Is there a difference in the behaviour and subsequent management of ectopic pregnancies seen at first scan compared to those ectopic pregnancies which commence as pregnancies of unknown location?

Aims The primary aim was to assess whether ectopic pregnancies (EPs) visualised on primary scan behave differently to EPs initially characterised as pregnancies of unknown location (PUL). The secondary aim was to assess whether the EP group is more likely to have surgical management compared to the PUL ectopic pregnancy group. 
Materials and Methods Prospective observational study. Consecutive first trimester women presenting from November 2006 to March 2012 underwent transvaginal ultrasound (TVS). Women diagnosed with an EP on TVS were divided into two groups: visualised EPs noted on the first TVS, and PULs which subsequently developed into EPs. Twenty-five historical, clinical, biochemical and ultrasonographic variables were collected. Different management strategies (expectant, medical, surgical) once an EP was confirmed on TVS were recorded. Univariate analysis was performed to compare differences between the two groups as well as rates for the three final management strategies. 
Results A total of 3341 consecutive women underwent TVS. On initial scan, 86.2% were classified as intrauterine pregnancy, 8.8% as PUL and 5.0% as EP (145 tubal/23 nontubal EPs). There were 194 tubal EPs in final analysis: 49 of 194 (25.3%) initially classified as PUL and 145 of 194 (74.7%) diagnosed as EP at primary TVS. When comparing the EP to the PUL EP group, the pain scores were 3.34 versus 1.91 (P-value < 0.001), the mean sac diameters were 35.2 versus 18.5 mm (P-value = 0.0327), and the volume of the EP masses were 8.21E+04 versus 1.40E+04 (P-value = 0.0341). Cumulative surgical intervention rate was significantly higher in EP compared to PUL EP group (P-value = 0.036). 
Conclusions EPs seen at the first ultrasound scan appear to be more symptomatic, larger in diameter and volume compared to EPs which started as PULs. Cumulative surgical intervention rate was noted to be higher in this group with EP seen on ultrasound at the outset. © 2016 The Royal Australian and New Zealand College of Obstetricians and Gynaecologists.