After urgent drainage of an obstructed kidney by internal ureteric stenting; is ureteroscopic stone extraction always needed?

Peer review under responsibility of Arab Association of Urology.

Figures & data

Table 1 Potential categorical factors associated with stone-free status at time of JJ stent removal.

		Stone-free	Stone for URS	P
Categorical variables		N (%)	N (%)
Sex	Male	47 (41.9)	65 (58.1)	0.5
	Female	36 (42.8)	48 (57.2)
Diabetes mellitus	No	61 (40.6)	89 (59.4)	0.24
	Yes	22 (47.8)	24 (52.2)
Hypertension	No	50 (38.4)	80 (61.6)	0.12
	Yes	33 (50)	33 (50)
ASA score	I	40 (34.1)	57 (65.9)	0.94
	II	37 (43)	49 (57)
	III	5 (45.4)	6 (54.6)
Preoperative MSUC	No growth	68 (47.2)	76 (52.8)	0.02
	Positive growth	15 (28.8)	37 (71.2)
Stone opacity	Opaque	25 (21.9)	89 (78.1)	⩽0.001
	Lucent	58 (70.7)	24 (29.3)
Stone site	Lumbar ureter	45 (45.9)	53 (54.1)	0.2
	Iliac ureter	30 (43.4)	39 (56.6)
	Pelvic ureter	8 (28.5)	20 (71.5)
Stone site	Proximal	75 (90.4)	92 (81.4)	0.08
	Distal	8 (9.6)	21 (18.6)
Indications	Uraemia	62 (52.5)	56 (47.5)	⩽0.001
	Sepsis	21 (26.9)	57 (73.1)
Solitary (anatomical/ functional) kidney	No	31 (31.9)	66 (68.1)	⩽0.004
	Yes	52 (52.5)	47 (47.5)
Grade of preoperative hydronephrosis	Mild	66 (45.5)	79 (54.5)	0.27
	Moderate	14 (31.8)	30 (68.2)
	Marked	3 (42.8)	4 (57.2)

ASA, American Society of Anesthesiologists.

Table 2 Potential continuous factors associated with stone-free status at time of JJ stent removal.

Variable	Stone-free	Stone for URS	P
Mean (SD)
Age, years	54.7 (11.7)	50.1 (13.3)	0.013
BMI, kg/m^2	34.8 (8.5)	31.5 (8.3)	0.01
Urine pH	5.5 (0.73)	5.5 (0.71)	0.5
Serum uric acid level, mg/dL	7.05 (1.8)	6.7 (1.7)	0.2
Haemoglobin level, g/dL	11.3 (2.4)	12.7 (3.4)	0.1
Stone length, mm	8.4 (2.8)	9.4 (2.8)	0.02
Stone width, mm	6.3 (2.5)	7.1 (2.1)	0.013
Stone density, Hounsfield units	485.6 (308)	685.9 (314)	<0.001
Median (range)
Duration of obstruction, days	4 (1–60)	7 (1–365)	0.002
JJ stent duration, months	4 (0.5–6.3)	2 (0.5–6.2)	0.002

Table 3 Multivariate assessment of potential factors for the need of URS at the time of ureteric stent removal.

	Regression coefficient	P	OR (95% CI)
Stone width, mm	0.314	0.038	1.369 (1.018–1.842)
Preoperative urine culture:
Negative (reference)
Positive	1.199	0.046	3.318 (1.022–10.766)
Stone opacity on X-ray:
Lucent (reference)
Opaque	2.430	<0.001	11.36 (3.455–37.382)

Figure 1 ROC curve for significant continuous predictors of stone free probability at time of JJ stent removal for stone width (A) and stone surface area (B).