Indocyanine green (ICG) imaging: case report of innovative isthmocele diagnosis and repair in a post-ablation patient and literature review

Abstract

Objective

To present a case of a 43-year-old woman with a uterine isthmocele causing severe abnormal uterine bleeding (AUB) and chronic pelvic pain and to demonstrate the effectiveness of indocyanine green (ICG) fluorescence in minimally invasive surgical management.

Case Presentation

A 43-year-old woman, gravida 7, para 2052, was referred for surgical management of a uterine isthmocele after experiencing persistent AUB and chronic pelvic pain despite multiple conservative treatments, including nonsteroidal anti-inflammatory drugs (NSAIDs) and hormonal therapy. The patient expressed a desire to avoid hysterectomy.

Methods

Preoperative evaluation included a 2-dimensional transvaginal ultrasound (2D-TVUS) with saline infusion sonohysterogram (SIS), which revealed a 10-mm echolucent space at the anterior uterine isthmus, confirming the diagnosis of isthmocele. The patient underwent hysteroscopic and robotic-assisted laparoscopic resection of the isthmocele. ICG fluorescence was utilized to enhance visualization during the procedure. ICG was prepared by mixing a 25 mg vial with 10 cc of sterile water to achieve a 2.5 mg/cc concentration, with 2 cc (5 mg) injected into the uterine cavity via syringe through the inflow port of the uterine manipulator 10 minutes before the surgical incision.

Results

The surgical procedure was successful, with improved residual myometrial thickness observed in follow-up imaging. The patient reported resolution of AUB and pelvic pain two months post-surgery.

Conclusion

This case demonstrates that ICG imaging enhances defect localization and surgical precision, reducing operative time and complications. By optimizing the procedure and minimizing intraoperative challenges, ICG represents a significant advancement in isthmocele repair surgery, offering improved outcomes for complex uterine pathologies.

We present a 43-year-old woman, gravida 7, para 2052, who was referred for surgical management of a uterine isthmocele. Patient initially presented with severe abnormal uterine bleeding (AUB), characterized by irregular and prolonged menstrual periods that significantly impacted her quality of life. She also experienced chronic pelvic pain, which further exacerbated her condition. Despite multiple attempts with conservative medical management, including nonsteroidal anti-inflammatory drugs (NSAIDs) and hormonal therapy, her symptoms persisted. Given her complex obstetric and gynecologic history, including failed tubal ligation and endometrial ablation, and her strong desire to avoid a hysterectomy, a minimally invasive surgical approach was deemed appropriate. Despite not desiring future fertility, the severity of symptoms and the failure of conservative treatments warranted surgical intervention.

A 2-dimensional transvaginal ultrasound (2D-TVUS) revealed a 10-mm echolucent space at the anterior uterine isthmus, indicative of an isthmocele. Preoperative 2D-TVUS with saline infusion sonohysterogram (SIS) confirmed absent residual myometrial thickness (RMT) and a distorted endometrial cavity, suggestive of Asherman’s syndrome (Fig. 1A) from prior endometrial ablation.

Fig. 1.

2-Dimensional transvaginal pelvic ultrasound (2D-TVUS) with SIS. A. Preoperative 2D-TVUS with SIS of the lower uterine segment (LUS) and bladder demonstrating a 10-mm isthmocele reaching the posterior bladder mucosa (blue arrow) with absent residual myometrial thickness (RMT). B. 2-month postoperative 2D-TVUS with SIS demonstrating improved residual myometrial thickness (RMT) and successful isthmocele repair. Hyperechogenic and distorted endometrial echo (orange circle) consistent with prior diagnosis of Asherman’s syndrome secondary to history of endometrial ablation. Improved residual RMT > 3 mm with hyperechogenic scar tissue and acoustic shadowing at the level of the LUS (yellow circle) confirming successful isthmocele repair

Given the patient’s contraindications to hormonal therapy and desire for uterine preservation, she underwent hysteroscopic and robotic-assisted laparoscopic resection of the isthmocele. Her history of endometrial ablation resulted in cervical stenosis (Fig. 2a) and dense adhesions (Fig. 2b), which necessitated hysteroscopic adhesiolysis (Fig. 2c). Indocyanine green (ICG) was prepared by mixing a 25 mg vial with 10 cc of sterile water, resulting in a concentration of 2.5 mg/cc. 2 cc (5 mg) of ICG was injected directly into the uterine cavity via syringe through the uterine manipulator inflow port, 10 minutes before the surgical incision (Fig. 2d). This dosage was chosen based on a prior study using ICG in the laparoscopic repair of an isthmocele which was adequate for enhancing visualization during the procedure [1]. The visualization of ICG was only achieved after peritoneal entry during extensive adhesiolysis in the ventral region of the uterine isthmus which aided in determining the actual isthmocele versus alteration of normal tissue planes due to adhesiolysis.

Fig. 2.

