Chad R. Tracy, University of Iowa, Department of Urology, 200 Hawkins Dr., 3 RCP, Iowa City, IA 52242-1089, USA. e-mail: firstname.lastname@example.org
Study Type – Therapy (case series)
Level of Evidence 4
What's known on the subject? and What does the study add?
Of patients treated with an indwelling ureteric stent 80–90% experience lower urinary tract symptoms that are a hindrance to health-related quality of life. The prevalence of the extraction/retrieval string after ureteroscopy for stone disease and stent placement varies significantly between surgeons and published series, but the benefits of eliminating the need for a secondary procedure such as cystoscopy and stent removal, as well as the decrease in cost to the patient are well established.
Published reports have not addressed the prevalence of post-procedure related events (PREs) in patients who have received an indwelling ureteric stent with the extraction/retrieval string still intact after ureteroscopy for stone disease. By analysing PREs (Emergency Room visits, unscheduled clinic visits, and telephone calls) related to their stent or procedure for patients with and without an extraction/retrieval string, the feasibility of the extraction string can be validated and the misconceptions about their use can be alleviated.
• To review a retrospective ureteric stent cohort with and without extraction string to compare post-procedure related events (PRE), as ureteric stent placement after endoscopic management of urolithiasis is common, but data regarding the potential benefits or disadvantages of ureteric stent placement with extraction string are sparse.
PATIENTS AND METHODS
• Between June 2009 and June 2010, 293 patients underwent ureteroscopy with or without lithotripsy for stone disease.
• In all, 181 patients had a unilateral procedure and underwent stent placement postoperatively.
• Records were retrospectively reviewed for operative data and PRE occurring within the first 6 weeks after surgery, defined as unscheduled clinic or Emergency Room visits, or adverse event telephone calls.
• Of 181 patients who underwent ureteric stent placement, 43 (23.8%) included an extraction string.
• In all, 34.3% of all patients had a PRE, including 37.2% and 33.3% of patients with and without extraction string, respectively (P= 0.64).
• PRE occurred in men with or without an extraction string (27.8 vs 32.4%, respectively; P= 0.71) and women with or without an extraction string (44.0 vs 34.3%, respectively, P= 0.39).
• PRE occurred with relatively equal frequency between men and women (P= 0.28).
• Only two women (4.7%) reported removing their stent prematurely, on postoperative days 2 and 6.
• Ureteric stent placement with extraction string after ureteroscopy for stone disease does not seem to result in more PRE, regardless of gender.
• Prospective randomised trials are needed to determine the benefits and disadvantages of ureteric stents with extraction string.
Placement of an indwelling ureteric stent after ureteroscopy for stone disease is common practice . While some reports indicate that stents may not be necessary for ‘routine’ ureteroscopy [1–4], the choice to leave a post-procedural stent is primarily determined by the operative surgeon. As there are no clear guidelines about the timeline for removal of an indwelling stent, there is, likewise, a wide variability in surgeon preference [5,6]. Unfortunately, stent placement often leads to significant postoperative morbidity, and negatively affects health-related quality of life . Postoperative symptoms and morbidity may easily be reduced by decreasing the time that the stent is left in place. If the extraction string connected to the stent is left in place, the patient may be able to remove the stent at the assigned time without dependence on the surgeon's or clinic's schedule, thus enabling earlier removal.
It is well established that an indwelling ureteric stent after uncomplicated ureteroscopy or extracorporeal lithotripsy does not positively affect stone-free rates, and generally leads to increased LUTS, dysuria, haematuria, and even hospitalisations [1–7]. As the definition for uncomplicated ureteroscopy is hard to establish, it can even be more difficult to definitively establish a regimen for the duration that a ureteric stent is left in place, if the surgeon chooses to leave one at the conclusion of the procedure. Many would think that the morbidity associated with the extraction string is minimal compared with the symptoms of the stent itself, resulting in use without consideration. On the other hand, urologists may feel that the risk of accidental removal, potential for increased symptoms (particularly for women who may ‘agitate’ the string during post-micturition hygiene), or the possibility of a retained stent could jeopardize postoperative outcomes and satisfaction. Regardless of opinion, identifying the prevalence of post-procedure related events (PRE) in patients undergoing ureteric stent placement with and without an extraction string, could help determine its role in postoperative stent removal.
PATIENTS AND METHODS
Following Institutional Review Board approval, we performed a detailed chart review of 293 patients who underwent ureteroscopy for stone disease with or without lithotripsy and/or stone ‘basketing’ from June 2009 to June 2010 at our institution. Patients were excluded from analysis if they did not have a ureteric stent placed postoperatively and/or underwent a bilateral procedure. Demographic and patient characteristics were collected, including age, gender, body mass index (BMI), and race. Operative variables collected included side, operative duration, and use of extraction string vs no string. Postoperative morbidity was assessed by review of the first 6 weeks after the procedure, with PRE defined as Emergency Room (ER) visits, unscheduled clinic visits, and telephone calls. Patients were deemed to have no PRE, or PRE regardless of the number of events experienced. We also noted premature stent removal by the patient or replacement of a stent for symptoms within the first 6 weeks.
