Factors Affecting Bleeding During Percutaneous Nephrolithotomy: Single Surgeon Experience

Abstract

Purpose:

To investigate variables that affect bleeding during percutaneous nephrolithotomy (PCNL), focusing on the experience of a single surgeon.

Patients and Methods:

The records of 649 PCNL procedures that were performed by the same surgeon were reviewed retrospectively. The effect of surgical experience; patient and stone-related factors, including age, sex, hypertension, and diabetes, serum creatinine level, history of ipsilateral renal procedures, stone surface area and type, degree of hydronephrosis, preoperative hemoglobin level; operative factors, such as the calix of puncture, number of accesses, operative time; and intraoperative complications, such as pelvicaliceal system perforation on bleeding (described as decrease in hemoglobin level and need for blood transfusion), were investigated. For statistical assessment, univariate analyses and multivariate stepwise regression analyses were used.

Results:

A 92.3% success rate was achieved after one session PCNL. The overall blood transfusion rate was 10.8%. The number of accesses, stone type, diabetes, preoperative hemoglobin level, and operative time were the most important factors for blood transfusion requirement. In the receiver operating characteristic curve, the best cutoff point of operative time was 58 minutes for the blood transfusion requirement. Multivariate stepwise regression analyses showed that there was an association between diabetes, operative time, number of accesses, and stone type with the decrease in hemoglobin levels. No correlation between surgical experience and decrease in hemoglobin level as well as blood transfusion necessity was found.

Conclusions:

Depending on the results achieved by a single surgeon, multiple access tracts, staghorn calculi, presence of diabetes, and prolonged operative time, but not surgical experience, significantly increased blood loss during PCNL.

Introduction

H igh success rates that exceed 90% have been reported with percutaneous nephrolithotomy (PCNL), but bleeding is still one of the most common and significant morbidities, with reports that quote an average hemoglobin drop ranging from 2.1 to 3.3 g/dL.^1

–7 Most of the bleeding that is related to PCNL can be managed with supportive treatment, and only 0.8% of patients need angioembolization to control intractable bleeding.⁸ Without a shadow of a doubt, establishing optimal access to the renal collecting system is a key point for diminishing bleeding and improving success.

To date, studies that evaluate factors with potential impact on bleeding during PCNL reflect results from series including different attending surgeons working within an academic training program with fellow and resident case participants.^9
–11 The differences in surgical technique and experience of attending surgeons may affect the outcomes and, moreover, it is difficult to define the impact of surgical experience on bleeding with multisurgeon studies. For these reasons, we aimed to identify the variables that significantly influence the bleeding during PCNL, using a large database belonging to a single surgeon.

Patients and Methods

Between September 2002 and July 2009, the data of 649 patients (344 male, 305 female) who underwent procedures that were performed by the same surgeon (AHT) were assessed in our study to exclude the possible bias of surgical experience. All data were maintained prospectively using Microsoft^® Excel^® and analyzed retrospectively regarding the factors with potential impact on bleeding.

Preoperative radiologic investigation consisted of excretory urography, and/or urinary ultrasonography and noncontrast spiral tomography in selected cases. All patients were evaluated preoperatively for renal function, hemostasis, and urinary infection.¹²

Access to the selected calix was performed by the attending urologist intraoperatively with the aid of the C-arme using an 18-gauge needle with the patient in the prone position as previously described.¹² The tract was dilated with a high-pressure balloon dilator (Nephromax,^TM Boston Scientific) up to 18 atm pressure, using an inflator (LeVeen^TM Inflator, Boston Scientific); a 30-F Amplatz sheath (Boston Scientific) was placed over the inflated Nephromax. Fragmentation of the stone burden was accomplished using a pneumatic lithotriptor (Vibrolith, Elmed) or ultrasonic lithotripter (Swiss Lithoclast,^®,EMS). Forceps were used to remove stone fragments. Additional tracts were created when indicated at the same session. Flexible nephroscopy was performed at the end of the procedure in patients with suspected residual stones. Holmium-yttrium-aluminum-garnet laser lithotripsy was preferred if residual fragments deep in the calices were detected. A 14F nephrostomy tube was placed inside the renal pelvis or the involved calix at the conclusion in the majority of cases.

