Ingrown chorionic villi of the first trimester as a result of a non-developing pregnancy in the post-cesarean scar, associated with the development of arteriovenous malformation: а clinical case

Abstract

Background: Identification of residual chorionic tissue and ingrowing chorionic villi after uterine cavity curettage due to non-developing pregnancy, spontaneous abortions, and medical abortions has been a poorly studied problem. The most challenging is the differential diagnosis of this condition when the chorion grows into the scar from a caesarean section and is associated with arteriovenous malformations of the uterine wall. Nowadays, ultrasound has been recognized as the primary diagnostic method; however, the absence of specific echo-signs makes magnetic resonance imaging (MRI) and computed tomography (CT) the methods of choice and final diagnosis.
 Clinical case: This was a 39-year-old patient with a history of 3 caesarean sections and non-developing pregnancy and complete spontaneous miscarriage at 4 to 5 weeks of gestation in March 2021. Her final diagnosis was “growing of the chorionic villi of the first trimester of gestation into the myometrium to the entire depth of the uterine wall and up to the serous membrane without germination of the latter (placenta increta). At admission to the clinic in April 2021, she complained of pelvic pain, ongoing low intensity intermittent uterine bleeding, weakness, dizziness, and breast pain. The ultrasound revealed a mass in the uterine cavity. The MRI showed an incompetent post-cesarean uterine scar and residual chorionic tissue spreading to the uterine serosa, with peripheral arteriovenous structures of a neoangiogenous type. Multiaxial CT with angiography could not exclude an arteriovenous malformation within the uterine wall and residual chorionic tissue. During embolization, the angiograms showed the arteriovenous malformation in the projection of the uterus, with afferent vessels as bilateral uterine and cervicovaginal arteries and efferent vessels as bilateral parametric veins, internal iliac and ovarian veins.
 Based on the clinical and imaging pictures, embolization of the uterine arteries was performed as a first step and laparoscopic clipping of the uterine arteries and hysterectomy with fallopian tubes as a second step. Postoperatively the patient improved and beta-chorionic gonadotropin levels decreased. She was discharged home on the 5th day with no complaints.
 The clinical case demonstrates the important role of MRI and CT in the differential diagnosis and assessment of the zone and degree of chorionic villi ingrowth, aimed at determination of the possibility of organ-preserving treatment, or the need to perform a radical surgery should metroplasty be impossible.
 Conclusion: If an additional intrauterine mass is visualized by ultrasound examination after pregnancy termination, the method of choice and final diagnosis is MRI, which is performed to exclude the ingrown chorionic villi and to assess the degree of their invasion. MRI also allows for assessment of the viability of the post-cesarean scar and the presence of neoangiogenesis areas at the periphery of the ingrowth zone. CT is a method of clarifying diagnostics used to exclude vascular malformations of the uterine wall.