Endometritis refers to an inflammation of the inner lining of the uterus (endometrium). The condition can be acute or chronic. Acute endometritis is a common cause of postpartum fever. Acute endometritis unrelated to pregnancy is also commonly infectious and a component of pelvic inflammatory disease (PID), which usually presents with salpingitis. Acute endometritis can complicate some gynecologic procedures. Chronic endometritis is less commonly infectious; many patients are asymptomatic.

Postpartum endometritis occurs in approximately 1%-3% of vaginal births and up to 27% of cesarean births. It can also occur after termination of pregnancy. It has been seen to occur up to a few weeks following delivery, although peak incidence is usually within a few days. Infections tend to be polymicrobial. Risk factors include postpartum hemorrhage, internal fetal monitoring, prolonged rupture of membranes, repeated digital vaginal examinations, prolonged labor, operative delivery, and retained placenta. Patients may present with lower abdominal cramping, pelvic tenderness, increased vaginal discharge, pain with intercourse, tachycardia, fever, and chills.

Nonpregnancy-related endometritis is usually caused by ascending infection from cervicitis. It can be acute (as part of PID). Although it could be polymicrobial, Gonorrhea, Chlamydia, group B Streptococcus, or Mycoplasma genitalium is usually implicated. In areas endemic for tuberculosis, this may also be a cause. Risk factors include having multiple sexual partners, recent uterine instrumentation, intrauterine device (IUD) use (more likely copper IUDs), and pelvic radiation creating scar tissue / outflow obstruction. Patients may present with increased abnormal uterine bleeding, vaginal discharge, fever, cramping, pain with intercourse, infertility, bleeding with intercourse, or symptoms of PID.

Chronic endometritis is often asymptomatic. When it is symptomatic, it most commonly presents with abnormal uterine bleeding. The cause of chronic endometritis is unknown in the majority of cases.