Contrast-enhanced ultrasound: a potential method for identifying the cause of postpartum hemorrhage in emergency settings

Introduction

Postpartum hemorrhage (PPH) remains a leading cause of maternal morbidity and mortality worldwide, with delayed or secondary PPH posing particular diagnostic and therapeutic challenges (1). Rapid and accurate identification of the underlying etiology is critical for guiding life-saving interventions (2). Contrast-enhanced ultrasound (CEUS), with its real-time, dynamic assessment of tissue perfusion and vascular architecture at the bedside, may facilitate immediate, point-of-care evaluation (3,4). This report presents two cases of severe secondary PPH in which CEUS played a pivotal role in rapidly establishing the diagnosis and directly informing markedly different clinical management strategies.

CEUS protocol

For CEUS, both patients received an intravenous injection of 2.4 mL of a sulfur hexafluoride microbubble contrast agent (SonoVue, Bracco, Switzerland), followed by a 15-mL flush of sterile saline. The agent was suspended in a 5-mL solution containing 59 mg of sulfur hexafluoride. Image acquisition was performed using an IU Elite ultrasound system (Philips Medical Systems, USA) with a C10-3v endocavitary probe and a C5-1 abdominal probe. The mechanical index was set to 0.06, and the dual-screen mode was used to simultaneously display the fundamental and contrast-enhanced images.

All procedures in this study were performed 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 patients for the publication of this article and the accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Case 1

A 30-year-old woman (gravida 1, para 0) presented to the Emergency Department of West China Second University Hospital with secondary PPH 23 days after an uncomplicated vaginal delivery. The patient had initially presented to our emergency department on postpartum day 18 with increased vaginal bleeding. After observation, her condition improved, and she was discharged with instructions to monitor her bleeding and weigh her sanitary pads daily at home. Five days later, she returned with significantly worsened hemorrhage. Based on the cumulative weights of the sanitary pads collected both at home and in the emergency department, the estimated total blood loss was approximately 800 mL.

Emergency transvaginal sonography (TVS) revealed retained products of conception (RPOC) measuring 2.8 cm × 1.3 cm × 3.0 cm in the uterine cavity. Color Doppler showed hypervascularity within the myometrium, and pulsed-wave Doppler analysis demonstrated high-velocity, low-resistance flow, suggestive of an associated arteriovenous malformation (AVM) (Figure S1). Due to persistent heavy vaginal bleeding, CEUS was performed to promptly determine whether hysteroscopic resection of RPOC was necessary to achieve hemostasis. CEUS identified a vessel originating from the area of enhanced myometrial vascularity (EMV) in the right lateral myometrium, traversing the myometrium and endometrium, and rupturing into the uterine cavity, forming a vascular lake measuring 2.2 cm × 0.9 cm × 1.3 cm. This lesion exhibited distinct perfusion kinetics, characterized by a classic “fast-in and slow-out” enhancement pattern. Compared to the surrounding myometrium (arrival time: 17 s; time to peak: 36 s; wash-out time: 125 s), the lesion showed earlier enhancement and earlier peak enhancement (arrival time: 14 s; time to peak: 19 s), with persistent hyperenhancement up to 229 seconds post-injection. The lesion was surrounded by a non-enhancing area measuring 2.5 cm × 1.6 cm × 2.6 cm, consistent with a perilesional hematoma (Figure 1A,1B).

Figure 1 Multimodal imaging findings from the emergency department for Case 1. (A,B) Bimodal CEUS images: left, contrast-enhanced image; right, fundamental image. (A) Cross-sectional CEUS imaging showed a myometrial vessel originating from the right uterine artery (arrows), breaking through the endometrium, and rapidly spurting into the uterine cavity, forming a UAP (dotted line), measuring 2.2 cm × 0.9 cm × 1.3 cm; an unenhanced area of contrast agent (hematoma) surrounds the UAP (arrowhead), measuring 2.5 cm × 1.6 cm × 2.6 cm. (B) Sagittal CEUS imaging showed persistence of the UAP during the late phase (dotted line). (C) MRI showed the UAP in the uterine cavity (arrow). (D) DSA showed abnormal concentration of the contrast medium (arrow). CEUS, contrast-enhanced ultrasound; DSA, digital subtraction angiography; MRI, magnetic resonance imaging; UAP, uterine artery pseudoaneurysm.

