PatientPlus articles are written for doctors and so the language can be technical. However, some people find that they add depth to the articles found in the other sections of this website which are written for non-medical people.

The Acute Abdomen

Synonym: Acute Abdominal Pain

See also:

• Abdominal pain in pregnancy
• Recurrent abdominal pain
• Abdominal pain in children
• Epigastric pain
• Left iliac fossa pain
• Right iliac fossa pain
• Left upper quadrant pain
• Right upper quadrant pain
• Loin pain

The term 'acute abdomen' is widely used but poorly defined. Essentially, it represents a rapid onset of severe symptoms that may indicate a life-threatening intra-abdominal pathology. Pain is usually a feature but this is not always the case. A pain-free acute abdomen is more likely in the elderly, children and in the third trimester of pregnancy. The differential diagnosis is extremely wide and definitive diagnosis is often difficult, particularly in primary care. This is due to the large number of tightly-packed and overlapping dynamic organs within the confines of the peritoneal cavity, and the potential for referred pain. It is a common problem, ranking in the top three symptoms of patients in emergency departments, accounting for 5–10% of presenting complaints.¹

Management of this condition in primary care should focus on careful assessment to reach a manageable differential list, with close attention paid to symptoms and signs that may indicate a need to investigate the situation further in hospital. It must be remembered that the clinical scenario in this syndrome can change rapidly and that conclusions previously reached by yourself or colleagues may need to be revised as events evolve. A failure to be open-minded and revise a previous diagnosis is often at the heart of medicolegal claims relating to patients with an acute abdomen.¹ This article will concentrate on diagnosing the important causes of this syndromal presentation in primary care/emergency department settings.

Major causes of the 'acute abdomen' This list is far from exhaustive but is a useful aide-memoire for those conditions commonly seen in the community. It concentrates on those diseases that it is important not to miss for medicolegal reasons.

• Acute cholecystitis
• Acute appendicitis or Meckel's diverticulitis
• Acute pancreatitis
• Ectopic pregnancy
• Diverticulitis
• Peptic ulcer disease
• Pelvic inflammatory disease
• Intestinal obstruction, including paralytic ileus (adynamic obstruction)
• Gastroenteritis
• Acute intestinal ischaemia/infarction or vasculitis
• Gastrointestinal haemorrhage
• Renal colic or renal tract pain
• Acute abdominal aortic aneurysm
• Testicular torsion
• Non-surgical disease, e.g. myocardial infarction, pericarditis, pneumonia, sickle cell crisis, hepatitis, inflammatory bowel disease, opiate withdrawal, typhoid, acute intermittent porphyria, HIV-associated lymphadenopathy or enteritis

Assessment of the patient with 'acute abdomen'
History

• Demographic details and occupation – any recent travel?
• Pain – Nature of onset, new or previously experienced?, site, nature, radiation?, ask patient to point to pain to confirm site and how localised/diffuse it is, how severe?, constant/intermittent/colicky?, relieving/aggravating factors?, improving or worsening?, pain worsened by movement or coughing? (suspect active peritonitis)
• Associated symptoms – Vomiting and nature of vomitus (undigested food or bile suggests upper GI pathology or obstruction; faeculent vomiting suggests lower GI obstruction), always ask about haematemesis ± melaena, stool/urine colour?, new lumps or bumps?, eating and drinking ok?, constipation?, flatus?, any fainting, dizziness or palpitations?, fever/rigors?, rash or itching?, urinary symptoms?, recent weight loss?
• Past history/medication – Previous surgery (ask about laparoscopy which many patients do not consider as surgery), medical conditions?, full medication including OTC and complementary preparations, allergies? When was last meal?
• Gynaecological and obstetric history Essential in women of child-bearing age – Sexual activity, could she be pregnant?, contraception, LMP, STIs/PID, previous gynae. surgery or tubal surgery?, IUCD use, previous ectopic pregnancy, vaginal bleeding?

Examination

• First impressions Observe the patient for a few seconds. Do they look ill, septic or shocked? Are they lying perfectly still (think peritonitis), or rolling around in agony? (think intestinal, biliary or renal colic). In patients with signs of systemic upset or who appear to be shocked or acutely unwell, assess quickly but carefully and arrange any early investigations you think you might need, if you are in an emergency department setting. In community settings make arrangements for rapid transfer to hospital for further assessment.
• Further assessmentAlways check pulse, temperature and blood pressure. Assess respiratory rate and pattern. If altered consciousness check GCS or AVPU scale – Alert, Voice response, Pain response, Unconscious.

