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

Pseudo-myometrial thinning in placental site trophoblastic tumors: a case series with multiparametric MRI

PURPOSE

Placental site trophoblastic tumor (PSTT) is a rare form of gestational trophoblastic neoplasm with few previous imaging case reports. We report multiparametric MRI findings in four cases of PSTT with special emphasis on the "pseudo-myometrial thinning" underlying the tumor.

METHODS

We reviewed multiparametric MRI and pathologic findings in four cases of PSTT from four institutions. Signal intensity, enhancement pattern, margins, and location of the tumors were evaluated, and myometrial thickness underlying the tumor and normal myometrial thickness contralateral to the tumor were measured on MRI. The myometrial thickness underlying the tumor was also measured in the resected specimen and compared with the myometrial thickness measured on MRI using the Friedman test.

RESULTS

All tumors showed heterogeneous signal intensity on T1-weighted imaging, T2-weighted imaging (T2WI), and diffusion-weighted imaging. Three of the four tumors had a hypervascular area on dynamic contrast-enhanced (DCE) MRI. A hypointense rim on T2WI and DCE-MRI was seen in all tumors. All tumors protruded into the uterine cavity to varying degrees and extended into the myometrium close to the serosa. The myometrial thickness underlying the tumor measured on MRI (median thickness, 1.2 mm) was significantly thinner than that measured on pathology (median thickness, 9.5 mm) and normal myometrial thickness contralateral to the tumor on MRI (median thickness, 10.3 mm) (P = 0.02), and there was no significant difference between the latter two.

CONCLUSIONS

The thickness of the myometrium underlying the tumor on MRI was approximately one tenth of the thickness on pathology. Thus, the tumors appeared to have almost transmural invasion even when pathologically located within the superficial myometrium. This "pseudo-thinning" of the underlying myometrium and the hypointense rim on MRI could be caused by focal compression of the myometrium by the tumor, possibly due to the fragility of the myometrium at the placental site.

"The dilemma of GTN versus benign causes of secondary PPH that were indeterminate by ultrasound examination: How to differentiate?: A new prospective diagnostic criterion of functional MRI and ultrasound"

OBJECTIVES

Early differentiation between causes of secondary postpartum hemorrhage (PPH) can sometimes be difficult and can cause serious complications if diagnosis and treatment are delayed. The study aimed to assess the efficacy of different imaging diagnostic criteria, which would help in differentiating between gestational trophoblastic neoplasia (GTN) from indeterminate benign causes; thus, aiding in making clinical decisions in a timely fashion.

METHODS

A comparative prospective study, were 33 patients complaining of 2ry PPH, with indeterminate diagnosis referred to the Radiology department female imaging unit between October 2020 and November 2022 for further assessment. Transvaginal ultrasound examination as well as functional MRI was done. The lesions were characterized and certain diagnostic criteria were evaluated.

RESULTS

The lesion epicenter, margin and depth of myometrial invasion detected by dynamic MRI have significant role to differentiate between GTN and other benign conditions mainly RPOC with higher sensitivity, specificity and accuracy of MRI compared to US. The p value, sensitivity and specificity as well as the accuracy of MRI were: 0.006, 50 %, 92 %, and 81.8 %; 0.000, 87.5 %, 92 % and 90.9 %; 0.002, 87.5 %, 92 % and 90.9 % compared to 0.5, 50 %, 64 % and 60.6 %; 0.01, 87.5 %, 64 % and 69.7 %; 0.2, 87.5 %, 40 % and 51.5 % by US respectively. The overall performance of MRI to reach accurate final diagnosis is higher than the US with accuracy rate of 97 % compared to 63.6 % in indeterminate cases.

CONCLUSIONS

MRI was found to show higher performance, compared to US in differentiating inconclusive cases of 2ry PPH.

Sonographic Findings of Vascular Signals for Retained Products of Conception in Women Following First-Trimester Termination of Pregnancy

OBJECTIVES

To evaluate the occurrence of retained products of conception (RPOC) after termination of pregnancy in the first trimester and to assess the vascular signals with transvaginal ultrasonography (TVUS) examination in the detection of retained products.

METHODS

A retrospective cohort study was performed using TVUS examination in patients following termination of pregnancy. In cases of RPOC, 3 scales of vascular signal were identified: type 1, no or small amount, spot flow signals; type 2, medium amount, strip-like flow signals; type 3, rich amount, circumferential-like flow signals. The correlation between vascular signals and placenta accreta spectrum (PAS) staging was proposed by sonography and histopathology findings.

RESULTS

The 3 vascular patterns were differently distributed within non-RPOC as well as RPOC patients with and without PAS: type 1 vascular signal detection rates of non-RPOC and RPOC were 97.8% (262/268) and 28.1% (18/64), respectively. Of 64 cases of RPOC, 48.4% (31/64) of the patients had type 2 vascular signals. Vascular signals were enhanced in RPOC with PAS patients whose diagnosis was confirmed by histopathology.

