What is the diagnosis and management for a 12-week pregnant patient with postcoital vaginal bleeding, hematuria, and thick malodorous vaginal discharge, with a history of alcohol use and no cervical motion tenderness?

Diagnosis and Management of Postcoital Bleeding with Malodorous Discharge at 12 Weeks Gestation

This patient most likely has bacterial vaginosis (BV) causing the malodorous discharge, with postcoital bleeding requiring urgent ultrasound evaluation to exclude placental causes before any digital cervical examination is performed.

Immediate Diagnostic Approach

Critical First Step: Imaging Before Pelvic Examination

• Perform transabdominal and transvaginal ultrasound immediately before any digital pelvic examination to exclude placenta previa, low-lying placenta, vasa previa, placental abruption, or threatened miscarriage, as digital examination is contraindicated until these are ruled out 1
• Transvaginal ultrasound is both safe and accurate for evaluating second trimester bleeding and has been proven not to increase infection risk even in high-risk scenarios 1
• Ultrasound will identify approximately 50% of placental abruptions and nearly all cases of placenta previa, which affects 1 in 200 pregnancies 1

Vaginal Discharge Evaluation

• Collect vaginal discharge for pH testing and microscopic examination using saline and 10% KOH preparations 2, 1
• The thick malodorous discharge with no cervical motion tenderness strongly suggests bacterial vaginosis rather than sexually transmitted infection 1, 2
• Perform the whiff test: a fishy odor after applying 10% KOH is diagnostic for BV or trichomoniasis 1, 2
• Examine saline wet mount for clue cells (epithelial cells with adherent bacteria) and motile trichomonads 1, 2
• Measure vaginal pH: pH >4.5 indicates BV or trichomoniasis rather than candidiasis 2, 1

Diagnostic Criteria for Bacterial Vaginosis

BV is diagnosed when 3 of 4 clinical criteria are present 1, 2:

• Homogeneous white discharge adhering to vaginal walls
• Clue cells on microscopy
• Vaginal pH >4.5
• Positive whiff test (fishy odor with KOH)

Additional Testing Required

• Cervical cultures for N. gonorrhoeae and C. trachomatis to exclude cervicitis as a bleeding source 1, 2
• Urinalysis to evaluate the "blood in toilet after urination" - this may represent hematuria from urinary tract infection or blood from vaginal source 1

Management Algorithm

If Ultrasound Shows Viable Pregnancy Without Placental Pathology

Treatment of Bacterial Vaginosis in Pregnancy

All symptomatic pregnant women with BV must be treated to relieve symptoms and potentially reduce adverse pregnancy outcomes including preterm birth, premature rupture of membranes, and postpartum endometritis 2, 1

Recommended First-Line Regimen 1, 2, 3:

• Metronidazole 500 mg orally twice daily for 7 days
• Patient must avoid all alcohol during treatment and for 24 hours after completion to prevent disulfiram-like reaction 1, 2, 3

Alternative Regimen 1:

• Metronidazole 2 g orally as single dose (though 7-day regimen preferred in pregnancy for lower peak serum levels that could reach fetal circulation) 3

Critical Pregnancy-Specific Considerations

• The 7-day metronidazole regimen is preferred over single-dose therapy in pregnancy because it results in lower peak serum levels, reducing fetal exposure 3
• Follow-up evaluation one month after treatment completion is mandatory to verify cure, as BV is associated with adverse pregnancy outcomes 2
• Treatment is especially important given her alcohol use history, as BV increases risk of chorioamnionitis and preterm birth 1, 2

If Cervicitis from STI is Identified

• Treat with ceftriaxone 125 mg IM plus azithromycin 1 g orally (doxycycline contraindicated in pregnancy) 1
• Treat sexual partner simultaneously 1, 2

If Trichomoniasis is Identified

• Metronidazole 2 g orally as single dose 2, 3
• Treat sexual partner to prevent reinfection 2, 1
• Avoid alcohol during and 24 hours after treatment 2, 3

If Candidiasis is Found (Less Likely Given Malodorous Discharge)

• Only topical azole therapy for 7 days is safe in pregnancy - oral fluconazole is absolutely contraindicated 2
• Clotrimazole 2% cream, one applicator intravaginally at bedtime for 7 days 2

Management of Postcoital Bleeding

If Ultrasound Shows Placental Pathology

• Placenta previa or low-lying placenta: pelvic rest, no intercourse, no digital examinations, close obstetric follow-up 1
• Placental abruption: hospitalization, continuous fetal monitoring, delivery planning based on severity 1
• Threatened miscarriage: expectant management with activity modification 4

If No Placental Pathology Identified

• Speculum examination (not digital) to visualize cervix for polyps, cervicitis, or friable cervix 1, 5
• Cervical polyps can be identified by ultrasound in the endocervical canal 1
• Most postcoital bleeding in pregnancy is benign, arising from increased cervical vascularity 5

Critical Pitfalls to Avoid

• Never perform digital cervical examination before ultrasound rules out placenta previa - this can precipitate catastrophic hemorrhage 1
• Never use oral fluconazole in pregnancy - only topical azoles are safe 2
• Never use single-dose metronidazole as first choice in pregnancy - 7-day regimen provides lower fetal exposure 3
• Never assume malodorous discharge is always BV - cervicitis from gonorrhea or chlamydia requires different treatment and has serious consequences if untreated in pregnancy 2, 1
• Never fail to counsel about alcohol avoidance with metronidazole - disulfiram-like reaction can occur 1, 2, 3
• Never skip the one-month follow-up after BV treatment in pregnancy - treatment failure increases preterm birth risk 2

Alcohol Use History Implications

• Document current alcohol consumption and provide brief intervention counseling, as alcohol use in pregnancy increases risk of fetal alcohol spectrum disorders 2
• Metronidazole treatment provides additional motivation for alcohol cessation during the treatment week 1, 3
• Consider social work referral for substance use support if ongoing alcohol use is identified 2