Sidney K.H. Yip

Equipment and technology in surgical robotics

Contemporary medical robotic systems used in urologic surgery usually consist of a computer and a mechanical device to carry out the designated task with an image acquisition module. These systems are typically from one of the two categories: offline or online robots. Offline robots, also known as fixed path robots, are completely automated with pre-programmed motion planning based on pre-operative imaging studies where precise movements within set confines are carried out. Online robotic systems rely on continuous input from the surgeons and change their movements and actions according to the input in real time. This class of robots is further divided into endoscopic manipulators and master–slave robotic systems. Current robotic surgical systems have resulted in a paradigm shift in the minimally invasive approach to complex laparoscopic urological procedures. Future developments will focus on refining haptic feedback, system miniaturization and improved augmented reality and telesurgical capabilities.

Team-based approach reduces learning curve in robot-assisted laparoscopic radical prostatectomy.

Aim:  We assessed the team approach in reducing the learning curve during our 2‐year experience transiting from open to robot‐assisted laparoscopic radical prostatectomy (rLRP).

Primary hyperaldosteronism secondary to unilateral adrenal hyperplasia: an unusual cause of surgically correctable hypertension. A review of 30 cases.

Unilateral adrenal hyperplasia (UAH) is a rare, surgically correctable cause of primary hyperaldosteronism (PH). We report 2 cases and review the literature for cases of PH secondary to UAH successfully treated via surgery. Two cases of UAH treated at our institution were retrospectively reviewed. In addition, we reviewed 28 cases of UAH previously reported in the English literature. Median patient age was 49 (range: 10–62) years, with a male to female ratio of 1.7:1. All patients were hypertensive, with a median preoperative systolic and diastolic blood pressure of 170 (range: 135–250) mmHg and 110 (range: 75–140) mmHg, respectively. Most patients were hypokalemic, with a median serum potassium level of 2.8 (range: 1.4–3.9) mmol/l. Ten out of 13 patients (77%) who underwent postural studies had a decrease or no change in the plasma aldosterone level, suggesting a unilateral source of hyperaldosteronism, and 9/17 patients (53%) who underwent a computed tomography (CT) scan were correctly localized. Twelve patients underwent adrenal scintigraphy with or without dexamethasone suppression, of whom 6 (50%) were correctly localized. In 1 patient, adrenal scintigraphy demonstrated localization to the opposite gland. Adrenal venous sampling (AVS) was performed in 22 patients and successfully localized the lesion in all the patients. At a median follow-up of 12 (range: 3–96) months postsurgery, 47% of patients (14/30) were completely cured of their hypertension and 50% (15/30) had improved control. All 30 patients were cured of hypokalemia. Although the existence of UAH remains controversial, it is increasingly accepted as a unique pathologic entity and has an excellent outcome after unilateral adrenalectomy.

Early Experience with Robot-assisted Laparoscopic Radical Prostatectomy

INTRODUCTION We assessed the feasibility of a robot-assisted laparoscopic radical prostatectomy (rLRP) programme through a review of our early experience. PATIENTS AND METHODS Seventeen patients underwent rLRP between 1 February 2003 and 31 December 2003 at Singapore General Hospital. All patients had histologically confirmed adenocarcinoma on prostate biopsy and a negative bone scan. The Da Vinci robot was employed. The Montsouris technique was used for our first eight patients, and the Vattikuti Institute Prostatectomy technique was used for all subsequent patients. We studied perioperative parameters and early surgical outcome prospectively. RESULTS The mean age at diagnosis was 63.9 +/- 5.6 years. The median Gleason sum was 6 (range, 5-9), and mean pretreatment prostate-specific antigen level was 10.5 +/- 5.4 ng/mL. The mean set-up time was 34 +/- 18 minutes, and mean dissection time was 247 +/- 43 minutes. Perioperative blood loss averaged 494 +/- 330 mL, and three patients required blood transfusion. Normal diet was resumed after 1.7 +/- 0.6 days. The mean duration of bladder catheterization was 9.8 +/- 6.1 days, and mean hospital stay was 2.7 +/- 1.3 days. There was no perioperative mortality or major complications, and no conversion to open radical prostatectomy. From Case 9 onwards, there was significant reduction in operating time (284 vs 215 minutes), blood loss (650 vs 400 mL) and hospital stay (3.8 vs 1.8 days). CONCLUSIONS rLRP is feasible in a practice with a low volume of radical prostatectomies. Significant improvement in perioperative parameters occurs after the first eight cases. This technique confers the benefits of enhanced precision and dexterity for complex laparoscopic work in the pelvic cavity.

