https://orcid.org/0000-0001-8774-6291
Abstract
Cesarean scar pregnancy (CSP) is a rare condition, accounting for 6% of ectopic pregnancies, with a rising incidence. If not diagnosed early, it may lead to severe complications such as hemorrhage, need for surgery, placenta accreta, and arteriovenous malformation (AVM). Treatment consists of expectant management, medical, or surgical regiments. A 31-year-old woman (G3P2) with one previous cesarean section presented for early pregnancy evaluation. Ultrasound initially showed an intrauterine pregnancy, but follow-up confirmed a missed abortion, and mifepristone/misoprostol regimen was initiated. At follow-up, persistent tissue at the cesarean scar raised suspicion of scar pregnancy. Declining human chorionic gonadotropin levels were noted, and expectant management implemented. Increased bleeding led to ultrasound and magnetic resonance imaging, revealing a 10 cm tumor suspicious of AVM. Fertility-preserving surgery with laparoscopic ‘niche’ resection technique was pursued, but hysterectomy was ultimately required. Histopathological examination showed placenta accreta. Early diagnosis and management of CSP are essential to reduce serious complications.
Introduction
Cesarean scar pregnancy (CSP) is a potentially life-threatening implantation in a prior cesarean scar that may lead to severe hemorrhage, placenta accreta spectrum (PAS), uterine rupture, and, rarely, uterine arteriovenous malformation (AVM) [1–4]. It is uncommon, with reported incidence estimates near 1 in 1800 to 1 in 2226 pregnancies, and it accounts for ~6% of ectopic pregnancies among women with a previous cesarean delivery. Reported treatment options include methotrexate, dilation and curettage, laparoscopic or vaginal excision, hysteroscopic resection, and uterine artery embolization, with management guided by gestational age, vascularity, hemodynamic status, and fertility wishes. In this case, a misdiagnosed CSP was initially managed medically as a missed abortion [1–5].
Case report
A 31-year-old woman (gravida 3, para 2), with one previous cesarean section and one prior vaginal delivery, presented for early pregnancy assessment due to uncertain gestational age. Initial serum human chorionic gonadotropin (hCG) was 39 466 IU/L.
Transvaginal ultrasound initially demonstrated an intrauterine gestational sac with a small embryo (Fig. 1). Due to the elevated hCG level and atypical imaging features, there was minor suspicion of molar pregnancy. Follow-up examination confirmed missed abortion, and medical evacuation was performed using mifepristone and misoprostol.
Ultrasound image showing perceived embryo (arrow). Suspected missed abortion.
Subsequent follow-up revealed persistent intrauterine tissue localized to the anterior lower uterine segment at the level of the previous cesarean section scar, raising suspicion of a type 1 CSP [5]. Serial hCG measurements showed a progressive decline.
Over the following weeks, the patient developed persistent vaginal bleeding, increasing pelvic pain, and clinical signs of infection. She was treated with antibiotics for suspected endometritis. Transvaginal ultrasound demonstrated a large heterogeneous mass measuring ~8 × 7 cm, located within the anterior uterine wall at the level of the cesarean scar (Fig. 2). The lesion exhibited mixed echogenicity with increased vascularity, predominantly at the periphery. There was no evidence of bladder invasion, and no free fluid was observed in the pouch of Douglas.
Ultrasound image showing 8 × 7 cm heterogenous, highly vascular mass. Suspected cesarean scar pregnancy.
Mini hysteroscopy was conducted to rule out malignancy. The lesion appeared macroscopically benign. Targeted biopsy confirmed retained products of conception (RPOC).
Magnetic resonance imaging (MRI) of the pelvis was performed. MRI demonstrated a nearly spherical lesion within the anterior myometrium measuring up to 10 cm in diameter (Fig. 3). The lesion was markedly heterogeneous, with areas of high signal intensity and pronounced diffusion restriction. Multiple large, dilated vessels were present within the lesion, indicating significant vascularity. The lesion protruded toward the superior aspect of the urinary bladder without evidence of invasion. The initial conclusion was choriocarcinoma or persistent trophoblastic disease. After multidisciplinary review, the findings were considered most consistent with uterine AVM secondary to retained tissue after medical abortion.
