Hematometra develops when the uterus becomes distended with blood secondary to obstruction or atresia of the lower reproductive tract—the uterus, cervix or vagina—which would otherwise provide an outflow for menstrual blood. It is most commonly caused by congenital abnormalities, including imperforate hymen, transverse vaginal septum or vaginal hypoplasia. Other causes are acquired, such as cervical stenosis, intrauterine adhesions, endometrial cancer, and cervical cancer.

Additionally, hematometra may develop as a complication of uterine or cervical surgery such as endometrial ablation, where scar tissue in the endometrium can "wall off" sections of endometrial glands and stroma causing blood to accumulate in the uterine cavity. It can also develop after abortion, as well as after childbirth. It can also develop after female genital mutilation.

Hematometra or hemometra is a medical condition involving collection or retention of blood in the uterus. It is most commonly caused by an imperforate hymen or a transverse vaginal septum.

It is generally treated surgically, with a hymenotomy or other surgery to remove any tissue that blocks the menstrual flow.

Hematocolpos is a medical condition in which the vagina fills with menstrual blood. It is often caused by the combination of menstruation with an imperforate hymen. It is sometimes seen in Robinow syndrome, uterus didelphys, or other congenital conditions.

A related disorder is hematometra, where the uterus fills with menstrual blood. It presents after puberty as primary amenorrhoea, recurrent pelvic pain with a pelvic mass. This can be caused by a congenital stenosis of the cervix, or by a complication of a surgical treatment.

Cervical agenesis is estimated to occur in 1 in 80,000 females. It is often associated with deformity of the vagina; one study found that 48% of patients with cervical agenesis had a normal, functional vagina, while the rest of the cases were accompanied by vaginal hypoplasia.

Cryptomenorrhea or cryptomenorrhoea, also known as hematocolpos, is a condition where menstruation occurs but is not visible due to an obstruction of the outflow tract. Specifically the endometrium is shed, but a congenital obstruction such as a vaginal septum or on part of the hymen retains the menstrual flow. A patient with cryptomenorrhea will appear to have amenorrhea but will experience cyclic menstrual pain. The condition is surgically correctable.

The patient usually presents at the age of puberty when the commencement of menstruation blood gets collected in the vagina and gives rise to symptoms.

A simple cruciate incision followed by excision of tags of hymen allows drainage of the retained menstrual blood. A thicker transverse vaginal septum can be treated with Z-plasty. A blind vagina will require a partial or complete vaginoplasty. Hematosalpinx may require laprotomy or laparoscopy for removal and reconstruction of affected tube.

Infertility may require assisted reproductive techniques.

If untreated, the accumulation of menstrual fluid in the uterus caused by cervical agenesis can lead to hematocolpos, hematosalpinx, endometriosis, endometrioma and pelvic adhesions.

Vaginal hypoplasia is estimated to occur in 1 in 4,000–5,000 live female births. It is often unnoticed until adolescence when pain and a lack of menstrual flow indicates the condition.

Most of the risk factors for endometrial cancer involve high levels of estrogens. An estimated 40% of cases are thought to be related to obesity. In obesity, the excess of adipose tissue increases conversion of androstenedione into estrone, an estrogen. Higher levels of estrone in the blood causes less or no ovulation and exposes the endometrium to continuously high levels of estrogens. Obesity also causes less estrogen to be removed from the blood. Polycystic ovary syndrome (PCOS), which also causes irregular or no ovulation, is associated with higher rates of endometrial cancer for the same reasons as obesity. Specifically, obesity, type II diabetes, and insulin resistance are risk factors for Type I endometrial cancer. Obesity increases the risk for endometrial cancer by 300–400%.

Estrogen replacement therapy during menopause when not balanced (or "opposed") with progestin is another risk factor. Higher doses or longer periods of estrogen therapy have higher risks of endometrial cancer. Women of lower weight are at greater risk from unopposed estrogen. A longer period of fertility—either from an early first menstrual period or late menopause—is also a risk factor. Unopposed estrogen raises an individual's risk of endometrial cancer by 2–10 fold, depending on weight and length of therapy. In trans men who take testosterone and have not had a hysterectomy, the conversion of testosterone into estrogen via androstenedione may lead to a higher risk of endometrial cancer.

Vaginal hypoplasia is the underdevelopment or incomplete development of the vagina. It is a birth defect or congenital abnormality of the female genitourinary system.

Some therapies for other forms of cancer increase the lifetime risk of endometrial cancer, which is a baseline 2–3%. Tamoxifen, a drug used to treat estrogen-positive breast cancers, has been associated with endometrial cancer in approximately 0.1% of users, particularly older women, but the benefits for survival from tamoxifen generally outweigh the risk of endometrial cancer. A one to two-year course of tamoxifen approximately doubles the risk of endometrial cancer, and a five-year course of therapy quadruples that risk. Raloxifene, a similar drug, did not raise the risk of endometrial cancer. Previously having ovarian cancer is a risk factor for endometrial cancer, as is having had previous radiotherapy to the pelvis. Specifically, ovarian granulosa cell tumors and thecomas are tumors associated with endometrial cancer.

Low immune function has also been implicated in endometrial cancer. High blood pressure is also a risk factor, but this may be because of its association with obesity. Sitting regularly for prolonged periods is associated with higher mortality from endometrial cancer. The risk is not negated by regular exercise, though it is lowered.