Key words
hemorrhoids - embolization - rectal artery
Pathophysiology of hemorrhoids
Pathophysiology of hemorrhoids
The hemorrhoidal plexus is a spongy vascular cushion at the anorectal junction above
the dentate line. The plexus is comprised of an arteriovenous conglomerate of vessels,
the smooth musculus canalis ani, and elastic connective tissue fibers. The physiological
vascular cushion helps to seal the anus and primarily contains terminal branches of
the superior rectal artery. Additional feeder vessels come from the internal iliac
artery via the middle rectal artery and from the internal pudendal artery via the
inferior rectal artery [1]. The vascular cushion receives nutrients from the vessels branching into the intermediate
spaces [2].
The terms hemorrhoidal disease or symptomatic hemorrhoids are used to describe symptoms
caused by enlarged hemorrhoids [3]. Hemorrhoidal disease is one of the most common diseases in industrialized countries
with an incidence of approximately 4 % of the total population [4]. Transanal bleeding, stool leakage, itching, and burning are typical symptoms of
hemorrhoidal disease [3].
The integrity of the hemorrhoidal plexus is compromised in hemorrhoidal disease. In
addition to vascular changes, there are inflammatory changes and degenerative processes
involving the elastic tissue and the muscle fibers that hold the hemorrhoidal cushions
in place [5]. The degeneration of supportive tissue results in enlargement and downward displacement
of the corpus cavernosum recti [6].
On the vascular level, a significantly greater diameter and a greater and faster blood
flow in the branches of the superior rectal artery were seen compared to healthy subjects
[7]. In this study, the vascular caliber also correlated with the severity of the disease.
With respect to molecular pathology, there are indications of increased angiogenesis
in hemorrhoid tissue with pathological changes. In addition to an increase in the
number of blood vessels, increased expression of the vascular endothelial growth factor
was found in tissue samples [8]. In addition, an overexpression of zinc-dependent matrix metalloproteinase 9 was
detected in hemorrhoid tissue [9]. In addition to the destruction of elastic fibers, the activated proteinase results
in increased activity of angioproliferative transforming growth factor-β [10].
Diagnosis and therapy
Hemorrhoidal disease is divided into four grades according to Goligher [11]. In grade one, proctoscopy shows slight bulging of the hemorrhoids. In grade two,
the hemorrhoids prolapse into the anal canal on defecation with spontaneous reduction.
In the case of grade three hemorrhoids, the prolapsed hemorrhoids protrude outside
the anal canal and do not spontaneously reduce but can be manually repositioned. Grade
four hemorrhoids are irreducible and constantly prolapsed.
The spectrum of treatment options ranges based on grade from basic treatment consisting
of a high-fiber diet, exercise, and fluids to sclerotherapy, rubber band ligation,
and surgical interventions.
According to the current S3 guidelines, sclerotherapy can be performed in the case
of grade one and grade two hemorrhoids [12]. A sclerosing agent is injected in the region of the feeding arteries or into the
hemorrhoids during proctoscopy. The most common complications include urological side
effects like prostatitis, urinary retention, and hematuria in up to 31 % of cases
[13]. There is a high recurrence rate of up to 81 % after 4 years [14].
In grade two hemorrhoids, rubber band ligation is recommended [12]. The hemorrhoid tissue is tied off at the base with a rubber band. The tissue dies
and falls off. The resulting scarring results in repair of the remaining hemorrhoid
tissue. Pain and bleeding are the most common complications. In newer studies, rebleeding
was seen in up to 13 % of cases and local pain in up to 45 % [15]
[16]. According to the current S3 guidelines, contraindications are coagulations disorders
and the intake of potent anticoagulation medications [12]. Surgical treatment is indicated in the case of grade three or four hemorrhoids.
Resection procedures are divided into segmental resection and circular resection procedures.
One of the segmental resection procedures presumably used most frequently in Germany
is the Milligan-Morgan hemorrhoidectomy procedure [12]
[17]. The hemorrhoidal cushions are removed and the proximal arterial blood supply is
stopped. Newer methods include stapled hemorrhoidopexy and Doppler-guided ligature.
