What causes swollen labia minora?

Causes of Swollen Labia Minora

Swollen labia minora results from infectious, inflammatory, traumatic, or dermatologic conditions, with the most common causes being Bartholin gland infection, contact dermatitis, trauma (including sexual activity), lichen sclerosus, and sexually transmitted infections.

Infectious Causes

Bartholin Gland Infection

• When Bartholin glands become infected, they present with swelling, erythema, and tenderness that can extend into the entire labia minora 1
• Although any vaginal organism can cause infection, STI pathogens including gonorrhea and chlamydia are common culprits 1
• The glands are located at the 4 and 8 o'clock positions in the posterior vestibule 1

Sexually Transmitted Infections

• Herpes simplex virus can cause vulvar swelling accompanied by painful ulcerations 1
• Gonorrhea and chlamydia may present with inflammation and swelling 1
• Syphilis (condylomata lata) can manifest as flesh-colored papules that may be confused with warts 1

Skene Gland Infection

• Infection presents as erythematous areas lateral to the urethra with potential swelling 1

Traumatic Causes

Sexual Trauma

• Vigorous sexual intercourse can cause vulvar hematoma with significant swelling and tenderness of the labia majora and minora 2
• Hematomas may contain substantial blood volume (up to 150 cubic centimeters) requiring surgical evacuation 2
• Trauma from sexual activity is the most common cause of non-obstetrical vulvar hematomas 2

Piercing-Related Complications

• Labia minora piercings heal in 2-6 weeks but can develop infection, pain, bleeding, hematoma formation, or allergic reactions during this period 1
• Multiple adverse outcomes including cyst formation and hypertrophic scarring can cause persistent swelling 1

Dermatologic/Inflammatory Causes

Lichen Sclerosus

• Presents as porcelain-white papules and plaques with areas of ecchymosis affecting the interlabial sulci and labia minora 1
• Has bimodal presentation peaks in prepubertal girls and postmenopausal women 1
• Main symptom is itch (worse at night), but pain occurs with erosions or fissures 1
• In children, ecchymosis may be striking and potentially mistaken for sexual abuse 1
• Autoimmune etiology with associations to other autoimmune diseases 1

Contact Dermatitis and Allergic Reactions

• Inflammation with redness and swelling can result from irritants or allergens 1
• Hypopigmentation changes may accompany chronic inflammation 1

Ulcus Vulvae Acutum

• Acute painful vulvar ulcerations with swelling of labia minora following viral infections (particularly influenza A) 3
• Can present with copious discharge and multiple ulcerations 3
• Clinically resembles genital aphthous ulcers 3

Anatomic/Congenital Causes

Labia Minora Hypertrophy

• Can be congenital or acquired through chronic irritation, exogenous androgenic hormones, or stretching 4, 5
• Causes inflammation, poor hygiene issues, and interference with activities 4, 5
• May present asymmetrically causing self-consciousness 4, 5

Critical Pitfalls to Avoid

• Do not dismiss ecchymosis in prepubertal girls as definitively indicating sexual abuse without considering lichen sclerosus, but also do not exclude abuse solely based on LS diagnosis 1
• Suspicious features requiring further investigation include LS in older prepubertal girls, associated STIs, or other abuse signs 1
• Always assess for STI pathogens when Bartholin or Skene gland infections are present 1
• Consider vulvar hematoma in post-coital presentations even without obvious external trauma 2
• Perform viral culture for HSV and serologic tests for syphilis when ulcers are present 1