Bladder varicosities as a diagnostic challenge in a case with suspected placenta accreta spectrum disease: a case description and analysis of the literature

Introduction

Placenta accreta spectrum (PAS) is a diagnosis describing abnormal adherence of the placental trophoblast beyond the uterine decidua (1). The prevalence of PAS is estimated to range between 0.01 to 1 percent of births, with a dramatic rise in incidence over recent years (2,3). Women with a prior history of cesarean delivery presenting with a placenta previa represent more than 90% of the cases of PAS (2,3). Prenatal diagnosis of PAS allows for preoperative planning, counseling and improved maternal and fetal outcomes. We present a case with sonographically identified bladder varicosities in a patient with suspicion for PAS and review challenges related to prenatal diagnosis and operative planning.

Case presentation

A 35-year-old woman G2P0101 was referred to University of Texas Health Science Center at San Antonio for PAS disorder due to a concern for PAS on ultrasound. Her current pregnancy was complicated by complete placenta previa and a history of one prior classical cesarean delivery at 25 weeks due to preeclampsia with severe features. Sonographic findings at 31 6/7 weeks were read as complete placenta previa, grade 1 lacunae, loss of sub-placental hypoechoic “clear zone”, increased vascularity, and placental bulge in the lower uterine segment. The smallest sagittal myometrial thickness was 3 mm. Figure 1 represents a transvaginal ultrasound with color Doppler that demonstrates increased vascularity in the low uterine segment.

Figure 1 Transvaginal ultrasound with color Doppler demonstrates increased vascularity in low uterine segment.

Given her history of prior cesarean delivery and current placenta previa, her a priori risk indicated an 11% probability of invasion. The Placenta Accreta Index (PAI) score was 1.5 based on an anterior placenta and the smallest sagittal myometrial thickness measures <3 mm. This score predicted 10% (4–22%) probability of invasion. Third-trimester magnetic resonance imaging (MRI) confirmed the presence of complete placenta previa. A T2 hypointense band was noted within the placenta in the lower uterine segment, which can be seen with PAS, however, no other findings were suggestive of PAS. Figure 2 demonstrates MRI with T2 hypointense band in the placenta. Table 1 lists findings and their association with PAS.

Figure 2 Magnetic resonance imaging with T2 hypointense band (white arrows) in the placenta.

The patient was counseled regarding our high clinical suspicion for varicosities in the lower uterine segment, but an inability to completely rule out PAS. Therefore, delivery was planned at 36 weeks of gestation. In the operating room the patient underwent regional anesthesia, urology performed cystourethroscopy with normal findings, and bilateral stents were placed without complications. A femoral artery sheath was placed by interventional radiology without complications. Cesarean delivery was performed with a vertical midline skin incision, an intra-operative ultrasound was performed to confirm the cephalad border of the placenta previa, and the uterus was entered with a classical uterine incision to avoid the placenta. A 3,820 g viable male was delivered without complications. The placenta separated and delivered spontaneously. Tranexamic acid and uterotonics were given after cord clamping for prophylaxis of postpartum hemorrhage. The uterus was noted to have increased varicosities along the lower uterine segment near the bladder and was preserved in this case. Figure 3 demonstrates intra-operative findings with increased varicosities along the lower uterine segment near the bladder. The total quantitative blood loss was 1,381 mL. The patient was discharged on day 2. The patient had a follow-up ultrasound performed at 6 weeks with normal findings and resolution of varicosities and had an uncomplicated postpartum course. Figure 4 shows a normal ultrasound of the post-partum uterus at 6 weeks.

Figure 3 Intra-operative findings with increased varicosities along the lower uterine segment near the bladder.

Figure 4 Ultrasound of post-partum uterus at 6 weeks.

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Discussion

This case illustrates the challenges associated with prenatal differentiation of PAS disease and bladder varicosities when significant vascularity is noted in the uterine-bladder interface. Inability to rule out PAS in this case led to activation of a multidisciplinary PAS team approach, use of significant medical resources, additional interventions, and patient-provider anxiety.

