Table 2. Key Studies evaluating the monitoring of beta-human chorionic gonadotropin (β-hCG) levels in accurately predicting ectopic pregnancy. .

The studies meeting the inclusion criteria for this review, including clinical prospective, retrospective, cross-sectional, and observational studies, demonstrated that β-hCG levels accurately predicted ectopic pregnancy and indicated related morbidity. Moreover, monitoring β-hCG levels significantly led to the best treatment course for effective resolution of ectopic pregnancy.

IU/L, International Units per Liter; p, Probability Variable.

Authors	Level of Evidence	Type of Study	Sample Size	Study findings
Al Sayed (2011) [24]	II.1	Prospective	160 patients	β-hCG levels positively predicted ectopic pregnancy. β-hCG levels higher than 5000 IU/L indicated significant risk of tubal obstruction (p = 0.0033).
Mavrelos et al. (2015) [25]	II.1	Retrospective	474 patients	Monitoring β-hCG levels helped predict ectopic pregnancy. Moreover, β-hCG estimates effectively determined a treatment course to manage ectopic pregnancy. β-hCG levels higher than 1500 IU/L led to successful resolution of ectopic pregnancy via surgical methods. Whereas β-hCG levels lower than 1500 IU/L necessitated expectant treatment to effectively resolve ectopic pregnancy (p < 0.05).
Orozco et al. (2015) [26]	II.1	Prospective	126 patients	Monitoring β-hCG levels accurately determined the success of medical treatment with Methotrexate in patients with ectopic pregnancy. Patients with successful Methotrexate treatment had median β-hCG levels of 1.482 ± 950 on day zero, 1.469 ± 1314 on day four, and 1.092 ± 1147 on day seven compared to those who failed methotrexate treatment, with their β-hCG levels of 2.166 ± 816 on day zero (p < 0.03), 3.595 ± 2.115 on day four (p < 0.001), and 3.663  ± 2.375 on day seven (p < 0.001), respectively.
Shiravani et al. (2022) [27]	II.1	Cross-sectional	365 patients	β-hCG levels of more than 6419 IU/L predicted surgery as the best treatment plan with 47% sensitivity and 90% specificity (p < 0.01). β-hCG levels also indicated the successful treatment with single-dose Methotrexate treatment. Patients who had successful resolution of ectopic pregnancy with single-dose Methotrexate had β-hCG levels of 1289.44 ± 1433.29 IU/L (p < 0.02) than those who failed treatment had β-hCG levels of 8110.21 ± 10060.76 IU/L.
Surampudi & Gundabatulla (2016) [3]	II.1	Retrospective	337 patients	Initial β-hCG levels indicated the best treatment option to effectively resolve ectopic pregnancy. Patients with an average initial β-hCG level of 3351.10 IU/L had successful treatment with Methotrexate. Whereas patients with higher β-hCG levels successfully resolved ectopic pregnancy through surgery. However, researchers did not perform statistical analysis.
Li et al. (2022) [28]	II.1	Observational	225 patients	Initial β-hCG levels did not indicate if the ectopic pregnancy would be patent or ruptured.   There was no significant difference in pre-treatment β-hCG levels in the study patients with patent ectopic pregnancy than those with tubal rupture (p = 0.3).
Cohen et al. (2022) [29]	II.1	Retrospective	122 patients	Changes in β-hCG levels accurately predicted if the ectopic pregnancy would rupture or remain patent. The β-hCG level percentage change in 48 hours before Methotrexate treatment predicted tubal rupture. For every change in the β-hCG level, the odds ratio was 1.08 with a 95% confidence interval of 1.04 – 1.12 (p < 0.001). Patients with an increment in β-hCG levels by more than 69% 48 hours before Methotrexate treatment had an 85% probability of tubal rupture. Moreover, patients with a β-hCG level increment of less than 20% 48 hours before Methotrexate treatment had a low risk of absolute tubal rupture.
Al Niami et al. (2021) [30]	II.1	Retrospective	30247 patients	β-hCG levels indicated ectopic pregnancy-related morbidity. Patients with ectopic pregnancies had an average β-hCG level of 5509 ± 4131 IU/L and predicted morbidity associated with ectopic pregnancy with a β-coefficient of 0.01 and a 95% confidence interval of 0.0006 – 0.022 (p < 0.04).