The aim of this cross-sectional study is to evaluate the hidden blood loss in patients who underwent open radical hysterectomy and identity its risk factors.

The electronic medical data of 100 patients who undergo open radial hysterectomy in the following year to treat cervical cancer will be analyzed retrospectively in this study. The amount of hidden blood loss will be calculated according to Gross's formula. And multiple linear regression analysis will be employed to identify its risk factors.

Inclusion Criteria:

1. Volunteer to participate in the study with informed consent;
2. Females aged 20-80 who are confirmed with cervical cancer and are treated with open radical hysterectomy and pelvic lymphadenectomy.

Exclusion Criteria:

1. Pregnancy, lactation, postmenopause, or planned pregnancy within two years;
2. Suspected or identified as other tumors of genital tract;
3. History of hyperparathyroidism, infectious diseases (tuberculosis, AIDS), autoimmune diseases, or digestive system diseases (malabsorption, crohn disease and dysentery);
4. Other diseases or heavy injuries that will interfere with the results;
5. Simultaneous participation in another clinical study with investigational medicinal product(s) or researcher thinks the subjects are not suitable for this trial.

The planned sample size was based on data from a previous study, in which the standard deviation was 5. We assumed an one-tailed α error of 0.05 and a sampling error of 1.0. we propose to enroll 105 participants and allow for a dropout rate of 10% for an effective sample size of 100.