‘Scrotal “Sack” – A Bag of Worms’: Scrotal Arteriovenous Malformation

ABSTRACT

Scrotal arteriovenous malformation (AVM) is an unusual entity with its own important clinical implications. Described only as a few case reports in medical literature, it not only can cause life-threatening haemorrhage because of its superficial location in the scrotum but also can result in infertility. We report the case of a 35-year-old man who had a progressively increasing scrotal swelling for almost 20 years and now presented for infertility workup. He had oligospermia on semen analysis with a normal testosterone level and no history of testicular infection or scrotal surgery. On scrotal sonography and computed tomography angiography, he was diagnosed to have bilateral scrotal AVMs which may have resulted in his oligospermia. Pre-operative embolisation and surgery was offered as a treatment option which the patient declined and was lost to follow-up. However, this case describes scrotal AVM as an important and possibly correctable cause of infertility. Usually diagnosed as scrotal lymphedema clinically, the case has been reported so that the clinician should be aware of this entity as a plausible cause of male infertility and the treatment could be refined and accelerated.

INTRODUCTION

Vascular malformations are anomalies in the morphogenesis of the vessels such as capillaries, veins, arteries or lymphatics. Scrotal arteriovenous malformation (AVM) is a very uncommon vascular scrotal lesion with sparse literature description. It represents <1% of vascular neoformations.[1] It may be congenital or acquired. It usually presents as tumorous growth, pain, bleeding or infertility.[2] Here, we report a case which highlights scrotal AVM as a possible cause of male infertility due to altered scrotal vascular anatomy and haemodynamics related to this pathology.

CASE REPORT

A 35-year-old man presented with progressively increasing scrotal swelling for the past 20 years. He ignored the scrotal swelling for so long as he felt hesitant and offended discussing it. Now, as his wife was not able to conceive after 6 years of marriage even after her normal fertility workup, he decided to consult a clinician for his scrotal swelling. His semen analysis showed oligospermia with a sperm count of 12 million/ml. The spermiogram also mentioned that the semen volume was normal (2 ml in one ejaculation) and showed normal viscosity. But the percentage sperm motility was low (26%). His basal total testosterone level was 539 ng/dl, well within the normal range for an adult male (reference range: 241–827 ng/dl). There was no history of testicular infection or scrotal trauma or surgery. He was not taking any medication that adversely affected spermatogenesis. On physical examination, the scrotal swelling was firm and non-tender with a normal scrotal skin. On Doppler sonography, multiple enlarged tortuous vascular channels were seen within the scrotal sac showing both arterial and venous spectral waveforms. Both the testes were normal in size, echo pattern and vascularity. Hence, an ultrasound diagnosis of scrotal AVM was kept. Computed tomography (CT) angiography was done for confirmation and to specifically delineate the arterial feeders and draining veins. CT angiography showed early contrast filling of bilateral common iliac veins during the CT arterial phase. The scrotal sac was enlarged and filled with multiple, chaotic extratesticular arterial and venous channels with a maximum calibre of 3 cm of one of the venous channels. CT revealed that the predominant arterial feeders were coming from hypertrophied distal branches of internal pudendal artery which is a branch of anterior division of internal iliac artery. The external pudendal artery, a branch of common femoral artery, was also supplying the AVM. These arterial feeders were seen on both sides with left sided predominance [Figure 1]. The venous drainage was mainly into bilateral common femoral veins and right external iliac vein. Both the testes appeared normal in size. As there were no previous records available, it was difficult to say whether the AVM was congenital or acquired. The patient was planned for pre-surgical embolisation followed by surgical exploration if required. However, the patient refused treatment due to unknown reasons and was lost to follow-up.

Figure 1.

A 35-year-old man with infertility and bilateral scrotal AVMs. CT angiography arterial phase coronal image shows (a) bilateral tortuous external pudendal arteries (long arrows) as arterial feeders of AVMs and draining into bilateral common femoral veins (short arrows) with early contrast filling of common iliac veins (b) hypertrophied bilateral internal pudendal arteries (arrows) also supplying the AVMs. Abdominal window sagittal (c) and axial image (d) shows multiple intrascrotal contrast-filled vascular channels consistent with the diagnosis of bilateral AVMs. AVM: Arteriovenous malformation, CT: Computed tomography

DISCUSSION

Scrotal AVM is a very rare entity with only a handful of cases reported in literature. The aetiology may be congenital or acquired.[2] Congenital AVM is present at birth and grows proportionately with the child's growth. Acquired AVMs can follow scrotal infection, trauma or can be iatrogenic after pelvic or scrotal surgeries. The presenting complaints may vary from feeling of lump in the scrotum to obvious scrotal swelling, vague pain, dragging sensation or heaviness, bleeding, infertility and even heart failures. The pathognomonic imaging feature is the presence of nidus seen on arterial imaging apart from arterial feeders and early venous drainage causing vascular steal phenomenon. It has to be differentiated from other scrotal vascular lesions such as varicocele, haemangiomas and lymphangiomas.[3] Out of these, varicocele is the most common treatable cause of male infertility and AVM is the least common cause.[4]

In normal scenario, the pampiniform venous network around the testis and spermatic cord absorbs the heat from the testicular artery and diverts it away from the scrotum towards core body, thereby keeping the scrotal temperature 2°C–3°C lower than that of the body which is the optimum temperature for spermatogenesis.[5] The scrotal vascular lesions including AVM hinder this heat dissipation leading to elevation in testicular temperature which adversely affects spermatogenesis. However, after successful treatment of scrotal AVMs, the sperm count has shown to be increased.[3,6]

The treatment depends upon size, anatomical location and haemodynamics of the vascular lesion. It requires multidisciplinary approach, and the management has to be individualised.[7] The treatment options include surgical resection, sclerotherapy or embolisation. Laser irradiation offers incomplete treatment, whereas radiation and steroid administration are ineffective.[8] Oral propranolol has also been tried in the treatment of scrotal AVMs with some success. It causes non-selective vasoconstriction and decreased expression of various growth factors in the body. This further leads to inhibition of angiogenesis as well as apoptosis of capillary endothelial cells thereby decreasing the size of vascular malformations.[9]

Minimally invasive radiological intervention like selective embolisation of the arterial feeders with coils, polyvinyl alcohol particles, N-butyl cyanoacrylate and onyx remains one option.[10] Pre-operative embolisation within 24–72 h before surgery offers a comparatively bloodless surgical field; however, complications such as impotence, scrotal skin ulceration, urinary bladder infarction and necrosis of gluteal muscles could be challenging to handle.[3] The other concern with this treatment option is unavoidable radiation exposure to the testes. Angioembolisation of scrotal vascular malformation exposes testes to 2 Gy of radiation. A dosage of 1–2 Gy causes oligospermia with a recovery period of 3 years and can cause permanent azoospermia if the dosage increases above 2 Gy.[3] Embolisation causes a temporary improvement as there is recruitment of new collaterals from the nidus and hence recurrence is a possibility. Surgical excision remains the other and definitive management option. The limitation in our study was that the patient did not accept the treatment, so post-treatment increase in sperm count on semen analysis is a wishful speculation only. Cryopreservation of semen prior to any procedure or management of infertility with intracytoplasmic sperm injection followed by definitive treatment for AVM should be discussed with such patients during counselling.

CONCLUSION

Scrotal AVM is a rare entity that can cause male infertility. Its early recognition and treatment may lead to elevation in sperm count and hence is a potentially curable cause of infertility.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.