In an adult with end‑stage renal disease on peritoneal dialysis for several months who develops sudden difficulty infusing dialysate, reduced outflow, abdominal pain, or a tenting sensation at the catheter site, how is an omental wrap diagnosed?

Diagnosis of Omental Wrap in Peritoneal Dialysis

Omental wrap is diagnosed primarily through imaging studies, specifically a plain abdominal radiograph (KUB) showing catheter tip displacement or malposition, followed by contrast peritoneography or CT scan to confirm omental encasement of the catheter tip.

Clinical Presentation

The clinical picture typically includes:

• Sudden onset of poor dialysate drainage (reduced outflow despite normal inflow)
• One-way obstruction pattern (fluid goes in but doesn't come out adequately)
• Abdominal discomfort or "tenting" sensation at the catheter site
• Migration of catheter tip away from the pelvis (often upward)
• Normal inflow pressures but elevated outflow pressures

Diagnostic Approach

Initial Assessment

Start with a plain abdominal radiograph (KUB) to evaluate:

• Catheter tip position (should be in the pelvis; omental wrap causes upward migration)
• Presence of catheter coiling or kinking
• Comparison with prior films showing catheter migration

Confirmatory Imaging

If plain films suggest malposition:

Contrast peritoneography is the gold standard:

• Inject radiopaque contrast through the PD catheter
• Look for loculation of contrast around catheter tip
• Demonstrates omental tissue wrapping around catheter holes
• Shows poor distribution of dialysate throughout peritoneal cavity

CT scan with contrast (alternative):

• Identifies soft tissue (omentum) surrounding catheter tip
• Rules out other causes of obstruction (adhesions, fibrin clots, constipation)
• More readily available than fluoroscopic peritoneography

Exclude Other Causes

The differential diagnosis includes:

• Constipation (check for stool burden on KUB)
• Fibrin clot/plug (may respond to thrombolytics)
• Catheter kinking (visible on plain films)
• Adhesions (suggested by history of peritonitis or surgery)

Clinical Pitfalls

Do not assume catheter dysfunction is always mechanical. The guidelines emphasize that documented loss of peritoneal function or extensive abdominal adhesions can limit dialysate flow 1. However, omental wrap is a specific mechanical problem distinct from adhesive disease.

Avoid delaying imaging. Early diagnosis prevents prolonged inadequate dialysis, which can lead to uremia, fluid overload, and hyperkalemia—all of which increase morbidity and mortality.

Consider timing. Omental wrap typically occurs weeks to months after catheter placement, not immediately post-insertion (which would suggest surgical malposition).

Practical Algorithm

1. Patient presents with drainage problems → Check for constipation first (simple, reversible)
2. If not constipated → Obtain KUB to assess catheter position
3. If catheter tip migrated upward → Perform contrast study (peritoneography or CT)
4. If omental wrap confirmed → Surgical intervention required (laparoscopic omentectomy or catheter repositioning)

The guidelines note that mechanical defects preventing effective PD are absolute contraindications to continuing PD without correction 1. Omental wrap falls into this category—it must be surgically corrected as it will not resolve spontaneously and medical management (lytic infusion, catheter manipulation) is ineffective for true omental encasement.