Conversion of a complete hydatidiform mole into invasive mole is indicated by all of the following except:
Plateau HCG
Enlarged Uterine size
Persistence of Theca-lutein cysts
Suburethral nodule
An invasive mole rarely develops metastasis and hence presence of suburethral nodule should not be regarded as an indicator of conversion of hydatiform mole into an invasive mole. Ref: Donald School Textbook of Ultrasound in Obstetrics and Gynecology By Kurjak, 2nd Edition, Page 251, 252; Essentials of Human Disease By Leonard Crowley, 2011, Page 313.