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CT-guided Transgluteal and Transperineal Percutaneous Biopsy and Drainage of Deep Pelvic Structures:
Anatomy, Indications, Technique, and Potential Complications
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T M Nguyen, W D Boswell, P A Nedumaran, H G Pimenta, F M Wu, V Duddalwar
USC
Department of Radiology, University of Southern California, Los Angeles, California 90033
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Introduction
Technique
Modifications
Potential complications
Deep pelvic masses and abscesses are a challenge
for percutaneous intervention due to vital organs that
may prevent safe access. Multiple approaches have
been described, such as transabdominal, anterolateral
extraperitoneal, transosseous, transgluteal, and
transperineal. These have all been proven to be safe
and effective for tissue biopsy, aspiration, and
drainage.
This exhibit will explore the relevant anatomy,
technique, possible complications, and technique
modifications of CT guided biopsy and drainage via
the transgluteal route through the greater sciatic
foramen, as well as abscess drainage via the
transperineal approach.
Transgluteal CT guided biopsy and drainage shares many of the
same principles as percutaneous intervention by any other route. This
includes the appropriate indications, contraindications and patient
preparation. However, aspects unique to the transgluteal approach
include patient positioning, route planning, and equipment.
Proper patient positioning and maintenance of such is vital for a
successful procedure. The optimum position is prone if the patient is
able to tolerate it. Patients who are recent post-operative, those with
relatively new abdominal wounds, or who are on a mechanical
ventilator pose a challenge. These patients can be placed in an oblique
or lateral decubitus position. However, they must be able to maintain
that position. Hence, pain control is very important. Local anesthesia
is used in all patients; conscious sedation or general anesthesia should
be considered in select cases. Devices such as pillows or straps can
also be used as appropriate to secure the patients position.
Although the safest route through the greater sciatic foramen is at
the level of the sacrospinous ligament as close to the lateral edge of the
sacrum as possible, some lesions require more superior or lateral
course. This is safe as long as all vital structures are identified and are
avoided.
Technique modifications may be necessary to successfully target a
lesion. These include CT fluoroscopy, angling of the CT gantry, use of
a curved needle through a coaxial system, injection of saline to
displace vital structures, and use of a blunt needle.
CT fluoroscopy may be useful for the exact positioning of a
needle. It has the potential to reduce procedure time and provide more
accurate positioning, but can increase radiation exposure to both the
patient and the operator. Angling the CT gantry is useful in targeting a
lesion cephalad to the sacrospinous ligament. It is technically more
difficult, however, to keep the needle in the exact same angle as the
gantry. Use of a curved needle allows an additional option for difficult
to access lesions.
Techniques to displace vital structures may be useful to access a
lesion. The degree of displacement is a function of the mobility of the
structure. Injecting sterile saline adjacent to a structure may displace it
enough to allow adequate access. This technique may obscure the
normal anatomy and/or target making the procedure more difficult.
Therefore it is crucial to inject slowly and check progress often.
The use of a blunt needle (Inter-V Hawkins Blunt Needle, Medical
Device Technologies, Inc, Gainesville, FL) is another technique that
may improve access to a lesion. This system is supplied with a coaxial
hollow needle and both sharp and blunt inner stylets. Torquing forces
can be applied to the system with the blunt stylet in place in an attempt
to displace the structure. In addition, the system can be advanced with
the blunt stylet in place allowing blunt dissection of soft tissue,
decreasing the risk of injury to vascular or nervous system structures.
Potential complications can be prevented with meticulous
technique and careful route planning. These include pain, hemorrhage,
nervous system injury, bowel injury, catheter malposition, and injury
to other vital structures (gynecologic and urologic).
Anatomy
Knowledge of the pelvic anatomy is of the utmost importance
due to susceptibility of injury to vasculature, nerves, bowel, and
gynecologic or urologic structures.
The greater sciatic foramen is a space in the posterolateral
pelvis bound posteriorly by the sacrum, anteriorly by the ischium,
superiorly by the ilium, and inferiorly by the sacrospinous ligament.
Contents of the greater sciatic notch include the piriformis muscle,
vessels from the internal iliac system, and nerves of the sacral
plexus.
The piriformis muscle originates from the anterior surface of
the sacrum and exits the greater sciatic foramen to insert on the
greater trochanter of the femur. Superior to the piriformis muscle
exits the superior gluteal vessels and nerves; inferior to the muscle
exits the inferior gluteal vessels and nerves, internal pudendal
vessels and nerve, sciatic and posterior femoral cutaneous nerves,
and the nerves to the obturator internus and quadratus femoris.
