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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_738_Библиотеки_им_академика_М_И_Перельмана.pdf
Management Of Hydatid Cyst
Operative Indications
Cystic echinococcosis, while uncommon in the United States, is endemic in certain parts of the world such as the Middle
East and Africa. The infection is often indolent, and the liver and lungs are the most frequently involved organs. Current
classification based on ultrasonography reflects the functional state of the parasite. Active cysts demonstrate multiple septations, hydatid sand, and daughter cysts (1); whereas inactive cysts typically reveal heterogeneous hypo- or hyperechogenic degenerative contents and cyst wall calcifications. The diagnosis is suspected based on clinical signs and symp-
Hydatid cyst
1
Management of Hydatid Cyst 173
toms and epidemiological data. In the majority of cases definitive diagnosis can be established using a combination of imaging techniques and either serological or immunoassay techniques.
Although certain types of hepatic hydatid cysts are successfully treated by medical therapy or by percutaneous aspiration and injection, surgery remains the treatment of choice in most cases. Indications for surgery are large cysts with multiple daughter cysts, a superficial cyst with a high risk for rupture, infected cysts, cysts communicating with the biliary tree,
or symptomatic cysts. Small asymptomatic cysts, multiple small cysts, or those which are dead or calcified do not require
surgical intervention in most cases. Albendazole is a broad-spectrum antihelmintic drug that is active against intestinal nematodes. When planning surgical therapy in an active cyst, preoperative administration of albendazole should be considered
in order to reduce parasite viability. It should be administered at 10 to 15 mg/kg/d postprandially in two divided doses,
1 month, and then 4 days before surgery.
Surgical therapy is most commonly performed using an open surgical technique. Laparoscopic treatment is being reported with increasing frequency in recent years and can be considered in selected cases. A major disadvantage of laparoscopy,
however, is the lack of precautionary measures to prevent spillage under the high intra-abdominal pressures caused by pneumoperitoneum. Liver resection can also be considered for hydatid disease, but this procedure is associated with higher morbidity and should be reserved for cases of recurrence or when the cyst has destroyed, or is compressing, an entire hemiliver or segment. The most common surgical procedure for hydatid liver disease is the pericystectomy, with removal of the
cyst contents, germinal layer, and pericyst wall.
Surgical Technique
When performing a pericystectomy, a right subcostal incision is typically
employed. As with other hepatic surgical procedures, it is important to fully assess
the extent of disease outside of and within the liver before determining the type
of procedure needed. Intraoperative ultrasonography (IOUS) may be useful in
order to determine the relationship of the cyst to vascular and biliary structures
within the liver. In addition, IOUS can help determine the best approach and the
likelihood of cyst viability.
174 Atlas of Gastrointestinal Surgery: Liver
We recommend a total pericystectomy using an opencyst technique, particularly when the cyst wall is thin and
2
rupture is possible. For this approach, a scolicidal agent such
as hypertonic saline is first carefully injected into the cyst following gentle aspiration (2). Prior to this, the area around
the liver is packed with hypertonic–saline-soaked laparotomy pads.
Inner
germinal layer
Outer
laminated layer
Daughter cysts
Hydatid fluid
The cyst cavity is then opened with the
electrocautery making certain not to spill
the cyst contents (3).
3
Management of Hydatid Cyst 175
The cyst wall and contents are then gently removed using a suction device (4)
and forceps.
The pericyst wall is then removed
using sharp electrocautery or a dissector, and small vascular branches
4
are controlled using clips or sutures
(5).
5
176 Atlas of Gastrointestinal Surgery: Liver
Biliary
communication
sutured
The resection cavity is carefully
inspected for biliary communications
which, if identified, are suture ligated
(6). The cyst cavity should be filled
with an omental pedicle in order to
prevent a cyst recurrence, particularly
6
if large (7).
Omental pedicle
7
Hepatic Hemangioma Enucleation
Operative Indications
Cavernous hemangiomas are the most common primary tumor of the liver, ranging between a 1 and 8% prevalence in the
general population. They are thought to be vascular malformations that enlarge by means of ectasia rather than neoplastic
growth. They can be single or multiple and lesions of greater than 4 cm in size are referred to as giant hemangiomas (1).
The increasing use of imaging studies are identifying these hepatic tumors in higher numbers. Most of these lesions are asymptomatic and are managed conservatively. Large hemangiomas can be symptomatic, typically associated with abdominal pain.
Other symptoms include fullness, early satiety, nausea, vomiting, and fever. Kasabach-Merritt syndrome, with thrombocytopenia secondary to platelet trapping within the hemangioma, also may occur. While risk of bleeding and rupture is rare,
debilitating discomfort can impact on patient quality-of-life. In such cases, surgical intervention should be considered.
Hemangioma
1
178 Atlas of Gastrointestinal Surgery: Liver
Operative Technique
The exposure of the liver begins with an incision which allows adequate visualization and manipulation of the liver and surrounding structures. The type of incision is
not different than when performing most liver resections, most commonly a right subcostal incision. Intraoperative ultrasonography is performed in order to identify the
relationship of the tumor to adjacent vascular pedicles and to identify other lesions
when present. The liver is mobilized as with other liver resections, typically requiring full mobilization of the ipsilateral liver.
utilizes an “enucleation” technique. With this method, the tumor is dissected free
Unlike liver resections for other indications, resection of a hepatic hemangioma
along a boundary just outside the tumor edge. Here, the surrounding liver has been
compressed, creating a form of pseudocapsule which facilitates dissection. Moreover, these benign tumors, while highly
vascular, do not have a main blood supply but are fed by small branches from the liver parenchyma.
