Role of the systemic immune-inflammation index in threatened abortion patients and predicting of abortion

Our study aimed to compare the systemic immune inflammation index (SII), one of the hematological inflammation parameters, between pregnant women diagnosed with threatened abortion (TA) and healthy pregnant women, and to evaluate the prediction of abortion in pregnant women with TA.

This retrospective study compared 150 patients with TA group and 150 age- and gestational week-matched healthy pregnant women (control group). Complete blood count parameters were assessed. SII, white blood cells (WBC), neutrophil to lymphocyte ratio (NLR), red cell distribution width (RDW), plateletcrit (PCT), platelet distribution width and monocyte to lymphocyte ratio (MLR) values were calculated. The SII value was calculated as follows: platelet count × (neutrophil/lymphocyte).

SII, NLR, MLR, WBC, RDW, and PCT values were significantly higher in the TA group compared to the control group (923 ± 683 vs. 579 ± 364 [p < 0.001], 3.3 ± 2.0 vs. 2.1 ± 1.1 [p < 0.001], 0.3 ± 0.1 vs. 0.2 ± 0.2 [p < 0.001], 9.84 ± 2.87 vs. 8.6 ± 1.6 [p < 0.001], 13.9 ± 1.9 vs. 14.4 ± 2.3 [p = 0.032] and 0.3 ± 0.1 vs. 0.2 ± 0.0 [p < 0.001], respectively). Using receiver operating characteristics curve analysis to predict abortion in AI patients, the highest area under the curve was found for SII (0.727 for SII and 0.666 for NLR).

SII, NLR, MLR, RDW, and platelet to lymphocyte ratio (PLR) levels were significantly increased in patients with TA. This study supports the idea that several inflammatory pathways may play an important role in the pathogenesis of this disorder. SII may be a much better marker than NLR and PLR for predicting the inflammatory status of the disease and abortion in an ongoing pregnancy.