Antibiotic prophylaxis was maintained with quinolones.¹² Patients received oral ciprofloxacin until the withdrawal of the nephrostomy tube.

Plain radiography of the kidneys, ureters, and bladder was obtained on postoperative day 1. In patients who were rendered stone free and in those with clinically insignificant residual fragments, the nephrostomy tube was removed on postoperative day 2, after antegrade nephrostography showed ureteral drainage down to the bladder. A Double-J catheter was placed when urine drainage from the tract persisted more than 24 hours after the removal of the nephrostomy tube.¹³ Repeated PCNL, ureteroscopy, and shockwave lihotripsy (SWL) were considered as accessory treatment alternatives when indicated.

All patients were evaluated with excretory urography and/or spiral CT after 3 to 6 months postoperatively. PCNL was considered successful when the patient was stone-free or did not need any further intervention (clinically insignificant residual stone fragments [CIRF]).¹⁴

Complete blood cell count (performed 24 hours before and at the time of discharge after the procedure) and the number of blood units transfused determined the perioperative total blood loss. It was considered that a 1-unit blood transfusion increased the hemoglobin (Hb) level by 1 g/dL and hematocrit (Hct) by 3%. Therefore, drops in hemoglobin and hematocrit levels were calculated as follows: ([preoperative Hb (Hct) - postoperative Hb (Hct)] – [number of units transfused * 1 g/dL (3% for Hct) Hb per unit transfused]).⁹

Preoperative factors that were analyzed were patient age, sex, body mass index (BMI), the presence of hypertension, diabetes mellitus, serum creatinine level, history of ipsilateral open renal surgery, PCNL or SWL treatment, side and type of the stone, stone burden, the degree of hydronephrosis, and the surgeon's experience. The operative factors analyzed were calix of puncture, number of access tracts, operative times, and intraoperative complications, such as pelvicaliceal system perforation.

Surgical experience was classified to three groups as the first 60 cases, 61 to 115 cases, and after 115 PCNLs.¹⁵ Stone size was calculated according to European Association of Urology guidelines.³ Stone types were categorized as staghorn calculi (partial or complete) and nonstaghorn, including pelvic, multiple, and isolated caliceal stones.¹⁶ The operative time was documented as the time from the puncture until the final placement of the nephrostomy tube. Hydronephrosis was graded as either nil/mild or moderate/severe using ultrasonographic criteria.¹⁷

Chi-square, Fisher exact, Student t, Mann Whitney U, and Kruskal-Wallis tests were used for univariate analyses. Median hemoglobin drop of the study was considered as a cutoff point. Multivariate binary logistic regression was performed for further investigation if any parameter was found to be significant with univariate test. In all analyses, two-sided hypothesis testing was carried out, and probability values less than 0.05 were deemed significant.

Results

Mean age and mean BMI were 43.2 ± 15.2 years (range 7–81 y) and 26.4 ± 5.0 kg/m² (range 15.2–50.8 kg/m²), respectively. Mean stone size was 780 ± 535 mm² (range 100–3500 mm²). Staghorn stone was detected in 28.4% (n = 184) of the patients. A history of ipsilateral open surgery, SWL, and PCNL was present in 129 (19.9%), 159 (24.5%), and 33 (5.1%) patients, respectively. A total of 502 (77.3%) patients were treated with single-access PCNLs, and the remaining patients (22.7%) underwent multiple-access procedures. The mean operative time was 58.6 ± 20.7 minutes (range 15–180 min). The mean interval to nephrostomy tube removal was 2.8 ± 1.4 days (range 1–15 d). Thirty-seven patients (5.7%) underwent tubeless and stentless PCNL. An overall success rate of 92.3%, including CIRFs in 17.1%, was achieved after one session PCNL.

