Overview of Neo-Vascular Lesions after Delivery or Miscarriage.

The concept of intrauterine neo-vascular lesions after pregnancy, initially called placental polyps, has changed gradually. Now, based on diagnostic imaging, such lesions are defined as retained products of conception (RPOC) with vascularization. The lesions appear after delivery or miscarriage, and they are accompanied by frequent abundant vascularization in the myometrium attached to the remnant. Many of these vascular lesions have been reported to resolve spontaneously within a few months. Acquired arteriovenous malformations (AVMs) must be considered in the differential diagnosis of RPOC with vascularization. AVMs are errors of morphogenesis. The lesions start to be constructed at the time of placenta formation. These lesions do not show spontaneous regression. Although these two lesions are recognized as neo-vascular lesions, neo-vascular lesions on imaging may represent conditions other than these two lesions (e.g., peritrophoblastic flow, uterine artery pseudoaneurysm, and villous-derived malignancies). Detecting vasculature at the placenta-myometrium interface and classifying vascular diseases according to hemodynamics in the remnant would facilitate the development of specific treatments.

Hypervascular retained product of conception: Characteristic magnetic resonance imaging and possible relationship to placental polyp and pseudoaneurysm.

The cases of two patients who developed myometrial vascularization following dilatation and curettage are described. In case 1, pathological diagnosis was possible with the resected specimens. This patient had hypervascular retained products of conception (RPOC). In case 2, the natural course of this pathological condition was observed, confirming a process of regression during repeated withdrawal bleeding. The three principal magnetic resonance imaging (MRI) findings in these cases were: (i) presence of a remnant; (ii) breaking of the junctional zone in contact with the remnant; and (iii) vascularization/flow voids infiltrating into the myometrium from the broken junctional zone. These three MRI findings differed in degree and varied in combination in each case of RPOC. Uterine artery pseudoaneurysms have been reported as intrauterine vascularization after abortion or delivery with subsequent spontaneous regression. These reports may include cases of hypervascular RPOC.

The role of asymmetric thickening of the uterine myometrium during pregnancy.

PURPOSE: This study aimed to examine the role of local uterine contractions during pregnancy depicted as asymmetric thickening of the myometrium ultrasonographically. METHODS: 419 pregnant women at 12-21 weeks of gestation who visited our outpatient department were studied. These subjects visited either for regular antenatal examinations or because of ill-defined subjective symptoms. Ultrasonographic examination was conducted to detect asymmetric thickening of the uterine myometrium. Blood flow in the region of myometrial thickening was studied by color Doppler imaging. RESULTS: Among 419 subjects, 27.38 % (112/419) patients visited our outpatient department showed asymmetric thickening of myometrium. Since cervical changes or progression to labor occurred in none of the subjects, the reviewed symptoms were considered to be benign contractions. Many women with ill-defined symptoms showed asymmetric thickenings of the myometrium (73.75 % sensitivity and 84.32 % specificity). Myometrial thickening under the placenta tended to be associated with abundant blood flow (88.46 % sensitivity and 87.21 % specificity). This different pattern of the blood flow was considered to correlate to arcuate artery resistance but did not correlate to the severity of ill-defined symptoms. Among those patients having no clinical symptoms, 53 exhibited asymmetric thickening of the myometrium. This phenomenon might be the caution of ill-defined symptoms. CONCLUSION: Asymmetric thickening of the uterine myometrium during pregnancy represented the ill-defined symptoms. Different patterns of blood flow images at this local contraction did not correlate to the severity of these symptoms.