Surgical Management of Angiomyolipoma: Nephron-sparing Surgery for Symptomatic Tumour

Angiomyolipoma (AML) is a benign renal tumour that occasionally requires intervention. We evaluated the surgical management of symptomatic angiomyolipoma, with special attention to the feasibility of nephron-sparing surgery. A retrospective study was conducted enlisting 23 patients (including 3 patients with tuberous sclerosis) who had their AML treated surgically from 1991 to 1998. The study included 7 males and 16 females, with a mean age of 49 years (range 24-75). The mean tumour size was 12.3 cm (range 1.5-30.0) including 7 lesions < or = 4 cm and 16 lesions > 4 cm. The presenting features included abdominal/loin pain (9 patients), spontaneous rupture (5 patients), non-specific symptoms (7 patients) and incidental findings (2 patients). AML was diagnosed by computed tomography in 16 patients and malignancy was suspected in 7 patients. The latter group included 5 patients with lesions smaller than 4 cm, one of them having coexisting AML and renal cell carcinoma. All patients underwent elective surgery, with the exception of one, who required a semi-emergency operation. Nephron-sparing surgery using frozen section in 5 patients (all diagnostic) was carried out on 16 patients, including all 5 patients with previous haemorrhage and 2 patients with suspected lesions from preoperative studies. Total nephrectomy was performed in 7 patients, including the other 5 patients with lesions suspected to be malignant. There was no operative mortality. Two complications were encountered in the entire group. We conclude that elective nephron-sparing surgery is feasible, even for massive angiomyolipoma or after previous rupture, especially when the diagnosis is made by preoperative imaging and/or intraoperative frozen section.

Routine vascular control using the Hem-o-Lok clip in laparoscopic nephrectomy: Animal study and clinical application

BACKGROUND AND PURPOSE During laparoscopic nephrectomy (LPN), a stapling device is often used for vascular control, especially of the renal vein. Herein, we report our experience using a polymer clip (Hem-o-lok) for routine control of the vessels during LPN in the animal and clinical setting. PATIENTS AND METHODS Fifty ablative and fifteen live-donor nephrectomies were performed in domestic pigs. Hem-o-lok clips (10 mm; Weck Closure System, Research Triangle Park, NC) were routinely used for vascular control. In addition, from January 2001 to July 2002, 46 patients underwent hand-assisted laparoscopic (HAL) (N=40) or laparoscopic (N=6) nephrectomy for renal disease or donor nephrectomy. Venous control was achieved solely by the Hem-o-lok clips where at least two clips were applied on the patient side. Arterial control was obtained by the Hem-o-lok clips either alone or in combination with the metal clips. The technical difficulty in obtaining vascular control, transfusion requirement, and clinical outcome were evaluated. RESULTS In the animal study (total 65 nephrectomies), individual vascular control was obtained by the Hem-o-lok clip in all cases except two, where vascular injury during dissection necessitated endoscopic stapling of renal hilum or open conversion. The warm ischemic time for animal donor kidney harvest was uniformly <2 minutes. In the clinical study, arterial control was obtained mostly by a combination of Hem-o-lok and metal clips. Venous control using the Hem-o-lok was successful in all 46 cases without any slipping of clips or uncontrolled bleeding. The mean operating time was 148 minutes. No open conversion was required. The transfusion rate was 6.5% (N=3), with none of the transfusions being related to inadequacy of vascular control using the Hem-o-lok. Major complications included deep vein thrombosis and postoperative retroperitoneal hemorrhage (same patient) and acute respiratory distress syndrome (N = 1). The mean postoperative stay was 5.2 days (range 1-20 days). CONCLUSION The Hem-o-lok is a reliable and economical device for vascular control in laparoscopic renal surgery.

Clinical experience and results of ESWL treatment for 3093 urinary calculi with the Storz Modulith SL 20 lithotripter at the Singapore General Hospital

We study the outcome of 2700 patients treated for 3093 urinary calculi over a period of 60 months. All patients underwent Extracorporeal Shock Wave Lithotripsy (ESWL) treatment using the Storz Modulith SL20, predominantly on an outpatient basis (99.9% using intravenous pethidine for analgesia). The treatment outcome of 1666 renal calculi and 1427 ureteric calculi were analysed and stratified according to size and site. Follow-up status at 3 months was available for 91.8% of patients. For renal calculi, the overall success rate was 81% (re-treatment rate 29.7%). The majority of failures were stones larger than 2cm and those situated in the lower pole of the renal calyces. The overall success rate for ureteric calculi is 85% with similar clearance rates throughout the ureter (re-treatment rate 22.8%). Failures were predominantly with stones larger than 2cm. For the entire series, the morbidity rate requiring hospital admission was 2.9%, there was no mortality. The commonest cause for admission was for pain control (1.8%). To our knowledge, our experience with this lithotriptor is the largest to date. We have demonstrated that ESWL with Storz Modulith SL20 is safe, well tolerated and highly effective for the treatment of urolithiasis.

