Management of Vascular Complications

Vascular Anatomy in Gynecologic Oncology Surgery

The gynecologic oncology surgeon has developed an in-depth knowledge of the vascular anatomy in the female pelvis through training and experience. She or he routinely identifies the major vascular structures when exploring the pelvis and abdomen. In the pelvis, arteries and veins course side by side and are conventionally given the same name ( Fig. 22.1 ). The right and left ovarian arteries typically arise from the lower abdominal aorta, above the origin of the inferior mesenteric artery (IMA), which is often used as a landmark during paraaortic nodal dissection. The lower abdominal aorta ends as it bifurcates into the right and left common iliac arteries. In turn, the respective common iliac artery branches into the external iliac artery laterally, and the internal iliac artery (also known as the hypogastric artery) medially. The external iliac artery and vein form the lateral pelvic wall border and serve as the principal blood supply and venous drainage of the lower extremity, respectively. The location of the internal iliac vessels is typically ascertained during gynecologic surgery. The uterine artery arises from the anterior division of the internal iliac artery. The uterine and ovarian veins course alongside their respective arteries. The left ovarian vein drains into the left renal vein, and the right renal vein empties directly into the inferior vena cava (IVC). The left renal vein typically crosses the midline anterior to the aorta to join the IVC. The incidence of retroaortic and circumaortic left renal vein is roughly 7% and should be recognized when one is performing nodal dissection in the aortocaval window, to avoid injury. The uterine veins typically drain into their respective internal iliac veins, which then join the respective external iliac veins to form the common iliac veins.

The potential for significant bleeding during pelvic surgical procedures is well recognized. Such bleeding may occur, in part, because of the concentration of the major vessels and the intricate venous plexus. Deliberate ligation (or clipping) and division of crossing venous tributaries in the pelvis help avoid vessel tearing and prevent excessive bleeding. There is a rich collateral network between the right and left internal iliac arteries and veins, respectively. In addition, there is a natural anastomotic network between the superior rectal artery, which is the terminal branch of the IMA, and the middle rectal artery, a branch of the anterior division of the internal iliac artery. Similar anastomotic connections exist between the inferior mesenteric vein, which usually joins the splenoportal system, and middle rectal vein, which drains into the internal iliac vein. Hence ligation of the internal iliac artery or vein, or their respective branches and tributaries, is generally well tolerated without clinical consequences. However, when possible, the authors recommend preservation of flow to at least one internal iliac artery, to avoid the rare but potentially disabling occurrence of pelvic ischemia. IMA flow can usually be interrupted without consequences except in rare instances in which it is thought to be a major blood supply to the left colon or in the event that both internal iliac arteries are occluded (or surgically ligated). Intraoperatively, the finding of a large IMA (with poor back-bleeding when divided) can indicate that the vessel is an important blood supply to the bowels. A transected IMA can be reimplanted directly onto the aorta or via an interposition reversed saphenous vein graft.

Major injury to the common iliac, external iliac, common femoral, and superficial femoral arteries requires vessel repair or reconstruction to maintain lower limb perfusion. The profunda femoral artery can usually be sacrificed without causing limb ischemia as long as the superficial femoral artery is preserved. Occasionally, extra-anatomic bypasses can be considered when direct anatomic major arterial reconstruction cannot be achieved. The common femoral and iliac veins are the main venous drainage for the lower extremity, and acute ligation of these vessels will commonly lead to severe ipsilateral leg swelling. Occasionally, ligation of the external iliac vein may not cause severe postoperative limb swelling, if it had been chronically occluded and if venous drainage is maintained via collaterals. The two most consistent tributaries of the external iliac vein are the inferior epigastric and the deep circumflex iliac veins (see Fig. 22.1 ). These tributaries can serve as collaterals between the leg and the abdominal wall venous plexuses in the presence of central venous obstruction involving the external or common iliac veins. Preservation of the external iliac and common femoral veins is recommended to prevent severe limb swelling. However, these can be ligated when massive hemorrhage is encountered during difficult surgical dissection as a lifesaving measure. Similarly, ligation of the common iliac vein or IVC to stop life-threatening hemorrhage is acceptable.

Gynecologic Malignancy Involving Major Vessels

At times, gynecologic cancers can abut, invade, or encase major blood vessels. En bloc segmental resection of the involved large blood vessels with extirpation of the tumor may be indicated for curative intent ( Fig. 22.2 ). Decisions regarding operative management must involve the consideration of several key factors related to both the tumor and the specific vessels involved. Relevant factors to consider include the extent of the disease, plans for any adjuvant therapy, and the biological responsiveness of the tumor to other treatment modalities. In addition, one must also consider whether the patient has other known sites of residual disease. In these complex cases, careful preoperative planning and collaboration between the primary gynecologic oncology surgeon and a vascular surgeon are paramount for a successful patient outcome. The decision making should be customized to the individual patient, based on the type and extent of the malignancy being treated and the importance of the vascular structure involved.

