Common Causes of Vaginal Discharge

When a female has symptoms of abnormal vaginal discharge & odor, vaginal pain & itchiness, and/or burning sensation when passing urine, she may be infected by one of these organisms: bacteria, fungus or protozoa parasite.

Bacteria infection in the vagina is called bacterial vaginosis. It is most commonly caused by Gardnerella vaginosis, or less commonly by Bacteroides, Fusobacterium, Ureaplasma, Mycoplasma etc, when the balance of good & bad bacteria in the vagina is disrupted. Besides vaginal irritation, bacterial vaginosis typically produces fishy-smell thin gray/white homogenous vaginal discharge which is adherent to the vaginal wall. It is not considered as a sexually transmitted disease as sexually inactive female can still be infected. However, the risk of infection increases with multiple sexual partners and douching.

      Bacterial vaginosis: white thin discharge, with fishy smell

Vaginal candidiasis is a fungal infection in vagina usually caused by yeast Candida albicans. Certain amount of yeast live in the normal vaginal tract with other bacteria. When the amount of yeast overgrow other bacterias, such as when broad-spectrum antibiotics are taken or poor immunity, vaginal candidiasis can occur. The vaginal discharge is white and curd-like but lack odor. It is quite common and is not considered a sexually transmitted disease.

      Candidiasis: White thick curd-like discharge

Trichominiasis is caused by infection of a protozoa called Trichomonas vaginalis. It typically produces greenish & yellowish foul-smelling vaginal discharge and causes significant pain during sexual intercourse. It is a sexually transmitted disease and can affect male as well. It is said that 70% of infected female have no symptoms though.

      Strawberry Cervix: typical in Trichomoniasis

All three types of infection can occur during pregnancy, and are known to increase the risk of preterm labour and low birth weight. To know what type of organism it is, vaginal fluid/discharge can be taken and study under a microscope. 

Bacterial vaginosis is the commonest cause of vaginitis, followed by candidiasis and trichomoniasis. Sometimes it is not easy to differentiate them without lab tests.

These infection can be treated when the type of culprit is identified or suspected:

• Bacterial vaginosis: 
• oral metronidazole 500mg twice a day for 7 days OR
• oral metronidazole 2g as single dose OR
• oral clindamycin 300mg twice a day for 7 days OR
• topical clindamycin (cream/suppository) at bedtime for 3 nights

• Vaginal candidiasis: all types of anti-fungal (oral OR topical - in the vagina)
• oral fluconazole 150mg single dose OR
• oral itraconazole 200mg twice a day for one day OR
• anti-fungal cream/suppository at bedtime usually for 3-7 days

• Trichomoniasis: 
• oral metronidazole 500mg twice a day for 7 days OR
• oral metronidazole 2g as single dose

Most infection can recur after treatment. Sometimes sexual partners have to be treated as well. For treatment during pregnancy, please consult your doctor.