Overall blood transfusion rate was 10.8% (n = 70). In univariate analysis, factors that affected blood transfusion requirement were preoperative Hb level (P = 0.018), diabetes mellitus (P = 0.003), hypertension (P = 0.034), stone size (P < 0.0001), the number of accesses (P < 0.0001), stone type (P < 0.0001) and operative time (P < 0.0001) (Table 1). In the receiver operating characteristic curve, the best cutoff point of operative time was 58 minutes with sensitivity of 75.7% and specificity of 67.2% (area under the curve [AUC] = 0.666, P = 0.0001) for the blood transfusion requirement. In staghorn calculi, the best cutoff point of stone size was 1250 mm² with a specificity and sensitivity of 67.4% and 62.5%, respectively (AUC = 0.63, P = 0.012) for necessitating blood transfusion. According to stepwise multivariate binary regression analysis, the number of accesses, stone type, diabetes, preoperative Hb level, and operative time were the most important factors for blood transfusion requirements (Table 2).

Table 1.

Factors Affecting Blood Transfusion Requirement Assessed by Univariate Analyses

	Transfusion (-)	Transfusion (+)
Parameters	% (n)	% (n)	P value
Age (years)			0.98^a
<15	2.6 (15)	2.9 (2)
15–49	62.0 (359)	61.4 (43)
≥50	35.4 (205)	35.7 (25)
Sex			0.13^a
Female	45.9 (266)	55.7 (39)
Male	54.1 (313)	44.3 (31)
BMI			0.53^a
<25 kg/m²	47.0 (272)	52.9 (37)
25–<30 kg/m²	32.3 (187)	31.4 (22)
≥30 kg/m²	20.7 (120)	15.7 (11)
Stone size			<0.0001^a
<400 mm²	33.7 (195)	17.1 (12)
400–1000 mm²	47.3 (274)	40.0 (28)
>1000 mm²	19.0 (110)	42.9 (30)
Stone opacity			0.24^b
Opaque	96.9 (561)	100 (70)
Nonopaque	3.1 (18)	0 (0)
Side			0.80^a
Left	49.9 (289)	52.9 (37)
Right	50.1 (290)	47.1 (33)
Grade of hydronephrosis			0.06^a
Nil or mild	39.9 (231)	28.6 (20)
Moderate or severe	60.1 (348)	71.4 (50)
Previous open surgery			0.12^b
(+)	19.0 (110)	27.1 (19)
(–)	81.0 (469)	72.9 (51)
Previously PCNL			0.24^b
(+)	5.5 (32)	1.4 (1)
(–)	94.5 (547)	98.6 (69)
History SWL			0.89^b
(+)	24.7 (143)	22.9 (16)
(–)	75.3 (436)	77.1 (54)
Diabetes mellitus			0.006^b
(+)	12.8 (74)	25.7 (18)
(–)	87.2 (505)	74.3 (52)
Hypertension			0.029^b
(+)	19.7 (114)	31.4 (22)
(–)	80.3 (465)	68.6 (48)
Preoperative creatinine level (mg/dL)			0.34^b
≤1.5	95.3 (552)	98.6 (69)
>1.5	4.7 (27)	1.4 (1)
Number of accesses			<0.0001^b
Single	80.8 (468)	48.6 (34)
Multiple	19.2 (111)	51.4 (36)
Calix of puncture			0.62^a
Lower	87.4 (409)	82.4 (28)
Middle	5.3 (25)	5.9 (2)
Upper	7.3 (34)	11.7 (4)
Stone type			<0.0001^b
Staghorn calculi	24.9 (144)	57.1 (40)
Nonstaghorn calculi	75.1 (435)	42.9 (30)
Surgeon experience			0.34^a
≤60	8.9 (52)	11.4 (8)
61–115	8.5 (49)	8.6 (6)
>115	82.6 (478)	80.0 (56)
Intraoperative complications			0.98^b
(+)	1.2 (7)	1.4 (1)
(–)	98.8 (572)	98.6 (69)
Mean duration of operation (min)			<0.0001^a
≤58 min	55.5 (321)	28.6 (20)
>58 min	44.6 (258)	71.4 (50)
Mean preoperative hemoglobin level	13.70 ± 1.70	13.00 ± 2.10	0.007^c

Chi square test.

