Coccobacilli on Pap Smear: Clinical Significance and Management
The presence of coccobacilli on a Pap smear most commonly indicates bacterial vaginosis (BV), which should prompt clinical evaluation for symptoms and consideration of treatment if the patient is symptomatic or at risk for complications. 1
What Coccobacilli Indicate
Coccobacilli on a Pap smear typically represent a shift in vaginal flora consistent with bacterial vaginosis, where normal lactobacilli-dominant flora is replaced by mixed anaerobic organisms including Gardnerella vaginalis, Mobiluncus species, and other anaerobes. 1 These bacteria-covered epithelial cells are often reported as "clue cells" or "shift in vaginal flora" on cytology reports. 2, 1
Important caveat: The Pap smear is not an effective screening test for sexually transmitted diseases or vaginal infections—it is designed for cervical cancer screening. 2 The identification of microorganisms is an incidental finding with variable accuracy depending on the organism. 3
Clinical Correlation Required
Symptomatic patients: If the patient has malodorous vaginal discharge (especially fishy odor after intercourse), vaginal pH >4.5, or other symptoms, treat for bacterial vaginosis with metronidazole or clindamycin. 1
Asymptomatic patients: The management is more nuanced. Research shows that among asymptomatic women with inflammation on Pap smear, approximately 60% have positive cultures for various pathogens, with BV being most common. 4 However, 40% have normal flora despite inflammatory changes. 4
Management Algorithm
For ASCUS with severe inflammation and coccobacilli:
- Identify and treat specific infections if the patient is symptomatic. 2
- Repeat Pap smear after 2-3 months following appropriate treatment. 2
- If inflammation persists without identified infection, continue repeat Pap smears every 4-6 months for 2 years until three consecutive negative results. 2
For normal cytology with incidental coccobacilli:
- Evaluate for clinical symptoms of BV (discharge, odor, irritation). 1
- Consider wet mount examination showing clue cells, vaginal pH testing, and whiff test to confirm BV diagnosis. 2, 1
- Treat if symptomatic or if patient has risk factors for complications (pregnancy, planned gynecologic procedures). 1
Associated Findings and Risks
Bacterial vaginosis has been linked to multiple complications including cervicitis, pelvic inflammatory disease, postoperative infections, mild abnormal Pap smear results, and possible association with cervical intraepithelial neoplasia. 1 The presence of Trichomonas on Pap smear significantly increases the likelihood of concurrent BV (46.5% vs 24.5% without Trichomonas). 5
Key Clinical Pitfalls
Do not rely solely on Pap smear for infection diagnosis: Inflammation on Pap smear cannot reliably predict the presence of genital tract infection, especially in asymptomatic women. 4 Direct testing (wet mount, culture, or molecular testing) is more accurate. 2, 3
Do not delay Pap smear unnecessarily: While mucopurulent discharge may compromise interpretation, if the patient is unlikely to return for follow-up, obtain the Pap smear after careful removal of discharge with a saline-soaked cotton swab. 2
Asymptomatic treatment is controversial: Treatment of asymptomatic women with BV and their male partners remains debated. 1 Focus treatment on symptomatic patients or those with specific risk factors for complications.