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 ABDOMINAL PAIN

 Acute abdominal pain: step-by-step assessment4

33

proceed to Acute lower abdominal pain (p. 38).

7  Consider other causes ± surgical review

or further imaging if any concern

Organise CT angiography to look for fea-tures of mesenteric ischaemia in anypatient with severe, diffuse pain, shockor unexplained lactic acidosis – especiallyif patients are elderly or have vasculardisease/atrial fibrillation. The abdominalexamination may be unremarkable untiladvanced stages.

Consider atypical presentations of

common disorders such as acute appendi-citis or inflammatory bowel disease. Aretrocaecal appendix may present withflank pain while any area of the gut maydevelop a Crohn’s inflammatory mass.

Both gastroenteritis and hypercalcaemiamay cause abdominal discomfort with con-spicuous vomiting and minimal abdominalsigns – measure serum calcium and enquireabout infectious contacts and recent inges-

tion of suspicious foodstuffs.Functional disorders, e.g. irritable bowel

syndrome (IBS), are a frequent cause ofacute abdominal pain. The diagnosis of IBSis discussed on page 88, but enquire abouta background of longstanding intermittentabdominal pain with altered bowel habitand review the notes for previous similaradmissions.

A period of observation with repeated

clinical evaluation is very often the key tosuccessful diagnosis; for example, abdomi-nal pain that was originally central andnon-specific may, on repeat examination,have migrated to the RIF, suggesting adiagnosis of acute appendicitis. Patientswho remain systemically well and whosepain appears to be settling has settled canusually be discharged safely, with outpa-tient review. Those with marked systemic

upset or other features causing concern butno clear underlying cause require furtherinvestigation ± surgical review.

typically restless and unable to lie still.Visible or dipstick haematuria is present in90% of cases and vomiting is commonduring bouts of pain.

Exclude an AAA if the patient is at highrisk e.g. elderly male with vascular disease,or the presentation is atypical e.g. absenceof haematuria/restlessness/radiation togroin: request an urgent USS and, if thisconfirms the presence of an AAA, arrangeimmediate surgical review. Otherwise,organise abdominal CT (or IVU if CT isnot available) to confirm the presence of astone.

In patients with a confirmed stone, checkrenal function and look for features of infec-tion proximal to the obstruction includingan↑temperature/WBC/CRP or leucocytes/nitrites on urinalysis. If you suspect proxi-mal infection, take urine and blood cul-tures, give IV antibiotics and refer urgentlyto urology.

Suspect pyelonephritis if flank pain isnon-colicky and associated with inflamma-tory features (see Box 4.1), leucocytes andnitrites on urine dipstick, or loin/renalangle tenderness ±  lower urinary tractsymptoms. Consider alternative diagnosese.g. acute cholecystitis, appendicitis, ifthere is prominent abdominal tenderness/guarding or if urinalysis is negative for bothleucocytes and nitrites. Take blood andurine cultures, start IV antibiotics andarrange prompt renal USS to exclude aperinephric collection or renal obstruction.

6 Pain localised to upper or lower abdomen?

The localisation of pain within the abdomencan be very helpful in narrowing the dif-ferential diagnosis (see Figs 4.1 and 4.2).

• If the patient has predominantly RUQ,LUQ, epigastric or generalised upperabdominal pain, proceed to acute upper

abdominal pain (p. 34).• If the patient has RIF, LIF, suprapubicor bilateral lower abdominal pain,