Fisher exact test.

Student t test.

BMI = body mass index; PCNL = percutaneous nephrolithotomy; SWL = shockwave lithotripsy.

Table 2.

Predictive Factors for Blood Transfusion Requirements: Outcome of Multivariate Binary Logistic Regression Analysis

Factors	P value	OR	95% CI
Number of accesses	0.001
Single (reference)		1
Multiple		2.77	1.56–5.00
Stone type	0.003
Other types (reference)		1
Staghorn calculi		2.50	1.43–4.35
Diabetes mellitus	0.007
No (reference)		1
Yes		1.96	1.30–2.63
Preoperative hemoglobin level	0.009	1.23	1.06–1.43
Duration of operation	0.02
≤58 min (reference)		1
>58 min		1.92	1.07–3.45

OR = odds ratio; CI = confidence interval.

The average Hb and Hct drop after PCNL procedures were 1.82 ± 1.42 g/dL (median 1.5 g/dL; range 0.0–6.6 g/dL) and 5.10% ± 4.13% (median 4.3%; range 0.4%–22.1%), respectively. Angioembolization was indicated in two (0.3%) patients (one pseudo-aneurysm and one arteriovenous fistula), and another (0.15%) patient underwent nephrectomy because of extended bleeding and unstable hemodynamics.

According to the number of accesses, decrease in Hb was 1.70 ± 1.32 g/dL and 2.25 ± 1.65 g/dL (P = 0.001) and decrease in Hct was 4.70% ± 3.78% and 6.46% ± 4.91% (P < 0.0001) in single and multiple accesses groups, respectively. Total blood loss was found to be 1.64 ± 1.34 g/dL in stones that were smaller than 4 cm², while mean blood losses were detected to be 1.75 ± 1.36 g/dL and 2.25 ± 1.58 g/dL for stones that measured 4 to 10 cm² and >10 cm², respectively (P = 0.001). For stones >10 cm², the total blood loss was significantly increased when compared with stones that measured <4 cm² and 4 to 10 cm² (P < 0.0001 and 0.002, respectively). Stone type and diabetes mellitus also significantly correlated with declines in postoperative Hb and Hct levels (Table 3).

Table 3.

Impact of Patient, Stone, and Operation-Related Factors on Bleeding During Percutaneous Nephrolithotomy