The prenatal detection and risk stratification of PAS are primarily made by ultrasound (3-8). However, ultrasound is an operator-dependent imaging modality with substantial variability in image quality among physicians. Placenta previa and prior cesarean delivery remain the two most clinically important risk factors for PAS. In our case, the patient had a history of one prior classical cesarean delivery, an anterior placenta previa and additional independent risk factors such as advanced maternal age and in vitro fertilization (IVF) pregnancy (9). Despite her low a priori risk (11%) and low PAI score with 10% probability of invasion, she had several worrisome features concerning for PAS. Loss or irregularity of the retroplacental hypoechoic “clear zone” was concerning for PAS, with sensitivity ranges from 74.9% to 91.6%. The sonographically identified bladder-uterine interface irregularities are sensitive for PAS (increta and percreta) in 46% and 62%, respectively, with high specificities. While uterovesical hypervascularity is not sensitive for accreta, it has high sensitivity and specificity for increta and percreta PAS (7). Neovascularization in PAS is related to high-volume, high-velocity flows from the radial and arcuate arteries, dislodging the trophoblastic plugs from the tips of arcuate arteries, leading to anomalies of both the uteroplacental and intervillous circulation (lacunae formation) (10-13). In cases of PAS, peak velocities may reach or exceed 30 cm/s (12). In 81% of cases, hypervascularization is within or under the placental basal plate (13). This is in contrast to urinary bladder varices in pregnancy, which form as a result of venous stasis from increased pressure in the pelvis (11,14). Hence, these veins demonstrate very low velocity on color Doppler interrogation, which is only detectable with a low pulse repetition frequency (11).

Finally, a placental bulge beyond the normal uterine contour has a sensitivity of 91.7% for increta and percreta (15). The combined sensitivity of ultrasound for PAS ranges from 81.2% to 93%, while the specificity ranges from 94.7% to 98.9%, depending on the PAS grade (7).

Distinguishing between urinary bladder varices and retroplacental PAS neovascularization is a clinical dilemma due to similar appearances on prenatal ultrasound. Adu-Bredu et al. (11), proposed sonographic features for prenatal differential diagnosis of those two conditions. The authors described how sonographic findings such as myometrial thickness, size, orientation, blood flow velocity in the vessels, and assessment for a “separation sign” can help with distinguishing PAS and bladder varices. In cases of bladder varicosities, the myometrial thickness should be preserved and measured greater than 2 mm, with positive “separation sign” demonstrating preserved “clear space”. The location of varices around the urinary bladder appears straight and parallel to the urinary bladder interface, which appears rounded on the sagittal plane, and demonstrates very low velocity on color Doppler. Authors suggest that a definitive diagnosis be made at the time of the surgery before fetal extraction for the proper surgical intervention and to avoid iatrogenic interventions such as extensive midline laparotomy, fundal hysterotomy, and prophylactic uterine artery embolization (11). In the reported case, attention to such details on prenatal ultrasound could have aided clinicians with the correct differentiation of PAS versus bladder varicosities prenatally, allowing proper pre-operative planning and judicious use of additional services (ureter stent placement, prophylactic uterine artery embolization, anesthesia service etc.). This case illustrates that not only does a formal assessment of sonographic findings and application scoring systems matter in risk assessment but also matching sonographic features to a particular clinical context with known pathophysiology.

Current studies do not show additional benefit of MRI in diagnosing PAS, although it may provide further information in assessing extent of invasion in cases of placenta percreta. Additionally, diagnostic accuracy of MRI is dependent upon clinician experience which can vary across institutions (2,3,9). T2 hypointense bands are the most sensitive MRI feature for PAS with sensitivities ranging from 82.6% to 89.7%, and could be additionally associated with increased maternal hemorrhage and hysterectomy, however, bands have lower specificity, ranging from 49.5% to 63.4% (10).

There are two published case reports of bladder varicosities in the setting of placenta previa managed differently, highlighting the diagnostic challenges. In both cases, the patients presented with placenta previa with uterovesical hypervascularity. In the first case, follow up imaging revealed placental migration away from the lower uterine segment, allowing for diagnosis of varices (16). In the second case report, the patient underwent a classical cesarean delivery at 34 2/7 weeks, and bladder varicosities were seen intra-operatively with preservation of the uterus (14).

Our case illustrates challenges associated with prenatal differential diagnosis between PAS and bladder varices. Distinguishing prenatally between these two pathologies is paramount in determining delivery planning strategy, since they have quite different managements (timing of delivery, laparotomy approach, anesthesia support, need for additional services such as ureter stents placement or prophylactic uterine artery embolization, etc.). A methodical approach to sonographic evaluation with correlation of findings to the pathophysiology of either PAS or bladder varices is important in accurate prediction. Delivery strategy should use a stepwise approach and use of additional services with caution unless diagnosis is confirmed intra-operatively to avoid unnecessary interventions. Given the high morbidity associated with PAS cases, cases with suspected PAS should be referred to specialized Placenta Accreta Centers for ascertainment of diagnosis, surgical planning, and delivery.

Acknowledgments

None.

Footnote

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-2025-312/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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