Etiology

Potential causes can be divided according to age: premenarchal, during the reproductive years (nonpregnant and pregnant), and postmenopausal.

Premenarchal bleeding

Uterine bleeding occurs in 3% to 5% of female neonates on day 3-5 of life.[9] The neonatal endometrium is shed following maternal progesterone withdrawal.[10]

Bleeding after this age (and prior to menarche) is always abnormal. Bleeding is associated with early development of secondary sexual characters, in particular breast development, and probably indicates precocious puberty.

Trauma is the most common cause of vaginal bleeding in girls younger than 10 years.[1] Local inflammation of the vagina due to infection or a foreign body (e.g., toilet paper) can also cause bleeding.[11]

Rare but serious causes of premenarchal bleeding include sexual abuse and childhood genital malignancy of the vagina.[1][12] Rhabdomyosarcoma is the most common lower genital tract malignancy in young girls, with a peak incidence before age 2 years. Tumors appear as a ‘grape-like’ cluster of tissue.[13]

Bleeding during reproductive age (not pregnant)

Abnormal bleeding occurs most commonly in this group.

The bleeding source may be anywhere in the reproductive tract including the uterus, the cervix, or the vagina itself. Abnormal uterine bleeding, including abnormal menstrual bleeding and intermenstrual bleeding, is discussed in a separate topic, Evaluation of abnormal uterine bleeding.

Postcoital bleeding is often caused by cervical ectropion, polyps, or cervicitis. Cervical cancer and vaginal cancer are serious causes of postcoital bleeding. Condylomata acuminata and vaginitis may also cause vaginal bleeding.

Cervical ectropion

Cervical ectropion (also called cervical erosion) occurs when endocervical glandular epithelium expands beyond the os and becomes visible on the ectocervix. The ectropion tissue is darker pink than the surrounding squamous epithelium and may be friable. Ectropions are commonly seen in adolescent women, pregnant women, and women using hormonal contraception.[14] Most are asymptomatic.[Figure caption and citation for the preceding image starts]: Cervical erosionScience Photo Library; used with permission [Citation ends].com.bmj.content.model.assessment.Caption@60c12dd3

Cervical polyp

Polyps are benign neoplastic growths which can arise from the cervix or endocervix. They typically occur in multiparous patients ages over 40 years. They are often smooth, lobular, and friable. They may be detected incidentally during a speculum examination or cause postcoital bleeding.[14][Figure caption and citation for the preceding image starts]: Cervical polypScience Photo Library; used with permission [Citation ends].com.bmj.content.model.assessment.Caption@22a1cf45

Cervicitis

Infection of the cervix can cause bleeding and is often accompanied by mucopurulent discharge. The most common causative organisms are Chlamydia trachomatis and Neisseria gonorrhoeae, although no organism is identified in many cases.​[15]​​Trichomonas vaginalis, Mycoplasma genitalium, and herpes simplex virus can also cause infectious cervicitis. Infection with these organisms can also cause symptoms of urethritis.

Cervicitis may also occur without infection if the cervix is exposed to mechanical or chemical irritants, e.g., pessaries, diaphragms, tampons, spermicides, or feminine hygiene products.[16][17]

Cervical cancer

In addition to vaginal bleeding, cervical cancer may cause malodorous vaginal discharge, although this is rarely the only symptom. Dyspareunia and pelvic or back pain suggest more advanced disease.

Human papillomavirus (HPV) infection is the most important etiologic factor.[18]​ Incidence of cervical cancer correlates with early onset of sexual activity, multiple sexual partners, cigarette smoking, immunosuppression, low socioeconomic status, and oral contraceptive use.[19][20][21]

Globally, there were approximately 660,000 new cases of cervical cancer, and 350,000 related deaths in 2022.[18]​ One systematic review of UK women with postcoital bleeding reported that the risk of cervical cancer is 1 in 44,000 at age 20-24 years, 1 in 5600 at age 25-35 years, 1 in 2800 at age 35-44 years, and 1 in 2400 at age 45-54 years.[22]

Vaginal cancer

Primary vaginal cancer is rare, accounting for <1% of cancers affecting individuals assigned female at birth; neoplastic lesions are more commonly metastases.[23]​ HPV infection is the most important etiologic factor.[23]

Vaginitis

Although vaginitis is a common condition, it is rarely severe enough to cause bleeding. There may be associated vaginal discharge, pruritus, dyspareunia, and dysuria.

