Life-Threatening Anaphylactoid Reaction Manifesting as Ventricular Arrhythmia and Pulmonary Edema Following Methylene Blue Injection During Chromopertubation: A Case Report

Methylene blue dye is commonly used for chromopertubation during diagnostic laparoscopic procedures. Although this dye is considered safer in diluted doses, several cases of cardiovascular complications, including collapse, allergic reactions, and methemoglobinemia due to methylene blue dye, have been reported. We report a case of unstable ventricular arrhythmia followed by delayed pulmonary edema in the postoperative period with a very low dose of methylene blue. A 29-year-old female with secondary infertility underwent diagnostic hysterolaparoscopy under general anesthesia. Diluted methylene blue dye (30 mL of 0.5 mg/mL) was administered transcervically to assess tubal patency, confirming bilateral tubal blockage without dye spillage. Three minutes after dye injection, the patient suddenly developed unstable ventricular tachycardia with cardiovascular compromise (blood pressure, 72/40 mmHg) and required vasopressor support for stabilization. The patient was extubated uneventfully and shifted to the postoperative ward on vasopressor support. After one hour, the patient developed tachypnea with increased oxygen requirement. Acute pulmonary edema was diagnosed based on findings of bilateral coarse crepitations, more than six B-lines on point-of-care ultrasound, and normal cardiac contractility. The patient was managed with noninvasive positive-pressure ventilation via mask, along with close monitoring of vital signs and urine output. Her respiratory and cardiovascular status stabilized within five hours. This rare combination of intraoperative ventricular arrhythmia and delayed pulmonary edema after low-dose methylene blue highlights the need for heightened vigilance and readiness for prompt resuscitative support during chromopertubation, even with very small doses of methylene blue.