Parameters	Decrease in hemoglobin (mg/dL)	P value	Decrease in hematocrit (%)	P value
Age (years)		0.87^a		0.90^a
<15	1.54 ± 1.23		4.41 ± 3.18
15–49	1.83 ± 1.43		5.09 ± 4.17
≥50	1.82 ± 1.42		5.16 ± 4.14
Sex		0.18^b		0.06^b
Female	1.76 ± 1.46		4.76 ± 3.91
Male	1.92 ± 1.69		5.32 ± 4.30
BMI (kg/m²)		0.10^a		0.11^a
<25	1.89 ± 1.43		5.32 ± 4.32
25–30	1.87 ± 1.46		5.06 ± 4.06
≥30	1.58 ± 1.43		4.41 ± 3.69
Stone size		0.001^a		0.001^a
<400 mm²	1.63 ± 1.34		4.77 ± 4.06
400–1000 mm²	1.75 ± 1.37		4.79 ± 3.78
>1000 mm²	2.25 ± 1.58		6.24 ± 4.77
Stone type		<0.0001^b		<0.0001^b
Staghorn calculi	2.20 ± 1.56		6.14 ± 4.58
Nonstaghorn calculi	1.67 ± 1.33		4.68 ± 3.87
Stone opacity		0.31^b		0.14^b
Opaque	1.83 ± 1.43		5.14 ± 4.16
Nonopaque	1.42 ± 1.08		3.53 ± 2.50
Side		0.51^b		0.98^b
Right	1.79 ± 1.39		5.11 ± 4.11
Left	1.87 ± 1.46		5.14 ± 4.20
Grade of hydronephrosis		0.20^b		0.06^b
Nil or mild	1.74 ± 1.39		4.81 ± 4.14
Moderate or severe	1.87 ± 1.44		5.27 ± 4.12
Previous open surgery		0.33^b		0.32^b
(+)	1.91 ± 1.43		5.18 ± 3.60
(–)	1.80 ± 1.42		5.07 ± 4.24
Previous PCNL		0.35^b		0.42^b
(+)	2.03 ± 1.47		5.46 ± 3.77
(–)	1.81 ± 1.42		5.08 ± 4.15
History SWL		0.07^b		0.73^b
(+)	1.66 ± 1.40		4.97 ± 4.09
(–)	1.87 ± 1.43		5.13 ± 4.15
Diabetes mellitus		0.007^b		0.008^b
(+)	2.12 ± 1.41		6.21 ± 4.28
(–)	1.76 ± 1.53		4.95 ± 4.10
Hypertension		0.04^b		0.03^b
(+)	2.04 ± 1.46		5.75 ± 4.36
(–)	1.77 ± 1.41		4.92 ± 4.06
Access number		0.001^b		<0.0001^b
Single	1.70 ± 1.32		4.70 ± 3.79
Multiple	2.25 ± 1.65		6.46 ± 4.91
Duration of operation (min)		0.0001^b		0.001^b
≤58 min	1.58 ± 1.21		4.48 ± 3.64
>58 min	2.07 ± 1.57		5.72 ± 4.51
Creatinine level (mg/dL)		0.79^b		0.54^b
≤1.5	1.82 ± 1.42		5.12 ± 4.16
>1.5	1.80 ± 1.45		4.57 ± 3.67
Surgeon experience		0.67^a		0.42^a
≤60	1.87 ± 1.48		5.60 ± 3.89
61–115	1.83 ± 1.32		5.22 ± 4.47
>115	1.82 ± 1.43		5.03 ± 4.13
Intraoperative complications		0.79^b		0.87^b
(+)	1.83 ± 1.43		5.13 ± 4.17
(–)	1.71 ± 0.91		4.77 ± 2.77

Kruskal-Wallis test.

Mann Whitney U test.

BMI = body mass index; PCNL = percutaneous nephrolithotomy; SWL = shockwave lithotripsy.

Outcome of multivariate logistic regression analysis showed that there was an association between diabetes mellitus, operative time, number of accesses, and stone type with decreased postoperative serum Hb level (Table 4).

Table 4.

Outcomes of Multivariate Binary Logistic Regression Analysis: Factors Affecting Total Blood Loss

	Factors	Significant	OR	95% CI
Factors affecting decrease in hemoglobin	Stone type	0.001
	Other types (reference)		1
	Staghorn		1.92	1.33–2.72
	Number of accesses	0.030
	Single (reference)		1
	Multiple		1.45	1.05–2.00
	Duration of operation	0.024
	≤58 min (reference)		1
	>58 min		1.52	1.07–1.97
	Diabetes mellitus	0.017
	No (reference)		1
	Yes		1.75	1.11–2.77

According to median hemoglobin level.

OR = odds ratio; CI = confidence interval.

