Lower Left Abdominal Pain: Causes, Diagnosis, and Management
Lower left abdominal pain is most commonly caused by acute diverticulitis, but can also result from other conditions including colitis, inflammatory bowel disease, epiploic appendagitis, bowel obstruction, hernia, gynecological conditions, pyelonephritis, and urolithiasis. 1
Common Causes
- Diverticulitis: The most common cause in adults, especially in those over 40 years old, with prevalence increasing with age (10% at age 40, rising to 70% in older patients) 1, 2
- Colitis/Inflammatory bowel disease: Can present with similar symptoms to diverticulitis
- Epiploic appendagitis: Inflammation of fatty appendages of the colon
- Gynecological conditions: Including ovarian cysts, pelvic inflammatory disease, ectopic pregnancy
- Urological conditions: Urolithiasis, pyelonephritis
- Bowel obstruction or hernia
- Abdominal wall pathology
Clinical Presentation
- Diverticulitis: Typically presents with acute or subacute left lower quadrant pain, fever, and change in bowel habits 2
- Epiploic appendagitis: Usually presents with more focal left lower quadrant tenderness (82.1%) without associated symptoms 3
- Diverticulitis vs. IBS: Moderate to severe and prolonged left lower abdominal pain for at least 24 consecutive hours is characteristic of symptomatic uncomplicated diverticular disease (SUDD) 4
Diagnostic Approach
Initial Evaluation
Laboratory tests: Complete blood count and C-reactive protein
- CRP >50 mg/L suggests diverticulitis
- CRP >170 mg/L suggests severe disease 2
Imaging: CT abdomen/pelvis is the preferred first-line imaging
Imaging Recommendations
CT Abdomen and Pelvis with IV contrast:
- First-line imaging modality for left lower quadrant pain 1, 2
- Sensitivity 98-99%, specificity 99-100% 2
- Most useful for detecting small quantities of extraluminal air and accurately diagnosing diverticulitis 1
- Helps determine disease severity and complications such as abscess formation 1
Ultrasound:
- Alternative when CT is unavailable or contraindicated
- Sensitivity 61-90%, specificity 90-100% 2
- Particularly useful in pregnant patients or young women with possible gynecologic pathology 5
MRI:
- Preferred next step if ultrasound is inconclusive
- Advantages include lack of ionizing radiation and superior soft tissue resolution 1, 2
- Particularly useful in pregnant patients 2
Important Clinical Considerations
- Clinical impression alone is insufficient for diagnosis, with accuracy only 40-65% without imaging 2
- 24% of patients diagnosed with appendicitis had no right lower quadrant pain or tenderness, and 7% of patients with diverticulitis had no left lower quadrant pain or tenderness 6
- Elderly patients (>65 years) often present atypically and have higher risk of complications 2
Management Approach
For Diverticulitis (most common cause):
Uncomplicated diverticulitis:
- Outpatient treatment with antibiotics for 5-7 days
- Options include amoxicillin-clavulanate 875/125 mg orally twice daily or ciprofloxacin 500 mg plus metronidazole 500 mg twice daily 2
Complicated diverticulitis:
- Hospitalization for IV antibiotics
- Surgical consultation
- Percutaneous drainage for abscesses ≥3-4 cm 2
Follow-up:
- Reassessment within 48-72 hours
- High-fiber diet (25-30g daily) once acute episode resolves
- Colonoscopy 6-8 weeks after resolution to exclude malignancy 2
Pitfalls to Avoid
- Relying solely on clinical impression without imaging, as this can lead to misdiagnosis 2
- Assuming all left lower quadrant pain is diverticulitis, especially in younger patients
- Performing colonoscopy during acute diverticulitis (contraindicated due to risk of perforation) 2
- Overlooking gynecological causes in women of reproductive age
- Failing to recognize that right upper quadrant pain is negatively associated with abnormal CT findings 6
By following a systematic diagnostic approach with appropriate imaging, clinicians can accurately diagnose the cause of lower left abdominal pain and implement appropriate management strategies.