Isolated outflow obstruction often improves with use of laxatives to induce diarrhea as the vigorous peristalsis can move the catheter and reduce extrinsic compression of the catheter lumen. Patients are often reluctant to take laxatives and argue that they are not constipated so the intervention is better explained as induction of diarrhea. Appropriate bowel regimes in PD have already been discussed, but it is important to highlight that a larger dose of laxative is required for acute catheter malfunction. If catheter drainage does not improve after induction of diarrhea then an abdominal radiograph should be performed to assess for PD catheter position. A PD catheter is considered migrated if the tip of the catheter lies outside of the true pelvis. A migrated catheter may return to the true pelvis after treatment with laxatives which is why a radiograph should be performed only after the obstruction has proven refractory to laxatives. If the radiograph indicates migration then a guidewire manipulation should be performed under fluoroscopic guidance. If the catheter is not migrated on the radiograph then a trial of tidal automated PD (APD) or CAPD with upright drainage is worthwhile. Tidal APD, where a residual volume of a few hundred millilitres of fluid is left in the abdomen after each exchange, can be particularly useful for catheters that drain well initially and then slow as the residual dialysate volume contracts [60].

Fluoroscopic guide-wire manipulations are an important adjunctive procedure for salvage of poorly functioning PD catheters [52]. The radiologist inserts a stiff guide-wire through the catheter and clears out any fibrin or other intraluminal debris. The wire also serves to straighten a coiled catheter and can remedy the malposition of the catheter with respect to bowels or adhesions. The wire can also be used to reposition a migrated catheter, though this can be technically challenging and the risk of repeat migration is high and repeat malfunction is high (Table 11.1) [52, 61–67] The largest case series of fluoroscopic manipulations was reported in 2010 [66]. In this case series of 70 catheters manipulated for flow obstruction, 63% were functional at 30 days. Predictors of a successful outcome included pelvic location of catheter (i.e. a non-migrated catheter) and secondary catheter malfunction (i.e. catheter became obstructed after a period of good function). Fluoroscopic manipulation can be associated with some abdominal discomfort and the patient should be aware of this prior to the procedure. There are no guidelines for the use of prophylactic antibiotics with this procedure but some centers recommend post- procedure intraperitoneal antibiotics and change of the catheter transfer set.

Obstruction that does not resolve with fluoroscopic guide wire manipulation requires surgical intervention. Traditionally, a persistently obstructed catheter would be replaced and a new one inserted, but over the past few decades there is increased interest in laparoscopic salvage for refractory drainage failure. Laparascopic salvage has a number of advantages over removal and reinsertion. It allows for direct visualization of the intra-abdominal anatomy and diagnosis as well as treatment of the precise cause of the malfunction whereas simple removal/reinsertion runs the risk of the same problem recurring with the new catheter [48]. Omental wrapping of the catheter, often due to a low lying omentum, is the most frequent cause of malfunction found at laparoscopy [68–71]. Omental wrapping of the catheter can cause migration as the omentum may pull the catheter out of the pelvis. In these cases, the catheter can be freed from the omentum and returned to the pelvis and the redundant omentum tacked up with an omentopexy. Catheter migration without omental wrapping, presumably due to excessive torque on the catheter during insertion, is also a common finding and treatment may require suturing of the catheter in the pelvis. Other frequent findings include compartmentalization of the catheter due to adhesions, wrapping of the catheter from the fimbrae of fallopian tubes, as well as intraluminal obstruction due to blood and fibrin clots [72]. Laparoscopic salvage of PD catheters is associated with a high published rate of immediate success, typically greater than 80% although there is considerable variability in the rates of recurrent obstruction [68–71]. PD can typically be restarted soon after laparoscopic manipulation in keeping with the principles described above in the section on early use of the PD catheter.