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Approach to abdominal pain


Essentials

  • 1

    Abdominal pain accounts for 4% to 10% of all emergency department visits.

  • 2

    Abdominal pain most frequently arises from pathologies in the gastrointestinal and the genitourinary systems; however, it may also result from cardiovascular, pulmonary, metabolic, infective and/or toxic causes.

  • 3

    Special consideration should be given towards assessment of abdominal pain in elderly, immunocompromised or obese patients, women of childbearing age and children. These patients require careful assessment to avoid missed diagnoses and poor outcomes.

  • 4

    In up to 25% to 40% of patients, the exact cause of the abdominal pain may not be determined in the emergency department. Decisions regarding admission, discharge or prolonged observation should be based on degree of symptom control, possible diagnoses, and patient risk profile.

  • 5

    Patients with abdominal pain should be given adequate analgesia (including the use of opioids). Adequate analgesia can aid diagnosis and does not conceal signs of an acute abdomen.

Introduction

Abdominal pain is a common emergency presentation and may be caused by a broad range of differentials. Assessment of abdominal pain in the emergency department focuses on the identification of the cause of pain, but further key aims are to identify or exclude acute life-threatening conditions and to consider safe patient disposition. It may not be possible to conclusively diagnose the cause of pain during emergency assessment, so disposition decisions must frequently be made on the basis of risk assessment, patient characteristics and the likelihood of various diagnoses.

The assessment of patients with abdominal pain is challenging because

  • symptoms and signs may be non-specific early in the disease process.

  • the presentation may be atypical, especially for very young, immunocompromised, obese or elderly patients.

  • the degree of pain or abnormal physical findings may not be commensurate with the severity of the disease.

Epidemiology, pathophysiology and differential diagnosis

It has been estimated that abdominal pain accounts for approximately 4% to 10% of all emergency department (ED) visits. A significant proportion (18% to 42%) of these patients will require admission. Older patients presenting with abdominal pain are more likely to require admission (50% to 60%), are more likely to require surgery (18% to 20%) and are at higher risk of death.

Patterns of abdominal pain

  • Visceral pain

    • Visceral pain arises by stimulation of nociceptors in visceral structures (gut, heart, renal tract, biliary structures, pancreas). Obstruction and distension of a hollow organ is a frequent cause, with other causes including ischaemia, mucosal irritation and localized inflammation. Pain is often characterized as poorly localized, although it may manifest in the abdominal region that correlates with the embryonic segments of the viscera. Foregut structures will typically produce visceral pain in the upper abdomen, midgut structures in the periumbilical region, and hindgut structures in the lower abdomen ( Table 7.2.1 ).

      Table 7.2.1
      Differential diagnosis of pain by location (list is not exhaustive)
      Right upper quadrant Epigastrium Left upper quadrant
      Hepatobiliary pathology
      Duodenal ulcer, duodenitis
      Renal colic, pyelonephritis
      Retrocaecal appendicitis
      Pneumonia, pulmonary embolism       		Gastritis, peptic ulcer
      Hepatobiliary pathology
      Pancreatitis
      Aortic aneurysm
      Early appendicitis
      Myocardial infarction       		Gastritis, peptic ulcer
      Renal colic, pyelonephritis
      Splenic pathology
      Pancreatitis
      Pneumonia
      Right lumbar or flank Midline or periumbilical Left lumbar or flank
      Renal colic, pyelonephritis
      Aortic aneurysm
      Psoas abscess
      Appendicitis       		Visceral pain from midgut structures
      Early appendicitis
      Aortic aneurysm       		Renal colic, pyelonephritis
      Aortic aneurysm
      Psoas abscess
      Right lower quadrant Suprapubic Left lower quadrant
      Appendicitis
      Ectopic pregnancy, tubo-ovarian pathology, endometriosis, pelvic inflammatory disease
      Urinary tract infection, ureteric colic
      Diverticulitis
      Hernia
      Aortic aneurysm
      Testicular torsion, epididymo-orchitis       		Cystitis, bladder pathology
      Urinary tract infection
      Prostatitis
      Ectopic pregnancy, tubo-ovarian pathology, endometriosis, pelvic inflammatory disease       		Similar to causes for right-lower-quadrant pain except for appendicitis (very rarely left-sided)
      Pain radiating to the back
      Perforated peptic ulcer
      Acute pancreatitis
      Abdominal aortic aneurysm, aortic dissection
      Note: Pain from inflammatory bowel disease, diverticulitis, colitis, gastroenteritis, volvulus, intestinal obstruction, adhesions, ischaemic colitis and constipation may localize to any part of the abdomen.