In the case of stapled hemorrhoidopexy, a circular stapling device is used to remove
a ring of rectal mucosa [18]. This results in lifting of the hemorrhoids in the cranial direction and ligation
of the terminal branches of the superior rectal artery. In the case of Doppler-guided
ligature of hemorrhoidal arteries, the arteries are identified and ligated using a
special proctoscope under Doppler ultrasound guidance [19]. These surgical treatments are performed under general anesthesia. Depending on
the method, anal and rectal trauma can occur.
Hemorrhoid embolization
Endovascular hemorrhoid embolization is a new treatment for hemorrhoidal disease.
Due to the newness of the method, it has not yet been included in the guidelines.
However, according to current data, hemorrhoid embolization seems to be particularly
suitable for patients with problematic bleeding in grade two or three hemorrhoidal
disease and for patients with contraindications for surgery. The latter group includes,
for example, patients taking potent anticoagulation medications and patients who cannot
undergo sedation [20]. The procedure can be performed in addition to prior hemorrhoid operations. If hemorrhoid
embolization does not achieve the desired effect, surgical treatment can be performed.
The technique is described in detail based on the example of a case treated at the
authorsʼ hospital.
A 56-year-old man presented with recurrent at times massive perianal bleeding and
chronic itching. Prior treatment with rubber band ligature did not provide lasting
success. A previously performed colonoscopy to rule out other differential diagnoses,
e. g. tumors, which can cause recurrent bleeding, was unremarkable. Proctoscopy showed
two grade two and one grade three hemorrhoids.
After the administration of local anesthesia, the common femoral artery was punctured
using the Seldinger technique and a 4F sheath was inserted. A 4F diagnostic catheter
in SHK 1 configuration (Cordis Corporation, Miami Lakes USA) was inserted into the
inferior mesenteric artery and nonselective angiography with manual contrast injection
was performed (see [Fig. 1]). Superselective probing of the superior rectal artery with a 2.4F microcatheter
(Direxion, Boston Scientific Corporation, USA) and 0.016“ microwire (Fathom, Boston
Scientific Corporation, USA) using the coaxial technique was then performed. For exact
evaluation of the blood supply to the hemorrhoidal plexus and the position of the
terminal branches, cone beam CT with manual contrast injection was performed with
the catheter positioned above the branching into the terminal branches (see [Fig. 2]). In total there were four terminal branches with a typical horizontal course in
anteroposterior projection at the level of the cranial symphysis. The terminal branches
were probed individually with a microwire and microcatheter using the roadmap technique
and were first embolized with 250-µm hydrogel particles (Embozene, Boston Scientific,
USA) and then embolized with 0.018” microcoils. In the case of forced contrast injection
into the right anterior terminal branch, anastomosis to the medial rectal artery ([Fig. 3]), which was also occluded with a microcoil, was seen. In total, 13 figure-eight
2 × 5 mm coils, 14 straight 5 mm coils, and 1 VortX 3 × 2.5 mm coils (Boston Scientific,
USA) were used. The goal was to achieve complete stasis in the vessels and absence
of contrast enhancement of the hemorrhoidal plexus ([Fig. 4]). The foreign material was removed and a compression bandage was applied.
Fig. 1 Digital subtraction angiography of the inferior mesenteric artery. The terminal branches
of the superior rectal artery are visualized at the bottom of the image. Due to the
large size of the depicted inferior mesenteric artery, deep intubation with a 4F catheter
is possible without risk.
Fig. 2 Cone-beam CT of the superior rectal artery. The vessel branches that feed the hemorrhoidal
plexus are pictured. The blue region of interest incorporates the hemorrhoid plexus.
The area was segmented to automatically detect the depicted vessel feeders with the
EmboGuide system (EmboGuide, Philips healthcare, Eindhoven, The Netherlands). The
utilization of the EmboGuide system in this context currently constitutes an off-label
use.
