Is C-reactive protein (CRP) elevated in a woman of reproductive age with an ovarian cyst?

CRP Elevation in Ovarian Cysts

CRP is typically NOT elevated in uncomplicated ovarian cysts, but can become significantly elevated when complications occur, particularly cyst rupture (mean 6.6 mg/dL) or when ovarian torsion progresses to necrosis. 1, 2

Baseline CRP in Uncomplicated Ovarian Cysts

• Simple ovarian cysts without complications generally do not cause CRP elevation. 3
• Among patients with benign ovarian cysts requiring surgery, those with uncomplicated cysts or simple torsion without necrosis maintain relatively normal CRP levels (mean 0.9 mg/dL in torsion without rupture). 1
• CA125 is the preferred serum marker for evaluating ovarian masses, not CRP, as CA125 can be elevated in benign conditions including ovarian cysts, endometriosis, and pelvic inflammatory disease. 3

CRP Elevation with Ovarian Cyst Complications

Ruptured Ovarian Cyst

• Ruptured ovarian cysts cause marked CRP elevation with mean levels of 6.6 mg/dL (66 mg/L), significantly higher than uncomplicated cysts (0.9 mg/dL, p<0.01). 1
• This elevation reflects peritoneal inflammation from cyst contents and hemorrhage into the peritoneal cavity. 1
• The magnitude of CRP elevation in ruptured cysts is comparable to that seen in pelvic inflammatory disease (mean 76.1 mg/L in PID). 4

Ovarian Torsion with Necrosis

• CRP remains relatively normal in early ovarian torsion without necrosis (mean 0.9 mg/dL), but becomes elevated when necrosis develops. 1, 2
• When ovarian necrosis occurs, CRP levels rise significantly, though the sensitivity for detecting necrosis is only 35% with specificity of 83% using a cutoff of 0.3 mg/dL. 2
• CRP <0.3 mg/dL combined with short duration from symptom onset (<10 hours) suggests greater potential for ovarian conservation. 2
• Experimental models confirm that ovarian torsion causes significant CRP elevation (0.91 vs 0.39 mg/L in controls, p<0.001) within 2 hours of torsion. 5

Clinical Differentiation Algorithm

When evaluating a woman with known ovarian cyst presenting with acute abdomen:

1. Measure CRP along with imaging to differentiate complications:

   • CRP <1 mg/dL: Suggests uncomplicated torsion without rupture or necrosis 1
   • CRP 6-7 mg/dL (60-70 mg/L): Highly suggestive of cyst rupture 1
   • CRP >7 mg/dL with prolonged symptoms (>10 hours): Consider ovarian necrosis 1, 2

2. Combine CRP with cyst size on imaging:

   • Larger cysts (mean 9.7 cm) with low CRP favor torsion 1
   • Smaller cysts (mean 6.7 cm) with elevated CRP favor rupture 1

3. Consider time from symptom onset:

   • Early presentation (<10 hours) with low CRP suggests viable ovary in torsion 2
   • Delayed presentation (>10 hours) with elevated CRP increases necrosis risk 2

Important Clinical Caveats

• CRP is a non-specific inflammatory marker that can be elevated in multiple gynecologic conditions including pelvic inflammatory disease (93% sensitivity, 83% specificity for PID with CRP >10 mg/L), endometriosis, and adenomyosis. 3, 4
• Approximately 6 of 35 patients (17%) with non-infectious gynecologic disorders (ovarian cysts, fibroids, unexplained pelvic pain) may have mildly elevated CRP (12-59 mg/L) without infection. 4
• Multiple non-gynecologic factors influence CRP including age, sex, race, BMI, smoking, diet, sleep, and medications—interpretation requires clinical context. 3
• The 10 mg/L cutoff commonly used to exclude acute pathology may not apply to ovarian cyst complications, where lower elevations (6-7 mg/dL) are clinically significant. 1