Based on the patient’s CEUS findings and clinical presentation, the clinicians concluded that the PPH was most consistent with a pseudoaneurysm arising from abnormal communication between EMV and the uterine cavity. The surrounding blood clot appeared to provide temporary hemostasis, correlating with the intermittent (“on-off”) pattern of vaginal bleeding. Given the high-velocity flow in the parent vessel (characterized by rapid enhancement) and the relatively large size of the pseudoaneurysm, as well as the severity of hemorrhage, emergency uterine artery embolization (UAE) was recommended for hemostasis rather than hysteroscopic surgery.

While the patient was considering treatment options, pelvic magnetic resonance imaging (MRI) was performed to further confirm the diagnosis, and the results were consistent with the CEUS findings (Figure 1C). Throughout this process, the patient experienced an additional 300 mL of vaginal blood loss. The patient ultimately consented to undergo UAE. Selective right internal iliac digital subtraction angiography (DSA) revealed a pseudoaneurysm arising from the right uterine artery, evidenced by abnormal contrast concentration (Figure 1D). The lesion was embolized using microcoils and Gelfoam particles. The patient recovered well postoperatively, and vaginal bleeding ceased. Follow-up CEUS was performed at 3 days (Figure 2A) and 14 days (Figure 2B) after UAE, respectively. The results showed homogeneous, moderate enhancement of the myometrium, indicating good recovery. The intracavitary hyperechoic mass was markedly reduced in size, with no evidence of internal contrast enhancement.

Figure 2 CEUS findings after UAE for Case 1. Bimodal CEUS images: left, contrast-enhanced image; right, fundamental image. (A) Three days after UAE, sagittal CEUS imaging showed a 2.5 cm × 0.9 cm × 1.9 cm mass with no internal contrast perfusion (arrowheads), while the myometrium exhibited homogeneous, moderate enhancement (arrow). (B) Fourteen days after UAE, sagittal CEUS imaging showed a 1.3 cm × 0.6 cm × 1.7 cm hyperechoic mass in the uterine cavity with no internal contrast perfusion (arrows). CEUS, contrast-enhanced ultrasound; UAE, uterine artery embolization.

Case 2

The patient, a 27-year-old woman (gravida 1, para 0), presented to the Emergency Department of West China Second University Hospital with severe PPH 8 days after a cesarean delivery. The total blood loss was estimated to be approximately 850 mL over 5 hours, based on the weights of sanitary pads used at home and in the emergency department.

TVS revealed a heterogeneous hyperechoic mass measuring 10.6 cm × 3.9 cm × 5.5 cm, occupying the endocervical canal and uterine cavity, with no significant internal blood flow, indistinct borders, and an irregular shape (Figure 3A). The emergency physician attempted to achieve hemostasis using uterotonics, uterine massage, and an intrauterine balloon tamponade; however, the balloon was expelled from the uterine cavity, and hemostasis was initially ineffective. The patient experienced approximately 340 mL of vaginal blood loss during the emergency observation period, resulting in a hemoglobin level of 68 g/L.

Figure 3 Imaging findings for Case 2. (A) Transabdominal sagittal ultrasound showed a heterogeneous hyperechoic mass, measuring 10.6 cm × 3.9 cm × 5.5 cm, in the endocervical canal and uterine cavity (arrowhead), with no significant internal blood flow, unclear boundaries, and an irregular shape. (B,C) Bimodal CEUS images: left, contrast-enhanced image; right, fundamental image. (B) Sagittal CEUS imaging showed moderate enhancement of the myometrium (arrow) with no abnormal accumulation of contrast agent within it, and the absence of contrast agent within the intrauterine mass (arrowhead). (C) Cross-sectional CEUS imaging showed a clear demarcation between the intrauterine mass (arrowhead) and the normal myometrium (arrow). (D) Sagittal transvaginal ultrasound imaging 12 days later revealed a significant reduction in the intrauterine lesion (arrow) and good uterine recovery. CEUS, contrast-enhanced ultrasound.

Given the patient’s anxiety, the physiological stress of the postpartum state, and the onset of hemodynamic instability with anemia, an immediate etiological diagnosis was required to guide life-saving interventions. Drawing on previous experience with Case 1, bedside emergency CEUS was performed. CEUS demonstrated homogeneous myometrial enhancement with an arrival time of 14 seconds, peak enhancement at 30 seconds, and wash out by 125 seconds. No abnormal contrast accumulation was observed, effectively ruling out aberrant vasculature or AVM. A hyperechoic mass in the uterine cavity remained avascular throughout the observation period, with no contrast agent entering the lesion and clear demarcation from the surrounding myometrium, confirming the absence of active intrauterine bleeding. Overall, these findings indicated that the mass was neither RPOC nor a pseudoaneurysm (Figure 3B,3C). Thus, the intrauterine mass was diagnosed as an intrauterine blood clot.