All ureteric stent placements were done fluoroscopically with or without direct visualisation. Other than one 7 F stent, all stents had a 6 F circumference and ranged from 22 to 28 cm, depending on patient height. All stents were from Cook Medical (Bloomington, IN, USA). For those patients with an extraction string left in place, the string was cut at the level of the knot and tied with a small loop proximal to the stent, similar to the technique previously described by Jones . However, in contrast to the study by Jones, we cut the suture on the exterior of the patient (≈10 cm) after placement, rather than more proximally at the loop (which leaves the loop within the bladder; Fig. 1). The purpose of tying the loop closer to the stent was to prevent an outside loop that could inadvertently be caught by the patient. Likewise, the stent string was not affixed to the patient in any fashion.
Patients with and without an extraction string were compared according to pre-, intra-, and postoperative variables, as previously defined. Pearson chi-square (sig. two-tailed) was used for nominal variables and the t-test (sig. two-tailed) for continuous variables.
In all, 181 patients underwent unilateral ureteroscopy and stent placement by seven surgeons over a 1-year period. Of these 181, 43 patients (23.8%) had a ureteric extraction string left in place, with most of these patients being under the care of a single surgeon. For baseline patient demographics, there were no differences between patients with our without a string with respect to age (P= 0.52), gender (P= 0.4) or BMI (P= 0.37; Table 1). Patients who underwent ureteric stent placement with extraction string had shorter procedures (45.0 vs 66.8 min, P < 0.001) and were more likely to have had a preoperative stent in place at the time of surgery (67.4 vs 44.9%, P= 0.01). There was no statistical difference between groups for use of a ureteric access sheath (32.6 vs 15.2%; P= 0.12) or use of ‘basketing’ for fragment removal (53.5 vs 32.6%; P= 0.14). Exact stone burden was not assessed, but the location of the stone(s) did not differ between those with and without an extraction string (P= 0.24).
During the 6-week follow-up period, 34.3% of all patients had PRE, including 37.2% and 33.3% of patients with and without extraction string, respectively (P= 0.64; Fig. 2a). PREs occurred equally in men with or without an extraction string (27.8 vs 32.4%; P= 0.71), as well as women with and without an extraction string (44.0 vs 34.3%; P= 0.39; Fig. 2b). Additionally, the use of an extraction string resulted in an equivalent number of PREs between men and women (P= 0.28; Fig. 2c). Two women (4.7%) reported removing their stent prematurely on postoperative day 2 and 6, although neither episode resulted in an unscheduled appointment or need for the stent to be replaced. All patients, other than one man (2.3%) who refused to remove his own stent, removed their stent at home, with no patient having a retained stent at follow-up based on routine postoperative imaging (CT, plain film, or renal ultrasonography).
Over 80% of ureteroscopies with lithotripsy result in an indwelling ureteric stent . For those patients who do have a stent placed, there are several potential benefits to leaving an extraction string, including ability to remove the stent at home, decreased cost (lack of need for cystoscopic removal and/or clinic visit), and the ability to reduce or eliminate retrograde stent migration, which may occur in up to 8% of patients . Despite these potential benefits, previous studies have shown that more than two-thirds of urologists do not leave an extraction string when placing an indwelling stent after ureteroscopy . The surgeon's decision to avoid the use of an extraction string can be influenced by the remuneration from cystoscopy and stent removal or the perceived increase in patient morbidity. Morbidity can present in the form of increased LUTS or theoretical risk of increased infection rates, especially in the female patient due to the short urethral length. In the present analysis, we found that placement of an extraction string did not increase morbidity and was associated with no additional complications.
Multiple studies have reported increased morbidity of stent placement compared with no stent after ureteroscopy [4,5], with 80–90% of patients having significant stent-related symptoms . It stands to reason, therefore, that the shorter the stent is left in place, the shorter duration of stent-related symptoms. Although most urologists aim to remove the stent within 7 days , in practice this can depend widely on non-patient related factors, e.g. clinic schedule and transportation to/from the clinic, especially in the case of a tertiary care centre where patients often travel a significant distance. Therefore, it is not uncommon for stents to be left longer than the intended period and, in some cases, left indefinitely when a patient is ‘lost to follow-up’. By leaving an extraction string, these logistical considerations are mitigated and the patient can pull the stent on the assigned day. Indeed, all but one patient in the present study removed their stent successfully at home, with a compliance rate of 97.7%. This patient simply presented to clinic for removal. Due to the retrospective nature of the study and that many of the patients’ stents were removed by their local urologist, we were unable to determine the exact length of indwelling stent time for each patient. However, it is common practice at our institution to have ureteric stents with and without an extraction string removed within 2 weeks. If the stent was left longer in the group with no extraction string, it would potentially allow more time for a stent-related PRE, which would bias the results against those without a string.
