 Solution

Choose the method that can remove the whole bladder stone with the least overall danger in that patient. Here lithotomy means cutting into the urinary bladder to extract the stone; lithotrity means instrumental crushing through the urethra. The latter is not the later technique of external shock-wave treatment, and “no incision” does not mean “no tissue injury”.

The stone. A small, accessible, freely movable stone that can be grasped and broken without excessive force favours lithotrity. Great bulk, great hardness, an awkward shape, several substantial stones or a stone fixed in a recess increases the difficulty of fragmentation and complete clearance. The amount of debris matters: pieces left in the urinary bladder can irritate it, obstruct the passage or provide material for further growth. A historical comparison must count the burden of manipulation and clearance, not imagine that pulverization makes the stone disappear. No single size threshold can be specified independently of the instrument, the stone and the patient.

The access passage and the urinary bladder. Urethral stricture, inadequate urethral calibre, an existing false passage or difficult prostatic obstruction can make introduction of a useful crushing instrument unsafe. A urinary bladder that tolerates exploration, holds a reasonable volume and empties effectively is more favourable than one with marked cystitis, bleeding, extreme irritability or retention of urine. The operator must also consider kidney function, active infection and general reserve. A severely ill patient should not be exposed to a prolonged elective sequence of instrumentation merely because the stone itself seems crushable.

Age and anatomy. In a small child, the urethra may not admit an adequately strong instrument, which helps explain the historical preference for lithotomy in many children. Age is a proxy for anatomy and tolerance, not an absolute law: small instruments and different modern access routes change the comparison. In an older man, the prostate, urinary bladder emptying and general illness can be more important than age alone. In a woman, easier access through a shorter urethra may favour an endoscopic route, but forceful dilation or extraction can still damage the continence mechanism.

The operation and its operator. Cutting risks haemorrhage, urinary leakage, injury and postoperative infection; crushing risks injury from the instrument and retained or impacted fragments. Each method requires skill, appropriate apparatus and aftercare. A contemporary 1859 lecture explicitly contrasts older complicated drilling apparatus with the curved crushing instrument then in use. That is evidence that the available instrument was part of the decision, rather than a timeless property of “lithotrity”. ^[ref]

Practical selection. With a modest stone, passable urethra, tolerably healthy urinary bladder, effective emptying and suitable expertise, lithotrity has a strong rationale. When the stone is too large or resistant for safe fragmentation, access is unsafe or fragments cannot reasonably be cleared, extraction through another route becomes preferable. At the same time, poor general health may make either operation hazardous, so the preliminary task can be stabilization and management of associated disease rather than immediate choice of an instrument.

Modern guidance usually favours transurethral endoscopic fragmentation where feasible, offers a percutaneous route when transurethral treatment is unsuitable, and retains open surgery as an option for very large stones. In children, urethral injury risk can determine the route. These current options illustrate the same anatomical trade-offs but must not be imported wholesale into an 1865 recommendation. Nor should a historical preference for cutting in children be treated as a modern rule. ^[ref]