Patients with peritonitis may take shallow, rapid breaths to reduce pain. Any evidence of anaemia? Is there visible peristalsis or abdominal distension? Look for signs of bruising around the umbilicus (Cullen's sign – associated with haemorrhagic pancreatitis and ectopic pregnancy) or flanks (Grey Turner's sign associated with retroperitoneal haematoma).

Check supraclavicular and groin lymph nodes. Assess whether patient is dehydrated (skin turgor/dry mucous membranes). Auscultate abdomen in all four quadrants. Absent bowel sounds suggest paralytic ileus, generalised peritonitis or absolute intestinal obstruction. If they are high-pitched and tinkling then sub-acute intestinal obstruction is likely. However, intestinal obstruction can present with normal bowel sounds.² If there is reason to suspect aortic aneurysm, listen carefully for abdominal and iliac bruits. In patients whom you consider might be over-emphasising the degree of abdominal pain, pressure with a stethoscope can be used to gauge if the response is similar to that of the palpating hand (ie, patient unaware that they should show signs of pain during this manoeuvre). Percuss the abdomen to assess whether swelling might be due to bowel gas or ascites. Patients who display tenderness to percussion are likely to have generalised peritonitis and this should act as a red flag for serious pathology.

Palpate the abdomen gently at first, then more deeply, starting away from the pain and moving towards it. Some clinicians like to palpate before auscultating and percussing but if there is severe pain it may reduce subsequent co-operation and disturb bowel gas patterns, so some authors suggest leaving this till last in the acute situation.^2,3 Feel for masses, tenderness, involuntary guarding and organomegaly (don't forget the bladder). Test for rebound tenderness and look in the groins for evidence of herniae.
Always examine the scrotum in men as pain may be referred from unrecognised testicular pathology.

Further examination
Always ask yourself if rectal or pelvic examination is needed and if so perform it, if there is an appropriate chaperone. – Put your finger in it or you may put your foot in it. Check lower limb pulses if there could be an abdominal aortic aneurysm. Dipstick urine and send for culture if appropriate.
In a woman of child-bearing age, assume that she is pregnant until proven otherwise: use a pregnancy test if one is available.
Examine any other system that might be relevant, eg chest, cardiac.

Investigation This is mainly relevant for patients in emergency departments or secondary care. With the exception of a urinary pregnancy test, there are few tests that are useful in the outpatient management of the patient with acute abdominal pain. On the whole, if you are concerned enough to be ordering blood tests or imaging then the patient should probably really be sent to the acute surgical team, or undergo assessment in the emergency department. The following tests are often used but are largely non-specific and must be interpreted in concert with the clinical context and appropriate medical/surgical expertise.

• Blood tests: FBC, U&E, LFT, amylase/lipase, glucose, clotting, and occasionally Ca²⁺, ABG (pancreatitis)
• Group and Save or crossmatch
• Blood cultures
• Urinalysis
• USS
• Radiology - AXR (supine), CXR (erect), IVP, CT, US scan
• Consider ECG if >40yrs
• Peritoneal lavage following trauma

Recognising severe cases/red flags to raise suspicion of serious pathology

• Hypotension
• Confusion/impaired consciousness
• Signs of shock
• Systemically unwell/septic-looking
• Signs of dehydration
• Rigid abdomen
• Patient lying very still or writhing
• Absent or altered bowel sounds
• Associated testicular pathology
• Marked involuntary guarding/rebound tenderness
• Tenderness to percussion
• History of haematemesis/melaena or evidence of latter on PR examination
• Suspicion of medical cause for abdominal pain

Criteria for admission There are no hard-and-fast rules by which to make this judgement. It will vary with the clinical situation and confidence/experience of the clinician involved. Any of the above red flags would indicate a need for admission in the vast majority of cases. Be wary of not admitting patients who have no support at home or live alone, if the situation has a chance of deteriorating. Ask yourself if there are significant grounds to suspect any of the important surgical causes of abdominal pain as listed above, and if so then err on the side of caution and admit for further assessment. Patients who cannot take oral fluids for more than a few hours or who have severe persistent diarrhoea are likely to need admission. If there is significant co-morbidity such as diabetes or ischaemic heart disease you should have a low threshold for admission. If you decide to manage patients with early or non-specific abdominal pain in the community, take care to make concrete follow-up arrangements and give advice on what should prompt them to seek further medical attention, and document all this.

