There are several positions that may be used depending on the approach and the patient’s overall condition. Positioning influences the percutaneous path of the needle and is essential for a safe procedure. It is important to ensure patient comfort to minimize motion in an effort to prevent inadvertent needle puncture of nearby organs or vasculature. The positions commonly used for this procedure are prone, lateral decubitus, oblique, and supine.

The prone position is most common and permits posterior approaches [1]. Pillows are placed beneath the iliac crests to reduce lumbar lordosis. This position is not preferred in obese patients or in patients who cannot maintain a safe airway [1]. The lateral decubitus or the oblique position can be used if the prone position is not tolerated. Supine positioning is usually the most comfortable and is used with an anterior approach obviating this particular complication.

Retroperitoneal hematoma is a well-recognized but relatively rare condition, with an incidence of approximately 0.1% and possibly as high as 0.6% in patients on anticoagulation therapy [11]. The incidence, however, is increasing due to complications related to interventional and image-guided procedures [12, 13]. Despite advances in procedures and imaging, detection and treatment of retroperitoneal hematoma remain challenging [14]. Diagnosis is often delayed due to a lack of specific symptoms, and the bleeding may initially go unrecognized. A timely and accurate diagnosis is critical for survival of the patient; even if patients do not die of rapid exsanguination, they may die later on from complications of compartment syndrome [12, 15].

The American Society of Regional Anesthesia and Pain Medicine (ASRA) in conjunction with the European Society of Regional Anaesthesia and Pain Therapy (ESRA) , the American Academy of Pain Medicine (AAPM) , the International Neuromodulation Society (INS) , the North American Neuromodulation Society (NANS) , and the World Institute of Pain (WIP) came up with interventional-specific guidelines on the use of antiplatelet and anticoagulant medications in 2015 [16]. The guidelines delineated in the consensus document [16] are helpful for practitioners to understand when drugs should be ceased and restarted; however, these should only serve as a guide as each case requires its own evaluation of risks versus benefits. New antithrombotic drugs are always being added to the market and may not be listed as time progresses. Celiac plexus block or neurolysis was considered an intermediate risk procedure. Patients are at higher risk if they are of old age, with history of bleeding tendency, concurrent use of antithrombotics, liver cirrhosis, or advanced hepatic or renal disease.

There are patient factors that can increase risk for bleeding complications including thrombocytopathia/thrombocytopenia (e.g., von Willebrand’s disease), varices, and vascular variability, among others. Procedural factors include several passes of the needle(s) or a “traumatic entry,” low-gauge (thicker diameter) needles, blunt tip needles, etc.

It is important to obtain a thorough history and physical examination in order to pick up any of these risks. Laboratory diagnostic tests are not routinely ordered, but if there are concerns from the patient’s history or physical exam, such as a history of chemotherapy, bruising, bleeding gums when brushing teeth, epistaxis, etc., these should be explored with laboratory testing. Imaging is not ordered routinely prior to intervention, but often imaging is available for other reasons and should be obtained and reviewed. As with laboratory workup, if there are concerns based on the history and physical, imaging can be ordered or done in conjunction with the procedure.

Patients with uncontrolled retroperitoneal bleeding rarely present with obvious cutaneous manifestations such as Grey Turner or Cullen signs. Instead they initially exhibit subtle signs of hemorrhage like relative hypotension and mild tachycardia. Confounding the picture even more is the fact that hypotension is a common side effect of celiac plexus block. Loss of sympathetic tone and dilated abdominal vasculature as a result of celiac plexus block can lead to orthostatic hypotension, a complication seen in up to 38% of patients [17, 18]. It is usually transient (1–3 days) and can be managed with intravenous hydration, but assuming a patient’s hypotension is a result of the procedure when the true cause is a hematoma that delays the diagnosis, prolongs bleeding, and could potentially lead to greater morbidity or mortality [19, 20]. It is also important to consider that patients on beta-blockers may not be able to have a tachycardic response, becoming hypotensive with no change in heart rate [12].

Other signs and symptoms of retroperitoneal hematoma include abdominal pain, abdominal distention, bruising, severe back pain, flank pain, lower quadrant pain, groin discomfort, and femoral neuropathy [21]. Femoral neuropathy is often the result of bleeding after puncture of the femoral artery during coronary angiography [22]; however, retroperitoneal hematoma from other causes can lead to femoral neuropathy, and this has been infrequently reported in the literature. The most commonly reported associations are with various bleeding disorders and therapeutic anticoagulation [23], but theoretically retroperitoneal hematoma can result from any cause of bleeding into the retroperitoneal space, such as intratumoral bleeding, ruptures of a retroperitoneal organ, or aneurysm [24, 25]. Femoral neuropathy from retroperitoneal hematoma can present with severe groin and hip pain radiating to the anterior thigh and lumbar region and later on can lead to characteristic paresthesia in the anteromedial thigh and leg [23] (Table 21.1).

Imaging plays an important role in the diagnosis of retroperitoneal hematoma, providing useful information on the type, site, and extent of fluid collections. Ultrasonography is a rapid means of detecting hematoma without exposing patients to radiation, but it may not be precise enough to identify the cause. Unfortunately, ultrasound is often distorted by body habitus or underlying bowel gas, or limited by a patient’s discomfort or operator skill [26, 27]. Hemodynamically stable patients with a negative diagnosis from ultrasound but a high clinical suspicion for retroperitoneal hematoma should undergo stat CT scanning [14].

CT scanning is noninvasive, rapidly obtainable, and highly sensitive for diagnosing retroperitoneal hematoma. Bleeding from arteries at high risk during a celiac plexus, such as the suprarenal aorta, the celiac axis, or the SMA, is most likely to result in an upper abdominal midline supra-mesocolic retroperitoneal hematoma [28, 29]. In an unenhanced CT scan, a hematoma will appear as an abnormal soft tissue density that compresses adjacent normal structures [30]. Active bleeding can be seen by extravasation of contrast material, which appears as a hyperattenuating pool or jet, with attenuation similar to adjacent vessels [31, 32]. If CT angiography shows contrast outside of the vessels, urgent treatment is required. In fact, some argue that angiography should not be performed unless an interventional radiologist is prepared to embolize, if an arterial injury is identified [33].

Treatment of a retroperitoneal hematoma remains controversial, and there are no specific guidelines detailing when to use endovascular or open surgical intervention to stop the bleeding. It depends on the resources of where the patient lands. If the patient is hemodynamically stable with no evidence of active bleeding, conservative management with close monitoring, fluid resuscitation, blood transfusion, and normalization of coagulation factors is recommended. Panetta et al. have suggested that hemodynamic instability despite 4 or more units of blood transfused within 24 h, or 6 or more units transfused within 48 h, is an indication for further investigation and endovascular treatment [34].

Embolization is becoming more common as an alternative to open surgery for treating retroperitoneal hematoma and should be performed whenever arterial extravasation is seen [12]. In a retrospective analysis of 25 patients with an extraperitoneal hematoma, Farrelly et al. found transcatheter embolization to be an effective and safe procedure for treatment of bleeding extraperitoneal hematoma [35]. Several small case series have also shown successful cessation of bleeding in retroperitoneal hemorrhage with endovascular embolization [36–38]. Coils, gelatin, and polyvinyl alcohol have all been used for embolization, though a prior study commented that proximal coiling of the bleeding artery might not be sufficient in the retroperitoneum [36]. Embolic agents should be placed both proximal and distal to the bleeding site to prevent rebleeding. While there is a high technical success rate of embolization, extraperitoneal hematomas are associated with a relatively poor prognosis, with high patient mortality around the time of angiography, but this is often due to other comorbidities [35].