Discussion

PCNL is the treatment modality of choice for most renal stones larger than 300 mm² and also for complex renal stones.³ This procedure has the advantages of higher stone clearance and cost-effectiveness compared with other treatment alternatives, such as SWL and open surgery. The procedure, however, is associated with several complications, such as fever, urinary infection, renal colic, septicemia, and bleeding necessitating blood transfusion. One of the most important complications is bleeding necessitating transfusion whose incidence has been reported to vary between 0.8% and 45 % in the literature.^2,7,18 This divergence stems from differences in transfusion strategies of various clinics. In our routine practice, indication for transfusion in the early postoperative period (48 hours after the procedure) included symptomatic anemia and/or a Hb level of <10 g/dL. Also no correlation exists between estimated and actual total blood loss.⁷ Therefore, actual blood loss was calculated from postoperative Hb and Hct values in addition to the requirements of blood transfusions.

Among patient-related factors, diabetes mellitus was the independent predictive factor affecting the bleeding risk assessed by multivariate regression analysis in the present study. Hypertension correlated with decreased Hb and Hct levels in univariate analysis; however, it did not affect total blood loss in stepwise multivariate regression analyses. The relationship between diabetes as well as hypertension and bleeding after the initial trauma of tract formation was explained with arteriosclerosis.⁹ In addition, diabetes affects the whole vascular system, resulting in microangiopathies, which are highly vulnerable to bleeding.¹⁹

According to the outcome of univariate analysis, size and type of the stone were determined as factors affecting total blood loss. In the multivariate analysis, however, among stone-related factors, only stone type (staghorn calculi) was found to be significantly related to bleeding. Turna and associates¹⁰ reported that stone type had the most significant effect on blood loss and underlined that the most prominent stone types vulnerable to bleeding were partial and complete staghorn stones. Srivastava and colleagues,¹¹ however, found that the stone size was the only significant factor that could predict the occurrence of blood loss after PCNL. Staghorn and bulky stones increase the number of maneuvers necessary for complete clearance of the pelvicaliceal system from stone fragments. Moreover, the use of rigid nephroscopes to reach the stones inside different calices may cause injury to the renal parenchyma and caliceal necks, leading to increased risk of bleeding. The use of flexible nephroscopes, however, can decrease the requirement of transfusion and the risk of bleeding without affecting success rate.

Multiple tracts are often needed to remove complex and staghorn calculi inside complex caliceal patterns. The bleeding rate is correlated with multiple tracts. Kukreja and coworkers⁹ performed multiple-tract procedures in 27.9% of renal units with an average blood loss of 2.36 ± 1.3 g/dL and a transfusion rate of 16.6%. These corresponding parameters, however, were 1.4 ± 1.0 g/dL and 4.6% for a single access, respectively (P < 0.0001). Requirement for blood transfusion was higher in the three accesses group.⁹ The present study demonstrates that the number of accesses is one of the two most important predictive factors related to total blood loss and the necessity for transfusion. In addition, according to univariate analysis, multiple accesses increased transfusion requirements 4.46 times compared with single-tract approaches. Stoller and colleagues⁷ reviewed 127 PCNLs performed on 96 patients and declared that the average blood loss for uncomplicated single-stage, single-puncture PCNL was 2.8 g/dL of Hb. Multiple punctures and/or renal pelvic perforation were associated with a twofold greater blood loss. In the present study, the mean decrease of Hb was 1.67 g/dL in the single-tract group and 2.25 g/dL in the multiple-tract group.

To minimize the unfavorable impact of multiple accesses on bleeding, various alternative techniques or instruments can be used. The development of flexible nephroscopy, holmium laser lithotripsy, and improved grasping devices and baskets has made single-access PCNL feasible in selected patients.²⁰ A large renal stone burden can be successfully managed with a combination of single percutaneous access and flexible nephroscope with its limited blood loss. Flexible nephroscopy, however, was used in the majority of cases with suspected stone in the present study and, therefore, no statistical assessment could be done.

