This study selected patients who underwent cesarean section and were scheduled to undergo Saline Infusion Sonohysterography (SIS) for evaluating the structure of the incision. Clinical characteristics and clinical symptoms were collected. Combined with hysteroscopy, MRI, conventional ultrasound and SIS examination results, the study analyzed the detection rate of cesarean section diverticula by SIS, the changes in diverticulum size and the diagnostic efficacy of residual muscle layer thickness at the incision site. The surgical methods and clinical symptom improvement of patients with CSD after surgery were followed up for half a year to one year. The study aimed to clarify the guiding value of SIS in clinical decision-making and patient prognosis for patients, and to analyze the etiological relationship between the true incidence of CSD and clinical complications. Thus, it provided evidence-based basis for clinical events of cesarean section surgery → CSD → CSD complications → surgical treatment of CSD → patient prognosis, promoting the progress of precise diagnosis and treatment of female reproductive health.

Background and Rationale:

The precise assessment of the structure of the cesarean section incision is the core of achieving "individualized surgery". Through multi-dimensional analysis of anatomical structure, functional status, and patient needs, one can precisely select hysteroscopy, laparoscopy, or combined surgical methods, significantly improving symptom relief rate, diverticulum closure rate, and reducing the risks of recurrence and pregnancy complications. However, preoperative precise diagnosis is the prerequisite for treatment. The SIS technology can obtain a good acoustic window through a simple uterine cavity water injection method, clearly displaying the structure of the cesarean section incision, enhancing the diagnostic confidence of ultrasound doctors, providing more detailed diagnoses for patients and clinicians, and is expected to replace diagnostic hysteroscopy operations. In the future, it is necessary to promote the standardization of assessment and technology transformation, ultimately achieving the leap from "treatment based on symptoms" to "precise repair" of CSD, improving the long-term prognosis of patients.

Study Design and Methodology:

This is a single-center, prospective, observational cohort study. The objective is to To explore the diagnostic value of the acoustic contrast imaging technique using normal saline for the uterine cavity in the assessment of the incision structure after cesarean section.

This study included patients who were scheduled for cesarean section for secondary infertility from January 2023 to July 2025 as the research subjects. General clinical data of the patients were collected, including age, history of cesarean section, gynecological history, time of secondary infertility, whether there was excessive menstrual bleeding or dysmenorrhea, etc.

Data Collection and Assessments:

This study included patients who were scheduled for cesarean section for secondary infertility from January 2023 to July 2025 as the research subjects. General clinical data of the patients were collected, including age, history of cesarean section, gynecological history, time of secondary infertility, whether there was excessive menstrual bleeding or dysmenorrhea, etc.The primary ultrasonographic parameters to be recorded include:

During TVUS, assess whether a diverticulum is present at the cesarean section incision site. If identified, measure its longitudinal diameter, transverse diameter, depth, residual myometrial thickness, and the distance from the lower margin of the diverticulum to the external cervical os, in accordance with international consensus guidelines. During SIS, evaluate the presence of a diverticulum. In cases where a diverticulum is detected, apply the conventional TVUS measurement protocol to quantify all relevant dimensions and assess for associated complications-including cysts or polyps-as well as overall uterine cavity morphology. Concurrently, collect MRI and hysteroscopy findings.

Follow-up and Endpoints:

Following surgical intervention, participants will undergo longitudinal follow-up, including documentation of the surgical approach, clinical symptom status at 6 months postoperatively, and pregnancy outcomes at 12 months postoperatively. Analyze the aggregated data to determine the clinical decision-making utility of SIS.

Inclusion Criteria:

• More than 6 months after cesarean delivery;
• Presenting with clinical symptoms-including abnormal uterine bleeding, dysmenorrhea, prolonged menstrual spotting, or secondary infertility;
• Requiring saline infusion sonohysterography (SIS) to evaluate the cesarean scar.

Exclusion Criteria:

• Multiple cesarean deliveries;
• Patients contraindicated for saline infusion sonohysterography (SIS), including pregnancy or suspected pregnancy, failure to meet vaginal hygiene criteria, inability to cooperate during the procedure, or suboptimal image quality;
• Cases with incomplete clinical data or lost to follow-up.

The research population comprised adult women with a prior cesarean delivery who presented to Tangdu Hospital with symptoms including abnormal uterine bleeding, dysmenorrhea, prolonged menstrual spotting, or secondary infertility.

De-identified individual participant data (IPD) underlying the results reported in the published article will be shared. Data will be available to researchers who provide a methodologically sound proposal, purely for the purpose of achieving the aims in the approved proposal.

Data will be available beginning 6 months and ending 36 months following article publication.

To gain access, data requestors will need to contact the corresponding author and sign a formal data access agreement.