Ventricular shunt placement is a widely accepted and effective method for managing hydrocephalus, with ventriculoperitoneal (VP) shunts being the most used type of shunt for this condition [1]. While VP shunt complications are relatively common, they typically occur at the distal end rather than the proximal end of the shunt [2]. Among these complications, shunt catheter migration into unusual body sites is rare, with umbilical migration accounting for approximately 8.6% of reported cases [3]. This rarity poses a significant diagnostic challenge, as umbilical VP shunt migration can closely mimic other umbilical pathologies, such as a patent urachus. A patent urachus is a rare congenital anomaly in which a persistent connection between the bladder and the umbilicus leads to similar clinical symptoms, including persistent umbilical fluid drainage. Urachal anomalies are uncommon, accounting for only 1.5% of diagnosed cases, further complicating the diagnostic process [4]. The overlap in clinical and radiological findings between umbilical VP shunt migration and patent urachus can create a diagnostic dilemma, potentially leading to misdiagnosis and inappropriate management. Here, we present a case of umbilical VP shunt migration in a 14-month-old boy whose symptoms and initial imaging findings were highly suggestive of a patent urachus.

A 14-month-old boy with communicating hydrocephalus was referred to the urology department with a one-month history of persistent, clear, non-sticky, odourless umbilical fluid leakage. He also experienced fever and diarrhoea during the same period. A VP shunt had been inserted when he was one month old. Clinically, the patient was alert with no signs of meningitis. On examination, the umbilicus appeared normal without any protrusion of foreign objects or redness. Mild abdominal distension was noted, and the bladder was not palpable in the suprapubic region. The patient had a history of febrile seizures and communicating hydrocephalus at 20 days old and had previously undergone three VP shunt revisions at 4, 5, and 9 months of age.

Further evaluation with blood laboratory tests revealed relative lymphocytosis. Abdominal ultrasonography (USG) showed a tract extending from the superior part of the bladder to the umbilicus, suggesting a patent urachus (Fig. 1). To confirm the diagnosis, a non-contrast computed tomography (NCCT) scan of the abdomen was performed. The NCCT revealed tenting of the superior portion of the bladder toward the umbilicus due to the thickening of the median umbilical ligament, further supporting the initial diagnosis of a patent urachus (Fig. 2). Based on these findings, the patient was scheduled for urachal excision surgery.

However, during the operation, the urologist discovered that the distal end of the VP shunt had migrated from the bladder superiorly to the umbilicus, positioned between the umbilical arteries, rather than a patent urachus (Fig. 3). Meanwhile, the urachus itself was found to be obliterated. Considering this unexpected finding, the case was referred to the neurosurgical team, and the patient subsequently underwent a VP shunt revision. Two weeks after the procedure, the patient's symptoms had completely resolved, with no further complications.

VP shunt placement is the most common pediatric neurosurgical procedure for managing hydrocephalus, although it still carries some risk of complications [5]. These complications include issues such as obstruction, infection, and drainage-related malfunctions like over-drainage and under-drainage [6]. However, there is limited literature on the rarer complications, such as distal catheter migration. The most frequently reported sites of distal migration are the oral cavity or anal opening (36.7%), abdominal wall (11.7%), vaginal opening (7.5%), urethral opening (6.7%), and umbilical sites (5.8%), with the available data primarily limited to case reports [7].

Several hypotheses have been proposed to explain the mechanism of VP shunt migration. One theory suggests that the viscera or body wall could be weakened due to an inflammatory reaction caused by the adhesion of the distal catheter to the tissue, making it easier for the catheter to protrude [8][9]. Another proposed mechanism involves constant pressure and peristaltic movement, which can increase the likelihood of catheter protrusion [10]. The type of catheter used can also influence migration risk; stiffer catheters are more prone to migration than softer, more flexible ones [11]. Furthermore, some researchers have hypothesized that certain patient-related factors — including young age, the length of the catheter inserted into the peritoneal cavity, localized wound dehiscence, weakened immunity, improper surgical techniques, and ischemic necrosis of the skin — could contribute to distal VP shunt migration [2][12]. In our patient, we suggest that a systemic infection caused by a local inflammatory reaction, characterized by fever and increased peristaltic movement due to diarrhoea, likely facilitated the umbilical VP shunt migration.

The most common symptoms of a patent urachus include continuous or intermittent umbilical fluid drainage, umbilical wetness, tenderness, and abdominal pain [4][13]. These symptoms are like those seen in umbilical VP shunt migration, which can also cause watery or purulent discharge from the umbilicus, abdominal distension and restlessness, abdominal pain, and umbilical obstruction [10]. In our patient, the continuous watery leakage from the umbilicus initially suggested a patent urachus. However, the possibility of umbilical VP shunt migration could not be ruled out due to the overlapping clinical presentation, thereby creating a diagnostic dilemma. Therefore, the use of appropriate diagnostic tools is essential in such cases.

Several diagnostic modalities are available to evaluate a patient with a suspected patent urachus, including USG, computed tomography (CT) scan, voiding cystourethrogram (VCUG), and sinogram. Among these, USG and CT scan are the most used, with CT scan having higher sensitivity in diagnosing a patent urachus [14]. In our patient, the abdominal NCCT scan and USG showed tenting of the superior bladder toward the umbilical region, which typically reflects a patent urachus rather than VP shunt migration. Radiological findings in umbilical VP shunt migration, as reported in other cases, usually show a migrated tip of the distal VP shunt causing fluid accumulation or a fistula without involving or elevating the bladder [10]. Conversely, elevation of the bladder toward the umbilical region connected by a tract is more characteristic of a patent urachus [4].

In our case, the ultrasound and CT scan were highly sensitive, reliable, and commonly used diagnostic tools for detecting a patent urachus. However, they can still present diagnostic pitfalls in patients with VP shunts who are suspected of having a patent urachus. Given this potential for misdiagnosis, the use of additional diagnostic tools, such as VCUG or a sinogram, should be strongly considered, particularly in hydrocephalus patients with VP shunts who present with umbilical leakage. These supplementary evaluations can provide more comprehensive insights and help avoid diagnostic errors and inappropriate surgical management.

This case highlights a rare and challenging situation in diagnosing umbilical VP shunt migration, which bears similarities to a patent urachus. The unusual and overlapping findings between these conditions underscore the importance of using additional diagnostic tools, such as VCUG or sinogram, to provide further clarity and ensure appropriate surgical management, especially in VP shunt patients with suspected patent urachus. Early recognition and accurate diagnosis of such rare complications are essential for improving patient outcomes and avoiding unnecessary surgical interventions.