We present two cases of nulliparous women with no history of amenorrhea who were referred to our unit following finding of a hypervascularized solid adnexal mass. In both cases a malignant tumor of tubal origin was suspected at transvaginal sonography. However, following laparoscopy, histological examination revealed that the masses were the result of an undetected tubal ectopic pregnancy that had failed spontaneously, with massive vasodilatation of pelvic blood vessels surrounding the trophoblastic tissue. We recommend consideration of the potential diagnosis of a previously undetected, failed tubal ectopic pregnancy in fertile women presenting with an adnexal mass, even when there is no history of amenorrhea or a positive pregnancy test.
A 32-year-old nulliparous woman was referred for second-level transvaginal sonography (TVS) after an ultrasound examination performed by her private gynecologist had revealed an incidental finding of a left adnexal complex mass. The patient was asymptomatic, with a regular menstrual cycle, reporting 5 days of menstrual bleeding every 28 days. She had been taking oral contraceptives for 3 years, but had stopped taking them 9 months prior to the scan in order to become pregnant. TVS showed the presence of an inhomogeneous solid lesion, measuring 57 × 42 × 50 mm, on the left side of the uterus (Figure 1a). The ovaries and uterus were of normal morphology and size (Videoclip S1). Power Doppler imaging, with pulse repetition frequency set at 800 Hz, showed that the mass was surrounded by a ‘nest’ of dilated blood vessels with a tortuous course (Videoclip S2). Pulsed-wave Doppler imaging revealed a peak systolic velocity as high as 98 cm/s and low-resistance blood flow, suggesting the presence of vascular malformation (Figure 1b). CA 125 serum levels, β-human chorionic gonadotropin (β-hCG) levels and a full blood cell count were within normal limits.
Pelvic computed tomography confirmed the presence of a mass on the left side of the uterus, separated from the ovary, with high blood flow in the phase of maximum contrast. Abdominal aortography and selective arteriography of the left common iliac artery, left hypogastric, left renal and inferior mesenteric arteries confirmed the presence of a tangle of blood vessels at the level of the left adnexal site. Following the recommendations of the gynecologic oncologist, surgery was delayed and another transvaginal scan was scheduled in order to evaluate any alterations in size or morphology of the mass.
A further TVS examination 2 months later showed no change in the findings. The patient underwent operative laparoscopy at which the mass proved to be of tubal origin; the ovaries and uterus were normal. Histological examination of a frozen section of the mass revealed the presence of trophoblastic tissue embedded in the tubal wall, surrounded by several tortuous thick-walled blood vessels (Figure 2). The final histological diagnosis therefore confirmed the presence of a previously undetected tubal ectopic pregnancy with proliferation of blood vessels and with dilated arteries and veins surrounding the mass.
A 43-year-old nulliparous woman was referred for a second-level gynecological TVS examination owing to suspicion of ovarian cancer. The patient was suffering from pelvic pain and mild fever, had a regular menstrual cycle and had never taken oral contraceptives. She was not planning to become pregnant. In 2006 she had undergone laparoscopic removal of a left ovarian cyst, which turned out to be a dermoid cyst. TVS showed the presence of an inhomogeneous, predominantly solid lesion with a small anechoic internal cystic space, measuring 28 × 32 × 27 mm, on the left side of the uterus. The ovaries and uterus were of normal morphology and size. Power Doppler imaging, with pulse repetition frequency set at 1.2 KHz, showed the presence of a thick artery entering the mass and several encircling blood vessels (Figure 3a). Pulsed-wave Doppler revealed a peak systolic velocity as high as 75 cm/s and low-resistance blood flow, suggesting the presence of a vascular malformation (Figure 3b). The serum CA 125 level was 16 UI/mL and β-hCG testing gave a negative result. The patient underwent an operative laparoscopy with removal of the left adnexa because the mass was adherent to the ovary, and at laparoscopic inspection the surgeon could not exclude a malignancy of tubal origin. A definitive histological examination of the frozen section revealed the presence of trophoblastic tissue from a failed and previously undetected tubal ectopic pregnancy, surrounded by dilated blood vessels.
Tubal pregnancy is the most common of all ectopic pregnancies, accounting for about 95% of the total. This condition usually presents as a missed menstrual period, irregular uterine bleeding and even pelvic pain, but it can also be asymptomatic. Uterine bleeding caused by ectopic pregnancy may be mistaken for menstruation, especially if the timing corresponds to the expected menses or if the condition occurs in a woman with an irregular menstrual cycle. A high proportion of tubal ectopic pregnancies undergo spontaneous resolution and disappear at TVS after a variable amount of time. However, in some cases, trophoblastic tissue persists for several months within the tubal lumen. Moreover, vascular malformations may be induced by the trophoblastic tissue, and such anomalous blood vessels might persist for a long time. Vascular malformation of the Fallopian tube has been previously described in a case of ectopic pregnancy.
The combination of trophoblastic tissue, thick tubal wall and vascular malformation can result in a solid adnexal mass that appears hypervascularized on power Doppler imaging, which, in our cases, we initially misdiagnosed as a malignancy of tubal origin. In both cases, β-hCG testing gave negative results, most probably because the pregnancies had failed spontaneously several months before the patients came to our attention. TVS is highly accurate in the identification of a tubal ectopic pregnancy when a patient presents with missed menstrual bleeding and a positive pregnancy test. On the other hand, suspecting the presence of an ectopic pregnancy in a patient reporting no history of amenorrhea could seem inappropriate, but one must be aware that women with ectopic pregnancies often present with vaginal bleeding that might mimic a regular menstrual period. The sonographic features we observed at presentation, which were different from those commonly found in tubal ectopic pregnancies, as well as the negative β-hCG serum levels, contributed to this diagnostic error.
Acute pelvic inflammatory disease may present as a sausage-shaped twisted adnexal structure located in the proximity of the ovary. However, absence of the cogwheel sign and incomplete septa, as well as the predominantly solid content of the masses, ruled out such a diagnosis in the cases described here. Moreover, neither patient complained of abdominal pain, and blood tests were all within normal limits.
We recommend considering the hypothesis of a previously undetected, spontaneously aborted tubal ectopic pregnancy in a fertile woman presenting with an adnexal mass, even when there is no history of amenorrhea or a positive pregnancy test. Visualization of a solid adnexal mass separated from the ipsilateral ovary and crossed by a thick artery for which pulsed-wave Doppler reveals high velocity and low resistance to flow, can suggest a pregnancy-induced vascular malformation.
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Videoclip S1 Transvaginal sonographic transverse section of both adnexa, showing presence of the solid mass, separated from the ovaries and mobile on gentle pressure from the probe.
Videoclip S2 Bidirectional power Doppler imaging demonstrating dilated blood vessels with turbulent blood flow around and entering the mass.