OP02.07: Behaviour of serum hormone levels at 4 and 5 weeks gestation in an IVF treatment population

pregnancy of uncertain viability (IPUVI) after a single visit at the primary transvaginal scan (TVS). Methods: Prospective observational study. Between Nov 2006 and Jan 2010, all pregnant women presenting to the EPU underwent a TVS. Data was collected from women with an IPUVI at primary TVS. These women were followed up until the outcome (viable or non-viable pregnancy at the end of the first trimester) was established. More than 40 historical, clinical and ultrasonographic (US) end points were recorded for analysis, at which US data included the crown–rump length (CRL) as well as gestational sac (GS) and yolk sac (YS) measurements in 3 planes. Variables for preliminary model development were determined by stepwise logistic regression. Results: 2048 pregnant women underwent TVS, out of which 268 (13.1%) were classified with an IPUVI. 237 women with an IPUVI on primary TVS (84%) returned for follow up until the outcome was established (52.3% viable, 47.7% non-viable). 185 of these data sets have been used for model building. The variables used in the model were maternal age, gestational age in days by LMP, CRL in mm, mean GS size in mm, and previous normal vaginal delivery. The predictive ability of our model was measured with an AUC of 0.91 and its sensitivity and specificity for viable was shown to be 81.1% and 85.3% respectively. Conclusions: We have developed a valid model to predict the likelihood of a viable pregnancy at the end of the first trimester in women, who present with an IPUVI on primary ultrasound. This may help to counsel women with this common condition. We aim to test this model prospectively to evaluate its performance.