A 50-year-old woman presents to the clinic with rectal discomfort and bleeding for the last 2 months. Past medical history is significant for hypothyroidism and hyperlipidemia. She has 4 children that were delivered vaginally. Vital signs are within normal range. Physical examination reveals evidence of an external hemorrhoid.
D) Inferior rectal vein, internal pudendal vein, internal iliac vein, common iliac vein
An external hemorrhoid is ectoderm in origin and can be a source of pain and discomfort due to its nerve innervation by a branch of the pudendal nerve. It is drained by the venous system in order of the following: inferior rectal vein, internal pudendal vein, internal iliac vein, common iliac vein and lastly inferior vena cava.
Answer choice A: Internal pudendal vein, obturator vein, internal iliac vein, common iliac vein, is incorrect. The obturator vein does not drain the internal pudendal vein.
Answer choice B: Internal pudendal vein, inferior mesenteric vein, superior mesenteric vein, common iliac vein, is incorrect. The inferior mesenteric vein is not drained by the superior mesenteric vein and does not drain the internal pudendal vein.
Answer choice C: Inferior rectal vein, inferior mesenteric vein, common iliac vein, inferior vena cava, is incorrect. The inferior mesenteric vein does not drain the inferior rectal vein.
Answer choice E: Superior rectal vein, internal pudendal vein, common iliac vein, inferior vena cava, is incorrect. The internal pudendal vein does not drain the superior rectal vein.
Key Learning Point
External hemorrhoids occur distal to the dentate line and are innervated by branches of the pudendal nerve which can result in pain and discomfort if a venous plexus is thrombosed. The rectal venous plexus draining an external hemorrhoid drains in the order of inferior rectal vein, Internal pudendal vein, internal iliac vein, common iliac vein and, lastly, inferior vena cava. Typical complaints of an external hemorrhoid include pain, swelling, pruritus, burning, and rectal bleeding. Depending on the severity of signs and symptoms, treatment ranges from dietary and behavioral changes to surgery.
