Objective: To evaluate whether the use of power Doppler to confirm the presence or absence of blood flow within retained products of conception (RPC) in women with an incomplete miscarriage can predict subsequent successful expectant management.
Methods: Prospective observational study in the Acute Gynaecology and Early Pregnancy Unit (AGEPU) at Nepean Hospital from November 2006 to February 2009. Incomplete miscarriage was defined by the presence of a measurable focus of hyperechoeic material, in three planes, within the endometrial cavity using two-dimensional greyscale transvaginal ultrasound (TVS). Subjective qualitative power Doppler colour scoring (PDCS) of the RPC was performed. The vascularization of the RPC was scored using the colour scoring system of the International Ovarian Tumour Analysis (IOTA) group. PDCS 1 meant absence of vascularity, PCDS 2 represented minimal vascularity, PDCS 3 rather strong vascularity and PDCS 4 very strong vascularity. The correlation between the PDCS and successful expectant management of miscarriage was analysed. The volume of RPC was calculated using the ellipsoid formula and then compared with both the PDCS and the outcome of expectant management. Successful expectant management was defined as the resolution of symptoms and the absence of RPC on follow-up TVS.
Results: A total of 1395 consecutive pregnant women underwent TVS. Of them, 198 women were diagnosed with an incomplete miscarriage; 172 were managed expectantly. Complete data were available on 158 cases. In total 84.8% (134/158) were managed successfully whilst 15.2% (24/158) failed expectant management. Of the total, 89% (121/136) of women with a PDCS 1 had successful expectant management compared with 57.1 (8/14) with PDCS 2 and 62.5% (5/8) with PDCS 3. Comparing absence of flow (PDCS 1) to presence of flow (PDCS 2 or more), the rate of success was significantly higher in the first group (89 versus 60.9%, Fisher's exact test P= 0.00136). In the prediction of success, the absence of flow showed a sensitivity, specificity, positive predictive value, negative predictive value and positive likelihood ratio of 90.3, 37.5, 89, 40.9% and 1.445 (95% confidence interval: 1.055-1.979), respectively. There was no correlation between the volume of RPC and the PDCS; and there was no relationship between the volume of RPC and the success of expectant management.
Conclusions: PDCS can predict the likelihood of successful expectant management of incomplete miscarriage. The absence of flow on power Doppler is associated with a significant improvement in the rate of successful expectant management. This new approach may be helpful in quantifying the chances of successful expectant management in those women with an incomplete miscarriage at the primary scan.