Step 2 CK · Obstetrics & Gynecology

Gynecologic Infections & Pelvic Pain

Name: Gynecologic Infections & Pelvic Pain
Creator: Veli Bakalov, MD

Diagnose vaginitis by pH and microscopy, and never miss torsion or ectopic

Obstetrics & Gynecology·Gynecology·4 min read·9 high-yield points·Reviewed by Veli Bakalov, MD @HemeOncBuddy

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Work up vaginitis with pH, saline/KOH wet mounts, and the whiff test; normal pH is 3.8–4.5, raised in BV and trichomoniasis, normal in candida.
Bacterial vaginosis: thin gray discharge, fishy odor, pH >4.5, clue cells, positive whiff (Amsel 3 of 4); treat with metronidazole, no partner treatment.
Candida: thick cottage-cheese discharge, pruritus, normal pH, pseudohyphae on KOH; treat with fluconazole or a topical azole, and check for diabetes or HIV if recurrent.
Trichomoniasis: frothy yellow-green discharge, strawberry cervix, motile protozoa; it is an STI, so treat the patient (women: metronidazole 500 mg twice daily for 7 days, retest within 3 months) and partners.
PID is a clinical diagnosis (cervical motion tenderness, adnexal or uterine tenderness) treated empirically with ceftriaxone plus doxycycline plus metronidazole to prevent infertility and ectopic pregnancy.
Admit PID for pregnancy, tubo-ovarian abscess, severe illness, oral intolerance, or outpatient failure; RUQ pain with PID is Fitz-Hugh-Curtis perihepatitis.
Toxic shock (S. aureus TSST-1, tampons): fever, hypotension, erythroderma with later palm/sole desquamation; remove the source and give fluids plus clindamycin and vancomycin.
Ovarian torsion (sudden unilateral pain, vomiting, adnexal mass >5 cm) needs emergent laparoscopic detorsion even if Doppler flow is present.
Check a β-hCG first in every reproductive-age woman with pelvic pain to exclude ectopic pregnancy.

Vaginitis: pH, wet mount, and whiff

Bedside workup. Check the vaginal pH, examine saline and KOH wet mounts, and perform the whiff (amine) test, in which KOH releases a fishy odor. Normal vaginal pH is 3.8–4.5, maintained by lactobacilli. A high pH (>4.5) points toward bacterial vaginosis or trichomoniasis; a normal pH favors candida.

The three vaginitides

Feature	Bacterial vaginosis	Candida	Trichomoniasis
Cause	Gardnerella overgrowth, loss of lactobacilli	Candida albicans	Trichomonas vaginalis (flagellated protozoan)
Discharge	Thin gray-white, fishy odor	Thick white, "cottage cheese"	Frothy yellow-green, malodorous
Symptoms and signs	Little inflammation	Intense pruritus, erythema	Irritation; "strawberry cervix" (punctate hemorrhages)
pH	>4.5	Normal (<4.5)	>4.5
Microscopy	Clue cells; positive whiff	Pseudohyphae and budding yeast on KOH	Motile trichomonads (NAAT is more sensitive)
Treatment	Metronidazole (or clindamycin)	Oral fluconazole or topical azole	Metronidazole 500 mg twice daily for 7 days in women
Treat partners?	No	No	Yes—it is an STI

Bacterial vaginosis is diagnosed by Amsel criteria (3 of 4: thin discharge, pH >4.5, clue cells, positive whiff). It is not an STI, but it raises the risk of preterm birth and PID, so symptomatic pregnant women are treated too.

Vulvovaginal candidiasis follows recent antibiotics and occurs more with diabetes, pregnancy, and immunosuppression. Pregnant women receive topical azoles rather than oral fluconazole.

Recurrent or severe candidiasis should prompt evaluation for uncontrolled diabetes or HIV. Trichomoniasis warrants screening for other STIs and retesting women within 3 months.

Atrophic vaginitis in a postmenopausal woman also raises the pH, with thin, pale mucosa and scant discharge; it responds to vaginal estrogen.

