During this study, the preoperative imaging findings indicating whether the UR continued toward the bladder apex were consistent with the positive pathological findings at the bladder site. However, when preoperative imaging showed that the UR was near the umbilicus and did not continue toward the bladder apex, both the intraoperative findings and pathological examination results revealed fibromuscular tissue only; there was no urachus tissue at the resected site and the UR ended near the umbilicus. All UR cases were appropriately resected and there was a negative pathological remnant. Our institution’s policy (i.e., obtaining preoperative imaging findings and intraoperative findings to determine whether bladder apex removal is necessary) of determining the surgical approach for UR treatment was found to be acceptable.
UR cases usually present with lower abdominal pain and infection near the umbilicus. For pediatric cases, the differential diagnosis of these symptoms includes omphalitis, omphalomesenteric duct, and umbilical granuloma. Umbilical pilonidal sinus is also one of the possibilities for adult cases. Imaging methods such as US are useful for diagnosis; however, a definitive diagnosis confirmed by pathology is essential. There are four types of UR: patent urachus, umbilical-urachal sinus, urachal cyst, and vesico-urachal diverticulum . Nine of the 20 (45%) patients in our study had an umbilical-urachal sinus UR that continued toward the bladder apex.
The treatment strategy for UR is controversial. Complete resection of the UR has been historically performed because of the risk of urachal carcinoma for both adults and children attributable to epithelial or mesenchymal urachal neoplasms that can occur with the UR [8, 9]. Malignant urachal neoplasms are usually low-grade and diagnosed at advanced stages . Therefore, complete excision of an asymptomatic UR, even in pediatric patients, has been performed to prevent future malignant neoplasms. However, a recent study showed that only one out of every 5721 UR cases leads to urachal adenocarcinoma . Another study reported that conservative follow-up is an option for UR patients younger than 1 year [11, 12] and for UR patients after undergoing initial drainage treatment . Each individual pediatric patient with UR should be treated based on the imaging results. In some cases, simple and asymptomatic lesions are not excised; however, in other cases, large and suspicious lesions are excised . We treated symptomatic UR cases; however, we do not consider prophylactic excision of asymptomatic UR to be necessary for children.
There are two approaches to UR excision, TU and LATU. Laparoscopic excision of the UR was first reported in 1992 . Since then, several modified laparoscopic surgery techniques for UR have been developed and reported, with similar surgical outcomes and good cosmetic appearance [3, 4]. There are several laparoscopic UR excision methods in terms of port placement, arrangements, and bladder suturing; however, we adopted the LATU approach for excising UR. We considered preoperative imaging of the UR to be appropriate for determining the surgical approach and margin. Compared to the LATU approach, the TU approach has the advantage of being able to be performed in the preperitoneal space without opening the abdominal cavity to prevent late complications of postoperative obstruction. For children younger than 3 years, the TU approach is sufficient for complete excision of the UR including the bladder apex without opening the abdominal cavity. However, based on our experience, for children older than 3 years old or those younger than 3 years with a large body for their age, it is difficult to use the TU approach to completely excise the UR without adding the Y-shape midline skin incision. The cosmetic appearance is an important factor for pediatric UR patients; therefore, we select the LATU approach for children older than 3 years.
US, CT, and MRI are useful for diagnosing UR [15, 16]. We performed preoperative imaging for all patients. US is the first choice for diagnosing UR at our institution and was performed for all patients. We consider US to be sufficient for diagnosing UR. Because of the risk of radiation exposure, other imaging methods, especially CT, should be adopted only when it cannot be determined whether the UR exists at the bladder apex. MRI does not expose patients to radiation; however, obtaining images with MRI is time-consuming and often requires sedation for young children. It is easier to perform imaging examinations when the bladder is distended with urine to determine whether the UR is at the apex of the bladder; US can be repeated and performed with the bladder distended [15, 16]. Considering its simplicity and noninvasiveness, US is the best method for diagnosing the UR. However, intestinal gas or the abdominal wall thickness can prevent a detailed examination of the bladder site when using US. In such cases, MRI is an alternative option. CT is a useful tool, but it exposes patients to radiation, which is a disadvantage, especially for young children; therefore, its use should be limited as much as possible.
Our pathological examinations revealed that our surgical approach to UR allowed for complete UR excision. The results of preoperative imaging of the UR to determine its presence or absence were consistent with the pathological findings of the UR. When the UR ended before the bladder apex according to preoperative imaging, urachus tissue existed at the umbilicus but not at the fibromuscular cord-like structure according to intraoperative findings. These findings were also demonstrated pathologically. Therefore, the use of preoperative imaging was appropriate for determining the surgical margin and procedure. Our study proved that our surgical strategy for symptomatic UR results in appropriate surgical margins and avoids unnecessary and excessive surgical invasion.
This study had several limitations. It was single-center, retrospective case series. Our sample size was small; therefore, the results should be validated in a large population and at other institutions. Long-term follow-up was not performed; therefore, the potential risk of UR recurrence when complete excision was not achieved was not evaluated.