Encapsulating Peritoneal Sclerosis: Pathophysiology, Diagnosis, and Management of a Rare but Devastating Complication of Peritoneal Dialysis

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Introduction

Encapsulating peritoneal sclerosis (EPS) is a rare but life-threatening complication primarily associated with long-term peritoneal dialysis (PD) in patients with end-stage kidney disease (ESKD). Although uncommon, EPS carries a high morbidity and mortality, often due to progressive intestinal obstruction and malnutrition. Characterized by extensive fibrosis and calcification of the peritoneum, EPS forms a dense “cocoon” encasing the bowel loops, leading to encapsulation, tethering, and eventual obstruction. This article explores the pathophysiology, epidemiology, clinical features, imaging findings, differential diagnosis, treatment strategies, and prognosis of EPS, illustrated with imaging examples, and concludes with questions for learners.

Pathophysiology

EPS arises from chronic peritoneal inflammation and fibrosis. The process is believed to be “two-hit”:

  1. First Hit – Chronic peritoneal insult

    • Long-term exposure to bio-incompatible PD fluids, rich in glucose degradation products, triggers peritoneal injury.

    • Repeated episodes of peritonitis accelerate mesothelial cell loss and stimulate fibroblast activation.

  2. Second Hit – Inflammatory cascade and fibrosis

    • Chronic inflammation activates transforming growth factor-β (TGF-β), vascular endothelial growth factor (VEGF), and fibroblast proliferation, leading to collagen deposition.

    • Neoangiogenesis and tissue hypoxia worsen fibrosis.

Histopathology typically demonstrates dense peritoneal fibrosis, calcification, and chronic inflammatory infiltrates.

Epidemiology

  • Incidence: Estimated at 0.5–2.5% among long-term PD patients, but varies by geographic region and PD duration.

  • Risk factors:

    • Prolonged PD (>5–7 years)

    • Recurrent bacterial peritonitis

    • High glucose dialysate exposure

    • Certain genetic predispositions

  • Mortality rate: Up to 50% within 1 year after diagnosis in severe cases.

Clinical Presentation

EPS often presents insidiously and may mimic other abdominal disorders. Symptoms include:

  • Chronic abdominal pain and bloating

  • Nausea, vomiting, and anorexia

  • Progressive weight loss and malnutrition

  • Features of bowel obstruction: constipation, absence of flatus, abdominal distension

  • On examination: abdominal tenderness, palpable mass due to cocooned bowel loops

Imaging Features

Computed Tomography (CT) is the diagnostic imaging modality of choice. Findings include:

  • Peritoneal thickening and enhancement

  • Dense peritoneal calcification

  • “Cocoon-like” encapsulation of bowel loops

  • Loculated ascites

Magnetic Resonance Imaging (MRI) may show similar findings, with improved delineation of fibrosis.

Figures from the Case Document


Figure 1. Axial CT: Diffuse calcification along visceral and parietal peritoneum, with thickened peritoneal layers.


Figure 2. Abdominal CT: Encapsulation of small bowel loops with extensive fibrosis consistent with EPS.

Differential Diagnosis

EPS must be distinguished from other causes of peritoneal calcification and encapsulation:

  • Tuberculous peritonitis

  • Peritoneal carcinomatosis

  • Fungal peritonitis

  • Calciphylaxis

  • Other sclerosing peritonitides

Diagnosis

Diagnosis is established through a combination of:

  1. Clinical suspicion in long-term PD patients with recurrent abdominal symptoms.

  2. Imaging evidence of peritoneal thickening, calcification, and bowel encapsulation.

  3. Histopathology (laparoscopy or biopsy) confirming fibrosis and calcification.

Treatment

Treatment requires a multidisciplinary approach:

  1. Medical management

    • Cessation of PD and switch to hemodialysis

    • Corticosteroids and immunosuppressants (e.g., tamoxifen, azathioprine) to reduce inflammation

    • Nutritional support (enteral/parenteral)

    • Symptom management with analgesics and prokinetics

  2. Surgical management

    • Peritonectomy and enterolysis (“peeling off the cocoon”) in severe cases of bowel obstruction

    • Surgery is technically challenging and carries high morbidity, but offers survival benefit in selected patients.

