From the Guidelines
The factor most likely to increase the risk of a perirenal hematoma after Shock Wave Lithotripsy (SWL) is the higher power density created by some of the second and third generation machines, which can be associated with options like C. >2,000 shocks. When considering the risk factors for perirenal hematoma after SWL, several elements come into play, including the characteristics of the shock wave machine used, patient-related factors, and procedural details.
- The use of higher power density machines, as seen in some second and third generation lithotriptors, has been reported to increase the potential for postoperative complications, including the incidence of clinically significant perinephric hematoma and need for transfusion 1.
- Patient factors such as hypertension, diabetes mellitus, and the presence of larger stones (>2cm) can also influence the risk of complications after SWL.
- Procedural factors, including the number of shocks administered, can impact the risk of perirenal hematoma, with higher numbers of shocks potentially increasing this risk. However, based on the provided evidence, the higher power density associated with newer machines and potentially with higher numbers of shocks, such as >2,000 shocks, stands out as a significant risk factor. It's crucial to weigh these factors and consider the most recent and highest quality evidence when assessing the risk of perirenal hematoma after SWL, keeping in mind that the goal is always to minimize morbidity, mortality, and improve the quality of life for patients undergoing this procedure.
From the Research
Risk Factors for Perirenal Hematoma after SWL
The factor most likely to increase the risk of a perirenal hematoma after Shock Wave Lithotripsy (SWL) can be identified by examining the provided evidence. Key points include:
- Hypertension is a significant risk factor, as indicated by studies 2, 3, 4.
- Larger stone size is also a predisposing factor, as noted in 2 and 5.
- The number of shock waves and total energy used during the procedure can influence the risk of hematoma, as suggested by 3.
- Other factors such as BMI, preoperative microhematuria, and the use of antiplatelet aggregation drugs may also play a role in the development of perirenal hematoma.
Comparison of Options
Considering the options provided:
- A. Hypertension: Supported by 2, 3, 4 as a risk factor.
- B. Stone size >2cm: Indicated by 2 and 5 as a factor, but not as strongly associated with perirenal hematoma as hypertension.
- C. >2,000 shocks: While the number of shock waves is a factor, the specific threshold of >2,000 shocks is not directly cited in the provided studies as the most significant risk factor.
- D. UTI: Not mentioned in the provided studies as a risk factor for perirenal hematoma after SWL.
- E. Diabetes mellitus: Not identified as a significant risk factor in the provided evidence.
Evidence Summary
Based on the studies reviewed, hypertension and larger stone size are the most consistently identified risk factors for perirenal hematoma after SWL. Therefore, the factor most likely to increase the risk of a perirenal hematoma after SWL is: