Herlyn-Werner-Wunderlich Syndrome Presenting as an Incidental Retrovesical Cyst in an Infant: A Case Report.

Müllerian (paramesonephric) ducts are the primordial components of the female reproductive tract, and defects in their development can lead to a range of uterine anomalies, including hypoplasia, agenesis, and other structural abnormalities. Herlyn-Werner-Wunderlich (HWW) syndrome is a rare variant of Müllerian duct anomalies characterized by uterine didelphys, obstructed hemivagina, and ipsilateral renal agenesis. This syndrome is often diagnosed incidentally, typically presenting with symptoms related to urinary tract or reproductive system malformations. Early recognition is crucial to preventing complications such as infertility, chronic pain, and renal dysfunction. This case describes a six-month-old female infant, a product of in vitro fertilization, who was admitted to the neonatal intensive care unit due to persistent abdominal distention and vomiting. Initial investigations for Hirschsprung's disease were negative, and radiologic findings revealed a single kidney and grade III vesicoureteric reflux. At six months of age, the infant was readmitted with fever and recurrent vomiting. Imaging studies, including ultrasound and CT, revealed a large retrovesical cyst and left renal agenesis. An MRI demonstrated that the cyst arose from the uterus and vagina, likely due to a uterovaginal septum. Surgical intervention included vaginotomy and vaginoplasty, successfully resolving the cyst and restoring vaginal patency. Postoperative imaging confirmed an empty uterine cavity and no further cyst formation. This case underscores the importance of understanding the embryological development of the female reproductive and renal systems, as well as the early clinical suspicion of HWW syndrome. Timely diagnosis and intervention are critical to preventing complications such as obstructed menstruation, pelvic pain, and renal dysfunction. Despite its rarity, early recognition of this syndrome in infants and young children can significantly improve patient outcomes and quality of life.