Prognosis

  • EPS is associated with a high mortality, particularly when diagnosis is delayed.

  • Early recognition and intervention improve survival.

  • Long-term prognosis depends on bowel function recovery, nutritional support, and infection control.

Quiz

Q1. The most significant risk factor for encapsulating peritoneal sclerosis is:
A) Short-term peritoneal dialysis
B) High-protein diet
C) Long-term peritoneal dialysis with recurrent peritonitis
D) Tuberculosis infection

  • Answer: C

  • Explanation: Chronic PD exposure and repeated peritonitis episodes are the strongest predictors.

Q2. The hallmark CT finding in EPS is:
A) Hepatic steatosis
B) Cocoon-like encapsulation of bowel loops
C) Free intraperitoneal air
D) Portal vein thrombosis

  • Answer: B

  • Explanation: Cocooned bowel with calcified peritoneum is pathognomonic.

Q3. Which is the most definitive treatment option for advanced EPS with bowel obstruction?
A) High-dose antibiotics
B) Paracentesis
C) Peritonectomy and enterolysis
D) Continuation of peritoneal dialysis

  • Answer: C

  • Explanation: Surgical removal of fibrous encapsulation is indicated in obstructive cases.

Q4. Which cytokine plays a pivotal role in the pathogenesis of EPS?
A) Interleukin-2
B) Transforming Growth Factor-beta (TGF-β)
C) Tumor necrosis factor-alpha
D) Interferon-gamma

  • Answer: B

  • Explanation: TGF-β promotes fibrosis and collagen deposition in the peritoneum.

Q5. Mortality within one year of EPS diagnosis can be as high as:
A) 5%
B) 15%
C) 30%
D) 50%

  • Answer: D

  • Explanation: EPS is associated with a grave prognosis, particularly without early intervention.

References

[1] Kawanishi H, Kawaguchi Y, Fukui H, et al., “Encapsulating peritoneal sclerosis in Japan: A prospective, controlled, multicenter study,” Am J Kidney Dis., vol. 44, no. 4, pp. 729–737, 2004.
[2] Brown MC, Simpson K, Kerssens JJ, Mactier RA., “Encapsulating peritoneal sclerosis in the new millennium: a national cohort study,” Clin J Am Soc Nephrol., vol. 4, no. 7, pp. 1222–1229, 2009.
[3] Habib AM, Preston E, Davenport A., “Risk factors and outcome of encapsulating peritoneal sclerosis in patients on peritoneal dialysis,” Kidney Int., vol. 82, no. 4, pp. 417–422, 2012.
[4] Balasubramaniam G, Brown EA, Davenport A., “The Pan-Thames EPS study: treatment and outcomes of encapsulating peritoneal sclerosis,” Nephrol Dial Transplant., vol. 24, no. 10, pp. 3209–3215, 2009.
[5] Augustine T, Brown PW, Davies SJ., “Encapsulating peritoneal sclerosis: clinical significance and management strategies,” Nat Rev Nephrol., vol. 5, no. 9, pp. 543–551, 2009.
[6] Johnson DW., “Encapsulating peritoneal sclerosis: a rare but devastating peritoneal complication,” Nephrology (Carlton)., vol. 15, no. 1, pp. 2–10, 2010.
[7] Kawanishi H., “Surgical treatment for encapsulating peritoneal sclerosis,” Adv Perit Dial., vol. 18, pp. 139–143, 2002.
[8] Nakayama M, Miyazaki M, Honda K., “Encapsulating peritoneal sclerosis in patients undergoing long-term peritoneal dialysis,” Clin Nephrol., vol. 71, no. 5, pp. 430–439, 2009.

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