ABDOMINAL PAIN (UNDIFFERENTIATED)

“Napoleon in his Study”, Jacques-Louis David, oil on canvas, 1812, The National Gallery of Art, Washington, DC

This is Jacques-Louis David’s immortal “Napoleon in his Study” painted in 1812 at the apogee of his career. There has always been great debate as to why David depicted him with his hand over his abdomen concealed within his vest. Indeed there are numerous examples of Napoleon depicted in this manner by other contemporary painters. As this is a natural posture assumed by anyone with abdominal pain, one popular reason has had it that he was suffering from chronic abdominal pain and indeed Napoleon is thought to have possibly died from gastric carcinoma. Another popular conspiratorist theory was that this chronic pain was due to arsenic poisoning, however the poisoning was said to have occurred well after this portrait was done. The truth of the matter however is stylistic. It was simply customary at this time to depict a regal appearance in this manner, possibly in a perceived imitation of ancient Roman orators. Testimony to this theory are the many other eminent men of these times who where depicted in their portraits in exactly the same manner. Napoleon’s portrait is simply the most widely recognized one done in this style. When David’s portrait is studied in detail it can in fact be seen to be crammed full of symbolism depicting the power and glory of Empire.

Patients who present with undifferentiated abdominal pain will also adopt this posture and though the exact reason as to why they are holding their abdomens in this manner may be obscure the important point to recognize is that a message is being conveyed. As David wished to convey the regalness of his subject, our patients wish to convey their distress. History will interpret David’s message. In the ED we must interpret our patient’s message.

ABDOMINAL PAIN (UNDIFFERENTIATED)

Introduction

Undifferentiated abdominal pain is a common presentation to the ED.

Important issues will include:

1. How unwell is the patient?

2. What analgesia does the patient require?

3. Does the patient have particular risk factors:

● That will make clinical assessment difficult.

● For certain conditions.

4. How should the patient be investigated.

5. Does the patient require a surgical opinion?

6. Does the patient need ongoing observation / admission to hospital?

7. The importance of a follow up plan in patients who are to be discharged.

See also separate more specific guidelines on abdominal pain in the elderly.

Pathology

Differential Diagnoses of abdominal pain:

The possible causes are legion, but it is important to consider a wide range of possibilities, when the diagnosis is unclear:

The following is not exhaustive, but important conditions include:

● Peptic ulcer disease

● Gastritis

● Cholecystitis

● Biliary colic

● Pancreatitis

● Appendicitis

● Diverticulitis

● Bowel obstruction

● Hernias

♥ Inguinal/ umbilical/ internal

● Intussusceptions

♥ Usually seen in children

● Perforation of a hollow viscus, (from any cause)

● Mesenteric ischemia

● Abdominal aortic aneurysm:

♥ Acute expansion/ rupture.

● Acute hepatitis

● Renal colic:

♥ Typically this is more pronounced in the flanks, but stones at the VUJ can result in pain that is more pronounced in the iliac fossae.

● UTI:

● Spontaneous intra-abdominal hemorrhage:

♥ Is the patient on warfarin or other anticoagulant?

● Unrecognized or unreported trauma.

● Female pelvic conditions:

♥ Ectopic pregnancy

♥ Complications of ovarian cysts

♥ Torsion of ovary

♥ Endometriosis

Differential Diagnoses of Non Abdominal causes:

Always consider the possibility of a non-abdominal problem including:

Organic causes:

● ACS (especially inferior myocardial infarction, in cases of epigastric pain).

● Lower lobe lung pathology such as pneumonias or pulmonary embolism

● Metabolic disturbances:

♥ DKA

♥ Hypercalcemia

♥ Porphyria

● Opioid withdrawal.

Non organic causes:

● Anxiety / depression

● Narcotic seeker

● Psychiatric patients

● Munchausen syndrome

● Secondary gain measures

Clinical Assessment

Important points of history

● The degree of vomiting

● An inability to eat or drink

● Co-morbidities

● Past abdominal operations

● Is the patient a recurrent presentation?

♥ The threshold for investigation and admission must be lower.

Significant Examination Findings:

Significant examination findings include:

● Abnormal vital signs

● Altered conscious state

● Signs of dehydration

● Signs of “peritonism”

♥ Guarding, (voluntary or involuntary)

♥ Rebound tenderness

♥ Rigidity

Risk Factors Making Clinical Assessment Difficult

Beware of the following high risk circumstances, where the threshold for admission and investigation should be much lower as signs and symptoms are difficult to interpret and will often be atypical:

1. The very young.

2. The elderly:

● In particular the possibility of mesenteric ischaemia should be kept in mind

See also separate guidelines on abdominal pain in the elderly.

