LWBK1006-15 LWW-Govindan-Review December 7, 2011 19:5
Chapter 15•Advances in Diagnostics and Intervention 171common locations, are associated with certain complications. The adrenal
gland is one such organ. Because of its cranial location in the retroperi-
toneum, percutaneous biopsy may lead to pneumothorax. The pancreas
is another such organ. It is often surrounded by bowel, precluding an
unobstructed approach to a pancreatic mass. In such cases, a transcaval
approach is preferred. The differential diagnosis from any preprocedural
imaging will also dictate biopsy technique. Although liver masses may rep-
resent well-differentiated neoplasm (e.g., fibrolamellar HCC), core biop-
sies are required to distinguish them from normal liver or benign lesions,
such as focal nodular hyperplasia. Core biopsies are also valuable in diag-
nosing histology or retroperitoneal and pelvic masses that may be sarco-
mas. When ovarian cancer heads the differential diagnosis, alternatives to
percutaneous biopsy should be sought. High risk of tract and peritoneal
seeding make an open procedure the favored route of tissue sampling.Answer 15.8. The answer is D.
Percutaneous gastrostomy (also known as g-tube) is an alternative to an
endoscopically placed gastrostomy tube that has gained acceptance as a
method of providing nutrition or gastric decompression. It can be placed
quickly with less sedation than required for its endoscopic counterpart.
Percutaneous placement can be via a pull technique, where the catheter is
advanced into the stomach and a snare is used to retrieve it through the
skin, or in a push technique, where the catheter is pushed externally into
the stomach via a tract that is serially dilated. The former method may
allow for larger catheters to be placed, but the latter method may result in
less seeding of the tract in aerodigestive malignancies. Contraindications
to the percutaneous technique include uncorrectable coagulopathy, gastric
varices, and previous gastrectomy. Ascites may hinder endoscopic place-
ment because of the increased distance of stomach to skin and therefore
decreased effectiveness of gastric transillumination. It is not a contraindi-
cation for percutaneous placement. The presence of ascites may require
gastropexy, whereby the stomach is affixed to the abdominal wall. When
gastropexy has been performed or after a tract has been established (usu-
ally after 4 weeks of a gastrostomy tube in place), catheter replacement
may be performed without image guidance.Answer 15.9. The answer is D.
Percutaneous nephrostomy (referred to informally as a “perc” or
“PCN”) is a way of percutaneously draining a kidney that is usually
hydronephrotic. Preprocedural imaging is key to identifying the site of
obstruction and relevant information regarding the collecting system.
It is performed as a way to treat an infected, hydronephrotic kidney
(pyonephrosis), divert urine away from a fistula, or preserve renal func-
tion if the obstruction is temporary or treatable. Percutaneous nephros-
tomies are usually performed from a posterior or flank approach with
fluoroscopic or ultrasound guidance and do not require CT guidance.
Preprocedural antibiotics are used that target skin organisms to prevent
infection from the procedure itself. Postprocedural antibiotics depend on
the quality of the urine aspirated at the time of the procedure.