Infections of the vulva, vagina and cervix
- Lesion
Most lower genital infections are common and curable, but herpes stays for life and some of them raise the risk of preterm birth or HIV.
What it is
The vulva, vagina and cervix are infected by viruses, fungi, protozoa and bacteria, many of them sexually transmitted. Each leaves a recognisable trace on a smear or biopsy: multinucleated cells for herpes, molluscum bodies for poxvirus, pseudohyphae for Candida, motile flagellates for Trichomonas and clue cells for bacterial vaginosis. They matter because they are frequent, because herpes can pass to the newborn, and because ulcers and inflammation make HIV easier to acquire.
Structure
- Herpes: the intact vesicle is intraepidermal; by biopsy it is usually an ulcer with an acute inflammatory bed. Infected cells show the three Ms: multinucleation, molding and margination of chromatin.
- Molluscum: a cup-shaped lobule of hyperplastic epidermis whose cells fill with large eosinophilic to purple cytoplasmic inclusions that push the nucleus aside.
- Candida: superficial infection; pseudohyphae and yeasts among squamous cells with neutrophils, seen on smear, KOH preparation or PAS stain.
- Trichomonas: the cervix shows dilated vessels and punctate haemorrhages (colpitis macularis); smears show small grey-green organisms and squamous cells with perinuclear halos.
- Bacterial vaginosis: little inflammation; squamous cells carpeted by coccobacilli so their borders look blurred (clue cells).
Step by step
- The normal vaginal flora is dominated by lactobacilli, which keep the pH low and crowd out other organisms.
- Antibiotics, hormones, douching, sexual exposure or immune changes disturb that balance or introduce a pathogen.
- Fungi overgrow (Candida), anaerobes replace lactobacilli (bacterial vaginosis) or a sexually transmitted organism takes hold (Trichomonas, herpes, mycoplasmas).
- Herpes infects the epithelium, kills it to form ulcers, then travels up sensory nerves and becomes latent in the ganglia.
- Stress, hormones or weaker immunity reactivate the virus, which returns down the nerve and causes recurrent lesions and shedding.
Lower genital tract infections compared
| Infection | Organism type | What the patient notices | What the smear or biopsy shows |
|---|---|---|---|
| Genital herpes | DNA virus (HSV-2, also HSV-1) | Painful vesicles and ulcers, tender nodes, painful urination | Multinucleated cells with ground-glass nuclear inclusions |
| Molluscum contagiosum | Poxvirus | Small pearly papules with a central dimple | Molluscum bodies in the cytoplasm |
| Vulvovaginal candidiasis | Yeast | Itch, burning, thick white discharge | Pseudohyphae and budding yeast |
| Trichomoniasis | Flagellated protozoan | Frothy yellow-green discharge, irritation | Motile flagellates; punctate cervical haemorrhages |
| Bacterial vaginosis | Overgrowth of Gardnerella and anaerobes | Thin grey discharge with a fishy odour, little inflammation | Clue cells, few lactobacilli |
Clinical notes
- A primary herpes infection near delivery carries the highest risk of neonatal herpes; active lesions at labour are a reason for caesarean delivery.
- Genital ulcers and inflammation increase both acquisition and transmission of HIV.
- Bacterial vaginosis and mycoplasmas (Mycoplasma genitalium, Ureaplasma) are linked to chorioamnionitis, preterm rupture of membranes and preterm birth.
- In adults, genital molluscum is usually sexually transmitted; in children it spreads by contact and shared towels.
In the lab
- Herpes: PCR of lesion fluid is the most sensitive test; viral culture and direct immunofluorescence are alternatives; serum antibodies mean past infection, not a primary one.
- Wet mount and pH of discharge, KOH preparation and Gram stain separate candida, trichomonas and bacterial vaginosis; nucleic acid tests detect trichomonas and mycoplasmas.
Test yourself
Think of the answer, then tap the question to see it.
What does a smear from a herpetic vulvar ulcer show?
Multinucleated squamous cells with nuclear molding and ground-glass intranuclear inclusions, with chromatin pushed to the edge of the nucleus.
What are clue cells and which condition do they point to?
Squamous cells covered by coccobacilli so their borders look blurred; they point to bacterial vaginosis, where Gardnerella and anaerobes replace lactobacilli.
Which infection gives a strawberry cervix?
Trichomoniasis: punctate haemorrhages on the cervix (colpitis macularis) caused by the flagellated protozoan Trichomonas vaginalis.
Why does herpes recur after the ulcers heal?
During the first infection the virus travels up sensory nerves and stays latent in the sacral ganglia; reactivation sends it back to the skin and mucosa.
Elsewhere in DurgiPedia
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Bacterial Vaginosis (StatPearls (NCBI Bookshelf), 2026); Vaginal Candidiasis (StatPearls (NCBI Bookshelf), 2026); Trichomoniasis (StatPearls (NCBI Bookshelf), 2026).
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Representative model, for educational purposes only.