Case Study #11 - Abdominal Pain

Overview

• Patient: 65-year-old female
• Past Medical History: Atrial fibrillation (afib), hypertension, recent diagnosis of diverticulosis
• Presentation: Acute onset of constant, non-radiating, diffuse abdominal pain, unrelieved by any factors
  • Associated nausea, vomiting
  • Last bowel movement: 10 hours ago

Initial Examination

• **Vitals: **
  • Heart rate: 150 beats per minute (tachycardic)
  • Respiratory rate: 32 breaths/minute (tachypnic)
  • BP: 110/70 mmHg
  • Temperature: 101.4°F (febrile)
  • SpO2: 94%
• **Physical Exam: **
  • Cardiovascular: Tachycardic, irregular rhythm, S1 & S2 normal, no murmurs/rubs/gallops
  • Pulmonary: Tachypnic, bi-basilar crackles, no wheezing/ronchi
  • Abdominal: Grimacing in pain, soft, non-tender, normal active bowel sounds, no rebound tenderness

Differential Diagnosis

• Acute mesenteric ischemia
• Small bowel obstruction
• Diverticulitis
• Mesenteric ischemia
• Bowel perforation
• Pancreatitis
• Appendicitis
• Pyelonephritis
• Cholecystitis
• Peptic ulcer disease (PUD)
• Nephrolithiasis
• Abdominal aortic aneurysm (AAA)
• Sepsis
• Inferior MI (Myocardial Infarction)

Lab Investigations

• CBC: Leukocytosis 20k
• **CMP: **
  • Anion gap: 14
  • Bicarbonate: 16 (low)
• **ABG: **
  • pH: 7.25 (acidotic)
  • pO2: 84 (normal)
  • pCO2: 46 (slightly elevated)
  • HCO3: 15 (low)
• Lactate: 5.8 (elevated, indicating lactic acidosis)
• Lipase & Amylase: Normal limits
• Troponins: Negative
• Fecal Occult Blood Test: Negative
• Blood Cultures: Negative

Imaging

• Abdominal X-ray: No bowel obstruction, no pneumoperitoneum
• CT with Oral Contrast:
  • No bowel obstruction, gastric thickening, peripancreatic/perinephritic fat stranding, appendicitis, or dilated abdominal aorta
• Ultrasound with Doppler:
  • No cholecystitis, pancreatitis, hydronephrosis, appendicitis
  • Decreased flow in Superior Mesenteric Artery (SMA)
• CTA of Abdomen: Occlusion of the superior mesenteric artery confirmed

Diagnosis

• Acute mesenteric ischemia secondary to atrial fibrillation (not on anticoagulation)

EKG Findings

• Rate: ~150 bpm, irregular
• Rhythm: Atrial fibrillation
• No ST segment elevation or depression

Treatment

1. IV fluids (prefer Lactated Ringers)
2. NG tube to decompress bowel
3. Antiemetics for nausea
4. Analgesia for pain
5. Antibiotics to prevent bacteremia/sepsis
6. Anticoagulation with Heparin
7. +/- Thrombolysis: Consider if not a candidate for embolectomy
8. Embolectomy: If patient is a surgical candidate
9. Dilatation of vessels: Papaverine if perfusion needs improvement
10. Vasopressors (cautiously): Use inodilators like dobutamine/milrinone if needed

Key Points

• High suspicion for acute mesenteric ischemia in elderly females (>60) with atrial fibrillation, especially if not on anticoagulation, presenting with diffuse abdominal pain out of proportion to physical exam findings
• Differential diagnosis is broad; utilize history, physical exam, labs, and imaging effectively
• Keep mi and other systemic factors in mind even with primarily abdominal symptoms
• Approach should be methodical and cover both immediate treatment and underlying causes