  • Parietal pain

    • Parietal pain arises from nociceptor stimulation in the body wall, including skin, fascia, muscle, parietal peritoneum, pleura and pericardium. Parietal pain is typically well localized to the nociceptive stimulus. Intra-abdominal pathology produces parietal pain through inflammation of the parietal peritoneum. This may be limited to a discrete area, such as the right iliac fossa pain of appendicitis, or may be diffuse, such as that found in generalized peritonitis.

  • Referred pain

    • Referred pain is felt at a distance from the site of origin. It is thought that referred pain occurs because afferent pain fibres from areas of high sensory input (e.g. the skin) enter the spinal cord at the same level as nociceptive fibres from an area of low sensory input (e.g. the viscera). The brain, being more used to pain signals from the skin, wrongly interprets the pain signal from the viscera as that from the dermatome. Both visceral and somatic pain may manifest as referred pain. Some examples are

  • shoulder pain due to diaphragmatic irritation

  • pain at the tip of the scapula due to gallbladder pathology

  • epigastric pain due to acute myocardial infarction

Generalized abdominal pain

Generalized pain of the entire abdomen has a broad differential, with both benign and life-threatening aetiologies ( Box 7.2.1 ).

Box 7.2.1
Some potentially life-threatening causes of generalized, diffuse abdominal pain
Adapted with permission from Gray-Eurom K, Deitte L. Imaging in the adult patient with non-traumatic abdominal pain. Emerg Med Pract . 2007;9:2.

  • Haemoperitoneum from any cause (e.g. ruptured abdominal aortic aneurysm, ruptured ectopic pregnancy, trauma)

  • Mesenteric ischaemia

  • Perforated viscus

  • Peritonitis (any cause)

  • Pancreatitis

  • Bowel obstruction

  • Diverticulitis

  • Inflammatory bowel disease

  • Metabolic disorders (e.g. diabetic ketoacidosis), sickle cell crisis

  • Infective (e.g. typhoid fever, malaria)

Extra-abdominal causes of abdominal pain

There are a number of extra-abdominal causes of abdominal pain that must be considered along with abdominal causes ( Box 7.2.2 ).

Box 7.2.2
Extra-abdominal causes of abdominal pain
Adapted with permission from Purcell TB. Nonsurgical and extraperitoneal causes of abdominal pain. Emerg Med Clin North Am . 1989;7:721–740.

Thoracic

  • Myocardial infarction/unstable angina

  • Pneumonia

  • Pulmonary embolism

  • Herniated thoracic disc (neuralgia)

Genitourinary

  • Testicular torsion

Systemic

  • Diabetic ketoacidosis

  • Alcoholic ketoacidosis

  • Uraemia

  • Sickle cell disease

  • Systemic lupus erythematosus

  • Vasculitis

  • Hyperthyroidism

  • Porphyria

  • Glaucoma

Toxic

  • Methanol poisoning

  • Heavy metal poisoning

  • Spider bite

Abdominal wall

  • Muscle spasm

  • Muscle haematoma

  • Herpes zoster

Infections

  • Strep pharyngitis (more often in children)

  • Mononucleosis

Clinical features

Assessment of patients with abdominal pain

An accurate, focused history often highlights the likely aetiology of abdominal pain. Clinical impression derived from the history and examination will direct decisions regarding further diagnostic work-up. Simultaneous assessment and treatment is frequently necessary in time-critical conditions. Appropriate analgesia should be given early and does not compromise the accuracy of abdominal examination findings.

Patient history

  • Key points to identify in the history are as follows:

    • Factors that may influence likelihood of disease (such as risk factors for embolic disease, alcohol, use of non-steroidal anti-inflammatory drugs [NSAIDs])

    • Factors that may influence the assessment of abdominal pain (such as altered anatomy from prior surgeries or body habitus, impaired sensation, or renal impairment that alters medication dosing or contrast administration)

    • Factors likely to influence treatment of causes of abdominal pain (such as anticoagulants, anaesthetic risks, fasting status)

Patient demographics and background history

  • Age and sex: The likelihood of certain conditions is higher in patients of a specific age and sex ( Table 7.2.2 ).

