Prediction Model and Novel Classification System for Complications after Minimally Invasive Hysterectomy

The aim of the study was to develop and validate a novel model for predicting complications in minimally invasive hysterectomy and to define a standardized classification system, the Hysterectomy Complication Classes (HCCs).

This is a retrospective cohort study using merged data from four national Swedish registries. Data were randomly split into development and validation datasets. Multivariable logistic regression was used to identify risk factors and construct the prediction model, which was evaluated using area under the receiver operating characteristic curve (ROC_AUC). Participants/Materials: There were a total of 60,424 benign hysterectomies recorded in the Swedish National Quality Register for Gynecological Surgery, the Swedish National Drug Registry, Statistics Sweden, and the Swedish National Patient Registry.

The study setting comprised nationwide Swedish population-based registries covering benign hysterectomy procedures performed across Sweden.

The intervention consisted of minimally invasive hysterectomy performed using vaginal, laparoscopic, or robotic techniques, with uterus weight and surgical indication as key exposure variables.

Multivariable logistic regression models estimated odds ratios (ORs) for risk factors associated with a composite complication outcome. The final model was applied to the validation dataset, and predictive performance was assessed using the ROC_AUC.

The primary outcome was a composite complication measure including perioperative complications, blood loss >300 mL, conversion to open surgery, postoperative complications, reoperation, or antibiotic prescription within 6 weeks.

Key risk factors for complications were indication for hysterectomy, BMI, previous cesarean section, age, and uterus size, with a significant interaction between uterus size and surgical technique. The highest risk was observed in patients with uterus weight >1 kg undergoing vaginal hysterectomy (VH) (adjusted OR 25.5, 95% CI 3.3-199.8). Predicted complication probabilities were used to define five HCCs, ranging from HCC 1 (0-20%) to HCC 5 (81-100%). Validation demonstrated strong predictive accuracy across risk strata.

The composite outcome includes heterogeneous complications of varying clinical significance. Registry-based data may be subject to misclassification or underreporting. External validation outside Sweden has not yet been performed.

This comprehensive predictive model and the proposed HCC classification system provide a structured approach to estimating complication risk in minimally invasive hysterectomy. By accounting for patient variability and surgical factors, the HCC system supports individualized preoperative counseling and enhances comparability between surgical techniques.