Small uterine septum is an important risk variable for preterm birth

To evaluate whether a uterus with a small septum (arcuate uterus or class VI according to the American Fertility Society (AFS) classification) behaves similarly to a uterus with a larger septum (septate or subseptate uterus or AFS class V).

Observational study included 826 singleton deliveries to 730 women with a history of hysteroscopic resection of the uterine septum. Data on deliveries were obtained from the National Perinatal Registry of Slovenia (NPIS). Multiple gestations were excluded. We analysed and compared perinatal outcomes before and after hysteroscopic resection in two groups of women: in women with a small uterine septum (Group A) and in those with a larger uterine septum (Group B). Data on the septum length were obtained during hysteroscopic resection by comparing the length of the 1.4-cm long yellow tip of the electric knife to the length of the resected septum. A small uterine septum was defined as having a length of 1.3-1.5 cm.

The preterm birth rate in Group A (n=420) was 33.9% before and 7.2% after hysteroscopic resection (P<0.001); the preterm birth rate in Group B (n=406) was 36.5% before and 8.0% after hysteroscopic resection (P<0.001). The very preterm birth rate in Group A was 12.5% before and 3.1% after hysteroscopic resection (P<0.001); the very preterm birth rate in Group B was 15.0% before and 2.9% after hysteroscopic resection (P<0.001). After surgery, we registered a decreased need for neonatal intensive care, as well as a significant decrease in stillbirth and neonatal death rates in both groups of patients.

Similarly to a large uterine septum, a small uterine septum or arcuate uterus is an important hysteroscopically preventable risk variable for preterm birth.