Multidetector CT imaging of post-robot-assisted laparoscopic radical prostatectomy complications
- 1.4k Downloads
Robot-assisted laparoscopic radical prostatectomy (RALRP) is currently accepted as the preferred minimally invasive surgical treatment for localised prostate cancer, with optimal oncologic and functional results. Despite growing surgical experience, reduced postoperative morbidity and hospital stays, RALRP-related complications may occur, which are severe in 5–7 % of patients and sometimes require reoperation. Therefore, in hospitals with an active urologic surgery, urgent diagnostic imaging is increasingly requested to assess suspected early complications following RALRP surgery.
Based upon our experience, this pictorial review discusses basic principles of the surgical technique, the optimal multidetector CT (MDCT) techniques to be used in the postoperative urologic setting, the normal postoperative anatomy and imaging appearances.
Afterwards, we review and illustrate the varied spectrum of RALRP-related complications including haemorrhage, urinary leaks, anorectal injuries, peritoneal changes, surgical site infections, abscess collections and lymphoceles, venous thrombosis and port site hernias.
Knowledge of surgical procedure details, appropriate MDCT acquisition techniques, and familiarity with normal postoperative imaging appearances and possible complications are needed to correctly perform and interpret early post-surgical imaging studies, particularly to identify those occurrences that require prolonged in-hospital treatment or surgical reintervention.
• Robot-assisted laparoscopic radical prostatectomy allows minimally invasive surgery of localised cancer
• Urologic surgeons may request urgent imaging to assess suspected postoperative complications
• Main complications include haemorrhage, urine leaks, anorectal injuries, infections and lymphoceles
• Correct multidetector CT techniques allow identifying haematomas, active bleeding and extravasated urine
• Imaging postoperative complications is crucial to assess the need for surgical reoperation
KeywordsProstatectomy Robotic surgery Laparoscopic surgery Complications Haemorrhage Anastomotic leak Urine leak Computed tomography (CT) Cystography
During the last 20 years, the surgical treatment of prostate cancer (PC) evolved from open to laparoscopic prostatectomy. Currently, robot-assisted laparoscopic radical prostatectomy (RALRP) represents the preferred, minimally invasive surgery for localised PC. Since its introduction in 2000, RALRP has increasingly gained acceptance and popularity among urologists and is currently considered a safe, reproducible procedure with a limited learning curve for experienced surgeons and an acceptable complication rate in experienced hands [1, 2, 3].
During the last decade, several series have reported favourable results with RALRP compared to radical retropubic prostatectomy (RRP) in terms of reduced blood loss, postoperative pain and hospital stay, surgical margins (which are found positive in approximately 20 % of patients), preserved urinary continence and erectile function. However, despite the reduced morbidity, optimal oncologic and functional results, RALRP-associated complications do occur. The reported overall RALRP complication rates greatly vary (in the range 14.6–42 % of patients) according to operator experience and centre case load, criteria and severity of complications. Preoperative predictive factors include comorbidities, advanced age, prostate-specific antigen (PSA) values and Gleason score. The majority (approximately two-thirds) of occurrences are classified as minor complications (Clavien classes 1 and 2, including prolongation of postoperative course, drug or bedside treatment), but major (Clavien classes 3 to 5) complications occur in 5–7 % and require reoperation in 3 % of patients respectively [1, 2, 4, 5, 6, 7].
In hospitals with an active urologic surgical practice, radiology departments are increasingly requested to assess suspected early or delayed postoperative complications following RALRP. Based upon our experience, this article discusses basic principles of surgical technique and the optimal multidetector CT (MDCT) techniques in this setting, and reviews the normal postoperative imaging appearances and the spectrum of possible complications, to provide radiologists with an increased familiarity with postoperative imaging of RALRP patients.
Surgical technique notes
The daVinci surgical system (Intuitive Surgical; Mountain View, CA, USA) includes a surgeon’s console, a patient-side robotic cart with four arms manipulated by the surgeon and a high-definition three-dimensional vision system that provides a 10- to 12× magnification stereoscopic view of the operative field. The device senses the hand instructions, filters tremor, and translates and transmits movement to manipulate the tiny proprietary instruments, to provide the surgeon with enhanced vision and dexterity [1, 2, 3].