Condylomata acuminata

Condylomata acuminata (genital warts) are caused by HPV infection. The infection manifests as verrucous fleshy papules that may coalesce into plaques. The warts can occur anywhere in the anogenital area, including the vaginal and cervical mucosal surfaces, where local trauma can cause bleeding.[24]

Bleeding during pregnancy

Any condition which causes vaginal bleeding in a non-pregnant woman may also cause bleeding in a pregnant woman. The clinician must also consider additional, pregnancy-specific causes. The likely cause of bleeding varies according to gestation.

First trimester

Vaginal bleeding in early pregnancy could be caused by an ectopic pregnancy or miscarriage.[25]

Ectopic pregnancy refers to the implantation of an embryo outside the uterus, mostly commonly in the fallopian tube.[26] Common symptoms are abdominal pain, amenorrhea, and vaginal bleeding.[25]

Red flags include unstable vital signs or signs of intraperitoneal bleeding (e.g., acute abdomen, shoulder pain, cervical motion tenderness); urgent surgical intervention may be required to avoid maternal shock and even death.

Risk factors include age over 35 years, previous ectopic pregnancy, smoking, history of pelvic inflammatory disease, prior tubal surgery, and use of assisted reproductive technologies.[26] Compared with pregnancies in the general population, a higher proportion of pregnancies conceived with an intrauterine device in place are ectopic.[26][27]

Miscarriage is an involuntary, spontaneous loss of a pregnancy before 20-24 completed weeks (gestation varies, depending on country). It is associated with unprovoked vaginal bleeding with or without suprapubic pain. The majority of miscarriages occur in the first trimester. About 30% of all pregnancies may end in miscarriage.[28]

Second and third trimesters

Vaginal bleeding in the second or third trimester occurs less commonly than in the first trimester. Pathologic causes of bleeding include bleeding from the cervix with preterm labor, bleeding from placenta previa, vasa previa, placental abruption, or uterine rupture.[29] Miscarriage and cervical change with labor give rise to physiologic bleeding.​

Placental abruption (premature separation of the placenta from the uterus) complicates 0.3% to 1% of births.[30] Some cases occur following abdominal trauma.[31] The precise etiology of nontraumatic cases is unknown. Risk factors include pre-eclampsia, smoking, hypertension, maternal cocaine use, and previous placental abruption.[32][33][34] Bleeding is usually accompanied by abdominal pain and contractions.

Placenta previa is defined as the placenta overlying the cervical os. It can be complete, partial, or marginal, and may resolve as pregnancy progresses. Symptomatic placenta previa typically presents as second or third trimester painless vaginal bleeding.[29]​ Risk factors include previous abnormal placentation, previous cesarean delivery, advanced maternal age, increasing parity, in vitro fertilization, short interpregnancy intervals, and illicit drug use.[35][36]

Low-dose acetylsalicylic acid (ASA) for the prevention of preeclampsia does not appear to increase risk for antepartum bleeding.[37][38] ASA to prevent preeclampsia may increase risk for postpartum bleeding; evidence is inconsistent.[39][40][41][42]​​​​​​​​​

Postmenopausal bleeding

Vaginal bleeding is common in the first 4 to 6 months of estrogen and progesterone hormone replacement therapy (HRT). Persistent postmenopausal vaginal bleeding, and any postmenopausal bleeding in a woman who is not using HRT, requires further investigation.

Over 90% of women with endometrial cancer experience postmenopausal bleeding, and 9% of women with postmenopausal bleeding have endometrial cancer.[43]

Postmenopausal bleeding is also associated with ovarian cancer.[44]

Atrophic vaginitis associated with hypoestrogenism is common in postmenopausal women. Bleeding associated with atrophic vaginitis may be encountered after mechanical trauma associated with intercourse, with the use of imperfectly fitting vaginal pessaries, or unprovoked.

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