Maternal and fetal factors associated with symphyseal disjunction after vaginal delivery: An exploratory case-control study.

OBJECTIVE: Symphyseal disjunction is a rare event in childbirth, occurring almost exclusively after vaginal delivery. Radiologically, it is defined by a symphyseal gap greater than 10 mm. No comparative studies have been done on the potential risk factors involved in its development. The aim of the present study was to describe the circumstances of occurrence and risk factors for symphyseal disjunction. METHODS: This was an exploratory case-control study (1:4). Cases were from literature since January 2010 to December 2023 were joined with disjunctions observed in our center between April 2021 and April 2023. Controls were randomly selected from vaginal deliveries in our center during the same period. RESULTS: A total of 20 cases were observed (12 in the literature, 8 in our center). Pain was constant and gait disturbance frequent (85%). Disjunctions were mostly diagnosed a few days after birth (median 3.5 [1; 5.5] [extremes 0.5-90 days]). Surgical osteosynthesis was required in one quarter of the cases. Comparison with controls showed that neither parity, neonatal weight, instrumental delivery nor delivery conditions were associated with the occurrence of these disjunctions. On the other hand, neonatal head circumference at birth was significantly higher in the disjunction group (35 [34; 36] vs. 33 [32; 34] cm, P < 0.001). Significantly higher values of biparietal diameter were also observed in cases of disjunction compared to controls (84.1 [82.0; 86.1] vs. 81.4 [80.0; 82.9] mm, P = 0.005). CONCLUSION: Symphyseal disjunction is a rare event most often presenting with pain and difficulty in walking after vaginal delivery. Its occurrence seems to be related to the fetal head circumference, and not to the conditions of vaginal delivery.