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Fathelbab TK. et al., 2020: Anterior or posterior SWL in proximal ureteral stones opposite to 4th and 5th lumbar vertebrae?

Fathelbab TK, Hasanein MGS, Fawzy AM.
Urology Department, Minia Urology & Nephrology University Hospital, School of Medicine, Minia University, Minia, Egypt.
Specialized SWL Center, Nile SWL, Minia, Egypt.
Urology Department, Minia Urology & Nephrology University Hospital, School of Medicine, Minia University, Minia, Egypt.
Specialized SWL Center, Nile SWL, Minia, Egypt.

Abstract

Background: Results of SWL in treatment of upper ureteral calculi are conflicting which is definitely affected by stone locations along the proximal ureter, which is may be due to the more deep and medial course of the ureter distally over the thick and strong abdominal back wall which may hinder shock waves.

Methodology: One hundred patients with radiopaque proximal ureteral stone opposite 4th and 5th lumbar vertebrae who had SWL were randomized into two groups. First group had SWL through anterior belly wall in supine position with countertraction, the second group had standard posterior SWL. Patient's demographics and stone characters were evaluated assessing stone burden and calculating S.T.O.N.E score. Patients were followed up to assess stone-free rate using serial digital plain X-ray KUB.

Results: Anterior approach needed less power to reach SFR (p = 0.05) in less number of sessions where 90% of cases in anterior group had only one session to reach SFR versus 52% in posterior group (p = 0.001). Also, post-SWL pain, hematuria, obstruction and infection were significantly less in anterior group (p = 0.005). Although patients who had anterior approach showed statistically significant shorter time to stone expulsion. SFR does not differed significantly between study groups (p = 0.02). On further analysis; anterior SWL had a better chance to reach SFR (HR = 1.6, p = 0.001).

Conclusion: It seems that anterior SWL approach in supine position is safe and effective especially in mild obese patient with floppy abdomen. Patients who had anterior SWL approach had a better chance to achieve stone-free rate.
World J Urol. 2020 Apr 15. doi: 10.1007/s00345-020-03174-3. Online ahead of print. PMID: 32296925. FREE ARTICLE

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Comments 1

Hans-Göran Tiselius on Tuesday, September 22 2020 08:30

Almost 30 years of experience with SWL has taught me that that this treatment needs to be individualized to be maximally successful. This is particularly true for choosing the most appropriate treatment position. The position of the patient in the lithotripter should be determined by the patient’s anatomy and the geometrical properties of the shockwave path. All attempts to standardize the treatment in a stereotypic way is unfavourable and will result in inferior results.

It was early recognized that the area involving the lower lumbar vertebrae and the angle between them and the upper level of the pelvic brim comprises an obvious obstacle to propagation of shockwaves delivered from the patient’s back.

The authors of this report have a lithotripter that makes it possible to move the shockwave head from a posterior to an anterior position. This enables treatment without changing patient position. Whether this is advantageous or not is debatable, because several of my patients claimed that it was more comfortable with SWL in prone than in supine position.

Absorption of shockwave energy by skeletal structures always must be avoided. In addition to the anatomical region mentioned above this is true also for stones overlying transverse processes and ribs as well as for distal ureteral stones close to the sacrum bone. This is of course also the case for stones in the mid ureter covered by the sacro-iliac bones. One point not mentioned by the authors is the possible hinder caused by intestinal gas. This might be a problem particularly for stones in the left ureter.

The authors mention that in reference [3] (in their list), appropriate direction of the shockwave was not considered as an optimizing measure. This is not correct since adequate patient positioning was emphasized and even demonstrated in a figure.

The bottom-line of my comment is that there is no standard position for treatment of ureteral stones. It is necessary to consider the relation between the stone and skeletal structures as well as the depth of the stone. But for ureteral stones in the L4/L5 region, transabdominal administration of shockwaves is superior in most cases.

Hans-Göran Tiselius

Almost 30 years of experience with SWL has taught me that that this treatment needs to be individualized to be maximally successful. This is particularly true for choosing the most appropriate treatment position. The position of the patient in the lithotripter should be determined by the patient’s anatomy and the geometrical properties of the shockwave path. All attempts to standardize the treatment in a stereotypic way is unfavourable and will result in inferior results. It was early recognized that the area involving the lower lumbar vertebrae and the angle between them and the upper level of the pelvic brim comprises an obvious obstacle to propagation of shockwaves delivered from the patient’s back. The authors of this report have a lithotripter that makes it possible to move the shockwave head from a posterior to an anterior position. This enables treatment without changing patient position. Whether this is advantageous or not is debatable, because several of my patients claimed that it was more comfortable with SWL in prone than in supine position. Absorption of shockwave energy by skeletal structures always must be avoided. In addition to the anatomical region mentioned above this is true also for stones overlying transverse processes and ribs as well as for distal ureteral stones close to the sacrum bone. This is of course also the case for stones in the mid ureter covered by the sacro-iliac bones. One point not mentioned by the authors is the possible hinder caused by intestinal gas. This might be a problem particularly for stones in the left ureter. The authors mention that in reference [3] (in their list), appropriate direction of the shockwave was not considered as an optimizing measure. This is not correct since adequate patient positioning was emphasized and even demonstrated in a figure. The bottom-line of my comment is that there is no standard position for treatment of ureteral stones. It is necessary to consider the relation between the stone and skeletal structures as well as the depth of the stone. But for ureteral stones in the L4/L5 region, transabdominal administration of shockwaves is superior in most cases. Hans-Göran Tiselius
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Friday, October 30 2020

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