The emergency physician ultimately determined that the cause of PPH was uterine atony. Instead of performing additional surgical interventions, symptomatic management was implemented, including intravenous administration of tranexamic acid and oxytocin to reduce bleeding and promote uterine contraction, along with continuous bimanual uterine compression. Within two days, the patient’s bleeding significantly decreased, and she was discharged upon stabilization of her condition. A follow-up examination 12 days later showed a marked reduction in the intrauterine mass (blood clot) and good restoration of uterine size (Figure 3D).

Discussion

The management of secondary PPH remains a clinical challenge, primarily due to the difficulty of rapidly differentiating between surgical emergencies, such as uterine artery pseudoaneurysms (UAPs), and medical conditions, such as uterine atony and RPOC (1,2). Among the etiologies of secondary PPH, UAPs following uncomplicated vaginal delivery are particularly prone to oversight and misdiagnosis, as they lack the typical association with the traumatic events usually linked to pseudoaneurysm formation. However, subtle vascular injury to the spiral arteries during parturition, together with the hyperdynamic circulatory state of pregnancy, may promote pseudoaneurysm development (5). Conventional gray-scale and Doppler ultrasound, as first-line imaging modalities, are often limited by angle dependence and an inability to accurately characterize microvascular perfusion (6,7). This ambiguity carries significant risk, potentially leading to critical errors in treatment strategy. Our two cases illustrate the potential value of CEUS in addressing these critical diagnostic gaps.

Both cases presented with significant hemorrhage, In Case 1, characteristic CEUS perfusion kinetics—specifically persistent hyperenhancement with a “fast-in and slow-out” pattern—enabled the definitive diagnosis of a UAP. This effectively averted a potentially catastrophic hysteroscopic procedure and facilitated life-saving embolization. Conversely, in Case 2, CEUS confirmed the absence of active vascular pathology by demonstrating an avascular intrauterine mass. This negative finding was as critical as the positive finding in Case 1, providing the clinical team with the confidence to pursue intensive medical management for uterine atony, and thereby avoid unnecessary invasive interventions.

Our findings align with recent literature highlighting several key advantages of CEUS (8-11). Compared to conventional ultrasound, CEUS provides superior capability for the dynamic assessment of microvascular perfusion and the real-time detection of active bleeding, enabling the clear delineation of the UAP, including the cavity, neck, and rupture site, as well as early shunting in AVMs. Further, CEUS accurately distinguishes between avascular hematomas or organized tissues and viable RPOC based on enhancement patterns, effectively resolving diagnostic ambiguities encountered in conventional imaging (8).

Moreover, as demonstrated in Case 1, CEUS provided diagnostic information approaching that of MRI regarding tissue characterization and myometrial relationships, while offering greater speed and convenience (10,11). As a non-nephrotoxic and non-ionizing imaging modality, CEUS is safe for repeated assessments if needed (12,13). Additionally, the cost of CEUS is comparable to that of MRI, imposing no additional financial burden on patients (14). Its bedside applicability is particularly valuable for hemodynamically unstable patients, facilitating immediate triage without the potential delays and risks associated with patient transfer for MRI.

However, despite these potential advantages, CEUS faces certain practical limitations in clinical application. Its diagnostic accuracy is partially operator-dependent, demanding substantial expertise (15). In addition, its widespread adoption is restricted by resource limitations regarding contrast agents, software, and personnel in emergency settings (14). Therefore, CEUS should be regarded as a valuable complementary tool within clinical workflows, rather than a universal replacement for standard imaging.

In conclusion, these cases suggest that CEUS may serve as a valuable diagnostic tool that streamlines the management of critical PPH. By providing real-time assessment of microvascular perfusion, CEUS may facilitate more precise etiological diagnosis, helping to bridge existing diagnostic gaps and support appropriate selection between surgical and conservative management strategies.

Acknowledgments

None.

Footnote

Funding: This work was supported by the Sichuan Province Natural Science Foundation of China (No. 2024NSFSC0663).

Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-2026-1-0408/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 patients for the publication of this article 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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