Predisposing conditions include Prolonged rupture of the membranes Prolonged labor Repeated digital cervical examination Chorioamnionitis Internal fetal or uterine monitoring Cesarean delivery Retention or manual removal of placental fragments in the uterus Postpartum hemorrhage Bacterial colonization of the lower genital tract Bacterial vaginosis Anemia Diabetes Young maternal age Low socioeconomic status Infection tends to be polymicrobial; the most common pathogens include the following: Gram-positive cocci (predominantly group B streptococci, Staphylococcus epidermidis, and Enterococcus species) Anaerobes (predominantly peptostreptococci, Bacteroides species, and Prevotella species) Gram-negative bacteria (predominantly Gardnerella vaginalis, Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis) Infection may occur in the endometrium (endometritis), parametrium (parametritis), and / or myometrium (myometritis).