What are the differential diagnoses, evaluation, and management for a patient presenting with pink vaginal discharge?

Pinkish Vaginal Discharge: Differential Diagnosis and Management

Pinkish vaginal discharge most commonly represents blood-tinged discharge, which can arise from physiologic causes (cervical changes with labor, ovulation spotting, implantation bleeding), infectious cervicitis (gonorrhea or chlamydia), cervical lesions (polyps, ectropion), or pregnancy-related complications (threatened miscarriage, placental abnormalities). 1

Immediate Diagnostic Approach

Critical First Steps

• Perform a pregnancy test immediately in any woman of reproductive age presenting with pink vaginal discharge, as pregnancy-related causes (threatened miscarriage, placental abruption, placenta previa) carry significant morbidity and mortality risk. 2

• If pregnant, avoid digital pelvic examination until placenta previa and vasa previa are excluded by ultrasound, as digital examination can precipitate life-threatening hemorrhage. 2

• In non-pregnant women, perform a speculum examination to visualize the cervix and determine whether the pink color originates from cervical bleeding, cervical lesions, or true vaginal discharge mixed with blood. 1, 3

Point-of-Care Testing

• Measure vaginal pH with narrow-range pH paper: pH >4.5 suggests bacterial vaginosis or trichomoniasis, while pH <4.5 suggests candidiasis or physiologic discharge. 1, 4

• Prepare saline wet-mount microscopy at bedside to identify clue cells (bacterial vaginosis), motile trichomonads (trichomoniasis), or white blood cells (cervicitis or pelvic inflammatory disease). 1, 4

• Perform a KOH preparation to detect yeast or pseudohyphae if candidiasis is suspected, and note whether a fishy odor develops (positive whiff test suggests bacterial vaginosis or trichomoniasis). 1, 4

Differential Diagnosis by Clinical Context

Pregnancy-Related Causes (Highest Priority)

• In second or third trimester pregnancy with pink/bloody discharge, ultrasound is the mainstay for diagnosis to evaluate for placenta previa (1 in 200 pregnancies), placental abruption (1% of pregnancies), or vasa previa (1 in 2,500-5,000 deliveries). 2

• "Bloody show" (pink-tinged mucoid discharge) typically precedes labor and represents physiologic cervical change; this is expected and does not require intervention. 2

• First trimester pink discharge may indicate threatened miscarriage or implantation bleeding; ultrasound should confirm viability and exclude ectopic pregnancy. 2

Infectious Cervicitis

• Mucopurulent cervical discharge (yellow, green, or blood-tinged) with cervical friability strongly suggests Neisseria gonorrhoeae or Chlamydia trachomatis infection. 1, 5

• Obtain nucleic acid amplification testing (NAAT) for gonorrhea and chlamydia from cervical or vaginal swab in any sexually active woman with pink discharge and cervical findings, as these infections can present as vaginal discharge. 1, 5

• If cervicitis is confirmed or suspected, assess for pelvic inflammatory disease by checking for uterine, adnexal, or cervical motion tenderness; empiric broad-spectrum antibiotics must be started immediately if PID is suspected to prevent infertility and ectopic pregnancy. 1

Cervical Lesions

• Cervical polyps, ectropion, or friable cervical tissue can cause pink discharge, especially after intercourse or physical activity; these are typically visualized on speculum examination. 2, 6

• Any suspicious cervical lesion requires biopsy to exclude cervical dysplasia or malignancy, particularly in women with abnormal Pap smear history or high-risk HPV. 6

Ovulation or Hormonal Causes

• Mid-cycle spotting (ovulation bleeding) presents as scant pink discharge occurring 10-16 days before expected menses; this is physiologic and requires only reassurance if examination is normal. 6

• Hormonal contraceptive breakthrough bleeding can present as pink discharge, particularly in the first 3 months of use or with missed pills. 6

Infectious Vaginitis with Inflammation

• Severe trichomoniasis can cause vaginal inflammation with petechial hemorrhages ("strawberry cervix"), resulting in pink-tinged discharge; wet mount shows motile trichomonads in only 40-80% of cases, so NAAT is recommended. 1, 5

• Bacterial vaginosis itself does not cause pink discharge, but concurrent cervicitis or endometritis can; look for clue cells, pH >4.5, and positive whiff test. 1, 7

Management Algorithm

When Pregnancy is Confirmed

1. Obtain transabdominal and transvaginal ultrasound urgently to assess placental location, fetal viability, and exclude abruption or previa. 2

2. Hospitalize if bleeding is moderate to severe, or if placenta previa or abruption is diagnosed, as these conditions carry high maternal and fetal mortality risk. 2

3. Avoid tocolytics and digital examination until placental location is confirmed; cesarean delivery may be required for placenta previa. 2

When Cervicitis is Suspected

1. Start empiric treatment for gonorrhea and chlamydia immediately if mucopurulent discharge or cervical friability is present, using CDC-recommended regimens (ceftriaxone plus azithromycin or doxycycline). 1

2. Assess for pelvic inflammatory disease by checking for fever >38.3°C, uterine/adnexal tenderness, elevated ESR/CRP, or WBCs on wet mount; if any are present, initiate broad-spectrum antibiotics covering N. gonorrhoeae, C. trachomatis, and anaerobes. 1

3. Treat all sexual partners within the past 60 days to prevent reinfection and ongoing transmission. 1

When Initial Tests Are Negative

• If wet mount, pH, and whiff test are negative but symptoms persist, obtain NAAT for Trichomonas vaginalis, as microscopy misses 20-60% of infections. 1, 5

• Consider non-infectious causes: mechanical irritation from douching, new soaps, lubricants, or latex condoms; atrophic vaginitis in perimenopausal women; or desquamative inflammatory vaginitis. 5, 6

• Refer for colposcopy if cervical lesion is visualized or if pink discharge persists without identifiable cause, to exclude cervical dysplasia or malignancy. 6

Critical Pitfalls to Avoid

• Never perform digital pelvic examination in a pregnant woman with vaginal bleeding before ultrasound excludes placenta previa, as this can cause catastrophic hemorrhage. 2

• Do not diagnose based on discharge color alone; pink discharge can arise from multiple etiologies, and microscopy, pH, and NAAT are essential for accurate diagnosis. 1, 5

• Do not miss concurrent pelvic inflammatory disease in women with cervicitis; always assess for uterine and adnexal tenderness, as untreated PID leads to infertility, ectopic pregnancy, and chronic pelvic pain. 1, 3

• Do not rely solely on wet mount for trichomoniasis; sensitivity is only 40-80%, and NAAT should be obtained if clinical suspicion is high despite negative microscopy. 1, 5

• Do not treat empirically without attempting diagnosis, as inappropriate antibiotic use is common (42% of women in community practice receive inappropriate treatment) and leads to higher rates of recurrent visits. 8