Ectopic pregnancy
Pelvic inflammatory disease
Interstitial cystitis
Adenomyosis
Ovarian neoplasms
Pelvic adhesions
Irritable bowel syndrome
Colon cancer
Diverticular disease
Systemic Causes
Cirrhosis
Coagulopathy (Von Willebrand disease, ITP)
Group A strep vaginitis (prepubertal girls)
Hormone replacement therapy
Anticoagulants
Selective Serotonin Reuptake Inhibitors (SSRIs)
Hypothyroidism
Polycystic Ovary Syndrome
Secondary anovulation
Reproductive Tract Causes
Adenomyosis
Atrophic endometrium
Dysfunctional uterine bleeding<unk> 
Fibroids
Foreign Body
Infection (vaginitis, PID)
IUD
Neoplasia (especially in women >45 years old or in younger women with other risk factors)
Vaginal Trauma
Endometriosis
Ectopic pregnancy
Pelvic inflammatory disease
Tubo-ovarian abscess
Interstitial cystitis
Adenomyosis
Ovarian neoplasms
Ovarian cyst