41
Superior Hypogastric Plexus Block

Ricardo Plancarte Sánchez MD, PhD, FIPP and Marcela Sámano García MD

National Cancer Institute of Mexico, Mexico City, Mexico

Introduction

The superior hypogastric plexus (SHP) block is an excellent treatment for visceral pelvic pain, due to cancer and non-cancer etiologies. It was described in the 1990s and different percutaneous approaches have been described since then with good analgesic effect and low incidence of complications [1–4].

Anatomy

The continuation of the inferior mesenteric plexus and the sympathetic fibers from paravertebral trunks mainly from thoracolumbar ganglia T10–T12, and parasympathetic fibers of S2–S4 [5, 6]. These two fibers travel anterolateral to the aorta and join in the aortic bifurcation, in front of the sacral promontory, forming the SHP in the retroperitoneum; posteriorly it is divided in the hypogastric nerves, in two branches that are in contact with the colon and rectum and that form the inferior hypogastric plexus [4, 7, 8].

The SHP may encompass the inferior third of L5 body and the superior third of S1 [9]. It is important to take note of its position not only to the aorta and iliac arteries but also to the pelvic viscera (Figure 41.1).

**Figure 41.1** Topographic anatomy of hypogastric superior plexus. (a) Lateral view, (b) anterior view.

It is also important to mark the proximity of the SHP to the common iliac artery and vein, as well as to the pelvic viscera and psoas muscle (Figure 41.2). The branches of this plexus inervate right colon, uterus, cervix, tubes, upper vagina and bladder.

**Figure 41.2** Anatomy of SHP. (a) Axial view of a tomography showing the proximity of the SHP to the psoas, iliac vessels, and gut. (b) Cadaver image showing its topography.

Indications

An SHP block is indicated in pelvic visceral pain. Its etiology may vary including non-cancer and cancer causes [2] (Table 41.1). Normally, the procedure is most appropriate for patients with pelvic pain that does not respond adequately to pharmacologic treatment and in patients with severe adverse effects to analgesic therapy. Nowadays in cancer pain, the realization of this procedure in the early stages has had a good analgesic outcome, which is why a patient may be considered as a candidate for SHP block when opioid treatment is initiated.

Table 41.1 Oncologic and non-oncologic causes of pain that can be treated with SHP.

Non-oncologic	Oncologic
Chronic pelvic pain Endometriosis Pelvic inflammatory diseaseAdherence Interstitial cystitisDysmenorreaDyspaureunia	Prostate tumor Testicle tumor Ovary tumor Cervicouterine tumor Colon tumor Bladder tumor Post-radiation pain of the pelvic viscera

Non-oncologic

Oncologic

Chronic pelvic pain

Endometriosis

Pelvic inflammatory diseaseAdherence

Interstitial cystitisDysmenorreaDyspaureunia

Prostate tumor

Testicle tumor

Ovary tumor

Cervicouterine tumor

Colon tumor

Bladder tumor

Post-radiation pain of the pelvic viscera

Contraindications

The contraindications for SHP block are the same for other sympathetic blocks such as:

Infection (local or systemic)
Coagulopathy. Patient refusal

Technique

Described techniques of superior hypogastric plexus block require image guidance. Fluoroscopy is routinely used although tomography and ultrasound (US) may also be used. Many approaches are described, that include the posterior classical, intradiscal, and anterior approaches [1, 10, 11].

Classic Approach and its Modifications

The patient must be in prone position and it is recommended that a pillow is placed to rest the abdomen on and flatten any lumbar lordosis. As in every interventional technique, it is important to carry out an aseptic clean of the lumbosacral area.

To begin the procedure, is important to localize posterosuperior iliac crests and trace a line which corresponds to the L4–L5 interspace. It is recommended to localize by physical exam and verify using fluoroscopy in anteroposterior (AP) view. At this level, 5–7 cm from the midline bilaterally, the skin should be infiltrated toward the midline with lidocaine 1% until wheals are raised. A 7-inch, 22G needle with a curve in the tip along the shaft is inserted through one of the skin wheals with the needle bevel directed toward the midline, in a 45° angle of the coronal plane and about 30° caudal (off the medial sagittal plane) so that its tip is directed toward the anterolateral aspect of the L5 vertebral body (Figure 41.3a,b). It is important to take in AP and lateral views while the needle is advanced until reaching the SHP [2, 11] (Figure 41.4).

**Figure 41.3** Simulation of needle placement in a classical approach for the SHP block. (a) Sagittal view showing the 30° caudal inclination of the needle reaching its target. (b) Coronal view showing the 45° angle formed to advance it to the midline.

**Figure 41.4** AP fluoroscopy view of the classical approach with a single needle insertion.

The target is about 1 cm past the vertebral body until the “pop” may be felt or a loss of resistance proven. When we reach it in AP view, the needle tip’s location should be seen at the level of the junction of the L5 and S1 vertebral bodies and lateral views will confirm placement of the needle tip just beyond the vertebral body’s anterolateral margin. The injection of 3–4 cc of water-soluble contrast verifies the accuracy of needle placement. The spread of contrast media should be in the midline region in this radiologic view. While in lateral view, a smooth posterior contour corresponding to the anterior psoas fascia indicates that the needle depth is correct [2] (Figure 41.5a,b).