    Table 7.2.2
    Common causes of abdominal pain according to age group and gender
    Causes Age group Gender
    Biliary tract disease Peak age 35–50 yrs; rare in those <20 Female:male 3:1
    Ruptured ectopic pregnancy Childbearing age Female
    Appendicitis All ages and both genders, peak at young adulthood; there is a higher risk of perforation in the elderly, women, and children.
    Mesenteric ischaemia Elderly, those with vascular, thrombotic or embolic risks
    Abdominal aortic aneurysm Increased with advancing age Men more common
    Diverticulitis Increased with advancing age Men more common

  • A thorough history should be taken, including known medical issues, social history, menstrual history, family history, medications, use of cigarettes, alcohol and other recreational drugs and also history of allergies.

  • It is important to ascertain the presence or absence of pregnancy in all potentially pregnant female patients, with specific consideration of risk of ectopic pregnancy.

  • Always consider the possibility of trauma, even if not immediately evident on history.

Pain attributes

The nature and time course of pain are key clues to diagnosis. The following attributes should be noted:

  • Onset and progression of abdominal pain over time ( Box 7.2.3 ): Acute vascular events and rupture of a hollow viscus typically present with maximal pain at the onset. Ureteric and biliary colic also often presents with severe pain in the early stages. This is in contrast to pain from inflammatory processes, such as acute appendicitis, which tend to progress and ‘mature’ over hours.

    Box 7.2.3
    Temporal characteristics of abdominal pain
    From White MJ, Counselman FL. Troubleshooting acute abdominal pain. Emedmag 2002. with permission.

    Sudden maximal pain at or near onset

    • Perforated peptic ulcer

    • Ruptured abdominal aortic aneurysm

    • Ruptured ectopic pregnancy, ruptured ovarian cyst

    • Ovarian/testicular torsion

    • Mesenteric infarction

    • Pulmonary embolism

    • Acute myocardial infarction

    Progression to maximal pain within minutes

    • Acute pancreatitis

    • Renal and ureteric colic

    • Biliary colic

    • Strangulated hernia

    • Volvulus

    • Intussusception

    Gradual onset (increased pain over hours)

    • Appendicitis

    • Strangulated hernia

    • Inflammatory bowel disease

    • Chronic pancreatitis

    • Salpingitis/prostatitis

    • Cystitis

  • Location of pain (see Table 7.2.1 ), migration of pain and radiation of pain: Location of pain helps to identify the area of pathology, although occasionally this may be misleading, especially if the pain is referred. Migration of pain over time gives a clue to possible underlying aetiology—for example, pain from appendicitis typically starts at the umbilicus or epigastrium and later localizes to the right iliac fossa.

  • Radiation of pain may suggest specific conditions (see Table 7.2.1 ) (e.g. pain from acute pancreatitis and perforated peptic ulcers often radiates to the back).

  • Severity of pain: Severity of pain experienced is dependent on a number of factors in addition to the underlying pathology. Severity of pain is not always commensurate with the severity of the underlying illness. The elderly in particular often have a diminished sense of pain. Nonetheless, patients in severe pain should be assessed early and given pain relief. Pain scores may be used to record and monitor progress.

  • Character of pain: Colicky abdominal pain usually results from obstruction of a hollow viscus (e.g. the gallbladder). Constant non-colicky pain usually denotes an inflammatory or vascular process.

  • Precipitating and relieving factors: Pain from peritonitis worsens with movement, deep breathing, coughing or sneezing. Pain from peptic ulcer disease classically increases with hunger and decreases with food, antacids or milk. Pain from biliary colic tends to occur after full or fatty meals. Pain from acute pancreatitis classically worsens with supine posture and is relieved by sitting up.

  • Recurrent episodes of abdominal pain: This suggests chronic recurrent conditions, for example peptic ulcer, biliary colic, renal colic or diverticulitis. Mesenteric ischaemia and testicular torsion may also present with recurrent episodes.

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