Four mRNAs linked with pelvic inflammatory illness were revealed to be strongly associated with neutrophil immune infiltration, notably CALML4, COQ10B, DCPS, and PPP2R1A. The ROC revealed that CALML4 (area under the curve (AUC): 0.769, 95% confidence interval (CI): 0.638–0.881), COQ10B (AUC: 0.742, 95% CI: 0.587–0.881), PPP2R1A (AUC: 0.733 95% CI: 0.593–0.857), and DCPS (AUC: 0.745, 95% CI: 0.571–0.900) were potential markers for predicting pelvic inflammatory disease. Here, CALML4 is linked to pelvic inflammatory disease.