Access into upper calices may traumatize the posterior segmental artery with an associated higher risk of bleeding. Interestingly, in this study, according to a univariate analysis, when compared with middle and lower calices, accesses into upper calices did not affect the incidence of bleeding. The advantages of direct upper pole access are to achieve good exposure into the majority of the calices and renal pelvis, and obtain a possibility to reach the ureteropelvic junction and upper ureter as well as the ability to operate along the long axis of the kidney, which causes less torque of the rigid nephroscope and ultimately lesser bleeding. Therefore, we do not hesitate to perform an upper pole access when necessary. Contrary to the upper calix puncture, the inferior calix approach for staghorn stones carries the risk of angulation and torque effect on the kidney, potentially leading to renal trauma and bleeding. Matlaga and associates²¹ found that the location of the access tract was significantly associated only with the occurrence of hydrothorax, and multiple accesses did not affect the incidence of postoperative complications. In a prospective study, no correlation between the calix of access and bleeding could be demonstrated in multivariate analyses.⁹

Surgical experience is one of the potential factors that influence the risk of bleeding. Studies that report a negative correlation between surgical experience and the risk of bleeding are also present.²² In contrast to previous studies that were performed by different surgeons, the data from a single surgeon did not demonstrate any correlation between surgical experience, and total blood loss and the requirement for blood transfusion. Allen and coworkers¹⁵ suggested 60 PCNL procedures for surgical competence and 115 procedures for excellence. Therefore, surgical experience was classified as the first 60 procedures, 61 to 115, and after 115 procedures in the present study. Our results can be related to the selection of simple calculi needing only a single access generally in the learning period. Furthermore, an experienced surgeon will create accurate tracts that will necessitate less tracts to be performed, will operate on more patients with staghorn and complex calculi, and will have a shorter operative time compared with an inexperienced surgeon.

As is evident in the literature, various factors, including larger stones, inexperienced surgeons, complex stones, and multiple accesses, require longer operative times, which usually result in increased complication rates, such as bleeding. In our study, the best cutoff point of operative time was found to be 58 minutes for necessitating blood transfusion. For operative times exceeding 58 minutes, blood transfusion requirement increased 2.82 (1.64– 4.86) times.

We recognize several limitations of this study. First, the initial puncture was made under fluoroscopic guidance, and the access tracts were dilated using high-pressure balloon dilators in all cases. Therefore, these factors were not analyzed in the study. Second, the present study lacks data regarding type of lithotriptors. In a prospective comparison study, Lehman and associates²³ randomized 30 patients needing PCNL to either combination pneumatic and ultrasonic lithotripsy or standard ultrasonic lithotripsy and reported no difference in mean estimated blood loss. Gonen and colleagues²⁴ compared balloon dilation with Amplatz dilation for nephrostomy tract dilation and did not find any statistically significant differences in preoperative Hb concentrations, postoperative Hb concentrations, or blood transfusion rates between the two groups. On the contrary, some investigators have shown that an Amplatz or balloon dilator caused less blood loss when compared with an Alken dilator.⁹

In our study, a 30F tract was routinely used in all cases. Using a smaller tract size may be less traumatic in kidneys with nondilated calices and narrow infundibula, and it may reduce bleeding during PCNL.^25,26 The only disadvantage of using a smaller tract, however, might be the prolongation of the operative time. The existence of a positive correlation between the duration of the intervention and the risk of bleeding should not be forgotten.

Conclusions

Depending on the results achieved by a single surgeon, multiple accesses, staghorn calculi, presence of diabetes mellitus, and prolonged operative times, but not surgical experience, significantly increase blood loss during PCNL. Multiple-tract access and staghorn stone are the most important factors affecting bleeding in stepwise multivariate analysis. Our study also demonstrates that a statistically significant cutoff value of 58 minutes for operative time correlated well with transfusion rates.

Footnotes

Disclosure Statement

No competing financial interests exist.

Abbreviations Used

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