2.1.1 Simple renal cysts typically have thin walls with no calcification, septation or enhancement shown on contrast studies. Solitary simple cysts are common and are often diagnosed incidentally. In the minority of patients who are symptomatic, pain is the most frequent complaint.
2.1.2 Symptomatic renal cysts can be managed with analgesic medication, needle aspiration (with or without administration of a sclerosant) and open surgical cyst deroofing if aspiration is unsuccessful at relieving symptoms in the long term. In some patients, a nephrectomy may be necessary. Asymptomatic cysts do not usually require any treatment.
2.1.3 Laparoscopic deroofing is not used if there is any suspicion of malignancy. The management of polycystic kidney disease is different from that of simple renal cysts and is therefore not addressed in this guidance.
2.2.1 Laparoscopic deroofing of renal cysts is usually performed under general anaesthesia, using a retroperitoneal or transperitoneal approach. In the former, a small incision is made in the back and a dissecting balloon is inserted to create a space in the retroperitoneal tissues. In both approaches, carbon dioxide insufflation is used and small incisions are made to provide access for the laparoscope and surgical instruments. Ultrasonography may be used to help locate the cyst, which is usually aspirated, and part of the cyst wall is then excised. Fat or omentum may be interposed to prevent recurrence.
2.3.1 In a non-randomised controlled trial of patients with symptomatic simple renal cysts, pain recurred in all 5 patients treated with cyst aspiration and sclerotherapy at a mean follow-up of 17 months, whereas all 7 patients treated with laparoscopic deroofing were pain-free at a mean follow-up of 18 months.
2.3.2 In five case series of patients with symptomatic simple renal cysts (155 patients in total), the proportion of patients who were symptom-free ranged from 91% (41/45) after a mean follow-up of 52 months to 100% (20/20) after a mean follow-up of 6 months.
2.3.3 Four of these case series reported rates of cyst recurrence as 0% (0/13) after 6 months, 13% (3/23) after 34 months, 4% (2/45) after 39 months and 19% (7/36) after 67 months. For more details, refer to the 'Sources of evidence' section.
2.3.4 Some Specialist Advisers expressed no concerns about efficacy. Others stated that there is a possibility that cysts may refill after the procedure. The Advisers considered patient selection to be important because not all cysts cause symptoms.
2.4.1 Four studies of patients with simple renal cysts (91 patients in total) each reported one case of haemorrhage (overall incidence 4%). In two patients the cyst excision margin bled excessively; one case required conversion to open surgery but the other was controlled by an intracorporeal suture. Self-limited retroperitoneal bleeding occurred in one patient (in whom a retroperitoneal approach was used) and reactionary haemorrhage occurred in another. One study reported that 1 of 9 patients had prolonged ileus. One study reported wound infection in 8% (2/24) of patients and urine leakage in 4% (1/24).
2.4.2 In a case series of 17 patients, a cyst wall carcinoma was identified during one procedure and an open nephrectomy was performed immediately. No findings of malignancy were reported in three other case series (of 29, 20 and 36 patients, respectively). For more details, refer to the 'Sources of evidence' section.
2.4.3 The Specialist Advisers stated that theoretical adverse outcomes include haematuria, urinary tract infection, port site infection, urine leakage (from a parapelvic cyst), intraoperative bleeding, conversion to open surgery or nephrectomy, and injury to other internal organs or major blood vessels.