Is diaphragmatic paralysis a common complication after percutaneous nephrolithotomy (PCNL)?

Diaphragmatic Paralysis After PCNL is NOT Common

Diaphragmatic paralysis is a rare complication following percutaneous nephrolithotomy (PCNL), not a common one. While pleural complications occur in approximately 15% of PCNL cases, true diaphragmatic paralysis represents an exceedingly uncommon subset of these events 1.

Understanding the Actual Complication Rates

According to the Society of Interventional Radiology quality improvement guidelines, pleural complications (including pneumothorax, empyema, or hemothorax) occur in approximately 15% of PCNL cases 1. However, this broad category does not equate to diaphragmatic paralysis specifically.

What Actually Happens More Commonly:

• Pleural effusion: Occurs in up to 77% of patients post-PCNL, though most (69.8%) are asymptomatic 2
• Pneumothorax: More common with upper-pole calyceal puncture 1
• Hemothorax: Can occur but remains relatively uncommon
• True diaphragmatic paralysis: Extremely rare with only isolated case reports in the literature 3, 4

Why Diaphragmatic Paralysis is So Rare

The literature reveals only individual case reports of diaphragmatic paralysis following PCNL, with authors explicitly noting "the absence of reported cases of diaphragmatic paresis post PCNL lends to a dearth in knowledge regarding recognition and management" 3. This starkly contrasts with the 15% rate of general pleural complications.

Risk Factors for Pleural Complications (Not Paralysis):

When supracostal puncture is performed:

• Supracostal access increases risk of pleural complications (OR = 2.02) 2
• Upper-pole calyceal puncture specifically increases pneumothorax risk 1
• Most complications are Grade I (58.3%) or Grade II (12.5%) on the Clavien-Dindo scale 5

Clinical Implications

What to Actually Monitor For:

1. Pleural effusion (common, usually asymptomatic)

   • Volume >51 mL predicts moderate-to-severe respiratory symptoms 2
   • Only 4% experience severe symptoms; 1.2% require drainage 2

2. Pneumothorax (uncommon but recognized)

   • Threshold rate: 1% for standard PCN 1
   • Higher with intercostal approaches 1

3. Diaphragmatic injury (extremely rare)

   • May present with hemorrhagic shock if severe 4
   • Can cause unilateral hemidiaphragm elevation 3

Management When Diaphragmatic Injury is Suspected:

If you encounter the rare case of suspected diaphragmatic paralysis:

• Obtain chest radiograph showing hemidiaphragmatic elevation 3
• CT chest to confirm unilateral diaphragmatic elevation 3
• Conservative management with chest physiotherapy and incentive spirometry is typically effective 3
• Surgical repair only if associated with hemorrhagic shock or penetrating injury 4

Common Pitfalls to Avoid

Do not confuse pleural effusion with diaphragmatic paralysis. The 15% pleural complication rate includes pneumothorax, hemothorax, and effusions—not paralysis. In fact, 27.8% of pleural effusions post-PCNL are not even mentioned in radiology reports 2, suggesting many are clinically insignificant.

Do not overestimate the risk. While trauma guidelines note that hemidiaphragm paralysis can occur from phrenic nerve damage during diaphragmatic repair 6, this refers to traumatic diaphragmatic injuries requiring surgical repair—a completely different clinical scenario than routine PCNL.

The evidence is clear: diaphragmatic paralysis after PCNL is a case-report-level rarity, not a common complication that should routinely concern clinicians performing or counseling patients about this procedure.