High‐frequency power Doppler angiographic appearance and microvascular flow velocity in recurrent scar endometriosis

Endometrial tissue has been identified in numerous surgical or procedure-related scars, including Cesarean section scar1, 2, laparoscopic trocar tract2, amniocentesis needle tract3, and perineal episiotomy incision scar4, 5. The incidence of endometriomas associated with Cesarean section incision is approximately 0.03–0.4%1, 6. The pathogenesis of scar endometriomas can be explained by iatrogenic transplantation of uterine tissue into the abdominal wall during surgery. Color Doppler in conjunction with gray-scale ultrasonography aids in vessel location and characterization of the vascular pattern. These techniques have been of great benefit in the differential diagnosis of pelvic masses. Compared with color Doppler, power Doppler is associated with a better sensitivity in detecting small vessels with low-velocity flow. To our knowledge, this is the first report of a Cesarean scar endometrioma to be diagnosed by abdominal ultrasound and to be confirmed by pathology. The change in angiographic appearance demonstrated by power Doppler and microvascular blood flow velocity are also described. A 36-year-old woman, gravida 2, para 2, complained of dysmenorrhea and a mass on the left side of a Cesarean scar that was painful on palpation and which had been present for 2 months. Her obstetric history included two Cesarean deliveries when she was 27 and 32 years old. At the age of 33, she noted increased premenstrual tenderness on the left side of the abdominal scar. The symptoms were most pronounced during menstruation, and they resolved after the cessation of her menses each month. She also suffered from malar rash and generalized chronic joint pain with stiffness. Physical examination revealed a firm, tender, indurated and palpable mass measuring 2.0 × 2.0 cm on the left side of the Cesarean scar. Hormonal profile results were normal for serum estradiol, luteinizing hormone, follicle-stimulating hormone, dehydroepiandrosterone sulfate and testosterone. Examination of the abdominal wall with the use of power Doppler ultrasound was performed late in her menstrual cycle. The equipment used was a HP Image Point (Hewlett-Packard, Andover, MA, USA) with angio mode capacity and equipped with a 10.0-MHz linear probe. A hypoechogenic, irregular mass measuring 20 × 11 × 21 mm, with scanty peripheral blood flow, was demonstrated using angio mode. High-impedance flow (pulsatility index (PI) 1.75 and resistance index (RI) 0.83) in the periphery of the mass was also detected. The peak systolic velocity (PS) of these peripheral vessels was 9.92 cm/s, the end-diastolic velocity (ED) was 1.68 cm/s and the vascularity index (VI = PS/ED) was 5.90 (Figure 1). Scar endometrioma was suspected and a wide local excision was performed. A firm mass measuring 3 × 3 cm, embedded in the subcutaneous layer, adherent to adjacent fatty tissue was found at operation. On gross examination, the whole mass was located in the subcutaneous tissue. The white firm nodule measured 3.5 cm. On microscopic examination, cystic dilated endometrial glands were present, confirming the preoperative diagnosis. Initial high-frequency power Doppler sonography showing an irregularly shaped (20 × 11 × 21 mm), heterogeneous, hypoechogenic mass without papillary proliferations associated with ‘poor’ peripheral vascularization. Pulsatility index (PI) = 1.75, resistance index (RI) = 0.83, peak systolic velocity (PS) = 9.92 cm/s, end-diastolic velocity (ED) = 1.68 cm/s, vascularity index (VI) (VI = PS/ED) = 5.90. Five months after excision, the patient complained of severe dysmenorrhea and a palpable skin mass on the right of the new abdominal scar. A repeat ultrasound examination demonstrated a hypoechogenic, irregular mass measuring 30 × 19 × 11 mm with internal blood flow. The high-impedance flow within this mass was also demonstrated using power Doppler angiography. The PI for the internal vessels was 1.69, and the RI was 0.77. The PS was 19.0 cm/s, the ED was 4.29 cm/s, and the VI was 4.43 (Figure 2). Conservative treatment with Progyluton was given because the patient refused further surgery. The recurrent scar endometrioma: high-frequency power Doppler sonography revealed an irregularly shaped (30 × 19 × 11 mm), homogeneous, hypoechogenic mass without papillary proliferations associated with ‘rich’ internal vascularization. Pulsatility index (PI) = 1.69, resistance index (RI) = 0.77, peak systolic velocity (PS) = 19.0 cm/s, end-diastolic velocity (ED) = 4.29 cm/s, vascularity index (VI) (VI = PS/ED) = 4.43. Gray-scale ultrasonography combined with color Doppler can contribute to the differential diagnosis of benign and malignant superficial masses in the abdominal wall, in particular distinguishing between endometriosis, suture granulomas and hematomas. In the present case, the initial sonographic appearance was of an irregular, inhomogeneous and hypoechogenic structure without papillary proliferations associated with ‘poor’ peripheral vascularization. The above morphological characteristics were different from those of endometriomas described by Guerriero et al. who reported higher pulsatility and resistance indices of the peripheral vessels of scar endometrioma than ovarian endometriomas7. The appearance of the recurrent scar endometrioma was irregular in shape, homogeneous and hypoechogenic without papillary proliferations associated with ‘rich’ internal vascularization. In recurrent scar endometriosis, the Doppler spectral analysis revealed decreased sonographic indices and increased microvascular flow velocity (including PS and ED) when compared with the initial scar endometriosis. In summary, an irregular shape, inhomogeneous hypoechogenic density with peripheral poor vascularization and increased PI and RI were the main morphological characteristics of scar endometrioma in our patient with previous Cesarean section using high-frequency power Doppler ultrasound. However, if increased internal vascularization and decreased sonographic indices (PI, RI, and VI) when compared with the initial scar endometrioma are detected, recurrence should be suspected, as shown in the present case. In addition, in the future, high-frequency power Doppler angiography to visualize microvascular flow will be advantageous and effective for preoperative evaluation of superficial pelvic masses. Y.-C. Wu*, K.-H. Tsui*, J.-H. Hung*, C.-C. Yuan*, H.-T. Ng*, * Department of Obstetrics and Gynecology, Veteran General Hospital-Taipei, and National Yang-Ming University, 201, Section 2, Shih-Pai Road, Taipei, Taiwan, Republic of China