Ectopic Pregnancy Probability Calculator

Bayesian algorithm for diagnosing ectopic pregnancy using clinical, ultrasound, and hCG data

Instructions: Complete each consultation in sequence. Based on the probability result, the app will guide you on whether to proceed with management or schedule the next consultation. This calculator uses Bayes theorem with likelihood ratios from validated clinical data.

First Consultation

Signs and Symptoms ?

Select the clinical presentation. Pain or bleeding of any degree/amount is considered positive.

Risk Factors ?

Risk factors include: previous ectopic pregnancy, previous tubal surgery, history of pelvic inflammatory disease, or infertility.

Transvaginal Ultrasound Findings ?

Definitive findings (IUP, extrauterine fetal heartbeat, or gestational sac) will provide immediate diagnosis.

hCG Level (mIU/mL) ?

The discriminatory zone is 2000 mIU/mL. hCG should be measured using the same kit for all consultations.

Second Consultation (48-72 hours later)

Signs and Symptoms

Risk Factors

Transvaginal Ultrasound Findings

hCG Level (mIU/mL) ?

Third Consultation (48-72 hours later)

Signs and Symptoms

Risk Factors

Transvaginal Ultrasound Findings

hCG Level (mIU/mL)

Reference: Link CA, Maissiat J, Mol BW, Barnhart KT, Savaris RF. Diagnosing ectopic pregnancy using Bayes theorem: a retrospective cohort study. Fertil Steril. 2023;119(1):78-86. doi:10.1016/j.fertnstert.2022.09.016

Disclaimer: This calculator is for educational and clinical decision support purposes. Clinical judgment should always be exercised. Results should be interpreted in the context of the complete clinical picture.