Case 10: Diagnosis & Conclusions

Case 10 Index

Diagnosis: Peritonitis in Peritoneal Dialysis (PD)

Case Summary: Well done! This patient has peritonitis in the setting of peritoneal dialysis, one of the potential complications of PD. This young woman has had, until now, an uncomplicated 2 years on PD and is now presenting with abdominal pain worsening over 1 day. Just like with any non-PD patient, abdominal pain has a wide differential diagnosis, and we should be cautious not to anchor too quickly on peritonitis or other PD complications.

Let’s briefly review the differential diagnosis for abdominal pain that should not be forgotten just because your patient is on PD!
Intra-abdominal
Gastroenteritis
Appendicitis
Pancreatitis
Diverticulitis
Ischemic colitis
Biliary colic
Hepatitis
Constipation
Small or large bowel obstruction
Gynecologic
Pelvic inflammatory disease
Ectopic pregnancy
Endometriosis
Urinary
Urinary tract infection
Pyelonephritis
Nephrolithiasis (kidney stone)
Peritoneal
Peritonitis
Hemoperitoneum
Encapsulating peritoneal sclerosis
Other
Atypical chest pain (acute coronary syndrome)

While keeping our eyes out for non-PD related pathology, it is important to act quickly with any suspicion for peritonitis. Looking at the PD fluid itself can also be helpful in making a diagnosis. PD fluid should be sent immediately for cell count with differential, gram stain, and culture.

Click below on the various appearances of PD fluid you might find to see the differential diagnosis (not exhaustive but a good place start!) associated with each:
Normal
Cloudy:
Peritonitis
Intraperitoneal disease (appendicitis, cholecystitis, bowel ischemia)
Retroperitoneal disease (pancreatitis, renal cell carcinoma)
Drugs (vancomycin, amphotericin B)
Allergic reaction (increased eosinophils)
Chylous:
High triglycerides
Lymphatic obstruction
Trauma
Abdominal lymphomas
Pancreatitis
Drugs (calcium channel blockers)
Bloody (hemoperitoneum):
Coagulopathy
Retrograde menstruation
Ovulation
Strenuous exercise
Ovarian cyst rupture
Adhesions
Catheter-associated trauma

The fluid cell count and differential should come back relatively quickly. An elevated dialysate white blood cell (WBC) count >100 cells/microL and/or greater than 50% polymorphonuclear leukocytes (PMNs) would be consistent with bacterial peritonitis. Both gram-positive (predominantly coagulase negative Staphylococcus or S. aureus) and gram-negative organisms (mainly gastrointestinal pathogens) can cause peritonitis.

Empiric antibiotic coverage is crucial. Intraperitoneal antibiotics should be initiated as soon as possible; if unavailable, systemic IV antibiotics should be given.

Empiric Antibiotic Coverage
Gram-negative coverage
Third generation cephalosporin or aminoglycoside
Gram-positive coverage
Vancomycin or first generation cephalosporin

Antibiotic therapy should be narrowed as culture data allows. Up to 20-40% of cases, however, will be culture negative. These patients should continue empiric therapy and undergo repeat fluid testing in 3 days. Failure to improve should prompt further evaluation.

The majority of patients improve with antibiotic therapy, though some  conditions require peritoneal dialysis catheter removal. Infection with Pseudomonas, fungi, vancomycin-resistant enterobacter (VRE), or Mycobacterium should prompt removal. In addition, concomitant exit-site or tunnel-site abscess, failure of therapy after five days of antibiotics, or a relapsed episode of peritonitis with the same organism are indications for catheter removal. The main goal is to act quickly to provide the best chance for resolution!

For more on peritonitis and peritoneal dialysis in general, take a look below:

  1. Li PK-T, Szeto CC, Piraino B, Arteaga J de, Fan S, Figueiredo AE, Fish DN, Goffin E, Kim Y-L, Salzer W, Struijk DG, Teitelbaum I, Johnson DW: ISPD Peritonitis Recommendations: 2016 Update on Prevention and Treatment. Perit. Dial. Int. 36: 481–508, 2016
  2. Mujais S: Microbiology and outcomes of peritonitis in North America. Kidney Int. Suppl. S55-62, 2006
  3. Nessim SJ: Prevention of peritoneal dialysis-related infections. Semin. Nephrol. 31: 199–212, 2011

Case 10 Index
Case 10 Introduction
Case 10 Physical Exam
Case 10 Diagnostic Testing
Case 10 Additional Diagnostic Testing
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