Renal Colic on the ISS: Remote Management vs Evacuation
A 46-year-old astronaut is four months into a six-month ISS mission. He develops sudden severe left flank pain, nausea, and gross hematuria. Oral temperature is 37.8°C, blood pressure 138/84, heart rate 96. Point-of-care ultrasound shows a 6-mm echogenic focus at the left ureteropelvic junction with mild hydronephrosis but no perinephric fluid. He has no prior stones, no fever above 38°C, and no peritoneal signs. The ISS has oral analgesics, antiemetics, antibiotics, and limited ultrasound capability but no surgical or lithotripsy capability. Nominal Soyuz return is in eight weeks; an emergency return could occur in 24–36 hours but carries operational and crew risks. The crew medical officer must decide immediate treatment, evacuation threshold, and return-to-Earth plan.
1. What is the differential and immediate management on orbit?
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The leading diagnosis is an obstructing left ureteral stone at the ureteropelvic junction, supported by colicky flank pain, hematuria, and mild hydronephrosis. Alternatives include pyelonephritis, musculoskeletal strain, renal infarction, appendicitis or diverticulitis, and other causes of flank pain; left-sided appendicitis is less likely but not impossible. Immediate management includes pain control, antiemetics, hydration as tolerated, close temperature monitoring, urinalysis and culture if available, and serial ultrasound for hydronephrosis and urine output. Antibiotics should be started if infection is suspected, but fever may be blunted in spaceflight. Avoid nephrotoxic drugs and use NSAIDs cautiously if renal function is uncertain. Document stone size and location, and consult urology and the mission flight surgeon. The key reasoning is that a 6-mm obstructing stone is unlikely to pass uneventfully, and the ISS has no definitive urologic capability, so observation must be active and time-limited.
2. Should he be evacuated immediately, and what triggers emergency return?
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Immediate emergency return is not automatically required if pain is controlled, there is no fever, renal function is preserved, and hydronephrosis is mild and stable. However, the threshold for return should be low because the capability onboard is limited and complications can evolve over hours. Emergency return is triggered by uncontrolled pain, fever of 38°C or higher, suspected pyelonephritis or sepsis, worsening hydronephrosis, rising creatinine or falling urine output, anuria, persistent vomiting, or any clinical deterioration. The crew medical officer should set explicit reassessment intervals and prepare a contingency return plan. The judgement involves comparing the risk of a 24–36-hour emergency return-operational disruption, crew exposure, and landing risk-against the risk of an infected obstructed kidney in microgravity. If the stone remains obstructing and cannot be managed definitively onboard, earlier return should be planned even without a crisis rather than waiting eight weeks for nominal return.
3. What return-to-Earth and postflight plan should be arranged?
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Arrange urology consultation and plan for definitive ground-based care: noncontrast CT, renal function tests, urine culture, and likely ureteral stent or stone removal, especially if the stone remains at the ureteropelvic junction with hydronephrosis. If the astronaut remains stable, an early return rather than the nominal eight-week return may be the safer option, because a 6-mm obstructing stone has a meaningful chance of causing recurrent colic or infection. If he passes the stone before return, document its passage and still arrange imaging and metabolic evaluation. Postflight assessment should account for spaceflight-induced bone resorption, dehydration, and altered renal stone risk. The crew surgeon should coordinate with the landing medical team so analgesia, antibiotics, and imaging are available immediately after egress. Return-to-flight status should be deferred until urologic clearance and metabolic evaluation are complete.