3. Pregnancy

● Especially when advanced.

4. Patients on steroids/ immunosuppressive drugs

● The signs of inflammation are masked.

5. Immunosuppressed patients:

● HIV/ chemotherapy/ malignancy

6. Communication difficulties, which may include:

● Language barriers

● Confused or altered conscious state.

● Intellectually impaired.

● Psychiatric patients.

● Extremes of age.

6. Those with neurological deficits:

● Such as spinal cord injury.

Does the patient have risk factors for certain conditions?

These can include the following:

● Elderly patients with AF: Mesenteric ischemia.

● Patients with known gallstones: Calculus cholecystitis

● Elderly, diabetics, ICU patients: Acalculus cholecystitis.

● Gallstones, alcoholics: Pancreatitis

● Known peptic ulcer/ NSAIDs GIT perforation

● Previous abdominal surgery: Bowel obstruction

● Any female of child bearing age: Ectopic pregnancy.

The patient with minimal abdominal signs:

Note that an apparent lack of abdominal signs does not necessarily mean that there cannot be significant intra-abdominal pathology.

Important scenarios where pain appears to be out of proportion to the clinical signs include:

● The patient that is difficult to assess, ( as in the above high risk situations)

● Pancreatitis

● Mesenteric ischemia

Investigations

The extent of investigation will be determined by:

● The index of suspicion for a certain condition as guided by clinical assessment.

● How unwell or unstable the patient is.

● Underlying risk factors (as above)

Investigations to be considered will include the following:

Blood tests:

1. FBE

● Look for an elevated WCC

2. CRP

● An elevated level increases suspicion for significant underlying pathology

3. LFTs

4. Lipase:

● This should always be considered, pancreatitis is often diagnosed unexpectedly.

5 Beta HCG:

● Important in any female of child bearing age.

6. U&Es/ glucose

● May indicate how unwell the patient is, (dehydration, renal impairment)

● Glucose (DKA)

● Calcium level:

♥ Hypercalcemia can be a cause of ill defined abdominal pain

7. ABGs, (and lactate levels)

● If the patient is unwell and/or if mesenteric ischemia is suspected.

8. Troponin:

● This always needs to be considered in the differential diagnosis of upper abdominal pain that are difficult to asses and have high risk for ACS.

FWT

● Should usually be done as a “screen” for possible urinary tract pathology.

ECG:

● To help rule out possible myocardial ischemia.

Plain Radiology:

CXR:

● For free gas under the diaphragm.

● For lower lobe pneumonias which may be mimicking upper quadrant abdominal pain.

AXR, (erect and supine):

Note however that plain AXR has very low sensitivity and specificity for the diagnosis of abdominal pain, particularly in the elderly.

A normal AXR series does not entirely rule out a bowel obstruction, especially if the patient has significant abdominal signs / symptoms. There may be a proximal bowel obstruction or a “closed loop” of bowel. There may actually be one dilated loop of bowel or perhaps a few short fluid levels (i.e. technically within “normal” limits). This may be a still a significant finding if the patient has significant pain / vomiting)

Ultrasound:

Especially for:

● Biliary tract disease

● Gynecological problems (ectopic pregnancy or complicated ovarian cysts)

● Unstable suspected AAA.

● Pancreatic disease.

● Intra-abdominal blood/ fluid.

CT scan:

This is particularly useful, as diagnostic yield is far greater than plain radiography.

It is especially in:

● Unwell patients where the diagnosis is unclear

● Elderly patients where the diagnosis is unclear

Conditions which may be diagnosed include:

● Suspected diverticular disease.

● Suspected appendicitis

● Suspected GIT ischemia, (including CT angiography)

● Intra-abdominal abscess collections.

● Suspected AAA, where the patient is relatively stable.

● Suspected renal tract pathology.

Ideally radiologists prefer to do oral and IV contrast studies, however:

● Many patients may not be able to tolerate oral contrast due to vomiting or because they are too unwell.

● Some patients may not be able to have IV contrast because of renal impairment or contrast allergy.

A non-contrast CT scan can still be done in these cases.

This may not give ideal images, however much valuable information can still be ascertained, with respect to perforation, bleeding or bowel obstructions

Recent work has demonstrated the usefulness of non-contrast CT scanning in undifferentiated abdominal pain, and its superiority over traditional plain AXR. 3

CT scanning involves greater radiation dosing than AXR, however, on a risk-benefit basis this is of much less concern in the elderly. 4

In younger patients the technique of low dose CT abdominal scanning is currently receiving some interest and has shown some encouraging results. 5

Management

Initial management in the ED will include:

1. Attention to any immediate ABC issues.

2. IV fluids:

These should be commenced where:

● There are clinical signs of dehydration

● There have been protracted fluid losses on history, (vomiting / diarrhea) and/ or poor oral intake

● The patient is unwell

● Prolonged stays in the Emergency department where the patient remains nil by mouth.

