Initial Workup and Management for Abdominal Pain
The initial workup for abdominal pain should include prompt assessment of vital signs, focused physical examination based on pain location, laboratory tests (CBC, basic metabolic panel, liver function tests, lipase/amylase, urinalysis, and pregnancy test in women of reproductive age), and targeted imaging based on pain location with contrast-enhanced CT scan as first-line for nonlocalized pain. 1
Initial Assessment
History and Physical Examination
- Pain characteristics:
- Location (quadrant-specific approach)
- Duration, onset (sudden vs. gradual)
- Quality (sharp, dull, cramping)
- Radiation
- Alleviating/aggravating factors
- Associated symptoms:
- Nausea/vomiting
- Changes in bowel habits
- Fever
- Urinary symptoms
- Physical exam findings:
- Vital signs (tachycardia, hypotension suggest serious pathology)
- Abdominal tenderness, guarding, rebound
- Presence of peritoneal signs
- Abdominal distension (suggests obstruction)
Laboratory Testing
- Complete blood count (assess for leukocytosis)
- Basic metabolic panel
- Liver function tests
- Lipase/amylase (for suspected pancreatitis)
- Urinalysis
- β-hCG testing in all women of reproductive age 1
Imaging Based on Pain Location
Quadrant-Specific Approach:
- Right upper quadrant pain: Ultrasonography (88% sensitivity, 80% specificity for cholecystitis) 1
- Right lower quadrant pain: CT abdomen and pelvis (97% sensitivity, 94% specificity) 1
- Left lower quadrant pain: CT abdomen and pelvis (81% sensitivity) 1
- Nonlocalized pain: Contrast-enhanced CT abdomen and pelvis (nearly 100% sensitivity for many common causes) 1
- Suspected urolithiasis: Non-contrast CT abdomen and pelvis (97-100% sensitivity) 1
- Suspected gynecologic etiology: Transvaginal ultrasound for premenopausal women 1
Initial Management
Resuscitation
- Prompt administration of intravenous fluids, titrated to clinical response
- Vasopressors if fluid therapy alone is failing 1
Pain Management
- Multimodal analgesia:
- Scheduled acetaminophen and NSAIDs as first-line
- Opioids for severe pain (note: early administration of analgesia does not impair diagnostic accuracy) 1
Infection Management
- Initiate antibiotics once intra-abdominal infection is diagnosed or strongly suspected:
- Stable patients: Amoxicillin/Clavulanate 2g/0.2g every 8 hours
- Critically ill patients: Piperacillin/tazobactam 6g/0.75g loading dose, then 4g/0.5g every 6 hours 1
- For abscesses:
- <3 cm: Intravenous antibiotics
3 cm: Percutaneous drainage plus antibiotics
- Consider surgery if percutaneous drainage fails or septic shock persists 1
Special Populations
Pregnant Patients
- Ultrasound first, followed by MRI if inconclusive (avoid radiation) 1
Elderly Patients
- Lower threshold for CT imaging (clinical signs may be unreliable)
- Higher risk for serious pathology 1
Immunocompromised Patients
- Lower threshold for advanced imaging
- May present with atypical symptoms
- Higher risk for serious pathology and intra-abdominal abscess 1
Common Pitfalls to Avoid
- Delaying imaging in elderly patients
- Missing gynecologic causes in women of reproductive age
- Inadequate pain control (can lead to unnecessary suffering)
- Overlooking serious pathology in immunocompromised patients
- Failing to recognize sepsis early 1
- Attributing post-hysterectomy pain solely to surgical site without considering other etiologies 1
Surgical Considerations
- Obtain surgical consultation for:
- Peritoneal signs
- Evidence of bowel infarction
- Failed conservative management
- Persistent signs of septic shock 1
The American College of Radiology's imaging recommendations provide a structured approach based on pain location, which significantly improves diagnostic accuracy compared to older approaches that relied primarily on clinical assessment 2. While clinical evaluation is important to differentiate between urgent and non-urgent causes, its accuracy alone is insufficient to identify the correct diagnosis in many cases 3.