Endometritis is inflammation of the inner lining of the uterus (endometrium). Symptoms may include fever, lower abdominal pain, and abnormal vaginal bleeding or discharge. It is the most common cause of infection after childbirth. It is also part of spectrum of diseases that make up pelvic inflammatory disease.

Endometritis is divided into acute and chronic forms. The acute form is usually from an infection that passes through the cervix as a result of an abortion, during menstruation, following childbirth, or as a result of douching or placement of an IUD. Risk factors for endometritis following delivery include Caesarean section and prolonged rupture of membranes. Chronic endometritis is more common after menopause. The diagnosis may be confirmed by endometrial biopsy. Ultrasound may be useful to verify that there is no retained tissue within the uterus.

Treatment is usually with antibiotics. Recommendations for treatment of endometritis following delivery includes clindamycin with gentamicin. Testing for and treating gonorrhea and chlamydia in those at risk is also recommended. Chronic disease may be treated with doxycycline. Outcomes with treatment are generally good.

Rates of endometritis are about 2% following vaginal delivery, 10% following scheduled C-section, and 30% with rupture of membranes before C-section if preventive antibiotics are not used. The term "endomyometritis" may be used when inflammation of the endometrium and the myometrium is present. The condition is also relatively common in other animals such as cows.