CONCLUSIONS

The vascularity (amount of flow), vascular pattern (spot, strip- or circumferential-like flow), and the flow penetrating myometrium were significant findings for distinguishing concomitant RPOC with and without PAS. Additionally, RPOC may contribute to PAS progression, or PAS and RPOC in coordination strengthen the observed vascular signals.

Management of Hypervascular Retained Products of Conception With Massive Bleeding

Retained products of conception (RPOC) could be a factor for massive postpartum hemorrhage; however, a management protocol is yet to be established. Performing a surgical intervention is controversial due to the potential for natural healing. Herein, we report the management of a hypervascular RPOC case with massive bleeding. Abortion was performed in a 40-year-old patient with gravida 2 and para 0, at 20 weeks and five days of gestation following the detection of Down's syndrome on prenatal screening. Post-delivery transvaginal ultrasonography identified an intrauterine mass measuring 4cm × 5cm × 5cm. The patient was then followed up in the outpatient department. One month after the abortion, the patient developed abnormal vaginal bleeding. Transvaginal ultrasonography revealed a hypervascular myometrial RPOC with turbulent flow. Although the bleeding stopped upon her admission to our hospital, the patient developed recurrent abnormal vaginal bleeding after nine days of hospitalization, which resulted in a hemoglobin level drop to 5.9 g/dL. CT and MRI scan findings raised the suspicion of hypervascular RPOC or uterine artery pseudoaneurysm. Uterine artery embolization was performed, leading to diminished vascularity in the RPOC, which was confirmed through color Doppler ultrasonography. The remnant placenta was successfully resected hysteroscopically, and a subsequent transvaginal ultrasonography showed a decrease in blood flow. In conclusion, hypervascular RPOC, previously reported as uterine artery pseudoaneurysms, should be considered when detecting hypervascular myometrial lesions in postpartum ultrasonography. Hypervascular RPOC with hemorrhage might benefit from hysteroscopic resection after achieving hemostasis with uterine artery embolization. This case report highlights the potential risks of awaiting spontaneous resolution in large RPOC and suggests that timely surgical intervention is both effective and essential.

Accuracy of flow-void diameters on MR images in diagnosing uterine arteriovenous malformations in patients with pregnancy-related diseases

To evaluate the “flow void” diameter in patients with pregnancy-related diseases with and without uterine AVMs and assess the diagnostic performance of unenhanced MRI for uterine AVMs. From May 2014 to April 2019, 79 patients with pregnancy-related diseases were included, including 36 with and 43 without uterine AVMs confirmed by DSA. On MRI, the diameter of the most prominent “flow void” (hereinafter referred to as fv-D) was measured and compared between patients with and without uterine AVMs. The diagnostic performance of fv-D was estimated with receiver operating characteristic curves. The “flow void” sign was observed in patients with and without uterine AVMs (P > 0.05). The fv-D was significantly larger in patients with uterine AVMs in the myometrium and parametrium than in patients without uterine AVMs (P < 0.0001). The fv-D achieved a reliable diagnostic performance in the myometrium (sensitivity 80.6%, specificity 60.5%, negative predictive value 78.8%, positive predictive value 63%, AUC 0.727, cut-off: > 1.33 mm) and parametrium (sensitivity 97.2%, specificity 67.4%, negative predictive value 96.7%, positive predictive value 71.4%, AUC 0.881, cut-off > 2.6 mm). On MRI, fv-D could diagnose uterine AVMs. The fv-D had a much higher diagnostic efficiency in the parametrium than in the myometrium. The parametrium fv-D greatly improved the diagnostic sensitivity and provides a more accurate, noninvasive method of investigating possible uterine AVMs.

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.

Junctional zone endometrium alterations in gynecological and obstetrical disorders and impact on diagnosis, prognosis and treatment

PURPOSE OF REVIEW

To investigate the JZE alterations in gynecological and obstetrical disorders and impact on diagnosis, prognosis and treatment.

RECENT FINDINGS

JZE was found to be significantly extended in patients with endometriosis, leading to the conclusion that endometriosis is a primary disease of the uterus, much like adenomyosis. Statistical correlation was then demonstrated between the severity of endometriosis and the depth of the adenomyosis infiltrates, hence the thickening of the JZE. Stem cells, predominantly found in the JZE were also found in histological sections of leiomyoma, suggested to be the origin of leiomyoma. This reservoir of JZE stem cells is influenced by different stressors leading to their differentiation into leiomyoma, endometriosis, adenomyosis or endometrial cancer, according to the stressor. The variability in presentation was hypothesized to be connected to genetic and epigenetic factors. JZE was also suggested to act as a barrier, stopping endometrial carcinoma cells invasion and metastasis. In addition, JZE plays a major role in conception, pregnancy and postpartum.

SUMMARY

JZE is an important anatomical landmark of the uterus contributing to normal uterine function under the influence of ovarian hormones. Alterations of the JZE thickness and contractility can be used as pathognomonic clinical markers in infertility and chronic pelvic pain, for subendometrial and myometrial disorders, for example, adenomyosis and fibroids. Prospective randomized control trials will clarify the diagnostic steps, imaging modalities to follow and probably triage the patients between medical and surgical treatments.