Outcome of Percutaneous Nephrostomy for the Management of Pyonephrosis

OBJECTIVE The aim of this study was to evaluate the efficacy of percutaneous nephrostomy (PCN) drainage for the interim management of pyonephrosis. METHODS Ninety-two consecutive patients [29 men, 63 women; mean age, 57 years; range, 23 to 88] who underwent PCN for the treatment of pyonephrosis from 1996 to 1999 were evaluated retrospectively. The clinical presentation, bacteriology and patient outcomes were analyzed. RESULTS The majority [77%] of patients had underlying obstructing urinary calculi. Other causes of obstruction included strictures [9%], papillary necrosis [7%], pelvi-ureteric junction obstruction [4%] and malignant stricture [3%]. The microorganisms cultured were Escherichia coli [30%], Klebsiella [19%], Proteus [8%], Pseudomonas [5%], Enterococcus [5%], and Candida spp [5%]. The microorganisms were sensitive to gentamicin [79%], ceftriaxone [71%], cephalexin [54%], nitrofurantoin [40%], cotrimoxazole [35%], nalidixic acid [32%] and ampicillin [29%]. Only 30% of bladder urine cultures were positive for microorganisms; the addition of PCN cultures improved this yield to 58%. The antibiotic regimen was revised according to the PCN culture whenever there was a discrepancy. After PCN, 69% of patients underwent minimally invasive procedures as definitive treatment of the obstructing lesion. Only 14% of patients required open surgery. There was low procedure-related morbidity [14%] and low overall mortality [2%]. CONCLUSIONS PCN cultures yield important bacteriological information. The procedure is associated with minimal morbidity, facilitates definitive treatment and provides therapeutic benefit.

Extramammary Paget’s disease of scrotum

We describe 4 cases of extramammary Pagets disease of the scrotum with underlying invasive carcinoma from 1997 to 1999. Three patients had metastatic inguinal lymphadenopathy. The delay in diagnosis was significant (mean 1 year). The diagnosis was made by skin biopsy in all patients. Histologically, intraepidermal cells with enlarged vesicular nuclei and vacuolated cytoplasm, which was mucin positive, were found. The mainstay of treatment is wide surgical excision, but positive margins remain a major problem. Other modes of treatment have been advocated but the efficacy for invasive disease is low. The key to successful control of the disease is therefore a high index of suspicion and early diagnosis.

Correlation between prostate needle biopsies and radical prostatectomy specimens: can we predict pathological outcome?

Aims: Prostate needle biopsy findings provide important information when considering treatment options. We examine the correlation between needle biopsy and radical prostatectomy pathology to predict patients at high risk of harbouring adverse pathological findings. Methods: We reviewed data from 100 consecutive patients who underwent radical prostatectomy between 1 January 2003 and 31 January 2005 at the Singapore General Hospital. Pre‐operative clinical findings and needle biopsy pathological data were prospectively collected and compared with the final histology. Results: The mean pre‐biopsy PSA level was 9.4 ± 5.1 µg/L. Median maximum percent of tumour in any core was 50% (range 5–100) and mean percentage of positive cores was 34.5 ± 23%. There was under‐grading of the final tumour score in 27 (27%) patients on biopsy as compared with the radical prostatectomy, while over‐grading occurred in eight (8%) patients. On stratifying patients pre‐operatively into low risk and high risk groups, patients in the high risk group had a significantly higher chance of having adverse radical prostatectomy histology such as extraprostatic extension, positive surgical margins or tumour volume >3.0 mL (p = 0.041, OR = 3.96, 95%CI 1.13–13.86). Conclusions: Our results demonstrated good pathological correlation between prostate needle biopsies and their radical prostatectomies. Patients with Gleason scores of 7 or more, maximum percent of tumour in any core >50%, or percent of positive cores of >50% on needle biopsy had a higher risk of having adverse pathological findings at radical prostatectomy. The converse, however, is not necessarily true, as a result of sampling error during the biopsy.