Operative Options

Educational Objectives

The goals of this program are to improve the treatment of urinary stones in the pregnant patient, maximize outcomes in the treatment of stone disease, and improve the prevention and treatment of venous thromboembolism (VTE) in urologic

surgery patients. After hearing and assimilating this program, the clinician will be better able to:

1.   Describe the epidemiology of urinary calculi during pregnancy and identify the risk factors for stone formation.

2.   List the indications for surgical intervention in the pregnant patient with stone disease and explain the options for the relief of obstruction and for definitive treatment.

3.   Discuss recent studies looking at possible long-term adverse effects of schock wave lithotripsy and steps that may improve treatment outcome.

4.   Explain the benefits and limitations of mechanical and pharmacologic thromboprophylaxis for the prevention of VTE and describe the recommended thromboprophylaxis for various patient populations.

5.   Follow the diagnostic algorithm for the detection of VTE and recommendations for the initial treatment of deep ve­nous thrombosis.

Faculty Disclosure

In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty and members of the plan­ning committee to disclose relevant financial relationships within the past 12 months that might create any personal con­flicts of interest. Any identified conflicts were resolved to ensure that this educational activity promotes quality in health care and not a proprietary business or commercial interest. For this program, the following has been disclosed: Dr. Razvi has received research grant support from Cook Urological and is a consultant for Olympus-Gyrus ACMI. Drs. Pace and Kempton and the planning committee reported nothing to disclose.

Acknowledgements

Drs. Razvi and Pace were recorded at Urology Update 2008, held October 25-26, 2008, in Toronto, ON, and sponsored by the Department of Surgery, Division of Urology, of the University of Toronto. Dr. Kempton spoke at Advances in Urology 2008, held December 12-13, 2008, in Atlanta, GA, and sponsored by the Department of Urology, Emory University School of Medicine, The Audio-Digest Foundation thanks the speakers and the sponsors for their cooperation in the production of this program.

What Should We Be Doing About Stones in Pregnancy?

Hassan Razvi, MD, Professor and Chair, Division of Urology, Schulich School of Medicine and Dentistry, Uni­versity of Western Ontario, London, ON

Epidemiology: urinary calculi during pregnancy relatively common (similar to that in nonpregnant patients); average age 27 yr; >80% present in second or third trimester

Known risk factors: multiparity; increasing age; white ethnicity; history of renal disease or hypertension; anatomic and physiologic changes of pregnancy do not appear to be risk factors for stone formation

Presentation: flank pain (in pregnant patient, pain more intense than in pyelonephritis in nonpregnant patient); gross hema­turia rare, microscopic hematuria universal; other presentations include preeclampsia, preterm labor, urinary tract infec­tion (UTI), and impairment of renal function

Diagnostic tests: renal ultrasonography (US) considered first-line imaging modality because of lack of ionizing radiation and rela­tively low risk to fetus; however,  US in pregnancy has low sensitivity for detecting stones; adjuncts to renal US that might improve sensitivity  —   Doppler imaging; presence or absence of ureteral jet; limited experience with transvaginal US in this setting but not contraindicated in pregnancy; limited intravenous pyelography (IVP)  —   used in past but now considered second-line investigation; conventional computed tomography (CT)  —  contraindicated in pregnancy due to high-dose radiation exposure; low-dose CT  —  in recent study, proved more sensitive than US for stone detection in pregnant women (stone found in 13 of 20 patients); authors con­cluded radiation exposure to fetus relatively low; data suggest that fetal radiation doses <5 rad carry relatively low risk, and that threshold for inducing birth defects or miscarriage higher than previously thought, eg, ³20 rad for induction of birth defects during first trimester, ³50 rad in second and third trimester; magnetic resonance imaging (MRI)  —  in case control studies, T2-weighted MRI with gadolinium more accurate diagnostic tool than US with Doppler imaging; limitations  —  no distinct stone signal; must rely on soft signs to identify stone; availability; time consuming; MRI has no known harmful effects on fetus, but experience with gadolinium in pregnant patients limited

Treatment considerations: in majority of cases, conservative management sufficient, as most patients pass stones sponta­neously; should patient require intervention, physician must rely on clinical judgment; trimester of pregnancy may influ­ence choice of treatment; avoid intervention in first trimester because of risk for miscarriage and in third trimester because of risk for preterm labor; involve perinatologist and high-risk obstetrics unit

Symptomatic therapy: standard therapy same as for all patients with stone disease; prophylactic antibiotics have no proven benefit in pregnant patient who does not have UTI; opiates considered first-line analgesics; nonsteroidal anti-inflamma­tory drugs (NSAIDs) contraindicated; small older Canadian study found epidural anesthesia aided in stone passage and provided excellent analgesia; medical expulsive therapy used widely in nonpregnant population, but no data on pregnant patients, and routine use not recommended because of risks

