Microwave ablation for treating liver metastases

There were no procedure‑related deaths following microwave ablation (MWA) reported in a randomised controlled trial (RCT) of 30 patients or in 4 comparative studies of 89, 81, 53 and 19 patients.

Peritoneal haemorrhage was reported in 1 patient in a case series of 736 patients (187 with metastases) treated by MWA; the patient was treated by blood transfusion (no further details provided).

Haemobilia was reported in 1 patient out of 6 treated by MWA in the matched‑cohort comparative study of 19 patients treated by MWA or radiofrequency ablation (RFA); this was managed conservatively (no further details provided).

Hepatic abscess was reported in 1 patient out of 14 treated by MWA in the RCT of 30 patients treated by MWA or RFA; this was treated by antibiotics (no further details provided). Multiple liver abscesses were reported in 1 patient out of 20 treated by MWA in the retrospective comparative study of 81 patients; the abscesses were drained percutaneously and treated by antibiotics. Liver abscess was reported in 2 patients with liver metastases in a case series of 1,136 patients (257 with metastases) treated by MWA; these were treated by aspiration or drainage (no further details provided). Hepatic abscess was reported in 1 patient in the case series of 736 patients (187 with metastases): this was treated by drainage (no further details provided).

Bile duct fistula was reported in 1 patient out of 14 treated by MWA in the RCT of 30 patients; this was treated by antibiotics (no further details provided). Biliary fistula was reported in 1 patient out of 37 treated by MWA plus resection, and in 1 patient out of 16 treated by resection alone in the non‑randomised controlled study of 53 patients (measurement of significance and length of follow‑up not reported).

Biloma was reported in 1 patient with liver metastases in the case series of 1,136 patients (257 with metastases); this was treated by drainage (no further details provided).

Jaundice caused by biliary stenosis was reported in 1 patient in the case series of 736 patients (187 with metastases); this was repaired surgically (no further details provided). Hyperbilirubinemia was reported in 1 patient out of 37 treated by MWA plus resection in the non‑randomised controlled study of 53 patients (no further details reported).

Asymptomatic left portal vein thrombosis with segmental liver infarction was reported in 1 patient in a case series of 26 patients with colorectal liver metastases treated by MWA (no further details provided).

Respiratory problems were reported in 15% (3 of 20) of patients treated by MWA in the retrospective comparative study of 81 patients; they were treated by non‑invasive ventilation support and were reported to be mainly associated with complications from the colorectal surgery (no further details reported). Transient deterioration of pulmonary function was reported in 1 patient who was asthmatic and who had a simultaneous lung ablation in the case series of 26 patients (no further details reported).

Pneumothorax was reported in 1 patient in the case series of 736 patients (187 with metastases); this was treated by drainage (no further details provided). Pneumothorax was reported in 8% (2 of 26) of patients in the case series of 26 patients; this was treated by thoracostomy.

Pleural effusion was reported in 1 patient out of 20 treated by MWA in the retrospective comparative study of 81 patients; it was treated by percutaneous drainage. Pleural effusion was reported in 2% (4 of 257) of patients with liver metastases in the case series of 1,136 patients (257 with metastases); this was treated by aspiration or drainage (no further details provided).

Haemothorax with intrahepatic haematoma was reported in 1 patient in the case series of 736 patients (187 with metastases); this was treated by drainage (no further details provided).

Skin burn was reported in 1 patient with liver metastases in the case series of 1,136 patients (257 with metastases); this was treated by full‑thickness resection and suture (no further details provided).

Infection was reported in 1 patient out of 37 treated by MWA plus resection in the non‑randomised controlled study of 53 patients (no further details reported).

Intestinal obstruction was reported in 8% (3 of 37) of patients treated by MWA plus resection in the non‑randomised controlled study of 53 patients (no further details reported).

Tumour seeding was reported in 1 patient in the case series of 736 patients (187 with metastases); this was treated surgically (no further details provided).

In addition to safety outcomes reported in the literature, specialist advisers are asked about anecdotal adverse events (events which they have heard about) and about theoretical adverse events (events which they think might possibly occur, even if they have never done so). For this procedure, specialist advisers reported diaphragmatic injury as an anecdotal adverse event. They considered that the following were theoretical adverse events: damage to adjacent structures (including lung, diaphragm, bowel, or gallbladder), vascular injury, ascites, impaired liver function, fever and pain.