What is the likely diagnosis for a sexually active adult with symptoms of unusual vaginal discharge, blood spots in the discharge, itchiness, and a foul odor, who recently had a new sexual partner without protection and has no known allergies or ongoing medical conditions?

Likely Diagnosis and Management

The most likely diagnosis is bacterial vaginosis (BV) or trichomoniasis, given the combination of unusual discharge, foul odor, and recent unprotected sexual contact, and empiric treatment covering gonorrhea, chlamydia, trichomoniasis, and BV should be initiated immediately without waiting for test results. 1

Differential Diagnosis Based on Clinical Features

The symptom constellation points to specific infections:

• Foul odor with discharge strongly suggests either bacterial vaginosis or trichomoniasis, as these are the primary STI-related causes of malodorous vaginal discharge 2
• Blood spots in discharge may indicate cervicitis from gonorrhea or chlamydia, which frequently present with mucopurulent cervicitis and abnormal vaginal bleeding 2
• Itchiness is most prominent with trichomoniasis (moderate to severe vulvar irritation) or candidiasis, though the foul odor makes candidiasis less likely 2
• Recent unprotected sex with new partner places this patient at high risk for multiple concurrent STIs 1

Immediate Empiric Treatment Protocol

Given the high-risk exposure and symptom profile, initiate empiric treatment immediately covering the most common sexually transmitted infections: 1

• Ceftriaxone 125 mg IM single dose (covers gonorrhea) 3, 1
• Azithromycin 1 g orally single dose OR Doxycycline 100 mg orally twice daily for 7 days (covers chlamydia) 3, 1
• Metronidazole 2 g orally single dose (covers trichomoniasis and bacterial vaginosis) 3, 1

This empiric approach is specifically recommended by the CDC when follow-up is uncertain or when patients meet high-risk criteria including new or multiple partners 1

Diagnostic Testing to Perform

While treatment should not be delayed, obtain the following specimens:

• Vaginal pH testing: pH >4.5 indicates BV or trichomoniasis rather than candidiasis 1, 2
• Whiff test: Fishy odor with KOH application confirms BV or trichomoniasis 1
• Wet mount microscopy: Look for clue cells (BV), motile trichomonads (trichomoniasis), or inflammatory cells suggesting cervicitis 1
• NAAT testing for gonorrhea and chlamydia from endocervical or vaginal specimens 3
• Culture or NAAT for Trichomonas vaginalis 3

The Infectious Diseases Society of America emphasizes that simultaneous testing for chlamydia, gonorrhea, and Trichomonas is optimal for detecting the most common treatable STIs in female patients 3

Critical Management Considerations

Partner treatment is essential to prevent reinfection, as patients who appear to "fail" therapy are most likely reinfected by untreated sexual partners 3, 1

Follow-up testing timeline: 1

• Return in 2 weeks if symptoms persist after empiric treatment
• Repeat testing for syphilis and HIV at 6-12 weeks if initial tests were negative and exposure risk was significant
• Test of cure is not routinely needed unless symptoms persist or compliance is uncertain

Common Pitfalls to Avoid

• Do not wait for test results before treating in high-risk patients with new sexual partners, as 25-40% of genital infections may not be specifically identified and delayed treatment increases transmission risk 3
• Do not rely on clinical diagnosis alone, as there is considerable overlap in symptoms between different infections and clinical diagnosis is neither sensitive nor specific 3
• Do not forget emergency contraception if unprotected sex occurred within 120 hours; offer levonorgestrel 1.5 mg orally as single dose 1
• Do not neglect partner notification and treatment, as this is the most common reason for treatment failure 3, 1