Indications for intervention: intractable pain; urinary sepsis; obstruction in solitary kidney; preterm labor; preeclampsia

Management options: for relief of obstruction  —  percutaneous nephrostomy effective option, particularly in first trimester, with ca­veats; ureteric stents good option later in pregnancy, with caveats

Definitive therapy: traditionally definitive management deferred until after delivery; however, with advent of smaller caliber, semi-rigid, flexible ureteroscopes and wide availability of holmium: yttrium aluminum garnet (Ho:YAG) laser, ureteroscopy emerging as valid therapeutic option; contraindications  —  septic patient; large-volume stone; multiple stones; upper ureteral and renal pelvic stones; procedure  —  general, spinal, or epidural anesthesia; although speaker rarely uses it, fluoroscopy should be available in case of stone impaction or other complication; consider routine stenting for drainage, at least for short postoper­ative period; outcomes  —  studies  report reasonably good stone-free rates and few major adverse events

Adverse effects: little clinical evidence to suggest devices used in ureteroscopy harmful to fetus, but some theoretic con­cerns; US may have some impact on development of fetal hearing,  (not proven in humans); some concern that electrohy­draulic lithotripsy may stimulate uterine contractility; focal energy delivery devices (eg, pneumatic)  safe and recommended modalities; shock wave lithotripsy (SWL) absolutely contraindicated in pregnancy, although no adverse outcomes noted in cases in which women treated before being aware of pregnancy; percutaneous stone removal also not recommended, due to radiation requirement and prone positioning

Asymptomatic stone in woman of childbearing age: study data show »25% of women became symptomatic over 5-yr pe­riod; Keeley study  —  compared observation and prophylactic SWL for treatment of asymptomatic renal calyceal stones; while no difference in stone-free rates, quality of life, renal function, or hospital admissions, observation associated with greater need for invasive procedures within 3 yr; potential risks to woman with stone  —  risk for preterm labor higher (rel­ative risk 1.7%); no heightened risk for low birth weight or fetal death; no observed effect of SWL on female fertility; suggests that women of childbearing age should be treated before conception

An Update on Shock Wave Lithotripsy

Kenneth Pace, MD, MSc, Assistant Professor, Department of Surgery, Division of Urology, and Co-Director, Fellowship in Laparoscopy and Endourology, St. Michael’s Hospital, University of Toronto, ON

Does SWL have long-term adverse effects? Krambeck et al, 2006  —  retrospective chart review and questionnaire found SWL associated with increased risk for hypertension (not significant when multivariate analysis done) and diabetes mel­litus (remained significant); however, no independent verification of diagnosis of diabetes; risk for acute pancreatic injury  —  in recent study, researchers measured substances liberated from inflamed pancreas (eg, lipase, amylase, gluca­gon, C-peptide), and found no correlation between SWL for upper or lower stones and increased risk for pancreatic in­jury; another study reported only rare cases of acute pancreatitis in patients treated for upper renal stones, and none in those treated for ureteral stones; over 19-yr follow-up, no increase in new-onset diabetes; risk for hypertension  —  in ran­domized trials comparing observation and SWL, authors found no correlation between SWL and worsening of systolic or diastolic blood pressure (BP), or onset of hypertension; long- and short-term renal function  —  acute renal complications known to occur with SWL, but incidence extremely low; hypothesis that, over long term, SWL could cause vascular in­jury within kidney that might lead to renal dysfunction and scarring; however, recent retrospective study of patients with solitary kidney (no confounding effects from contralateral kidney) treated for stones found no difference in serum creati­nine, no change in overall renal function over time, and BP actually decreased

Maximizing outcome with SWL: everyday steps  —  maximize energy or peak pressure delivered to stone; maximize num­ber of shocks administered to stone (within safe limits); perform appropriate targeting (by fluoroscopy or US) to ensure all energy delivered to stone

Potential areas for further improvement:  varying treatment rate  —  data suggest efficacy influenced by treatment rate (in 2 recent studies, patients with kidney and upper ureteral stones randomized to 60 or 120 shocks/min; in both trials, pa­tients did better with lower treatment rate [difference most profound with larger stones]); voltage escalation  —current standard practice to increase voltage as quickly as possible; goal to expose stone to highest peak pressure possible (however, some evidence that this may not be best method; in one recent study, increasing voltage gradually from 15 to 21 kV achieved better fragmentation than going directly to 21 kV; altered voltage escalation may also minimize renal injury by preconditioning or priming kidney); medical expulsive therapy  —  2 randomized trials demonstrate advantage to using tamsulosin after SWL; study found no difference for small stones, but for stones 11 to 24 mm in diameter, clearance rates superior with tamsulosin, and patients had less pain

