What are the differential diagnoses for left mid‑lower abdominal pain?

Differential Diagnosis of Left Mid-Lower Abdominal Pain

The most common causes of left mid-lower abdominal pain are diverticulitis, colonic pathology (colitis, fecal impaction, epiploic appendagitis), urolithiasis, gynecologic disorders in women, and less commonly retroperitoneal hemorrhage or rectus sheath hematoma 1, 2.

Primary Differential Diagnoses by Category

Gastrointestinal Causes (Most Common)

Diverticulitis is the leading diagnosis, though the classic triad of left lower quadrant pain, fever, and leukocytosis appears in only 25% of cases 1. Clinical misdiagnosis occurs in 34-68% of cases when relying on examination alone 1.

• Primary epiploic appendagitis (PEA) presents with focal, localized tenderness (82% of cases) without fever, rebound tenderness, or leukocytosis—distinguishing it from diverticulitis 3
• Colitis (infectious, inflammatory, ischemic)
• Fecal impaction
• Perforated colon cancer
• Inflammatory bowel disease (Crohn's disease, ulcerative colitis)

Urologic Causes

• Left-sided urolithiasis/renal colic 2, 4
• Urinary tract infection/pyelonephritis 4

Gynecologic Causes (Premenopausal Women)

• Ovarian pathology (cyst, torsion, hemorrhage)
• Tubal pathology (ectopic pregnancy, tubo-ovarian abscess)
• Pelvic inflammatory disease 1, 5

Vascular Causes

• Leaking abdominal aortic aneurysm 6
• Spontaneous retroperitoneal hemorrhage 2

Musculoskeletal/Abdominal Wall

• Rectus sheath hematoma 2
• Iliopsoas syndrome (diagnosed by sonopalpation) 5
• Incarcerated hernia 6

Rare Considerations

• Situs inversus with right-sided appendicitis presenting as left-sided pain 6
• Psoas abscess 6
• Testicular pathology (referred pain in males) 2

Key Clinical Discriminators

Features Suggesting Diverticulitis vs. Epiploic Appendagitis

Feature	Diverticulitis	Epiploic Appendagitis
Pain distribution	Diffuse left-sided (52%)	Focal LLQ (82%)
Fever	Common (40%)	Rare (7%)
Rebound tenderness	Common (52%)	Rare (14%)
Leukocytosis	Common (52%)	Rare (15%)

3

Red Flags Requiring Urgent Evaluation

• Hemodynamic instability (consider ruptured AAA, hemorrhage)
• Peritoneal signs (perforation, abscess)
• Fever with systemic toxicity (complicated diverticulitis, abscess)
• Pulsatile mass (AAA)

Common Pitfalls to Avoid

1. Over-reliance on clinical diagnosis alone: Misdiagnosis rates of 34-68% for diverticulitis emphasize the need for imaging confirmation 1

2. Missing gynecologic pathology in premenopausal women: These patients require consideration of both gynecologic and non-gynecologic causes, as presentations overlap significantly 1

3. Assuming all left lower quadrant pain is diverticulitis in elderly patients: While common, alternative diagnoses including malignancy must be excluded 4

4. Overlooking localized pain without systemic symptoms: This pattern suggests PEA rather than diverticulitis and can prevent unnecessary antibiotics or surgery 3

5. Failing to consider rare anatomic variants: Situs inversus with left-sided appendicitis, though rare, can lead to diagnostic confusion 6