352 DISCUSSION Various treatment options are considered for the manage- ment of lower ureteral stones, including open ureter- olithotomy, ureteroscopic lithotripsy (URS), and SWL. According to the 2007 Guideline for the Management of Ureteral Calculi of the AUA and the EAU guideline, URS stone-free rates were significantly better than SWL rates for distal ureteral stones ≤10 mm and ＞10 mm [4]. The availability of this modality and physician experience were considered. Complications such as sepsis, stricture, ure- teral injury, and urinary tract infection are the most rele- vant complications. Spontaneous stone passage was often reported without active treatment including URS and SWL. One study re- ported spontaneous expulsion in 25 to 53% of cases for dis- tal ureteral stones 5 to 10 mm in diameter [10]. Another study reported spontaneous passage of 68% of stones ＜5 mm in diameter and 47% of stones 5 to 10 mm in diameter [5]. Ureteric calculi more than 10 mm in diameter should be removed by emergency URS or medical expulsion treat- ment (MET), because large calculi tend to impact in the ure- ter and are unlikely to migrate in the distal region [11]. More distal stones are more likely to pass spontaneously, and Miller and Kane [12] reported that the interval to stone passage was highly variable and dependent on stone size and location. The hazard of expulsion at any time was 3-fold higher for stones located at the ureterovesical junction than for those in the distal part of the ureter [13]. Accordingly, the most important factors in predicting the likelihood of spontaneous stone expulsion are stone size and stone location [14]. The ureter demonstrates two continuous thin muscle layers with a loosely spiraled internal layer and a more tightly spiraled external layer. In the lower third of the ure- ter, a third outer longitudinal layer is present. The lower ureter is composed of transitional epithelium, a connective tissue layer, and three layers of smooth muscle [15]. Ureteral peristalsis is initiated by spontaneous activity of the renal pelvis pacemaker cell and is essentially regulated by the myogenic mechanism and neurogenic factors; there- after, electrical and mechanical activities are conducted to inactive distal regions [16]. The α-adrenoceptor pathway was first described in the human ureter in the 1970s [17]. Activation of α1-adrenoceptors leads to ureteral con- traction via activation of phospholipase C, which in turn leads to the formation of second messengers (inositol tri- phosphanate [IP3] and diacylglycerol [DAG]). IP3 is in- volved in the mobilization of calcium from the sarcoplasmic reticulum, whereas DAG increases calcium influx across the cell membrane via the activation of protein kinase C [18]. Thus, the histologic characteristics of the three smooth muscle layers in the lower ureter and the more dense innervation of the lower ureter than the upper and mid ureter have become subjects of research interest. The stimulation of the α1-receptors in the incomplete or complete ureteral obstruction by ureteral calculi increases Korean J Urol 2012;53:349-354 Cha et al the force of ureteral contraction and the frequency of ure- teral peristalsis. Thus, a blockade of α1-receptors inhibits basal tone, reduces peristaltic amplitude and frequency, and decreases intra-luminal pressure. α-blockers also in- duce an increase in the intra-ureteral pressure gradient around the stones that helps in stone expulsion [19]. Patients who elect for an attempt at MET, such as the use of an α-blocker, should have well-controlled pain, no clin- ical evidence of sepsis, and adequate renal functional reserve. The patients should be followed with periodic imaging studies to monitor stone position and to assess for hydronephrosis or severe adverse effects. If the outcome of this treatment is not satisfactory, active stone removal mo- dalities like URS or SWL should be required [4]. Follow-up at 7, 14, 21, and 28 days with blood test, urine test, and ra- diologic test should be practiced for such serious conditions. It is very important that the patient be advised of the attendant risk including the associated side effects of treatment modalities like URS, SWL, and MET, and that MET should be performed. Medical treatments using nonselective α-blockers for spontaneous stone expulsion have been reported. Agrawal et al. [20] reported that for stones ≤ 1 cm, 10 mg alfuzosin results in a 35% increase in the stone expulsion rate, de- creased expulsion time, and good control of colic pain com- pared with a control group. Pedro et al. [5] reported good pain control and stone expulsion time compared with a con- trol group by using alfuzosin but found no significant differ- ence in the stone expulsion rate between the afluzosin and control groups (73.5% vs. 77.1%). In the latter study, it is possible that the high rate of stone expulsion in the control group was unrelated to the effect of alfuzosin but rather re- flected the small size of the stones in both groups (4.08 mm and 3.83 mm). In our study, the alfuzosin group displayed a 27.9% increased stone expulsion rate compared with the control group (p=0.026). The α-1d receptor has the highest density in the distal ureter [18]. Tamsulosin, which is a selective α-1a and α-1d blocker, is a commonly used α-blocker for the medical treat- ment of ureteric stones. Al-Ansari et al. [21] reported that 0.4 mg tamsulosin produced a 26% increased stone ex- pulsion rate and decreased stone expulsion time. Resim et al. [7] reported that the same dose of tamsulosin produced an insignificantly increased rate of stone expulsion (13.3%) and decreased colic episodes and pain. Hermanns et al. [13] reported no significant difference in the expulsion rate be- tween the group using 0.4 mg tamsulosin and the control group (86.7% vs. 88.9%, respectively). However, these re- sults involved small-sized stones (mean, 3.8 mm) in both groups, similar to the study of Pedro et al. [5]. In Korea and Japan, 0.2 mg tamsulosin is taken orally twice daily to achieve the affects attributed to 0.4 mg tamsulosin. This regimen is expensive and onerous and ad- verse effects such as retrograde ejaculation and fatigue can be increased. In our country, 0.2 mg tamsulosin is used for control of symptoms of benign prostatic hyperplasia; be- cause the α-1d receptor is more dense in the lower ureter,