3. Analgesia:

Despite the teachings of traditional "wisdom", analgesia does not hinder the diagnostic process in abdominal pain.

Any patient who has significant pain should receive adequate and timely analgesia.

Patients should not be denied analgesia whilst awaiting surgical opinion.

For severe pain use: 2

Morphine:

Morphine 2.5 to 5mg IV as an initial dose, then titrated to effect every 5 to 10 minutes with further incremental doses of 2.5 to 5mg IV

In elderly patients or those with cardiorespiratory compromise, an initial morphine dose of less than 2.5mg IV and incremental doses of 0.5 to 1mg should be considered.

Patients should be reassessed to determine if the dose has been effective or if there are any adverse effects (especially sedation).

Fentanyl:

If morphine is contraindicated, consider fentanyl at 25 to 50 micrograms IV as initial equivalent dose

For less severe pain use: 2

● Paracetamol 1gram orally 4 hourly prn (to a maximum dose of 4 gram per 24 hour period)

If the oral or rectal routes are contraindicated, paracetamol can be given IV 1gram 6 hourly

With or without:

● Oxycodone immediate release 5 to 10 mg orally 4 to 6 hourly prn

Note that:

● Opioids may reduce the patient’s symptoms and only somewhat reduce the signs but they will not alter their localization.

● Fasting patients (nil by mouth) may be administered oral analgesia unless they have (or are suspected of having) any of the following conditions:

♥ Bowel obstruction

♥ Perforated viscus

♥ Compromised swallow e.g. stroke

♥ Compromised airway.

● Buscopan, may be useful for non-specific intestinal colic, but is best avoided in cases of true obstruction or ileus.

4. Antiemetics:

Options include:

● Prochlorperazine 12.5 mg IV

♥ Can be sedating.

● Metoclopramide 10mg IM/IV

♥ But best avoided in cases of mechanical obstruction or perforation as it induces gastric emptying.

● Ondansotron 4 mg IV

● Granisetron 1 mg IV

Disposition:

Following clinical assessment and investigation there often remains a group of patients in whom no clear diagnosis can be made.

If the diagnosis remains unclear following initial assessment and investigation in the ED, the patient may be considered for discharge providing:

● They are well, ie do not appear to have any significant examinations findings.

● They have been assessed in the light of possible risk factors.

● Symptoms have resolved or are minimal.

● Observations are stable.

● Investigations have not shown any significant abnormalities.

Always make arrangements for review and instruct the patient or carer about the symptoms that would warrant a review. Reviews may by the GP or again in the ED.

If the above criteria cannot be met the following options will need to be considered:

● Ongoing observation in the ED:

♥ Especially in cases where the patient presents over night, observation till morning and review by more senior staff / surgical unit may be appropriate.

♥ Some patients may be suitable for a period of observation in a Short Stay Unit.

● Surgical review:

If the patient has:

♥ Abnormal vital signs.

♥ Severe symptoms or significant symptoms that are not resolving, (consider particularly in patients who represent).

♥ Concerning signs such as peritonism or guarding.

♥ Significant abnormalities on investigation results.

♥ Patients with risk factors that may predispose them to particular conditions or that make clinical assessment more difficult. (see above).

♥ Simply uncertainty and concern regarding the patient.

References:

1. “Safety of Early Pain Relief for Acute Abdominal Pain”. A.R. Attard, M.J. Corlett et al. BMJ Vol. 305 5 Sept. 1992, p. 554.

2. The Acute Pain Management Manual NHMRC, 2011.

3. Gerhardt, RT, Derivation of a clinical guideline for the assessment of nonspecific Abdominal pain: the Guideline for Abdominal Pain in the ED Setting (GAPEDS) Phase 1 Study. Am J Emerge Med 2005; 23:709-17

4. Yeoh M. Elderly Patients with Abdominal pain; Clinical Position Statement, Austin Health, September 2010.

5. Nguyen L.K et al. Low-dose computed tomography versus plain abdominal radiography in the investigation of an acute abdomen. ANZ J Surg 82 (2012) 36 -41. (doi: 10.1111/j.1445-2197.2010.05632.x)

Dr J. HayesDr Stephan Herodotou.Reviewed May 2012