Preparation for pyeloplasty for ureteropelvic junction obstruction using a patient-specific laparoscopic simulator: a case report
© Yamanaka et al.; licensee BioMed Central Ltd. 2012
Received: 17 May 2012
Accepted: 24 August 2012
Published: 5 October 2012
Training systems for laparoscopic surgery are useful for basic training but are not suitable for specific training corresponding to the condition of a given patient. We, therefore, have developed an unusual training system: a patient-specific simulator for laparoscopic surgery. When specific data of each individual patient are entered, this system helps surgeons perform a “rehearsal” operation. We applied this technique in laparoscopic surgery by using volume data obtained by multislice computed tomography imaging.
A 39-year-old Japanese woman consulted a doctor because of back pain and underwent pyeloplasty after an examination revealed a ureteropelvic junction obstruction. Computed tomography data showed that the network of arteries and veins was very complicated. Therefore, we decided to use our simulator before performing surgery. Simulation was helpful because we could obtain information about the complicated vessel network and “rehearse” the procedure.
Our simulator allows surgeons to perform a sham operation with different perspectives and tactile sensations and has received favorable reviews from users.
KeywordsSurgical simulator Ureteropelvic junction obstruction Pyeloplasty Laparoscopy
In recent years, laparoscopic surgery has attracted attention as a minimally invasive type of surgery because of the small size of surgical wounds and early recovery. Teaching laparoscopic skills is a challenge in surgical training programs. Because of the highly technical nature and the steep learning curve, students and residents must acquire laparoscopic skills before performing laparoscopy in the operating room.
We report a case of ureteropelvic junction obstruction (UPJO) in which we used our simulator. Laparoscopic pyeloplasty has developed worldwide as the first minimally invasive option to match the success rates of open pyeloplasty[9, 10]. Success in this procedure requires a pre-operative examination of crossing vessels and the urinary tract. Simulation was helpful because the network of arteries and veins was very complicated in this case and we could “rehearse” the surgery.
A 39-year-old Japanese woman consulted a doctor because of back pain, and UPJO was detected after an examination. She was referred to our department and agreed to undergo laparoscopic surgery. A renogram showed that the function of her left hydronephrotic kidney was maintained to some extent, and surgery was thought to be effective. However, CT data revealed that the network of arteries and veins was very complicated. Therefore, we decided to use our simulator before surgery, and our patient agreed.
During the simulation, we first placed the camera and trocars on the body surface and obtained a virtual view of the abdominal cavity. When we changed the position of the trocar, the virtual view of the abdominal cavity also changed. Thus, we could choose a better position of the trocar in this pre-operative simulation. There were four renal arteries, two renal veins, and one gonadal vein that bifurcated in the middle. The lumbar vein was not important during surgery and therefore was not depicted.
The main features of the simulator and the operation
Number of renal arteries
Number of renal veins
Number of gonadal veins
1 (forked in the middle of itself)
1 (forked in the middle of itself)
Number of lumber veins
Unknown (out of operation area)
Unknown (out of operation area)
Number of ureters
Lesion of obstruction
Impression of surgeon
A meaningful simulation
Many commercially available laparoscopic simulators aim at the mastery of basic skills by practice with a programmed tutorial. These simulators can evaluate the basic skills by measuring the time or movement of forceps[2, 11]. On the other hand, because our simulator uses specific data of each individual patient, it meets the demands of a trained doctor who wants to simulate a complicated surgery. In renal and ureteral surgeries, the network of arteries and veins is complicated and varies. Therefore, we should obtain detailed information and be well prepared to avoid confusion and complications during the surgery. In fact, the vascular structure is complicated and reconstruction of the 3D data in our UPJO case was very time-consuming. Therefore, there were some structural differences between the simulated and actual vascular networks.
The higher the resolution of the images, the more accurate the reconstructed 3D images. Some reports suggested that a slice thickness of about 2mm is required to construct clear 3D images[12, 13]. At present, we are trying to combine the CT data (precontrast image, arterial phase, and nephrographic phase) and to improve the software so that tumors, vessel trees, or urinary ducts are highlighted in the simulation. (Now it can be depicted only in the software.) If we acquire more information about the patient, the precision of our simulator will improve. We are also trying to include the organ’s properties in the simulator so that it will provide a more realistic situation in the future.
By means of a patient-specific simulator, surgeries may be more accurate and proceed more smoothly because the surgeon has accurate anatomical information. In addition, it is possible that the time required for surgery, pre-operative risks, and complications will decrease. As we are finding from other clinical cases, surgeons could carry out meaningful pre-operative training and stated that the simulation was useful for constructing pre-operative images, although the operation time was not decreased. Trocar positions, which were simulated, were appropriate in other cases.
We need to validate the functionality of this simulator and improve the precision of the reconstructed 3D images before it can be made commercially available. However, we are cooperating with gynecology and general surgery departments to put our simulator to use, so we are confident that it will be the next-generation operative technology. (Our project is also available online.)
We reported a case of UPJO in which we used our simulator to “rehearse” the surgery. We demonstrated that our simulator was useful and could solve some problems. Our simulator has been improved, and its completion is under way.
Written informed consent was obtained from the patient for publication of this manuscript and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.
Digital Imaging and Communications in Medicine
Patient-specific virtual reality
Ureteropelvic junction obstruction.
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