Can β-Human Chorionic Gonadotropin in Uterine Cavity Lavage Serve as a Differential Diagnostic Tool for Pregnancies of Unknown Location? Insights from a Prospective Study.

Abstract

Objectives: This prospective study aimed to evaluate whether β-human chorionic gonadotropin (β-hCG) levels in uterine cavity lavage fluid can serve as a diagnostic tool to differentiate ectopic pregnancy from failed intrauterine pregnancy in patients with pregnancy of unknown location (PUL).

Design: This prospective interventional study was conducted at a tertiary referral center, enrolling a total of 113 hemodynamically stable patients with PUL.

Materials and methods: All enrolled patients underwent endometrial aspiration (EA), which was performed using a flexible Karman cannula to obtain tissue samples for histopathological examination. Based on histopathological results combined with clinical follow-up data, participants were subsequently categorized into two groups: those diagnosed with ectopic pregnancy and those with failed intrauterine pregnancy. Prior to performing EA, uterine lavage was performed to collect fluid samples from the endometrial cavity, and β-hCG levels were quantitatively measured in the lavage specimens. The primary outcome measure was the comparison of lavage β-hCG concentrations between the ectopic and failed intrauterine pregnancy groups, with the intent to establish a diagnostic cutoff value for clinical application. Secondary outcome measures included comparisons of serum β-hCG levels, endometrial thickness assessed via imaging, and clinical and demographic parameters between the groups.

Results: After exclusion criteria and incomplete data removal, 103 patients were included in the final analysis, comprising 81 individuals diagnosed with ectopic pregnancy and 22 with failed intrauterine pregnancies. Statistical analysis showed that the mean age was significantly higher in the failed intrauterine pregnancy group versus the ectopic pregnancy group (p = 0.03), while other demographic and clinical variables did not differ significantly between the groups. β-hCG concentrations in uterine lavage fluid were lower in the ectopic group compared to the failed intrauterine pregnancy group. This difference was significant in absolute terms (mean ± SD: 122.78 ± 115.41 mIU/mL vs. 321.09 ± 495.19 mIU/mL, p = 0.008) and after normalization to total protein content in the lavage fluid (100.67 ± 208.19 mIU/mg vs. 294.32 ± 510.69 mIU/mg, p = 0.001). In contrast, serum β-hCG levels and endometrial thickness did not show statistically significant differences between the two groups.

Conclusion: Lavage β-hCG appears promising as a tool for early PUL assessment by identifying the pregnancy location. This standardized methodology could expedite the diagnosis of high-risk pregnancies through a less invasive approach, thereby enhancing ectopic pregnancy management. Further research is needed to improve accuracy.