Obstetrics & Gynaecology Calculators

Assesses cervical favourability for induction of labour. Score ≥6 predicts successful induction.

Interprets gestational age in weeks to identify viability, anomaly scan, and term thresholds.

NICE-based risk factor assessment for pre-eclampsia to guide aspirin prophylaxis from 12 weeks.

RCOG Green-top assessment for VTE risk in pregnancy/puerperium to guide LMWH thromboprophylaxis.

Identifies deteriorating obstetric patients. Uses obstetric-specific physiological ranges.

Estimates fetal weight from ultrasound measurements using Hadlock 4-parameter formula.

Estimates likelihood of successful vaginal birth after caesarean (VBAC) using Grobman nomogram factors.

Mississippi classification for HELLP syndrome (Haemolysis, Elevated Liver enzymes, Low Platelets). Class I most severe.

Risk stratification for ectopic pregnancy based on β-hCG level, USS findings, and clinical features.

10-item validated screening tool for postnatal depression. Validated for antenatal use. Score ≥13 suggests probable depression.

5-component ultrasound-based assessment of fetal wellbeing. Each component scores 0 or 2. Total 0–10. Used for fetal surveillance in high-risk pregnancies. Score ≤6 may indicate fetal compromise.

International Ovarian Tumour Analysis (IOTA) Simple Rules classify adnexal masses as malignant (M-features), benign (B-features), or inconclusive. Applicable when using ultrasound. Sensitivity 92%, specificity 96% when applicable.

Combines ultrasound score (U), menopausal status (M), and serum CA-125 to calculate RMI. RMI >200 = high risk of ovarian malignancy; refer to specialist cancer centre. Validated in UK NHS setting (RCOG guideline).

5-item validated screen for physical, sexual, and emotional abuse in pregnancy and reproductive health settings. Any positive response requires further assessment and safety planning.

Modified version of the Bishop score assessing cervical favourability for induction of labour. Scores dilation, effacement, station, consistency, and position. Score ≥8 = favourable cervix; score <6 = induction likely to require cervical ripening.

Calculates appropriate dose of Rh(D) immune globulin (anti-D) after maternal-fetal haemorrhage in Rh(D)-negative women. Based on Kleihauer-Betke test result. Prevents Rh sensitisation.

Assesses severity of neonatal abstinence syndrome (NAS) in neonates exposed to opioids in utero. 21 signs scored at regular intervals. Total ≥8 for 3 consecutive scores suggests pharmacological treatment needed.

Colposcopy scoring tool assessing the severity of cervical lesions based on 4 signs seen at colposcopy. Correlates with cervical intraepithelial neoplasia (CIN) grade. Score 0–8: low score = CIN 1; high score = CIN 2/3.

5-component colposcopic scoring system for predicting severity of cervical intraepithelial neoplasia (CIN). Validated in Scandinavian and UK studies. Score ≥8 = high risk CIN 2+; score 0–4 = low risk.

Validated algorithm combining 3 clinical criteria with D-dimer threshold to safely exclude pulmonary embolism. Particularly validated in pregnancy (adapted YEARS). Reduces CT-PA use vs. Wells score.

2014 FIGO (International Federation of Gynaecology and Obstetrics) staging system for ovarian, fallopian tube, and peritoneal cancer. Used for prognosis and treatment planning.

Screens for pre-eclampsia risk using maternal factors per NICE NG133.

Assesses cervical favourability for induction of labour. Score >= 8 indicates a favourable cervix.

Predicts ovarian malignancy probability from USS features, menopausal status, and CA-125. RMI >= 200 warrants specialist referral.

Calculates weeks remaining to EDD from last menstrual period using the Naegele rule (LMP + 280 days).

Identifies women at risk of preterm birth who may benefit from cervical cerclage or vaginal progesterone.

Stages cervical cancer using 2018 FIGO classification to guide treatment selection (surgery vs chemoradiotherapy).

Classifies PID severity using CDC criteria to guide outpatient vs inpatient management.

Assesses risk of placenta praevia and placenta accreta spectrum (PAS) disorder. Guides third trimester USS and surgical planning.

Five-component fetal wellbeing assessment (Manning 1980): NST, fetal breathing, gross body movement, tone, and amniotic fluid volume. Each scored 0 or 2. Total 0–10. Used in third-trimester surveillance for high-risk pregnancies.

Obstetric adaptation of MEWS for inpatient maternity wards. Sums weighted scores from observations. Triggers for escalation per RCOG / MBRRACE-UK reports. Each parameter 0–3.

WHO-endorsed (2015) standardised classification of caesarean populations based on parity, labour onset, gestation, and presentation (Robson 2001). Used for audit and inter-unit comparison rather than individual decision-making.

Predicts likelihood of successful vaginal birth after caesarean (TOLAC) using maternal age, BMI, prior vaginal delivery, prior VBAC, and indication for prior CS (Grobman 2007; race-free recalibration 2021). Use the live MFMU online tool for individualised %; this calculator records the band.

Three-variable rule for DVT in pregnancy (Chan 2009): symptoms in the Left leg, ≥2 cm calf circumference difference (Edema), and First-trimester presentation. Score 0 has very low DVT prevalence; score ≥1 mandates duplex US.

Pregnancy-adapted YEARS algorithm (van der Pol 2019, Artemis study). Three YEARS items + D-dimer threshold that varies with item count. Safely excludes PE in 39% without imaging.