Urologists’ preferred methods: percutaneous nephrolithotomy (PERC) and ureteroscopy; good evidence that percutaneous ap­proach in management of lower-pole stones achieves higher stone-free rates than SWL (however, counterbalanced by short-term costs of increased morbidity and impairment of quality of life); ureteroscopy produces excellent stone-free rates in ureter, but not in lower pole

Venous Thromboembolism in Urologic Surgery

Christine Kempton, MD, Assistant Professor, Departments of Pediatrics, Hematology, and Medical Oncology, Emory University School of Medicine, Atlanta, GA

Venous thromboembolism (VTE): rate in major urologic surgery  —  asymptomatic (15%-40%); symptomatic (1%-5%); consequences  —  mortality (»2% from deep venous thrombosis [DVT] alone; »15% from pulmonary embolism [PE]); pro­longed or recurrent hospitalization; increased costs; postthrombotic syndrome (chronic swelling, pain, and possible ulcer­ations); risk factors  —  previous VTE; advanced age; thrombophilia, eg, factor V Leiden; family history of VTE; cardiovascular risk factors; other patient-related factors, including female sex, higher American Society of Anesthesiology class, ventilator de­pendence, and preoperative dyspnea

Mechanical methods of thromboprophylaxis: ambulation; graduated compression stockings (GCS); intermittent pneumatic compression (IPC) devices; major benefit  —  no risk for bleeding; limitations  —  less effective than pharmacologic prophy­laxis; effect on incidence of PE unknown; no standardization of size and pressures of GCS or IPC devices; poor compliance

Pharmacologic thromboprophylaxis: low-dose unfractionated heparin (UFH)  —  reduces risk for fatal postoperative PE from 0.7% to 0.1%; low molecular weight heparin (LMWH)  —enoxaparin or dalteparin; superior to UFH in high-risk patients and surgeries; once-daily dosing; lower risk of developing heparin-induced thrombocytopenia (HIT) than with UFH; limitation (influence of renal clearance; may need dose adjustment in patients with creatinine clearance <30 mL/min); fondaparinux (Arixtra)  —  lowest risk for HIT; once-daily dosing; limitation (influence of renal clearance)

Guidelines from American College of Chest Physicians (ACCP): low-risk (transurethral) procedures  —  early and frequent ambulation; laparoscopic procedures  —  ACCP unable to make recommendations; however, procedures considered low-risk, so ambulation and mechanical devices likely to be adequate; high-risk patients (open procedures)  —  can be low-dose UFH; mechanical methods; LMWH; fondaparinux; combination of pharmacologic and mechanical methods; patients at highest risk for VTE (open procedure plus additional risk factors)  —  start mechanical method preoperatively and continue through procedure, then initiate pharmacologic prophylaxis postoperatively; patients at highest risk for bleeding  —  begin mechanical method preoperatively; delay pharmacologic prophylaxis until risk for bleeding has decreased

Duration of thromboprophylaxis: typically limited to time of hospitalization; prophylaxis beyond hospitalization not studied in setting of major urologic surgery; however, in cancer surgery, extension to 1 mo reduces rate of VTE

Complications of pharmacologic therapy: bleeding; HIT; suspect HIT  —  if platelet level drops 30% to 50% from base­line; drop begins 5 to 10 days after start of heparin, or within 24 hr; if patient exposed to heparin within 100 days; clinical pretest probability necessary to interpret testing for HIT

Diagnosis of DVT: Wells score  —  low score £0; intermediate 1 to 2; high score ³3; D-dimer  —  must be done by highly sensi­tive assay; useful for ruling out VTE; sensitive but not very specific; may be more useful in later postoperative period; if pa­tient has low clinical probability and normal D-dimer, VTE unlikely

Diagnostic algorithm: if patient has low Wells score, do D-dimer measurement; if negative, no further evaluation necessary; if positive, do compression US; if patient has higher score (³2), do compression US first; if negative, D-dimer test useful; if positive, no further evaluation necessary; if US negative and D-dimer test positive, repeat US in »1 wk; if still negative, VTE adequately excluded; if positive, start treatment

Initial treatment of DVT: heparin (UFH or LMWH)  —  10 of 11 systematic reviews of clinical trials comparing UFH and LMWH showed that LMWH superior; peak level within 4 hr of administration; bleeding rates lower with LMWH be­cause levels more consistent; wafarin  —  start once heparin therapeutic; do not start with >5 mg (larger loading doses in­crease risk for bleeding); in elderly or chronically ill patients, start at lower dose (2-3 mg); drug interactions may necessitate higher or lower starting doses