Although a description of the surgical technique is beyond the scope of this pictorial review, some remarks are useful to the radiologist. Knowledge of procedural details (including the surgical approach, the use of surgical clips or patches, and if concomitant lymphadenectomy was performed) is necessary, since they result in key differences in postoperative imaging appearances and complications observed. According to surgeon’s preference and familiarity, radical prostatectomy can be performed using either a transperitoneal (TP) or extraperitoneal (EP) approach through the prevesical space of Retzius. In both cases, a vesico-urethral anastomosis (VUA) is created between the urinary bladder and the membranous urethra. With the latter approach urine leaks are confined to the extraperitoneal space, whereas the TP approach creates two potential routes of communication from the VUA to the peritoneal cavity, respectively anterior and posterior to the bladder [8, 9, 10].
According to both literature and our personal experience, the commonest indications for postoperative imaging include abdominal, pelvic and/or perineal pain, clinical or laboratory signs of blood loss, persistent ileus, fever and/or abnormal acute phase reactants, rising serum creatinine, high output from drainage tube and low urine output from a Foley catheter [4, 5, 6, 7].
Often performed as first-line investigation in postoperative urologic patients, ultrasound may quickly provide an overview of the urinary tract and assess the presence of peritoneal effusion and of space-occupying collections. However, ultrasound may be hampered by large body size, uncooperation and overlying bowel gas. Conversely, MDCT consistently provides a comprehensive visualisation of the entire abdomen and pelvis and therefore in the vast majority of cases represents the preferred modality to search for possible postoperative complications. Basically, in urologic patients a postoperative MDCT study should include: (1) a preliminary unenhanced acquisition to detect hyperattenuating blood and abnormal air collections; (2) arterial- and venous-phase images after intravenous contrast medium (CM) injection to assess the solid organs and identify extravascular CM indicating active bleeding; (3) excretory phase imaging obtained at least 5–20 minutes (up to 1-2 hours) after CM, in order to demonstrate the opacified urinary cavities and detect iodinated urine leaks and urinomas. Most usually interpreted on a dedicated workstation, MDCT studies should be complemented with multiplanar reformations and three-dimensional volume-rendering (3D-VR) images to effectively depict the postoperative anatomy and salient findings [6, 11, 12, 13].
In the early phases of our experience, most postoperative RALRP patients were investigated using a classical multiphasic MDCT exam protocol. When renal function impairment contraindicates CM administration, an unenhanced MDCT acquisition is helpful to demonstrate the postoperative anatomy and abnormal haemorrhagic or fluid space-occupying collections, although it cannot detect active bleeding and extraluminal urine. More recently, to limit the radiation dose erogated during multiphasic acquisitions, split-bolus MDCT urography protocols have been developed that allow for combined renal vascular, parenchymal and excretory acquisition. In several cases, we successfully adopted the time- and dose-efficient triple-bolus MDCT-urography protocol described by Kekelidze et al., which includes preliminary unenhanced scans, an initial 30 ml CM bolus injected at 2 ml/s flow for urinary opacification, a 7-min delay, a second (50 ml at 1.5 ml/s) and third (65 ml at 3 ml/s) CM injection separated 20 s from each other to provide parenchymal and vascular visualisation respectively, followed by a single MDCT volumetric acquisition. Therefore, triple-bolus MDCT urography provides simultaneous renovascular, corticomedullary, nephrographic and excretory imaging with a reduced effective radiation dose compared to the usual multiphasic MDCT protocols [13, 14].
Due to its intrinsically high contrast resolution, magnetic resonance imaging (MRI) provides an excellent visualisation of the normal post-prostatectomy anatomy and of possible neoplastic recurrence . In the emergency setting, the use of MRI is limited by lengthy examination time, scanner availability, constraints and artefacts in acutely ill patients. Compared to MRI, with appropriate acquisition techniques MDCT provides quicker reliable identification of blood collections, extravasated urine and active bleeding [10, 12, 13].
