Clinical and diagnostic features of uterine subinvolution and postpartum endometritis

Postpartum endometritis (PE) is the leading cause of pyoinflammatory complications in the postpartum period. At the same time, almost every second case of PE is associated with reduced contractility of the myometrium, which manifests as subinvolutive dimensions and volume of the postpartum uterus. However, uterine subinvolution (USI) is not only a nosological entity in its own right but also a pre-stage of PE and has several clinical and laboratory features that require prevention, timely diagnosis, and therapeutic intervention.

Objective: To investigate the clinical, anamnestic, laboratory, and instrumental diagnostic features of USI in women after spontaneous and operative delivery.

Materials and methods: This study retrospectively analyzed 200 records of postpartum women treated at Voino-Yasenetsky Krasnoyarsk State Medical University clinics from 2019 to 2022. Of these, 100 had mild PE, and 100 were diagnosed with uterine subinvolution. Each group was divided into two subgroups consisting of 50 postpartum women after spontaneous birth (SB) and 50 postpartum women after abdominal delivery.

Results: Significant differences were observed in the clinical course of the disease among women in the study groups. Complaints in postpartum women with USI occurred 4 days later (day 13) than those in patients with PE (day 9). After abdominal delivery, clinical manifestations were significantly more common than in the SB subgroups (p<0.05), including lower abdominal pain and bloody discharge in all postpartum women after cesarean section (CS); more than half of the patients had purulent discharge 66/100 (66%], p<0.05). In the CS subgroup, 9/50 (18%), 19/50 (38%), and 13/50 (26%) patients had lower abdominal pain, bloody vaginal discharge, and purulent vaginal discharge, respectively. More pronounced inflammatory changes in the blood tests were characteristic of postpartum women with PE (especially in the CS subgroup) due to higher levels of leukocytes, C-reactive protein, and ESR (p<0.05). Subinvolutive dimensions of the uterus were found by ultrasound in 78% of the women with PE.

Conclusion: USI has several clinical and laboratory features that can be considered as an isolated postpartum complication. The presence of inflammatory changes in the blood tests confirmed the predominance of the infectious component over the reduced contractile function of the myometrium in patients with PE after CS. In women with SB, reduced contractile function of the myometrium prevails without obvious clinical manifestations or inflammatory changes in the blood tests. The results of the present study emphasize the need for timely diagnosis of subinvolutive changes in the uterus.