MRI of the pelvis showing af 10 cm spherical lesion. Significant vascularity. Suspected arteriovenous malformation secondary to retained products of conception.
Because of the lesion size, vascularity, and the patient’s wish to preserve fertility, a planned fertility-sparing surgical approach was selected. Hysterectomy was accepted if conservative surgery proved unsafe.
Laparoscopy demonstrated a markedly enlarged uterus with a large (~10 cm) mass arising from the anterior uterine wall at the level of the cesarean scar, extending laterally toward both uterine arteries (Fig. 4). The bladder was densely adherent to the lesion, and separation remained extremely difficult. During dissection, a 1.5 cm injury to the bladder muscularis occurred, which was immediately recognized and repaired laparoscopically. Bladder integrity was confirmed intraoperatively with methylene blue instillation. Because of the lesion size, lateral extension, dense bladder adhesions, and inability to create a safe cleavage plane, the procedure was converted to total laparoscopic hysterectomy with bilateral salpingectomy. The specimen was removed vaginally using contained manual morcellation. The patient was discharged on the 2nd postoperative day with an indwelling urinary catheter for 10 days and antibiotic prophylaxis.
Laparoscopy showing a ~10 cm mass at the level of the cesarean scar. Observe the fundal part of the uterus at the bottom of the picture and the dense bladder adhesions (line demarcating uterine serosa and bladder).
Histopathological examination showed RPOC, trophoblastic invasion into the myometrium, consistent with PAS. Moreover, extensive fibrin deposition, necrosis, and thrombus formation were present. No premalignant or malignant features were identified, and there was no evidence of persistent trophoblastic disease or choriocarcinoma.
Discussion
This case illustrates how CSP may mimic a missed abortion and later evolve into a large, highly vascular uterine lesion resembling AVM or trophoblastic disease [1, 6–8]. The main diagnostic challenge was the overlap between RPOC, PAS, AVM, and malignancy. Although declining hCG levels were reassuring against gestational trophoblastic neoplasia, they do not exclude invasive placental tissue in a cesarean scar, as low or falling hCG may also occur in uterine AVM or enhanced myometrial vascularity (EMV). This highlights that hCG trends must be interpreted alongside imaging and histopathology [9].
Histopathology showing trophoblastic invasion without decidua supports abnormal implantation in a cesarean scar, consistent with PAS. Such lesions are highly vascular and prone to life-threatening hemorrhage due to defective decidualization, promoting abnormal angiogenesis, and arteriovenous shunts. In this context, sharp curettage or blind evacuation may be hazardous and worsen bleeding. Although MRI and Doppler ultrasound are useful, they may not reliably distinguish AVM from invasive retained placental tissue when vascularity is marked [5, 7].
The case highlights the need for individualized management. Fertility preservation is desirable in young patients, but it must not compromise safety [5].
While uterine artery embolization is often the first-line fertility-sparing treatment for uterine AVM with a success rate of ~88.4%, it can fail or result in recurrence, necessitating secondary surgical intervention [10].
Conservative surgery, such as laparoscopic niche resection, can be successful in selected cases to restore uterine anatomy [5]. However, large lesions with lateral extension and dense bladder adhesions carry a high risk of catastrophic hemorrhage and urinary tract injury. In such circumstances, conversion to hysterectomy is appropriate and should be viewed as a necessary safety decision rather than a failure of conservative treatment [5, 11].
In conclusion, this case emphasizes that CSP should be considered in any early pregnancy in women with a previous cesarean section, especially when ultrasound findings are atypical. Persistent vascular tissue after medical treatment should prompt reassessment of the diagnosis, including consideration of PAS and AVM. Early recognition is essential to reduce morbidity, and multidisciplinary management remains crucial when the diagnosis is uncertain or when fertility-sparing treatment is being considered [12].
Conflicts of interest
None declared.
Funding
None declared.
