Alcazar JL. Transvaginal ultrasonography combined with color velocity imaging and pulsed Doppler to detect residual trophoblastic tissue. Ultrasound Obstet Gynecol 1998 Jan;11(1):54-58.
The value of transvaginal B-mode ultrasonography combined with color velocity
imaging and pulsed Doppler to detect retained trophoblastic tissue was evaluated
prospectively in a series of 40 patients with postpartum (n = 15) or postabortion
(n = 25) bleeding. Color velocity imaging was used to identify color-coded blood
flow signals within myometrium and/or endometrium. Flow was subjectively
quantified as absent, scanty or abundant. Pulsed Doppler was used to assess blood
flow impedance by calculating the resistance index. The presence of abundant flow
with a lowest resistance index of less than 0.45 was considered as suspicious of
residual trophoblastic tissue. Twenty-two (55%) out of the 40 patients underwent
dilatation and curettage and chorionic villi were demonstrated in 15 of these.
Eighteen (45%) patients were managed conservatively. None of these patients
suffered complications or needed readmission for curettage, and all of them were
considered as not having retained tissue. On color pulsed Doppler ultrasound
examination, 15 patients had suspected retained tissue; all of these underwent
curettage and residual trophoblast was found in 14 (93.3%). Out of 25 patients
considered as having no residual tissue on color pulsed Doppler ultrasound
examination, seven underwent curettage and chorionic villi were found in one
patient (false-negative rate 6.7%) All patients managed conservatively had an
unsuspicious scan. We concluded that transvaginal ultrasonography combined with
color velocity imaging and pulsed Doppler could be useful to detect retained
trophoblastic tissue and to select patients suitable for conservative management.