Despite the lack of data supporting an increased rate of UTI with extraction string placement, some surgeons may feel that the string itself acts as a conduit for bacteria and may increase the rate of postoperative UTI and bacteriuria, especially in female patients due to their relatively short urethra. Unfortunately, at our tertiary medical centre, many patients who are post-stent placement may be treated locally for dysuria and urinary frequency as a presumed UTI. In this setting, it is rare for an outside institution to obtain a formal urine culture. Without the use of cultures in this setting, determining the rate of UTI would probably be inaccurate. Prospective analysis would probably determine whether an increased infection risk in patients with extraction string exists.
Apprehension for extraction string placement may also be due to fear of accidental removal, breakage of the string, or the forgotten stent. While reports exist of extraction string breakage during attempted removal requiring cystoscopy, no such events occurred in any of the present patients with an extraction string. Furthermore, only two stents were pulled prematurely, both in women, and neither of these women became symptomatic or required replacement of their stent.
There is no information currently available describing tolerability differences of the extraction string based on gender. As women clean the exterior urethra following each void, it is possible that they would be more likely to inadvertently tug on the extraction string, which may worsen their symptoms. Conversely, there is evidence to suggest that some surgeons think women are actually less symptomatic with the extraction string, as evidenced in a study by Nabi et al. , in which 44% of women were discharged with an extraction string compared with <1% of men. In the present study, there was no difference in PRE when comparing women with and without an extraction string and men with and without an extraction string. Furthermore, while there was a slight trend, there was no difference between men and women regarding PRE when an extraction string was left in place.
The objective of the present study was to address the feasibility of the extraction string in hopes of identifying a safe alternative to a clinic visit, and more so, a secondary procedure. Follow-up cystoscopic removal of the ureteric stent is not without risk and results in added patient anxiety and morbidity. Additionally, there is significant cost associated with cystoscopic stent removal. The estimated cost and reimbursement for cystoscopic stent removal varies, but in 2008 it was estimated to be ≈$1300 (American dollars) , which only includes extraction and does not consider time lost for work, telephone calls or unscheduled clinic appointments secondary to stent symptoms. The hospital charge for a patient undergoing ureteroscopy without stent placement was estimated to be 30% compared with the charges endured by the stented patient .
The present cohort of patients is retrospective, with one surgeon placing most stents in which an extraction string was left in place. It is possible that variability in surgical technique could lead to a discrepancy in PRE, based on factors other than the stent string itself. In a recent prospective study using the Ureteric Stent Symptoms Questionnaire (USSQ), the authors found that the most important factors for stent tolerability were gender, with women reporting more of an effect on general health, and whether or not the distal stent coil crossed midline . The study did not report on whether an extraction string was left in place and did not seek to determine if any intraoperative variables were associated with stent symptoms postoperatively. Ideally, a prospective randomised study would decrease the importance of heterogeneity in technique, such that data on the extraction string would potentially be more reliable.
We chose to define patient stent tolerability using the presence of PREs defined as ER visits, unscheduled clinic visits, and telephone calls. While this data does give us an indication of patient outcomes, it is not a validated instrument and is open to error as it relies on whether we were contacted by a patient rather than their actual symptoms or discomfort. Use of a validated questionnaire, such as the USSQ, would be superior in order to determine if there is a true difference in postoperative stent-related symptoms. Nevertheless, the decision of whether a patient would call in or present to the ER or clinic did not vary in the present study based on the presence or absence of the extraction string.
It is important to note that an extraction string may not be appropriate in all cases. Two of 43 (4.7%) of the stents in the group of patients with an extraction string were removed prematurely, indicating that it may not be wise to leave an extraction string in cases where a stent is deemed imperative, e.g. after a ureteric perforation, endopyelotomy, or in a patient with potential upper tract infection. Additionally, all patients had their stent placed after stone surgery, and the use of a string in patients with either ureteric malignancy or extrinsic compression cannot be included in this cohort.
In conclusion, use of a ureteric stent extraction string after ureteroscopy for stone disease is feasible and may reduce healthcare costs, morbidity during removal, and patient inconvenience without increasing morbidity defined as telephone calls, unscheduled clinic visits and ER visits. Further randomised prospective studies using validated outcomes measures are needed to determine whether placement of an extraction string has any negative effects.