Pre-hospital/emergency department care of suspected 'acute abdomen'

• NBM
• IV fluids, set up immediately if shocked and equipment available. Send blood for group and save/crossmatch
• Consider passing an NG tube if severe vomiting, signs of intestinal obstruction or extremely unwell and danger of aspiration
• Analgesia if warranted. Balance pain relief considerations with the need to preserve signs in subsequent surgical assessment
• Antiemetic – avoid using this as a symptomatic treatment without considering a diagnosis in community setting
• Antibiotics if suspect systemic sepsis, peritonitis, severe UTI. Use IV cephalosporin ± metronidazole in acutely unwell patients. If IV access cannot be obtained consider IM benzylpenicillin.
• Arrange urgent surgical review
• Admit if consider that surgery likely, unable to tolerate oral fluids, for pain control, medical cause possible or IV antibiotics required

Special Situations

• Children – Pain aetiology varies with age; history and examination can be difficult
• Pregnancy – Always consider ectopic pregnancy in women of child-bearing age. Causes of acute abdomen in late pregnancy are different and require expert combined obstetric/gynaecological/surgical evaluation.
• Older patients – The older patient tends to show milder, less specific symptoms and signs, so have a lower threshold for surgical assessment and a higher index of suspicion of serious pathology. A comprehensive assessment is needed to detect extra-abdominal disease that may increase surgical risk and should be optimised to reduce mortality. Aortic aneurysm and bowel ischaemia are more prevalent in the elderly, particularly in those with AF. Angiodysplasia of the colon is more common and can cause GI haemorrhage. Medical causes of abdominal pain are encountered more frequently.

The 'Top 5' medical causes of an acute abdomen to consider in older patients are: Inferior MI; Lower-lobe pneumonia/PE causing pleurisy; Diabetic ketoacidosis or Hyperosmolar Non-Ketotic Coma (HONK); Pyelonephritis; Inflammatory Bowel Disease.

Medicolegal Pitfalls and Tips

• Careful documentation of the clinical situation and decision-making process is essential and the only thing you will have to fall back on if a patient's condition deteriorates and there is an adverse outcome, followed by a complaint or claim
• Failure to appreciate the severity of illness through not assessing vital signs/taking heed of general condition
• Failing to take note of history from carers/parents of severe illness in a patient who now seems relatively well, particularly in children
• Failure to examine adequately or to document findings
• Failure to examine for a bladder, herniae or check scrotum
• Failure to carry out rectal or vaginal examination when it is indicated
• Failing to explain the reason for an intimate examination, leading to an accusation of impropriety
• Treating children as little adults and not considering paediatric-specific diagnoses
• Failing to make concrete follow-up arrangements or advising a patient of when they should seek further assessment, when managing patients in the community
• Delayed transfer of acutely unwell patients to hospital – Use 999 service where necessary
• Steroids or other forms of immunocompromise may mask symptoms and signs
• When pain outstrips signs, consider gut infarction or AAA
• Don't rely on a normal test result to discount pathology if the clinical condition suggests otherwise
• Failing to consider pregnancy or conduct a pregnancy test
• Be ready to re-assess your initial or a colleague's diagnosis where the clinical situation has changed

References used

1. Kavanagh S The Acute Abdomen – assessment, diagnosis and pitfalls.; Casebook 2004 Feb;12(1):11-17 [Full Text]. PDF of this edition of Casebook. By the author of this article, focusing on the medicolegal and practical clinical aspects.
2. Burkitt H et al., The Acute Abdomen and Acute Gastrointestinal Haemorrhage. In Essential surgery Churchill & Livingstone, Edinburgh (1990)
3. Town J; Bringing acute abdomen into focus.;Nursing. 1997 May;27(5):52-7; quiz 58.[abstract]

Internet and further reading

• Dang C, Aguilera P, Dang A, et al; Acute abdominal pain. Four classifications can guide assessment and management.;Geriatrics. 2002 Mar;57(3):30-2, 35-6, 41-2.[abstract]
• Leung A and Sigalet D Acute Abdominal Pain in Children.; Am Fam Phys 2003 June 1;67(11):2321-2328 [Full Text]
• American Family Physician Use of Opiate Analgesics for Acute Abdominal Pain

Acknowledgements EMIS is grateful to Dr Sean Kavanagh for writing this article. The final copy has passed peer review of the independent Mentor GP authoring team. ©EMIS 2006.

Last issued 05 Jul 2006