Following mobilization, the resection begins by developing a peritumoral plane at the liver capsule. Typically, these tumors
are only partially intraparenchymal and can be visualized from the surface. We find in cases when resecting giant hemangiomas,
early and frequent use of total partial inflow occlusion (Pringle maneuver) is useful and can significantly reduce blood loss during resection. Once the plane has been developed, careful blunt and sharp dissection using electrocautery or a dissector is accomplished along the outer border of the tumor.
Branches from the liver to the tumor are controlled using cautery,
staplers, or metallic clips (2). As the dissection proceeds,
2
the tumor often becomes decompressed of blood, further facilitating removal.
Minor oozing of the surface is controlled
using an argon beam coagulating device or
other thermal cautery devices. Prior to this
step, careful inspection, identification, and
control of bile leaks should be done.
Following surface cauterization, fibrin sealant
can be applied to the resection surface in
order to further aid in hemostasis and perhaps
further reduce the risk of postoperative bile leak.
The falciform ligament is then reattached and omentum placed over the raw resection surface if necessary.
Placement of abdominal drains is seldom required.
Pringle
maneuver
OTHER HEPATIC PROCEDURES:
Liver Tumor Ablation
Operative Indications
Although surgical resection remains the principle curative therapy for patients with primary or secondary liver cancer, many
patients are not candidates for resection. Moreover, some patients recur within the liver following a previous resection, and
few are candidates for re-resection. For these reasons, increasing interest has been focused on ablative approaches for the
treatment of liver tumors. Radiofrequency ablation (RFA) is currently the most common method. RFA involves placement
of thin, partially insulated electrodes (14 to 21 gauge) into a tumor. The electrodes and grounding pads are connected
to a radiofrequency generator, and during treatment, a 500-kilohertz current travels from the uninsulated portion of the
active electrode towards the grounding pads. This current produces ion agitation in the tissue surrounding the electrode,
which is converted by friction into heat and induces cellular death via coagulation necrosis. A variety of device designs are
available, including multi-tine electrodes, parallel probes, and saline-infused or cooled tips. Probe placement can be done
using percutaneous, laparoscopic, or open surgical techniques. Newer methods of interstitial thermal ablation using
microwave technology have also been introduced. We outline here open and laparoscopic RFA, but all methods rely on
the same principles of image-guided intratumoral probe placement and thermal tumor destruction.
Tumor size as well as location can preclude effective tumor ablation with curative intent. Tumor sizes larger than 4 to
5 cm are associated with an increased incidence of local recurrence. The location of a tumor near the main portal pedicles
is considered a relative contraindication to ablation. In addition to the inability to achieve an effective ablation due to the
high blood flow, ablation near the porta hepatis can result in liver failure due to injury and stricture of a central bile duct.
180 Atlas of Gastrointestinal Surgery: Liver
Operative Technique
Open Radiofrequency Ablation
Radiofrequency ablation can be done during an open laparotomy. This is usually done in cases where RFA is combined
with hepatic resection, when many tumors need to be treated, or when a tumor is in a location that is not amenable to
the other approaches. When performing RFA during open laparotomy, careful exploration of the abdominal cavity is first
performed to exclude the presence of extrahepatic malignancy, including assessment of peritoneal surfaces and periportal
nodal regions. The liver is then carefully inspected by both palpation and intraoperative ultrasonography (IOUS). In cases
in which a previous biopsy has not been obtained, core biopsy under IOUS guidance should be considered.
Careful planning of the zone of ablation is necessary to achieve complete necrosis of the target lesion. In some cases,
when using an expandable multi-electrode needle of sufficient size, complete ablation can be achieved with a single application, deploying the electrode from the center of the tumor. For example, a 3-cm spherical tumor and 1-cm margin can
be treated with the use of a device deployed to produce a 5-cm diameter volume of necrosis.
Once the target tumor is identified with the IOUS transducer, the RFA electrode needle is inserted under ultrasono-
graphic guidance. Optimally, the electrode is advanced in a track parallel and within the plane of the transducer so the
entire path of the needle can be visualized. When using a multi-electrode needle, the array is deployed within the tumor,
and position is confirmed ultrasonographically in two views (1a). Alternative probe designs include a single probe or multiple parallel needles (1b and 1c). With some RFA devices, central ablation can first be performed by partially deploying the array and sequentially advancing the electrodes to the desired volume.
Monitoring during thermal ablation can be performed using a variety of methods. Some RFA devices have the capac-
ity to measure tissue temperatures with thermistors located within the device. Alternatively, tissue impedance and current
can be monitored during treatment. With some devices, the power output is adjusted automatically to control impedance
and maintain tissue temperature between 70˚C and 105˚C. The ablation zone is visualized by IOUS during treatment.
Typically, local miniscule gas bubble formation results in hyperechogenicity within the treated tissue.
Liver Tumor Ablation 181
1a
Single
probe
1b
1c
Ablation zone
Tumor
Multiple
parallel
needles