Nonspecific vulvovaginitis: This is the most common cause of vaginal discharge in prepubertal girls, often due to poor hygiene, irritation from soap or shampoo, or introduction of bacteria from the gastrointestinal tract. The discharge is typically clear or white and may be accompanied by redness and itching.

Urinary Tract Infection (UTI): UTIs can cause vaginal discharge in young girls, especially if the discharge is accompanied by other symptoms like dysuria, frequency, or abdominal pain.
Pinworms: Pinworm infection can cause vaginal discharge, especially at night, along with perianal itching.
Foreign Body: A foreign body in the vagina can cause a foul-smelling discharge, and it's more common in curious toddlers who may insert objects into their vagina.

Sexual Abuse: Although less common, sexual abuse is a critical diagnosis not to miss, as it can present with vaginal discharge, trauma, or behavioral changes. A thorough investigation and examination are necessary if suspected.
Streptococcal Infection: A streptococcal infection can cause a vaginal discharge and is important to diagnose and treat to prevent complications like rheumatic fever.

Vaginal Tumors: Although extremely rare, vaginal tumors like sarcomas can cause abnormal vaginal bleeding or discharge in young girls.
Imperforate Hymen: A congenital condition where the hymen covers the vaginal opening, which can cause accumulation of menstrual blood (hematocolpos) and subsequent discharge if not diagnosed and treated.
Endocrine Disorders: Certain endocrine disorders, such as precocious puberty, can lead to vaginal discharge due to estrogenization of the vaginal mucosa.