Cervicitis and pelvic inflammatory disease

Cervicitis produces mucopurulent endocervical discharge and a friable cervix, most often from Chlamydia trachomatis and Neisseria gonorrhoeae, diagnosed by NAAT. Presumptive treatment is doxycycline 100 mg twice daily for 7 days, adding ceftriaxone 500 mg IM once when gonorrhea risk is present (age under 25, new or multiple partners, high local prevalence); tailor to NAAT results and treat partners. Untreated, infection ascends to cause pelvic inflammatory disease.

Pelvic inflammatory disease (PID) is ascending infection—gonorrhea and chlamydia, often polymicrobial—causing lower abdominal pain, cervical motion tenderness (the "chandelier sign"), adnexal and uterine tenderness, fever, and discharge. Diagnosis is clinical with a low threshold: treat empirically, without waiting for cultures, to protect fertility. Always check a pregnancy test to exclude ectopic pregnancy.

Outpatient regimen: ceftriaxone 500 mg IM once (1 g if 150 kg or more) plus doxycycline 100 mg orally twice daily and metronidazole 500 mg orally twice daily, both for 14 days.
Admit for IV therapy (ceftriaxone 1 g IV daily plus doxycycline plus metronidazole, or cefotetan or cefoxitin plus doxycycline; clindamycin plus gentamicin is an alternative) with pregnancy, tubo-ovarian abscess, severe illness, inability to tolerate oral therapy, or failed outpatient treatment.
Tubo-ovarian abscess: IV antibiotics with drainage if large or not improving; rupture is a surgical emergency.

Sequelae. Each episode compounds tubal scarring, leading to tubo-ovarian abscess, infertility, ectopic pregnancy, and chronic pelvic pain. Fitz-Hugh-Curtis syndrome is perihepatitis with right-upper-quadrant pain and "violin-string" adhesions between the liver capsule and the abdominal wall.

Right-upper-quadrant pain in a woman with PID is Fitz-Hugh-Curtis perihepatitis, not cholecystitis.

Toxic shock syndrome

Superantigen storm. Staphylococcus aureus TSST-1 acts as a superantigen, cross-linking MHC class II and T-cell receptors to trigger massive cytokine release. The classic setting is tampon or nasal/surgical packing use. Features are high fever, hypotension, a diffuse macular "sunburn" erythroderma that desquamates on the palms and soles about 1–2 weeks later, vomiting or diarrhea, and multiorgan involvement. Blood cultures are often negative.

Remove the sourcetampon, packing, or drain any focus
Aggressive fluidsand vasopressors for refractory shock
Clindamycin plus vancomycinclindamycin halts ribosomal toxin synthesis; vancomycin covers MRSA

Acute pelvic pain: torsion, cysts, and ectopic

In any reproductive-age woman with acute pelvic pain or abnormal bleeding, check a β-hCG first. A positive test with an empty uterus above the discriminatory zone is ectopic pregnancy until proven otherwise.

Acute pelvic pain in reproductive-age women

Condition	Clues	Next step
Ectopic pregnancy	Positive β-hCG, empty uterus, adnexal mass, bleeding	Methotrexate if stable; surgery if unstable
Ovarian torsion	Sudden, severe, unilateral pain with nausea/vomiting; adnexal mass	Emergent laparoscopic detorsion
PID	Gradual bilateral lower pain, fever, discharge, cervical motion tenderness	Empiric ceftriaxone + doxycycline + metronidazole
Ruptured ovarian cyst	Sudden pain, often after intercourse or exercise; free fluid on ultrasound	Analgesia and observation if stable
Appendicitis	Periumbilical pain migrating to the right lower quadrant, anorexia	Imaging and appendectomy

Ovarian torsion. An ovary enlarged by a cyst or dermoid (often >5 cm) twists on its pedicle, producing sudden severe unilateral pain with nausea and vomiting and a palpable adnexal mass. Doppler ultrasound may show reduced or absent flow or a twisted pedicle ("whirlpool sign"), but flow can persist, so a normal Doppler does not exclude torsion. Treat with emergent laparoscopic detorsion to salvage the ovary, preserving it even if it looks dusky.

Ovarian cysts. Most are functional (follicular or corpus luteum) and resolve; a simple cyst <5 cm is usually benign and can be rechecked by ultrasound. Features concerning for malignancy are solid components, thick septations, ascites, large size, and an elevated CA-125, especially after menopause. A ruptured cyst causes acute pain and hemoperitoneum that can mimic an ectopic pregnancy.