After discharge: anticoagulation therapy  —  for 3 to 6 mo; careful monitoring of international normalized ratio (INR); target INR, 2 to 3; GCS  —  majority of patients can be started with GCS below knee, even if DVT proximal; should be 30 to 40 mm Hg at ankle and should be difficult to get on; start within 1 mo of diagnosis and continue for   ³1 yr (longer if patient having additional symp­toms of postthrombotic syndrome); only treatment that can decrease likelihood of postthrombotic syndrome (by 50%)

Inferior vena cava (IVC) filters: used in patients with  —  proven DVT and contraindication for anticoagulation; complication of anticoagulation requiring its cessation;  recurrent VTE despite anticoagulation; complications  —  occur in 4% to 11% of patients; include insertion site venous thrombosis, and increased frequency of recurrent DVT; migration and penetration of IVC; speaker does not recommend

Suggested Reading

Akpinar H et al: Ureteroscopy and holmium laser lithotripsy in pregnancy: stents must be used postoperatively. J Endourol 20:107, 2006; Al-Bareeq R, Denstedt J: Percutaneous nephrolithotomy for the treatment of lower pole renal calculi. Can Urol Assoc J 2:628, 2008; Collins JW, Keeley FX Jr: Is there a role for prophylactic shock wave lithotripsy for asymptomatic calyceal stones? Curr Opin Urol 12:281, 2002; Crowther MA: Inferior vena cava filters in the management of venous thromboembolism. Am J Med 120:S13, 2007; Denstedt JD, Razvi H: Management of urinary calculi during pregnancy. J Urol 148:1072, 1992; Geerts WH et al: Prevention of venous thromboembolism: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Chest 133:381S, 2008; Krambeck AE et al: Diabetes mellitus and hypertension associated with shock wave lithotripsy of renal and proximal ureteral stones at 19 years of follow up J Urol 175:1742, 2006; Losek RL, Mauro LS: Efficacy of tamsulosin with extracorporeal shock wave lithotripsy for passage of renal and ureteral calculi. Ann Pharmacother 42:692, 2008; Montgomery JS, Wolf JS Jr: Venous thrombosis prophylaxis for urological laparoscopy: fractionated heparin versus sequential compression de­vices. J Urol 173:1623, 2005; Musch M et al: Complications of pelvic lymphadenectomy in 1,380 patients undergoing radical retro­pubic prostatectomy between 1993 and 2006. J Urol 179:923, 2008; Nabi G et al: Extra-corporeal shock wave lithotripsy (ESWL) versus ureteroscopic management for ureteric calculi. Cochrane Database Syst Rev:CD006029, 2007; Pace KT et al: Shock wave lithotripsy at 60 or 120 shocks per minute: a randomized, double-blind trial. J Urol 174:595, 2005; Park SJ et al: Evaluation of pa­tients with suspected ureteral calculi using sonography as an initial diagnostic tool: how can we improve diagnostic accuracy? J Ultrasound Med 27:1441, 2008; Pettus JA et al: Perioperative clinical thromboembolic events after radical or partial nephrectomy. Urology 68:988, 2006; Prandoni P et al: Below-knee elastic compression stockings to prevent the post-thrombotic syndrome: a ran­domized, controlled trial. Ann Intern Med 141:249, 2004; Rana AM et al: Semirigid ureteroscopy and pneumatic lithotripsy as defin­itive management of obstructive ureteral calculi during pregnancy. Urology 73:964, 2009; Rogers SO Jr et al: Multivariable predictors of postoperative venous thromboembolic events after general and vascular surgery: results from the patient safety in sur­gery study. J Am Coll Surg 204:1211, 2007; Scarpa RM et al: Clinically overt venous thromboembolism after urologic cancer sur­gery: results from the @RISTOS Study. Eur Urol 51:130, 2007; Schuler TD et al: Medical expulsive therapy as an adjunct to improve shockwave lithotripsy outcomes: a systematic review and meta-analysis. J Endourol 23:387, 2009; Secin FP et al: Multi-in­stitutional study of symptomatic deep venous thrombosis and pulmonary embolism in prostate cancer patients undergoing laparo­scopic or robot-assisted laparoscopic radical prostatectomy. Eur Urol 53:134, 2008; Semins MJ et al: The safety of ureteroscopy during pregnancy: a systematic review and meta-analysis. J Urol 181:139, 2009; Srirangam SJ et al: Management of urinary calculi in pregnancy: a review. J Endourol 22:867, 2008; Watterson JD et al: Ureteroscopy and holmium:YAG laser lithotripsy: an emerg­ing definitive management strategy for symptomatic ureteral calculi in pregnancy. Urology 60:383, 2002; White WM et al: Low-dose computed tomography for the evaluation of flank pain in the pregnant population. J Endourol 21:1255, 2007.