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Obstetrics » Obstetrics 1st Trimester
Molar pregnancy II
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Author(s) :
Chaitali Shah, FRCR
Presentation A 28 year old female presents with severe first trimester nausea and vomiting [hyperemesis gravidarum]. Her beta HCG titers are very high in the range of hundreds of thousands units.
Caption: Sagittal transvaginal scan.
Description: Sagittal view demonstrating that the endometrial cavity is filled with an echogenic mass containing cystic spaces.
Caption: Transverse transvaginal view.
Description: Transverse view demonstrating the echogenic mass with cystic spaces distending the endometrial canal. The myometrium appears normal.
Caption: Sagittal power Doppler view.
Description: Sagittal power Doppler view demonstrating that the mass is partially vascularized.
Caption: Transverse power Doppler view.
Description: Transverse view demonstrating the vascular and the avascular areas in the mass.
Caption: Spectral study of the vascular area in the mass.
Description: Spectral waveform demonstrates a mixed arterial and venous pattern, with low resistance arterial flow.
Differential Diagnosis Molar pregnancy.
Final Diagnosis Non-invasive molar pregnancy.
Discussion Molar gestation has already been discussed completely in a previous case (click here to view this case in a new window). However, this case demonstrates certain features that are different from the one discussed earlier.

The gray scale ultrasound features reveal an enlarged uterus with the endometrial cavity filled with a complex cystic mass. Benson, et al reported that the majority of first trimester complete moles demonstrated a typical sonographic appearance of a complex and echogenic intrauterine mass containing many small cystic spaces {which correspond to the hydropic villi on gross pathology}. There have been few reports of a large, central fluid collection that mimics an anembryonic gestation or abortion. Occasionally, there is merely a central mass of variable echogenicity, presumably because the villi are too small to be seen with sonography at that time. Histopathological features provide the final answer in such cases.

Studies have shown color Doppler to be useful in the evaluation and follow up of gestational trophoblastic tumors. Angiogenesis is an integral part of any tumor development and color Doppler usually reveals increased vascularity in the mole, followed by a decrease with treatment. Low resistance blood vessels with low pulsatility and resistance indices have been noted in malignant and aggressive gestational trophoblastic tumors. These may also be useful in predicting the response to treatment in addition to diagnosis.

Non-invasive moles are seen to be avascular and contain many cystic spaces within, which correspond to the swollen chorionic villi. Invasive moles and choriocarcinomas however show increased intratumoral blood flow, and focal areas of increased flow in the myometrium as well, if there is local invasion. Presence of extrauterine gestational disease confirms the aggressive nature of the mole. In borderline cases, the final diagnosis of invasion versus non-invasion is confirmed only by histopathology and hence all the evacuated moles need to undergo a complete pathological workup.

The case demonstrated here shows areas of increased vascularity concerning for invasion, however it was pathologically confirmed to be a non-invasive complete mole. Follow up ultrasound and beta HCG titers were confirmed to be in the normal range.

Case References 1.Benson C, et al. Sonographic appearance of first trimester complete hydatidiform moles. Ultrasound in Obstetrics and Gynecology. 16 (2000), pp. 188–191.

2.Kawano M, et al.Transvaginal color Doppler studies in gestational trophoblastic disease. Ultrasound Obstet Gynecol. 1996 Mar; 7(3): 197-200.

3.Yalcin OT, Ozalp SS, Tanir HM. Assessment of gestational trophoblastic disease by Doppler ultrasonography. Eur J Obstet Gynecol Reprod Biol. 2002 Jun 10; 103(1): 83-7.

4.Bidzinski M, et al. Clinical usefulness of color doppler flow examination during treatment of gestational trophoblastic disease. Ginekol Pol. 1999 Feb; 70(2): 88-92.

5.Sebire NJ, Rees H, et al. The diagnostic implications of routine ultrasound examination in histologically confirmed early molar pregnancies. Ultrasound Obstet Gynecol. 2001 Dec; 18(6): 662-5.

6.Woo JS, et al. Partial hydatidiform mole: ultrasonographic features. Aust N Z J Obstet Gynaecol. 1983 May;23(2):103-7.

Follow Up Histopathological features confirmed it to be a non-invasive complete mole.
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