Post-cesarean section endometritis accounts for 80 to 89.6% of all postpartum endometritis cases. Due to the fact that there is an increasing annual cesarean section rate in Russia, the problem of treating patients with pyoinflammatory complications after abdominal delivery is assuming a particular significance. The paper describes a case of a 30-year-old patient diagnosed with endometritis who was transferred from a Moscow Region’s hospital to the Moscow Regional Research Institute of Obstetrics and Gynecology on day 30 after cesarean section made because of the clinically narrow pelvis. It is highlighted through this clinical case that now postpartum endometritis particularly after cesarean section has a subtle, subclinical undulating course, the cause of which is long-term massive repeated antibacterial therapy cycles: there is improvement and mild clinical manifestations during antibacterial therapy, after discontinuation of the latter, the signs of inflammation and an irreversible change in tissues progress. Attention is given to that patients with postpartum endometritis should only be treated at hospital. Hysteroscopy is indicated for all patients with postpartum endometritis, particularly for the diagnosis of its necrotic forms. The results of this observation suggest that the maximally sparing volume of surgery (removal of uterine scar necrotic parts through normal tissue boundaries and application of secondary sutures, if this is technically possible) is indicated for young women who wish to preserve reproductive function in the presence of pyonecrotic endometritis with a formed incompetent uterine scar in the late postoperative period. The authors declare no conflicts of interest.