clinicians tend to consider these conditions high in their differential diagnosis. By far the most cases of abdominal pain, however, do not have a surgical cause. Even the acute abdomen, defined as severe abdominal pain, usually of sudden onset, likely to require surgical intervention to treat its cause, may have a non-surgical cause. And when this is forgotten unnecessary operations take place, putting the patient at risk.

Most undergraduate textbooks focus on surgical causes of abdominal pain. This article is a reminder of the myriad of medical causes of abdominal pain, from the mild to severe.

I discuss some of the medical conditions for which a well recognised part of their presentation includes abdominal pain. Some are obvious and everyday, but even the prevalence of some of the less considered conditions may be greater than you think.

You may find the mnemonic CRIMINAL helpful (box), but remember that this list applies mainly to adults. Children need special consideration. I have omitted obstetric and gynaecological causes because obstetricians and gynaecologists are surgeons, and the treatment of these conditions may ultimately be surgical. And this topic is also too large to include in this article.

Common, recurrent, and often mild

Irritable bowel syndrome—This is traditionally a diagnosis of exclusion of other causes that can be assessed using the Rome III criteria, which were introduced in 2006 to classify functional gastrointestinal disorders.^w1 Estimates of prevalence vary 10-20% in adults in Western countries. Pain can be dull, sharp, or colicky; is often poorly localised; and may have no specific triggers or alleviators, but a history of stress can often be elicited.

Lactose intolerance and coeliac disease—Lactose intolerance is common and affects all ethnic groups and both sexes. It results from a deficiency of lactase to metabolise lactose. Bloating and fullness are more common than pain. Coeliac disease results from intolerance to dietary gluten, and pain is usually in the form of bloating or cramps.

Constipation—This can present as abdominal pain at all ages but can be particularly severe in children and elderly people. Its diagnosis should be simple from the history and must be differentiated from bowel obstruction, in which there may be associated vomiting, considerable abdominal distension, and no flatus.

Myofascial pain syndrome—This form of musculoskeletal pain is common but is omitted from most undergraduate teaching. Although its pathophysiology is not understood, it is thought that unusually taut muscle bands act as trigger points, resulting in localised or referred pain in any of the skeletal muscles, including those over the torso, which can radiate into the abdomen. After surgery new trigger points may be created, and this may be responsible for some of the more chronic postoperative pain.

Referred

Abdominal pain can be referred from adjacent body cavities.

Cardiac pain—In particular, the pain of an inferior myocardial infarction can present as epigastric pain, so electrocardiography is mandatory in suspicious epigastric pain in patients with risk factors.

Lower lobe pneumonias, pulmonary emboli, and pleurisy—These generally present with upper right or left quadrant pain.

Spinal and hip pain—This pain can radiate around the abdominal wall.

Meningitis—This is less common but can cause abdominal pain, although it is unlikely to be the complaint with which the patient presents.

Metabolic

Diabetic ketoacidosis—An estimated 40-75% of patients who present with diabetic ketoacidosis complain of severe abdominal pain on presentation.^w2 The presence of abdominal pain is associated with the severity of metabolic acidosis, not with the concentration of hyperglycaemia or dehydration.^w3 Suspicion of a primary surgical cause should be raised if the abdominal pain does not resolve after resolution of the metabolic acidosis.

Lead toxicity—Poisoning by lead is well documented as causing abdominal pain, with or without vomiting, albeit usually with a constellation of other non-specific symptoms. This is increasingly seen secondary to ingestion of herbal medicines, particularly related to Ayurvedic treatments, which are popular in India.^{w4 w5} Take a complete drug history, and don’t forget to ask about complementary medicines. A high index of suspicion is important, but diagnosis will ultimately depend on blood tests. Treatment involves chelation, usually with EDTA.

Hypercalcaemia—Malignancy and hyperparathyroidism account for 80-90% of cases of hypercalcaemia, and it has the mnemonic “stones, bones, abdominal groans, and psychic moans.” The abdominal pains are largely blamed on the secondary effects of hypercalcaemia, namely pancreatitis, peptic ulcer disease, renal and gall stones, and constipation. Whether hypercalcaemia causes abdominal pain, without these often surgical sequelae, is less clear.^w6

Infection

Urinary tract sepsis, ranging from cystitis to pyelonephritis, are common differentials for low abdominal and loin pain. A common quandary in the primary care setting can occur between the pain of pyelonephritis and renal colic. Pelvic inflammatory disease is a common differential diagnosis for low abdominal pain.

Intestinal sepsis—Food poisoning is a common cause of abdominal pain and is particularly difficult to diagnose when it precedes the expulsive phases of vomiting and diarrhoea. Epigastric pain may indicate gastritis; periumbilical pain may indicate jejunoileal infection; and low abdominal pain may indicate colonic involvement. Metabolic abnormalities after diarrhoea and vomiting may also produce cramps.

