Acute abdominal pain resident survival guide

# Overview
Abdominal pain (or stomach ache) is a common symptom associated with transient disorders or serious disease. Diagnosing the cause of abdominal pain can be difficult, because many diseases can cause this symptom. Most frequently the cause is benign and/or self-limiting, but more serious causes may require urgent intervention.
Acute abdominal pain is a severe, persistent abdominal pain of sudden onset that is likely to require surgical intervention to treat its cause. The pain may frequently be associated with nausea and vomiting, abdominal distention, fever and signs of shock.

# Causes

## Life Threatening Causes
Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated.
- Abdominal aortic aneurysm
- Acute bowel obstruction
- DKA
- Ectopic pregnancy
- Mesenteric ischemia
- Myocardial infarction
- Perforated viscus (including peptic ulcer, bowel, esophagus, or appendix)
- Placental abruption
- Splenic rupture (It is usually secondary to trauma, EBV or leukemia)
- Volvulus

## Common Causes
- Acute pancreatitis
- Adnexal pathology (cyst or tumor that caused torsion, bleeding or rupture)
- Appendicitis
- Biliary disease (Acute cholecystitis)
- Bladder distension
- Chronic heroin or morphine use
- Crohn's disease
- Diverticulitis
- Dyspepsia
- Endometriosis
- Endometritis
- Hemophilia
- Hiatus hernia
- High dose steroids
- HIV infection (affecting the GI and hepatobiliary systems)
- Kidney stones
- Mesenteric infarction
- Pelvic inflammatory disease
- Peritonitis
- Sickle cell disease (as a part of vasoocclusive crisis)
- Splenic abscess
- Splenic  infarction
- Ulcerative colitis

# Management

### Diagnostic Approach
Shown below is an algorithm depicting the diagnostic approach of acute abdominal pain. 
 Abbreviations: ACS: Acute coronary syndrome; AAA: Abdominal aortic aneurysm; RUQ: Right upper quadrant; RLQ: Right lower quadrant; LUQ: Left upper quadrant; LLQ: Left lower quadrant

# Approach to a female of child-bearing age

## Differentiating Common Causes of Abdominal Pain
Shown below is a table summarizing some clues that help to distinguish the presentation of different diseases.

# Do's
- Start the approach to acute abdominal pain by rapid assessment of the patient using the pneumonic "ABC:" airway, breathing and circulation, to identify unstable patients.
- Consider abdominal aortic aneurysm, mesenteric ischemia and malignancy in patients above 50 years as it is much less likely for younger patients.
- Perform pelvic and testicular examination in patients with low abdominal pain.
- Re-examine patients at high risk who were initially diagnosed with pain of unclear etiology.
- Taking careful history, characterizing the pain precisely and thorough physical examination is crucial for creating narrow differential diagnosis.
- Correlate the CD4 count in HIV positive patients with the most commonly occurring pathology.
- Order a pregnancy test before proceeding with a CT scan in females in the child bearing age.
- Order an ultrasound or magnetic resonance among pregnant females to avoid exposure to radiation. In case the previous tests were inconclusive and appendicitis is suspected, the next step in the management includes proceeding with either laparoscopy or limited CT scan.
- Consider peritonitis with cervical motion tenderness as it isn't specific for pelvic inflammatory disease.
- Suspect abdominal aortic aneurysm in old patients presenting with abdominal pain with history of tobacco use.
- Suspect acute mesenteric ischemia or acute pancreatitis in patients presenting with poorly localized pain out of proportion to physical findings.
- Recommend initial imaging studies based on the location of abdominal pain:
- Ultrasonography is recommended when a patient presents with right upper quadrant pain.
- Computed tomography (CT) with intravenous contrast media is recommended for evaluating adults with acute right lower quadrant pain.
- CT with oral and intravenous contrast media is recommended for patients with left lower quadrant pain.
- Order ECG for old patients with upper abdominal pain with high cardiac risk factors.
- Administer narcotic analgesia for patients who present to the ED with moderate or severe abdominal pain.
- Perform diagnostic paracentesis (cell count, differential count, gram stain, culture, bilirubin and albumin) in patients with ascites and abdominal pain to rule out spontaneous bacterial peritonitis.

# Don'ts
- Fail to evaluate elder patients in the presence of overt clinical signs.
- Over rely on laboratory tests, they are only used as adjuncts.
- Do not delay the initial intervention.
- Do not order blood cultures routinely in all patients
- Dont delay resuscitation or surgical consultation for ill patient while waiting for imaging.
- Dont restrict the differential diagnosis of abdominal pain based on the location; for example, right-sided structures may refer pain to the left abdomen.