Fig. 3 Forced contrast injection into the right anterior terminal branch of the superior
rectal artery. Retrograde display of a feeder vessel from the medial rectal artery
to the hemorrhoidal plexus.
Fig. 4 Final angiogram. Complete stasis in the distal terminal branches of the superior
rectal artery that feed the hemorrhoidal plexus.
After a complication-free course, the patient was discharged the next day.
The six-week proctoscopic follow-up examination showed minimal reduction of the hemorrhoids.
However, over the next six months, the patient was completely symptom-free and without
further bleeding.
Results
The endovascular hemorrhoid embolization technique was first described in the Russian
literature [21]. In 2014 in a small case series including three patients, some of whom had previously
undergone surgery, Vidal reported a significant reduction in disabling bleeding [22].
Fourteen patients with grade two to four hemorrhoids, with half of the patients having
previously undergone surgery and ten having been treated with anticoagulants or having
hypocoagulation due to liver cirrhosis, were treated in a further study by Vidal et
al. [23]. A temporary, painful perianal reaction occurred in one case. In this first study,
incomplete embolization was initially performed. To avoid ischemic complications,
only two of the four terminal branches of the superior rectal artery were occluded
in the first six patients. Due to rebleeding, complete embolization was performed
in further sessions in four patients. In total, clinical improvement was seen after
one month in 72 % of patients. Patients with contraindications for surgical treatment
and patients with persistent symptoms in spite of prior surgery were treated in another
study by Vidal's working group. Primarily grade two hemorrhoids were treated and an
improvement of symptoms was seen in 72 % of patients [24]. In the study by Tradi et al., grade two and three hemorrhoids were treated [25]. An improvement of symptoms was seen in approximately two-thirds of patients. In
particular, decreased bleeding rates, improved quality of life, and reduction of hemorrhoids
were observed. Coils were exclusively used to embolize the distal terminal branches
of the rectal artery in the studies mentioned above.
However, relevant anastomosis of the medial rectal artery or a co-dominant supply
of the hemorrhoidal plexus via branches of the medial rectal artery was observed in
up to one fourth of patients in the case of forced contrast injection. These patients
benefited less frequently from hemorrhoid embolization [25].
The lack of occlusion of additional dominant arteries of the hemorrhoidal plexus apparently
results in incomplete embolization and consequently in a worse outcome.
Therefore, in the case we described, superselective particle embolization was performed
before coil embolization to also treat branches or the medial rectal artery. Inadvertent
embolization in other regions/organs due to flow direction is not to be expected.
Therefore, such collaterals are not a contraindication but rather an indication for
additional particle embolization in order to achieve an embolization result that is
as complete as possible.
Zakarchenko treated 40 patients with grade one to three hemorrhoids [26]. Additional particles were also used for embolization in this study. For this purpose
a 5F catheter was advanced to the point of branching and into the terminal branches
of the superior rectal artery. From this position, less selective embolization with
polyvinyl alcohol particles with a size of 300 µm was performed in addition to the
application of metal coils [26]. No complications were observed in this study. A reduction in hemorrhoid size and
symptom improvement were seen in 83 % of patients with grade three hemorrhoids and
in 94 % of patients with grade one or two hemorrhoids. Moreover, the contractility
of the anal sphincter remained unchanged one month after treatment. The average decrease
in blood flow to the hemorrhoids measured on Doppler ultrasound was 50 %.
In the study by Moggia, the procedure was used in patients with bleeding hemorrhoids
and resulted in symptom improvement and improved quality of life in 87.5 % of patients.
Complications were not observed within the follow-up period of 12 months [27].
Conclusion
Hemorrhoidal disease is one of the most common diseases in industrialized countries.
Treatments range from basic dietary measures to open surgery. Some promising studies
on hemorrhoid embolization have recently been published. A significant and lasting
decrease in symptoms without relevant side effects was able to be shown. This minimally
invasive endovascular procedure could be a useful addition to established treatments
for patients at high risk for surgical procedures.