The sacrospinous ligament is the inferior border of the greater
sciatic foramen. The major vessels and nerves lie superior to this
level, crossing anterior to the piriformis muscle. Ensuring that the
needle or catheter traverses the sacrospinous ligament decreases the
chance of inadvertent injury to these vessels and nerves.
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Figure 2: Coaxial needle biopsy. (A) Transverse CT image through the pelvis
in a rectal carcinoma patient status post previous low anterior resection, found
to have abnormal soft tissue adjacent to the anastamotic site (arrow).
(B, C) Patient is positioned right anterior oblique and a coaxial needle system
advanced through the greater sciatic foramen at the level of the sacrospinous
ligament to biopsy this tissue.
p
b
b
Figure 1: Normal anatomy. Transverse CT images through the pelvis with
intravenous and oral contrast. Piriformis muscle (p), gluteal vessels (arrows),
bowel (b), sacrospinous ligament (arrowheads).
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B
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Figure 6: Hemorrhage. (A) Post procedure image after drainage catheter
placement via the greater sciatic notch. The ipsilateral muscles are enlarged
due to hematoma. (B) Digital subtraction angiogram from the ipsalateral
internal iliac artery shows pseudoaneurysm of inferior gluteal artery. Embolic
coils were placed. (C) Post-embolism angiogram reveals a successful
embolisation.
Transperineal approach
A coaxial biopsy system is preferred to prevent unnecessary
repeat punctures and repositioning. Drainages can be performed by
the Seldinger technique, which offers more control and precision. A
trochar technique is useful for larger collections.
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Figure 5: Malpostioned catheter. (A) Prone CT images through the pelvis in
a patient status post sigmoidectomy with a contained post-surgical
anastamotic leak (arrow). Bowel (arrowhead). (B) Drainage catheter placed via
the greater sciatic notch, malpositioned into the bowel. (C) Drainage catheter
repositioned into presacral collection.
Figure 3: Drainage catheter placement. Presacral abscess (a) in a patient
with rectal carcinoma status post low anterior resection. Patient is placed in
a right lateral decubitus due to recent surgery and colostomy. A drainage
catheter is place via the left greater sciatic foramen by a trochar technique.
Notice the catheter traverses the sacrospinous ligament just lateral to the
lateral edge of the sacrum, avoiding vessels and nerves.
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Figure 4: Techniques to displace structures. (A) An enlarged
retroperitoneal lymph node (arrow) medial to the psoas muscle.
Descending colon (c) lies along the course of proposed biopsy route.
(B) A Hawkins needle is positioned with the sharp inner stylet, tip adjacent
to the segment of colon (c) to be displaced. (C) Sterile saline in injected
through the outer needle; the segment of colon is displaced anteriorly. (D)
The blunt needle is then placed through the hollow needle and advanced
through the retroperitoneal fat. Lateral force is then applied to the needle
system, further displacing the segment of colon anteriorly. A biopsy needle
can now be advanced to sample the lymph node.
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Figure 7: Transperineal drainage. (A) Transverse CT image in a patient status
post proctocolectomy shows a large presacral fluid collection (f). The collection
is inaccessible from an anterior approach. Although accessible through the
greater sciatic notch, the lack of any vital midline structures from patient’s
proctocolectomy favors a midline transperineal approach. (B) Saggital
reconstruction shows a drainage catheter in the fluid collection from a midline
perineum puncture.
References
Butch RJ, Mueller PR, Ferrucci JT, et al. Drainage of Pelvic Abscesses through the Greater Sciatic Foramen. Radiology
1986; 158:487-491.
Gupta S, Nguyen HL, Morello FA, et al. Various Approaches for CT-guided Percutaneous Biopsy of Deep Pelvic
Lesions: Anatomic and Technical Considerations. RadioGraphics 2004; 24:175-189.
Harishinghani MG, Gervais DA, Hahn PF, et al. CT-guided Transcluteal Drainage of Deep Pelvic Abscess: Indications,
Technique, Procedure-related Complications,and Clinical Outcome. RadioGraphics 2002; 22:1353-1367.
Harishinghani MG, Gervais DA, Maher MM, et al. Transgluteal Approach for Percutaneous Drainage of Deep Pelvic
Abscesses: 154 Cases. Radiology 2003; 228:701-705.