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Editor,—In 1996 a letter (Gut 1996;38:936) about the use of PAIR (puncture,aspiration,injection of a scolecidal agent,reaspiration) raised a criticism of Dr Morris, a leading expert on the treatment of echinococcosis.1 At the same time the WHO Informal Working Group on Echinococcosis launched a survey to evaluate the status of this procedure. A number of centres around the world known to be active in this field were requested to complete forms for patients treated with PAIR: 765 abdominal cysts, mostly hepatic, treated with this technique were reported from various countries. We report the results of this survey (table 1).
Results of the survey on PAIR by the WHO Informal Working Group on Echinococcosis
Either needles (18–22 gauge) or catheters (5–9 French gauge), depending on the size and location of the cysts, were used. Scolecidal agents were mainly 20% hypertonic saline and 95% ethanol solution. After aspiration and parasitological control of the fluid, a quantity of scolecidal agent, approximately equivalent to one third of the amount aspirated, was injected into the cysts and left for a time varying from 5 to 30 minutes, and then reaspirated: only in the cases of Giorgio and colleagues2 was the scolecidal agent not reaspirated. In all cases, except for two failures (0.26%) followed by surgery, various degrees of reduction in size (at least 50%) and involution (healing) of the cysts were observed on ultrasound follow up. Anaphylactic shock occurred in four cases (0.52%) and was promptly treated; in one case (0.13%) death ensued notwithstanding resuscitative manoeuvres. Recurrences were observed in 12 cases (1.57%) but in eight (1.05%) they were related to an insufficient amount of scolecidal agent (one tenth instead of the average equivalent of one third of the aspirated fluid). Spillage of the fluid in the abdominal cavity was observed in four cases (0.52%) but all patients were receiving prophylaxis with albendazole (seven days to four hours before to 1–4 weeks after) and no peritoneal dissemination occurred. Minor complications (fever, rash, abscess formation, and biliary fistules) were observed in 105 cases (13.7%); abscess formation was treated with echo guided percutaneous drainage. The follow up is more than five years for 75 cases at the time of presentation of this survey.
These data show that the use of PAIR is widespread and increasing, especially in countries where echinococcosis is endemic. This is also because of its low cost and high efficacy. These data are in accordance with the literature: as of today more than 2400 cysts have been punctured and reported in indexed journals, and success and complication rates are even lower than those of our survey. PAIR is a safe and effective therapeutic tool; the risk of anaphylaxis during PAIR has been greatly overrated. Complication rates, recurrences, and mortality rates are lower than those of surgery.3 Accuracy of follow up may be a problem where the population is nomadic, but so far no case of peritoneal dissemination after PAIR has been reported.
There is a need for further studies on PAIR. One of the main issues is to standardise at least some of the points of the various PAIR protocols, under the supervision of the WHO, to compare their efficacy, set up prospective studies, and distribute guidelines to optimise the use of the treatment. Whereas before we felt that the technique was limited to a narrow group of patients,4 today we believe that PAIR is not only an alternative but an effective first choice diagnostic and therapeutic tool in the management of human cystic echinococcosis.
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Reply
Editor,—I remain unconvinced of two basic things: is it (PAIR) safe and is it effective? With regard to safety these are three issues.
- (a)
- Anaphylaxis. This occurred in four patients after PAIR in the current report and caused one death. An additional three patients became hypotensive and 14 developed a rash. I believe this is a higher risk than surgery should entail.
- (b)
- Dissemination. The peritoneal dissemination of hydatid disease due to needling a liver cyst will take some time to present—how long? In a series of patients with peritoneal hydatid disease, presentation did not occur until nine years (5–14 years) after surgery.1-1 Current follow up of PAIR does not address this issue. Spillage of hydatid material only causes recurrence in approximately 30% of patients.1-2 Peritoneal hydatid can be a serious or fatal problem.1-1
- (c)
- Sclerosing cholangitis. A significant proportion of hydatid cysts communicate with the biliary tree; use of scolicidal agents even at open surgery has caused sclerosing cholangitis. The surgeon has the opportunity of identifying and protecting such a communication prior to the use of scolicide.
Is it effective? The comment that the recurrence rate of PAIR is now less than surgery is either simplistic or deliberately misleading. Filice et al state that 75 patients (or is it cysts?) have been followed up for five years—the type and frequency of follow up is not stated and this is really critical. Careful ultrasonic follow up can demonstrate recurrence following surgery in up to 22% of patients1-3 but one can equally well quote surgical series with poor follow up with low recurrence rates; to claim that recurrence rates are lower following PAIR when the type and completeness of follow up is not even stated in scientifically quite invalid.
That cysts shrink (variably) following PAIR is reported, but what does this mean—is this synonymous with parasite death? I doubt it! Only one PAIR study reported reaspiration at three days post-PAIR1-4and 2/14 patients had live proloscolices.
The use of albendazole for four hours to seven days prior to and for 1–4 weeks after PAIR is clearly an attempt to reduce the risk of recurrence. In my original laboratory work it took of the order of 30 days to be effective1-5 and in humans, two patients who received albendazole for one and three weeks, respectively, prior to operation had viable proloscolices.1-6 The use of post-spillage therapy to reduce the risk of implantation has been variably effective in animal models of spillage.1-7 1-8
We have made at least some attempt to define the minimum length of such therapy.1-8
The over representation of a poor presentation of data, which I suspect is of even poorer quality, does not improve my view of PAIR, or of the WHO working group. I am quite prepared to accept that PAIR may be the best available option in some areas of the world where surgery and perioperative care are compromised by economic factors or lack of experience, but its comparison with surgery should await careful long term follow up.
Footnotes
↵† D Vuitton, Besançon, France; P Schantz, Atlanta, USA; M Caremani, Arezzo, Italy; A Giorgio, Napoli, Italy; C Bastid, Marseille, France; J Stefaniak, Poznan, Poland; E Zeyhle, Nairobi, Kenya; H Wen, China; V Pelaez, Neuquèn, Argentina; R Pettinari, Chubut, Argentina; O Akhan, Ankara, Turkey; S Men, Ankara, Turkey; G Hernandez, Avila, Spain; H Schipper, Amsterdam, Netherlands.