Pleural effusion due to PPC in patients undergoing PD was first described in 1967 by Edward and Ungar , and its incidence rate was reported 0.64 to 5.1% in adults [1, 6] and 0.9 to 3% in children [1, 9, 10]. At our institute, we experienced two cases of PPC among 101 PD patients in the last 17 years (approximately 2%), which incidence rate was compatible to previous reports.
The exact mechanisms of developing PPC during PD are not well understood, but it is believed that abnormality of diaphragm and/or breakdown of lymphatic network lead to the pleural effusion [11,12,13]. Anatomical defects are more common in the right diaphragm, and there is a more abundant lymphatic network on the right side than on the left . The lateral edge of the central tendon has abundant lymphatic stomata . These factors may explain the preponderance of right-sided diaphragmatic fistula.
The definitive diagnosis of PPC can be made by the color change of pleural fluid after the injection of dialysate containing a dye such as indigo carmine or ICG into the abdominal cavity through the PD catheter, and/or the scintigraphy [1, 4]. If the patient is under artificial ventilation, we must be careful not to misdiagnose the existence of PPC because the resultant non-physiological pressure imbalance can cause the false-negative result for the diagnosis, as in our cases.
Treatment options include conservative management and surgical repair. Only 58% of the patients achieve long-term PD therapy without recurrence of pleural effusion .
Conservative treatments include spontaneous closure of the fistula by withholding PD [1, 4] and chemical pleurodesis . In our cases, we withheld PD for 3 months, as suggested by previous reports [15, 16]; however, this strategy was ineffective. Chemical pleurodesis therapy was not selected because of its low success rate and the possibility of inducing adhesions, which results in difficulty with the surgical approach.
Surgical repair is done by the either technique, thoracotomy or video-assisted thoracoscopic surgery. In 1984, Pattison et al.  reported the first case of surgical treatment using a Teflon patch for fistula closure and reported that if the fistula site could not be clearly identified, the success rate dropped to 38% and there was relatively high recurrence rate. In 1996, Di Bisceglie et al.  reported on the usefulness of VATS. Since then, VATS has become the standard procedure for the disease in adult patients, with a success rate of approximately 90%, and approaching 100% when specific lesions such as cysts or flaws have been confirmed [19, 20].
We selected VATS technique for our patients although they were under 2-year-old infants because it allows for a thorough observation of the lesions during surgery. To identify the fistula site, a dialysate containing indigo carmine and ICG was injected into the abdominal cavity through a PD catheter. By using these assistive procedures, the lesion could be identified and treated successfully. Among the dyes, only ICG was detected in the operative field. The sensitivity of the infrared camera for fluorescence might be much higher than that of the endoscopic visible light. Thus, we recommend that ICG would be preferred as an aid during surgery.
In case 1, a laparoscope was inserted for PD catheter replacement, and a small hole was identified on the peritoneal surface of the diaphragm. Since direct suturing could tear fragile tissue and an absorbable polyglycolic acid felt could cause undesirable adhesions and reduce dialysis efficiency, autologous tissue (the falciform ligament) was used for patch closure. It may be useful to observe the abdominal cavity when the communication site cannot be identified by thoracoscopy.