Typhoid—Caused by Salmonella typhi, typhoid can cause severe abdominal pain and tenderness, particularly in the second phase of the illness, when there is secondary invasion of the Peyer’s patches (incubation period 1-3 weeks). If there is a change in bowel habit it is towards constipation. A high fever, other systemic unwellness, and recent travel abroad should alert you to the possibility. Remember also that intestinal perforation can occur.

Neurogenic causes

Pain in a dermatomal distribution should alert you to the possibility of a neurogenic source of pain.

Herpes zoster postherpetic neuralgia—There may be 2-3 days of pain in a dermatome before any cutaneously visible evidence becomes obvious.

Tabes dorsalis—This slowly progressive degenerative disease of the posterior columns and roots of the spinal cord as a result of syphilitic infection can result in severe abdominal pain, especially in the epigastrium, and is associated with nausea and vomiting.

Spinal degeneration or injury—This may also result in radiculopathy over the abdominal wall.

Inheritable

Familial Mediterranean fever—This is a recurrent polyserositis, which can, therefore, present with peritonitis, pleuritis, pericarditis, and arthritis. It is more common in Mediterranean families. Abdominal pain is almost universal in these patients, and this may be so severe that it resembles an acute abdomen. These patients have often had unnecessary appendicectomies, cholecystectomies, and laparotomies. Colchicine is one of the common treatments.

Sickle cell disease—Abdominal pain commonly occurs in patients with this autosomal recessive disease. Part of the basis of the morbidity of sickle cell disease is the vaso-occlusive episodes that occur anywhere in the microcirculation because of sickled red cells, and pain is, therefore, a result of ischaemic tissue injury. When these occur in the abdominal cavity patients can present with an acute abdomen. In the spleen repeated infarcts render it fibrotic and defunct. In the kidneys papillary necrosis can occur as can microinfarcts in the liver and the pancreas, leading occasionally to pancreatitis. Generally, clinically significant ischaemia and infarction of the gut is uncommon, but failure to respond to conservative management should prompt the search for more substantial ischaemia.

Acute intermittent porphyria—This autosomal dominant condition is associated with defective haem metabolism. Estimates of prevalence in the United States are 1-5 in 100 000, and it affects women twice as commonly as men. Patients have attacks of abdominal pain usually between the ages of 18 and 40. Psychiatric symptoms and neuropathies also occur. Abdominal pain is usually severe and may last days. It is often epigastric and colicky. Constipation is also common, and there may be associated nausea and vomiting.

Hereditary angioedema (C1 esterase deficiency)—This is an autosomal dominant condition that results in low concentrations of the plasma protein C1 inhibitor, allowing unchecked activation of the complement cascade. Patients may present with cutaneous angioedema, obstruction of the airway, or severe abdominal pain. The abdominal pain is caused by oedema of the mucosa of any portion of the gastrointestinal tract and can be so severe as to mimic an acute abdomen.

All the rest

The list is long, but here are a few more.

Peptic ulceration—This was once principally managed surgically but is now medically managed, except in cases of perforation.

Psychogenic causes—These are extremely common causes of abdominal pain and can be difficult not only to diagnose but also to treat. Their separation from irritable bowel syndrome can also be challenging.

Drugs—Abdominal pain is a common side effect of prescribed drugs and also illicit drugs, such as cocaine, which can have vasospastic effects on gut perfusion.

Vasculitides—Many of the vasculitides can present with varying degrees of abdominal pain because of occlusion of gut vessels. This can sometimes be so severe as to result in mesenteric infarction needing surgery.

Competing interests: None declared.

Patient consent not needed (patient anonymised, dead, or hypothetical).

Provenance and peer review: Not commissioned; externally peer reviewed.

1. Thompson WG. The road to Rome. Gastroenterology 2006;130:1552–1556
2. Abdominal pain in diabetic metabolic decompensation. Clinical significance; JAMA Vol. 233 No. 2, July 14, 1975
3. Diabetic Ketoacidosis and Hyperglycemic Hyperosmolar Syndrome Diabetes Spectrum 15:28-36, 2002
4. Frith, D., Yeung, K., Thrush, S., Hunt, B. and Hubbard, J.; Lead poisoning - a differential diagnosis for abdominal pain. Lancet 2005 Dec 17;366(9503):2146.
5. Sood, A., Midha V. and Sood, N. Pain in abdomen – do not forget lead poisoning. Indian J Gastroenterology 2002; 21:225-226
6. Scott-Coombes, D. and Williams, A.; Hypercalcaemia and abdominal pain. Postgrad Med J. 1998 Jun;74(872):377-8

       

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