LAUSR

The prevalence of ectopic pregnancies diagnosed during the first trimester is estimated at 1% to 2%; among these, cesarean scar pregnancies (CSPs) occur when a pregnancy develops on a cesarean scar. Cesarean scar pregnancies are rare, but they are becoming more common with the recent increase of cesarean deliveries; in these cases, there is a blastocyst implantation in the anterior lower uterine segment, within the fibrous scar tissue that develops after the previous cesarean delivery. This kind of ectopic pregnancy is uncommon but potentially life threatening, with a high risk of uterine rupture and severe hemorrhage requiring a hysterectomy. A CSP can be potentially identified from the beginning to the term of pregnancy, but it is more commonly diagnosed during the first trimester. Abdominal pain and vaginal bleeding are the characteristic symptoms, but at least 33% of women report no symptoms. In terms of possible complications, a CSP may lead to placenta previa/accreta, uterine rupture with heavy hemorrhage, and development of an arteriovenous malformation (AVM). An AVM is an abnormal arteriovenous connection characterized by the absence of a capillary bed among arteries and veins; this abnormality results in a high-flow system with blood moving through the venous system under the arterial pressure. Arteriovenous malformations may have different locations; very rarely, they can be identified in the uterus, with fewer than 100 such cases described in the literature. An AVM can be congenital or the consequence of a uterine trauma, such as in cases of an early abortion, an intrauterine device, surgery, gestational trophoblastic disease, and oncologic disease. A uterine AVM in a CSP is an abnormal form of angiogenesis that evolves from an imbalance between the naturally erosive trophoblastic tissue, which tries to establish an adequate supply for the placenta, and the fibrous and defective tissues of a cesarean scar. We describe a rare case of an AVM that developed after medical treatment of a CSP, detailing its ultrasound (US) evaluation, pathologic characteristics, and clinical management with preservation of the patient’s fertility, obtained by a combined and conservative approach. A 34-year-old woman with a previous lowersegment cesarean delivery for a breech presentation and a uterine evacuation for first-trimester abortion had a diagnosis of a scar ectopic pregnancy at 8 weeks’ gestation. After the first diagnosis in a private hospital, the patient was referred to our attention; she was clinically stable, without abdominal pain or vaginal bleeding. We detected high β-human chorionic gonadotropin (β-hCG) serum levels (202,742 IU/L) and performed a transvaginal scan, which showed both a viable embryo, within a gestational sac located at the cervicoisthmic region, and a heterogeneous hematic mass with a maximum diameter of 57 mm, which enlarged the uterine cavity. The day after hospitalization, the patient reported vaginal bleeding and moderate abdominal pain. Opting for pregnancy termination, the woman was treated by injecting potassium chloride into the embryo’s heart and 50 mg of methotrexate (MTX) into the gestational sac, straight after amniotic fluid aspiration. A US examination after treatment showed a scar pregnancy with a nonviable embryo (Figure 1A). The discharge was performed 2 weeks later, with US evidence of a partially decreased intrauterine mass (maximum diameter of 48 mm) and a collapsed gestational sac. β-hCG serum levels decreased to 62,837 IU/L, and the patient was recommended to undertake a follow-up, monitoring the serum β-hCG trend and performing a series of planned transvaginal US (TVUS) examinations. Three weeks later, the patient reported sporadic vaginal bleeding; serum β-hCG levels were substantially reduced (3005 IU/L), but TVUS showed an increase of the heterogeneous intrauterine mass (maximum diameter of 60 mm). Administration of an additional intramuscular injection of MTX was followed by a β-hCG concentration reduction to 1900 IU/L. During the following weeks, serum β-hCG levels gradually decreased (300 IU/L 1 month after systemic MTX) despite the evidence of an increasing intrauterine mass diameter; furthermore, Power Doppler US showed turbulent and heavy blood flow inside and around the mass (Figure 1B). All of the above features supported the hypothesis of an AVM or a cesarean scar trophoblastic tumor.