On Percutaneous Drainage of Liver Hydatid Cysts

F. Saidi, MD

Department of Surgery, Shahid Beheshti University of Medical Sciences, Tehran, Iran

A number of articles have been published within the recent past, advocating percutaneous drainage of hydatid cysts of the liver.^1-6

The proposed method consists of aspiration of the fluid contents of the parasitic cysts under ultrasonographic control using fine needles or catheters, followed by injection of a scolicidal agent, either hypertonic saline or 95% alcohol, into the remaining cavity. As supplementary treatment, Benzimidazole derivatives are administered before and/or supported by serial serologic tests, the overall results have been reported as good to excellent. The proclaimed advantage of this minimally invasive approach has been a shortened duration of hospital stay of patients.

This technical approach to hydatid cysts of the liver is in line with the general trend of past few year, calling for a reduction of the overall trauma of surgery by avoiding, whenever possible, standard open operations. Following this theme, many intraabdominal, and some intrahepatic abscesses are now successfully drained by needle aspiration under sonographic or CT scan control. It was only natural that, in due course, hydatid cysts of the lever would be subjected to the same type of limited access treatment. The additional impetus, in this particular situation, is that the efficacy of medical treatment with Benzimidazole derivatives is no greater thana 50 percent. On the other hand, the morbidity and mortality of standard open operations of liver hydatids are not negligible.

However, aa closer look at the basic pathology of hydatid disease and a scrutiny of the reported cases, raises serious doubts about the validity of the claimed advantages of percutaneous drainage of hepatic hydatids:

Removal of the solid elements of the parasite, that is, the laminated and the germinative membranes, is essential in achieving cure for any given cyst. The laminated membrane, if left behind, is a nonabsorbable foreign body and hence a nidus for bacterial infection. The germinative layer, as the name implies, harbors innumerable viable scoleces. Drainage or needle aspiration of the fluid contents of lever hydatid cysts will decompress the high internal pressure of large viable cysts, the real reason why such cysts become symptomatic. This is only a temporizing measure, however, as liberated scoleces will, in the ling run, recreate another cyst, this time a multivesicular one. A single viable scolex, left behind, is potentially capable of multiplying by asexual reproduction into millions of new microscopic scoleces.

For this very reason, scolicidal agents were routinely used in all reported series of needle drainage of the hydatid fluid. The larger the cyst, obviously the grater the amount of such agent injected. However, it is physically almost impossible to reach and kill all scoleces by injecting any amount of any scolicidal agent into an aspirated pericyst cavity. Scoleces liberated after needle puncture of the membranes, readily escape within the interstices of the rough lining of the pericyst cavity, and those still attached to the germinativa membrane remain protected in the collapsed infoldings of this layer. More than one half of all liver hydatids are multivesicular, containing innumerable small and medium sized daughter cysts whose scoleces will certainly not be reached at all by scolicidal agents injected into their mother cyst. Incidentally, those scoleces entering hepatic bile ducts, pass harmlessly into the intestinal tract as they are incapable of becoming implanted upon mucosal a surfaces. They need not be chased after by scolicidal agent.

Incidentally also, 95% alcohol has little lasting effects on viable scoleces, as has been well demonstrated by injecting them, after exposure to alcohol, into the peritoneal cavity of immature mice. Immobility of scoleces, as seen under the microscope, is not a proof of their demise.

What is most perturbing about injecting scolicidal agents percutaneously into liver hydatids, without the control afforded by open operation, is the irreversible damage to the biliary system.⁷ All hepatic hydatid cyst communicate with the biliary tree, whether or not such communications are demonstrable by preliminary dye studies.⁶ The diffuse sclerosing cholangitis resulting from uncontrolled entry of hypertonic saline or any other scolecidal agent into the biliary tree, takes months and more likely years to manifest itself clinically.^8-10 A saline solution, if hypertonic enough to kill the sturdy scoleces, is strong enough to cause desiccation of the hepatic bile duct epithelium. Once established, sclerosing cholangitis is invariably fatal with no treatment other than transplantation currently available. The longer the injected scolecidal agent is left in the cavity to effect killing of all scoleces, the greater the invitation to such irreversible damage to bile duct epithelium.

The level of antibody titers, determined any time after percutaneous drainage of liver hydatids, is not a measure of the viability of the cyst, and has no prognostic value.

Given the fact that about 10 to 20 per cent of viable univesicular cysts liver hydatid cysts abort spontaneously over a period of 3 to 5 years from the time they are first detected, and the fact that one half of all such parasitic cysts are multivesicular and their daughter cysts not amenable to needle aspiration, it is doubtful if percutaneous drainage of lever hydatids can be advocated as either logical or effective. The size of size of hydatid cysts subjected to percutaneous drainage in the reported series varied from four to 10 cm. Cysts of this size or even larger, are invariably asymptomatic. They are usually discovered accidentally in the course of sonographic evaluation of some other unrelated condition. In such circumstances these cysts can be followed at ix monthly intervals using sonographic control. The success rate with this conservative approach is 60 to 70 percent: oral Albendazole or Mebendazole therapy will control 50% and 10 to 20% will abort spontaneously. For complicated liver hydatids, always symptomatic because they have ruptured into the biliary system with resulting obstructive jaundice, or because they have become secondarily infected, there is no alternative to open operative intervention under full visual control.

Anaphylactic reaction, the remaining hazard of needling viable univesicular hydatid cysts, is not worth talking about since it can be controlled by administering rapid acting steroid compounds. Remarkably, the level of serum IgE of the patient does not seem to have a direct bearing on the incidence or severity of such a response.

Echinococcosis Granuloses is a major public health problem, essentially restricted to pastoral areas in developing countries of the world, In such settings, reducing patient's length of hospital stay cannot be the driving force or a justification for percutaneous drainage of liver hydatids. Minimal access surgery is certainly a major economic consideration in technologically advanced countries where insurance companies focus on early discharge from hospitals. Bed occupancy rates in developing countries is no great issue, but the expense of procuring the technology and expertise of imaging facilities for needle guided drainage of liver cyst, is a major problem. The overall cost sustained by hospitals in developing countries, to drain the vast number of cyst which have to be discovered by screening method, and the large numbers found accidentally but need no treatment at all, can be staggering.

The fact that liver hydatids can b drained percutaneously, is no reason for doing so.

References

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