Furthermore, in patients with suspicion of VUA leak an additional focussed investigation with conventional radiographic cystography or MDCT cystography is recommended. At our department diluted iodinated CM to be used during MDCT cystography is prepared by removing 40–50 ml of normal saline from a 500-ml bag and injecting a similar amount of non-ionic contrast agent (such as 350 mgI/ml iomeprol or 370 mgI/ml iopromide) into the same saline solution bag. The bag is then connected to standard tubing for intravenous infusions, filling the tube with diluted contrast to avoid instilling air in the bladder. With the patient supine on the CT scanner table, slow retrograde infusion is obtained by gravity. Differently from conventional MDCT cystography to investigate bladder trauma and spontaneous colovesical fistulas, in postoperative patients the injected CM volume should not exceed 150 ml because of concern about excessive pressure on the newly created VUA. The volumetric MDCT acquisition at sufficient bladder distension is visualised with multiplanar image reformations at CT angiography window settings (width 600–900 level 150–300 Hounsfield Units, HU) and by maximum intensity projection (MIP) or 3D-VR techniques. The only potential pitfall of this technique is the possible occlusion of a limited anastomotic dehiscence by the Foley catheter balloon [8, 15, 16].
Normal postoperative anatomy and imaging findings
In patients operated on through a TP surgical approach, during the early postoperative days minimal or moderate residual intraperitoneal air is commonly observed, often associated with multiple air-fluid levels of the small bowel consistent with adynamic ileus.
During RALRP, the VUA is created with a Foley catheter in place. Traditionally, radiographic voiding cystography has been routinely performed after radical prostatectomy before catheter removal. Currently, the optimal interval between surgery and Foley catheter removal has still not been established. Early patient discharge and removal of the Foley catheter 8–10 days after RARLP without routine cystography are now accepted practice [6, 20, 21, 22].
Ureteral injury is an exceptional occurrence during RALRP, which can occur secondary to seminal vesicle dissection, extensive lymphadenectomy or bladder neck reconstruction. The resulting urinomas appear at MDCT as more or less confined fluid attenuation collections that may be sometimes misinterpreted as loculated ascites, but get filled by iodinated urine in the excretory phase acquisition. Furthermore, the site and features of the collecting system injury may be exquisitely depicted by multiplanar MIP or 3D-VR reconstructions (Fig. 10), thus allowing optimal operative treatment planning. Although small-sized urinomas usually reabsorb spontaneously, large collections need surgical or percutaneous treatment to prevent superinfection [10, 11, 12].
In our experience, despite anti-thrombotic prophylaxis postoperative venous thrombosis of the legs is commonly observed in RARLP patients. Therefore, MDCT images should be carefully scrutinised for filling defects of the iliac-femoral veins (Fig. 13). Finally, in patients with symptoms or signs of bowel dysfunction the possibility of trocar (port site) hernia causing small bowel obstruction should be considered (Fig. 13) [30, 31].
Urgent diagnostic imaging is increasingly requested by urologic surgeons when postoperative complications are suspected after RALRP. Knowledge of the surgical procedure details, appropriate MDCT acquisition techniques and special interpretation care are needed, particularly to identify postoperative haemorrhage, active bleeding, extravasated urine and infections. Furthermore, radiologists should be familiar with the usual postoperative imaging appearances and the varied spectrum of possible complications, particularly to identify those occurrences that require prolonged in-hospital treatment or surgical reoperation [10, 11].
Conflict of interest
The authors declare no conflicts of interest. No funding was received for this work.
Note of thanks
We would like to thank our professional nurses Nerea Bevilacqua, Nadia Cortesi, Eugenia Ferron, and Giacomo Nocera for their valuable help in developing and performing the MDCT urography and MDCT cystography techniques, as well as for their daily care of patients in the radiology department.
- 31.Spaliviero M, Samara EN, Oguejiofor IK et al (2009) Trocar site spigelian-type hernia after robot-assisted laparoscopic prostatectomy. Urology 73(1423):e1423–1425Google Scholar
Open Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.