Prone Versus Supine Percutaneous Nephrolithotomy: A Retrospective Comparative Cohort Study of Perioperative Outcomes and Initial Supine Adoption Experience

Kidney stones are hard, crystalline formations that can grow large enough to block the flow of urine, causing severe pain and potential damage to the organ. When these stones become too big to pass naturally or break down with shock waves, surgeons must remove them directly. The standard method for doing this is a procedure called percutaneous nephrolithotomy. In this operation, a surgeon makes a small incision in the patient's back, inserts a tube through the skin and into the kidney, and uses a specialized scope to locate and shatter the stone. For decades, the most common way to position a patient for this surgery has been lying face down, known as the prone position. This stance offers a direct path to the kidney but requires the patient to be turned over after being anesthetized, a maneuver that can be difficult for those with breathing issues, obesity, or other physical limitations. An alternative approach, where the patient lies on their back, has existed for years and offers easier access for the anesthesiologist and potentially a quicker recovery, but it has not been as widely adopted in many centers, particularly in India, where the traditional face-down method remains the norm.

Researchers at the All India Institute of Medical Sciences in Jodhpur set out to compare these two positions during a real-world transition. They wanted to see if a team of surgeons, already experts in the traditional face-down method, could safely switch to the back-lying method for their first batch of patients without compromising the outcome. The team looked back at the records of 167 patients who underwent this stone-removal surgery. Eighty-four of these patients were treated in the traditional face-down position, while the next eighty-three consecutive patients were treated lying on their backs. Before the surgery, every patient had a detailed scan to map the size and location of their stones. The surgeons then performed the operations, using X-ray guidance to navigate the instruments through the back and into the kidney, breaking the stones into pieces that could be washed out or removed.

The study revealed that both methods were equally effective at clearing the kidney of stone fragments. Whether the patient lay on their stomach or their back, the surgeons successfully removed all significant stone debris in roughly the same number of cases, with about eighty-four percent of patients in the face-down group and eighty-three percent in the back-lying group leaving the hospital with a stone-free kidney. However, the experience of the surgery itself differed in specific ways. The operations performed with patients lying on their backs were significantly faster, taking an average of sixty minutes compared to ninety-seven minutes for the face-down group. This difference was partly because the patients in the back-lying group generally had smaller stones to begin with, but even when the researchers matched patients with similar stone sizes, the back-lying surgeries remained quicker.

There were trade-offs in the details of the procedure. While the back-lying position allowed for a faster operation, it required slightly more X-ray exposure for the surgeons to guide their instruments, likely because the team was still learning the specific angles and techniques for this new orientation. In contrast, the face-down group had a longer hospital stay, averaging three days, while the back-lying group was discharged in just two days. The back-lying patients also reported needing less strong pain medication after the surgery. Complications were rare in both groups. Serious bleeding that required a special procedure to seal off a blood vessel happened in two patients in each group, and in all cases, the bleeding was stopped successfully without the need to remove the kidney. No patients died, and no major injuries to other organs occurred.

The researchers concluded that switching to the back-lying position is a safe and viable option, even for a team that has spent years mastering the face-down technique. The new method achieved the same high success rate in removing stones but offered the added benefits of a shorter hospital stay and less post-operative pain. The slightly higher X-ray dose observed was attributed to the learning curve of the initial adoption phase rather than a fundamental flaw in the method. The study suggests that as surgeons gain more experience with the back-lying position, the radiation exposure will likely decrease to match or even beat the levels of the traditional method. Ultimately, the findings indicate that patients with kidney stones can be treated effectively in either position, giving doctors the flexibility to choose the approach that best fits the individual patient's anatomy and health needs.