This study applied the logistic regression algorithm,which is penetrating every fields[5].At present, there have been a large number of studies on haemorrhage risk factors after PCNL in China.This model has good performance and is easy to use, which can provide strong support for doctors' clinical decision-making.
Semi-tubeless PCNL has the advantages of small trauma, quick recovery and high stone removal rate. It has become the recognized excellent treatment method in the treatment of complicated kidney stones, especially staghorn stones[3]. However, the recent studied still reported that more serious complications, such as haemorrhage, peripheral organ injury, and septic shock, occurred in 0.3–11.6% of patients[6]. Haemorrhage is the most common complication after semi-tubeless PCNL[7].We collected variables that may be associated with haemorrhage .
Previous studies have shown that diabetes is an independent risk factor for PCNL haemorrhage[8]. Diabetes leads to microangiopathy in the kidney, aggravates renal damage, reduces the vasoconstriction ability, and is prone to haemorrhage[9].The effect of operation time on haemorrhage has been confirmed. In line with the present studies, the longer the operation time is, the more likely it is to damage the kidney tissue, and the longer the bleeding time is[10].The more the number of puncture channels, the higher the risk of damage to the renal artery [11].
The stone score system is based on the number of kidney CT scans According to the stone related features, including coronal section stone size (s), stone distance (t), degree of obstruction (o), The number of affected calyces (n) and stone density (e) were quantified for each index and were comprehensively evaluated according to the total score[12] .
The Guy's kidney stone grade system divides kidney stones into four grades according to the results of KUB and IVU, from simple to complex Therefore, both variables are important indicators of the complexity of the reaction stones.It is easy to understand that higher values for stone score and Guys grade lead to a higher haemorrhage risk.Some scholars have found that BMI value and haemorrhage risk are unrelated[13].But we analyzed that all the patients with high BMI value were obese, which increased the difficulty of puncture and nephroscope swinging amplitude.The study conducted by Turna et al. observed decreased haemorrhage with balloon dilatation when compared to amplatz dilatation[9].However, in our study, we consider the association was not very significant[14].Previous scholars have argued that age is unrelated to haemorrhage. History of PCNL can also affect the haemorrhage. This study considered that previous surgical history can cause trauma to the kidney and affect the renal parenchymal healing.The variables above can reduce the risk of haemorrhage.In the process of visual channel establishment, the operator can observe the position of the needle in the kidney, the tissue of the needle path and large blood vessels without damage.The operator can also control the depth of the needle at any time and avoid the damage of large blood vessels and renal parenchyma caused in the process of puncture. Puncture was defined as being a correct puncture if the fornix or papilla of the posterior calyx was punctured and the trajectory of the tract was within 20 degrees posterior to the frontal plane of the kidney[15](Fig. 6).
A line represents the frontal plane of the kidney,B line represents the trajectory of the tract,α Is the angle between the A line and B line.Puncture was thought correct if the fornix or papilla of the posterior calyx was punctured and the trajectory of the tract was within 20 degrees posterior to the frontal plane of the kidney.
All patients underwent CT examination after operation.Doctors judged whether the puncture fell in the avascular plane according to CT.It has been documented to reduce the risk of severe haemorrhage by crossing the avascular plane of the Brodle line.For patients with nephrostomy, percutaneous nephroscopy can enter along the original fistula channel, reducing the risk of puncture. And the preoperative nephrostomy can fully drain the hydronephrosis and control the infection[14].
There were also several limitations in our study.First,This study was regressive and was performed with a relatively small sample size.Second, patients who did not meet the conditions of semi-tubeless PCNL were excluded and prone to selection bias.
In conclusion,for patients after semi-tubeless PCNL, high blood pressure,high stone score,non-visualization,high Guys grade,non-avascular area,diabet,advanced age,history of PCNL,long operation time ,solid kidney,non-preoperative nephrostomy,multiple channels,large channel size and high BMI are alarming variables for haemorrhage after semi-tubeless PCNL.Preoperatively, we can assess the postoperative haemorrhage risk with the model.