Hysteroscopic intrauterine views. a. Cervical stenosis. b. Dense uterine adhesions on hysteroscopy requiring lysis of adhesions, consistent with patient’s history of endometrial ablation. c. Isthmocele location on hysteroscopy. d. ICG intrauterine administration

ICG improved the visualization of the defect with ICG fluorescence using the Firefly mode of the robotic console (Fig. 3). The uterine defect was surgically removed and repaired with a two-layer closure using 0 delayed absorbable barbed sutures. Follow-up of SIS 2 months postoperatively, demonstrated improved RMT without fluid collection (Fig. 1B), and the patient fully recovered without complications. On follow-up, the patient reported a resolution of her AUB and pelvic pain, indicating a successful outcome. Ethical approval and patient consent were obtained in the write-up of this case report.

Fig. 3.

Robotic view of isthmocele. a. Initial misidentification of the isthmocele. b. Confirmation of the isthmocele using ICG fluorescence imaging with Firefly mode. Top photos: Utilizes white light laparoscopy for standard visualization. Bottom photos: Infrared technology enhancing isthmocele detection using ICG fluorescence imaging

Discussion

An isthmocele, although often asymptomatic, may cause symptoms such as AUB and pelvic pain [2]. An isthmocele can be defined as a pouch-like defect, also called cesarean scar defect or uterine niche, in the anterior uterine wall at the site of a prior cesarean section [3]. It can lead to complications such as infertility, abnormal placentation, scar dehiscence, uterine rupture, and ectopic pregnancy [2, 3, 4]. Contributing factors to the formation of isthmoceles include low or incomplete hysterotomy closures, prolonged active labor, early uterine adhesions, peripartum infection, and maternal comorbidities [5]. Accurate diagnosis typically involves two-dimensional transvaginal ultrasound (2D-TVUS) with saline infusion sonohysterogram (SIS), recognized for its specificity and cost-effectiveness.

Treatment favors minimally invasive techniques like hysteroscopy and/or laparoscopy, tailored by defect size and symptoms. For patients with a residual myometrial thickness of 2–3 mm, the hysteroscopic approach has been identified as the most effective method for addressing abnormal uterine bleeding, secondary infertility, and pain. However, when the RMT is less than 2–3 mm, the laparoscopic approach is preferred for optimal outcomes, reducing the risk of complications such as uterine perforation and bladder injury [6, 7].

Utilization of intrauterine ICG prior to surgical repair enhanced visualization of the isthmocele in this case. It allowed for more precise identification of the defect and facilitated a more effective surgical repair, involving a combined hysteroscopic and laparoscopic approach. This technique reduced operative time and minimized intraoperative complications, demonstrating its superiority over traditional methods. It is important to note that this technique works optimally in cases with no or very low RMT, as was present in our patient's case. In cases with cystic isthmoceles, where fluid accumulation creates a fluid-filled sac within the defect, this method may be less effective as the fluid could dilute the ICG and reduce its fluorescence, limiting visualization. A cystic isthmocele is a specific type of isthmocele characterized by the presence of fluid accumulation within the defect [8, 9]. The intrauterine application of ICG to enhance laparoscopic visualization of an isthmocele was previously described by Krentel et al. in 2022, showing promising results similar to our experience [1]. ICG can prove to be valuable particularly for identifying subtle anatomical defects that may be challenging to visualize despite using a combined hysteroscopic and robotic-assisted laparoscopic visual approach.

A systematic review revealed that hysteroscopic surgery for RMT of at least 2.5 mm is effective in treating secondary subfertility associated with an isthmocele [10]. Isthmocele surgery has been shown to relieve  AUB, pain, and infertility regardless of the surgical route chosen [11]. However, some evidence suggests that for patients with a history of infertility, ectopic pregnancy, lower gravidity, lower parity, and fewer cesarean sections, a laparoscopic isthmoplasty might be preferred [12].

Despite these findings, the literature sometimes presents a confusing clinical picture regarding the surgical management of isthmoceles. This is partly due to a lack of robust evidence supporting the role of surgery in improving fertility or reducing obstetric complications [13]. Nonetheless, our understanding of the best practices for managing isthmoceles continues to evolve as more research is conducted and additional data become available. This ongoing evolution highlights the necessity for further studies to clarify the most effective approaches and to establish standardized guidelines for clinical practice [14].

In conclusion, while the management of isthmoceles remains complex and sometimes controversial, advancements in surgical techniques, such as the use of ICG for enhanced visualization, offer promising improvements in patient outcomes. Continued research and comprehensive reviews of current literature are essential for refining these techniques and improving the standard of care for patients with isthmoceles.

Author contributions

T. Tam, MD, was involved in case report conception, manuscript writing, editing, and approval. C. Mabini, DO, C. Fernandez, MD, and E. Levine, MD were involved in manuscript writing, editing, and approval.

Funding

No funding was received for this research.

Data availability

No datasets were generated or analyzed during the current study.

Declarations

Conflict of interest

The authors declare that they have no conflicts of interest in this manuscript.

Ethical approval

Ascension Healthcare Human Research Protection Program deemed the case report to not fit the regulatory criteria for human subjects’ research and thus did not need to undergo IRB review and approval.

Informed consent

Written informed consent was obtained from the patient for publication of this case report per the CARE (Case Report) guidelines. A copy of the informed consent is available for review upon request. Ascension Healthcare Human Research Protection Program deemed the case report to not fit the regulatory criteria for human subjects’ research and thus did not need to undergo IRB review.