Preoperative Vascular Imaging

Thorough tumor staging is essential for optimal oncologic management. Improvement in radiologic imaging has contributed to the advances made in cancer staging and treatment outcome. Currently, multidetector computed tomography (CT) with multiplanar rendering provides unparalleled spatial resolution and diagnostic accuracy. The rapid acquisition time and widespread availability of CT scanning make it a preferred imaging modality for tumor staging inside the chest, abdominal, and pelvic cavities. The use of intravenous (IV) iodinated contrast adds better definition of the tissues and solid organs on CT imaging. Patency of the major arteries and veins can generally be determined on routine body CT imaging (when the testing protocol is designed for imaging of soft tissues and solid organs). However, computed tomography angiography (CTA) with early phase acquisition of images after the bolus administration of IV contrast is necessary for detailed evaluation of arteriosclerotic plaque or intramural disease of the major arteries. Delayed phase image acquisition after IV contrast bolus will demonstrate patency of the major veins or presence of intraluminal thrombus ( Fig. 22.3 ). CTA has replaced selective catheter-based angiography in rendering a diagnosis of vascular complication or disease. Selective catheter-based angiography is now reserved primarily for planned therapeutic endovascular interventions. Contraindications to iodinated contrast infusion include severe renal insufficiency and history of allergy (anaphylactic reaction) to iodinated contrast. Recommended renal protection against contrast-induced nephropathy includes hydration, bicarbonate infusion, and oral N -acetylcysteine for patients with a glomerular filtration rate (GFR) less than 45 mL/h. Steroids and antihistamine medications can be administered before IV contrast infusion in patients with reported allergic reaction to iodine.

Magnetic resonance imaging (MRI) has proven usefulness in evaluation of the female pelvis because of its multiplanar capability and sensitivity in tissue characterization. In particular, MRI plays a major role in determining the local and regional extent of cervical cancer. Magnetic resonance angiography (MRA) is performed with the use of IV gadolinium-based contrast material and can be used as an alternative to CTA to assess the major pelvic and abdominal vessels, particularly in patients with iodinated contrast allergy. An additional advantage of MRI is the avoidance of ionizing radiation. However, the spatial image resolution with MRI is inferior and the examination acquisition time much longer when compared with CT. The presence of implantable cardiac devices (pacemakers and defibrillators) or metallic joints is a contraindication to MRI. Patients with chronic renal disease should not receive IV gadolinium because of the risk of nephrogenic systemic fibrosis. In general, time-of-flight (TOF) acquisition during MRI will show adequate images of the major vessels without IV gadolinium.

Duplex ultrasonography is commonly used to evaluate for deep venous thrombosis (DVT) in the upper and lower extremities. Vascular duplex ultrasonography is noninvasive and does not involve radiation. B-mode vascular ultrasonography provides a two-dimensional image of the vessel wall and lumen. Color flow imaging and pulsed Doppler waveform analysis provide a real-time assessment of blood flow characteristics. The diagnosis of venous thrombosis is made when the visualized vein is not fully compressible, echogenic material is present, and color flow is reduced or absent ( Fig. 22.4 ). In addition, venous duplex ultrasonography may be used preoperatively to map out potential venous conduits (such as the great saphenous, femoral, or internal jugular veins) and obtain information regarding location, quality, diameter, length, and depth. Similarly, arterial duplex ultrasonography can provide invaluable assessment of the arterial patency and the presence and location of arterial disease in the lower extremities. Vascular duplex ultrasonography is a practical imaging modality that can be performed in the outpatient clinic or at the bedside. In addition, duplex surveillance is useful in detecting early restenosis and can improve the long-term outcome of vascular interventions ( Fig. 22.5 ).

Acute Major Intraoperative Vascular Injuries

Complications during gynecologic procedures performed with laparoscopic, robotic, or open surgical techniques are uncommon. However, injury to the major blood vessels in the abdomen and pelvis can be life-threatening. Fortunately, the incidence of inadvertent major intraabdominal vessel injury is less than 1 per 1000 cases. The risk of vascular injury is increased in patients with pelvic malignancy, in part because the bulky tumor mass can distort the surrounding anatomy, making surgical dissection more difficult. In addition, neoadjuvant treatments—in particular, radiation therapy—can lead to the effacement of the tissue planes around the vessels. The following section describes operative maneuvers to prevent or control major bleeding that are available to the gynecologic oncology surgeon.

Prevention of Vascular Injuries

Vascular injuries can occur as entrance accidents during the placement of trocars in a laparoscopic or robotic procedure. Injury can also occur during the dissection of perivascular nodal tissue or the dissection of a tumor lying against a major vessel during a laparoscopic, robotic, or open procedure. The optimal method for dealing with vascular injuries is to be aware that these can occur at any time and to never assume immunity against them. Best outcomes are usually the result of meticulous assessment of the anatomy and body habitus of the patient and, in oncologic procedures, the study of the anatomy of the tumor and its relation to the surrounding structures. Trocar injuries occur more frequently in patients with high body mass index (BMI). In oncologic procedures, the larger the burden of the tumor or nodal disease, the higher the risk of inadvertent vascular injuries. Gynecologic oncology surgeons must be able to read the imaging studies of the patient and use them as a road map, rather than relying solely on the radiologist’s report. If proximity to major vessels is detected, particularly in patients who have received preoperative radiation therapy to the operative field, it is wise to recruit the assistance of a vascular or cardiothoracic surgeon who is familiar with the dissection, repair, or replacement of major blood vessels. High-risk procedures that may require a vascular intervention should ideally be done early in the day, when the elements of both expertise and good clinical acumen are at their best.

Large pelvic tumors causing urinary flow occlusion (e.g., hydroureter or hydronephrosis) must also be suspected of having close contact with the other pelvic wall structures. Prior vascular embolization can reduce the bleeding from the tumor itself but does not preclude the possibility of vascular injury. Hypothetically, if a tumor shows evidence of very close proximity to a large artery where tissue planes have become effaced on imaging, placement of an endovascular stent within the involved vessel before oncologic resection may prevent significant bleeding in the event of an inadvertent tear in the vessel ( Fig. 22.6 ). However, the preemptive deployment of an endovascular stent before removal of tumor remains anecdotal, and more studies are needed to justify this technique.