Question
A 45-year-old man comes to the physician because of bright red blood in his stool for 5 days. He has had no pain during defecation and no abdominal pain. One year ago, he was diagnosed with cirrhosis after being admitted to the emergency department for upper gastrointestinal bleeding. He has since cut down on his drinking and consumes around 5 bottles of beer daily. Examination shows scleral icterus and mild ankle swelling. Palpation of the abdomen shows a fluid wave and shifting dullness. Anoscopy shows enlarged bluish vessels above the dentate line. Which of the following is the most likely source of bleeding in this patient?
| A. |
Superior rectal vein
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| B. |
Internal pudendal vein
|
| C. |
Inferior mesenteric artery
|
| D. |
Middle rectal artery
|
Show Answer
|
Correct Answer � A
Explanation
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|
Answer A) Superior rectal vein
The patient’s anoscopy findings of anorectal varices in addition to his past medical history of liver cirrhosis and upper gastrointestinal bleeding suggest portal hypertension.
Superior rectal vein
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Anorectal varices occur in patients with portal hypertension as a result of increased blood flow in the portosystemic anastomoses that connect the superior rectal vein with the inferior and middle rectal veins.
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The superior rectal vein receives blood from the region of the anal canal above the dentate line and drains into the inferior mesenteric vein (portal venous circulation).
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The superior rectal vein would be the source of bleeding in the case of lesions located above the dentate line, such as the anorectal varices seen in this patient.
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The inferior rectal veins, which receive blood from the region below the dentate line and drain into the internal pudendal veins (systemic venous circulation), would be the source of bleeding in the case of lesions located below the dentate line, such as external hemorrhoids.
Internal pudendal vein
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Blood from the region of the anal canal below the pectinate line drains into the internal pudendal veins via its tributary.
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The anorectal varices in this patient are located above the dentate line, which is why a different vessel is the more likely source of bleeding.
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External hemorrhoids, which manifest with painful rectal bleeding, drain into the internal pudendal veins.
Inferior mesenteric artery
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The inferior mesenteric artery does supply blood to the region of the anal canal above the dentate line via its branch, the superior rectal artery.
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However, the source of bleeding in this patient is an enlarged tortuous vein (varix), not an artery.
Middle rectal artery
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The middle rectal artery does supply blood to the region of the anal canal above the dentate line.
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However, the source of bleeding in this patient is an enlarged tortuous vein (varix), not an artery.
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