Risk factors and predictors of persistent ectopic pregnancy after interstitial pregnancy surgery

Abstract

Objective: To explore the related factors and early predictors of persistent ectopic pregnancy (PEP) in patients with interstitial pregnancy after operation. Methods: The clinical data of patients with interstitial pregnancy who underwent surgery in the Department of Obstetrics and Gynecology of Peking Union Medical College Hospital from January 2013 to August 2021 were collected. Patients were divided into two groups according to whether PEP occurred (8 patients in PEP group and 124 patients in non-PEP group). Using propensity score matching (PSM) analysis, the basic data, surgical methods, the ratio of postoperative to preoperative serum β-human chorionic gonadotropin (β-hCG), the duration of when the serum β-hCG had decreased to normal after the operation were compared and analyzed to find the related factors of PEP after interstitial pregnancy surgery. The sensitivity and specificity of the ratio of 24-48 hours postoperative β-hCG to preoperative β-hCG in predicting postoperative PEP were evaluated by drawing receiver operating characteristic (ROC) curve. Results: Before PSM, the ages of patients in PEP group and non-PEP group were (30.0±4.0) and (32.4±5.0) years old, respectively, P>0.05. After PSM, 8 PEP patients in the study group and 29 patients in the control group were matched successfully, and the ages of the two groups were (30.0±4.0) and (30.1±3.2) years old, respectively, P>0.05. After PSM, there was no significant difference in gravidity, parity, menopausal days, preoperative β-hCG level and maximum diameter of lesions, all P>0.05. After PSM, the proportion of patients with maximum diameter ≤ 2.6 cm in PEP group (6/8) was significantly higher than that in control group (31.0%, 9/29), P=0.025. The median (Q1, Q3) of the ratio of 24-48 hours postoperative β-hCG to preoperative β-hCG ratio was 52.9% (49.9%, 59.7%) in the PEP group, which was significantly higher than 31.5% (23.8%, 39.0%) in the control group (P=0.001); The median (Q1, Q3) of duration of when the serum β-hCG had decreased to normal after the operation in PEP group was 52.0 (34.8, 92.0) d, which was significantly higher than 24.0 (20.5, 31.0) d in control group (P<0.001). The ROC-Area Under Curve of the ratio of 24-48 hours postoperative β-hCG to preoperative β-hCG ratio for predicting postoperative PEP in the two groups was 0.892 (95%CI: 0.725-1.000, P=0.001). The cut-off value for predicting PEP was 48.5%, where the diagnostic sensitivity was 87.5%, the specificity was 93.1%. Conclusions: In the operation of interstitial pregnancy, the maximum diameter of lesion ≤ 2.6 cm is a related factor for postoperative PEP. There was no significant difference in the risk of PEP between cornuotomy and cornectomy. The ratio that 24-48 hours postoperative β-hCG/preoperative β-hCG ratio greater than 48.5% was a reference index for predicting postoperative PEP and guiding treatment.