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Hirschsprung's presentation

Discussion in 'Step I' started by DrPak, Aug 1, 2006.

  1. DrPak

    DrPak Senior Member
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    I got a question where the newborn failed to pass meconium. Digital examination of the rectum resulted in a gush of retained fecal material.

    My question is why should digital manipulation cause the fecal material to finally 'gush' out. The gunk is stuck in the megacolon, why should swishing ur finger around in there suddenly allow the colon to pass it out?
     
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  3. Mye Eye

    Mye Eye Ophtho Cookie Eater
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    could be that the cloacal membrane failed to rupture, and the finger "popped" it...was that one of the options?
     
  4. felipe5

    felipe5 Fingerpickin' Good
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    since the aganglionic portion of bowel is tonically constricted in a person with hirschprungs the finger should help stretch out that area allowing the built up meconium to pass....i'm sure that the process of stimulating the anus as well could help the little guy go as well
     
  5. DrPak

    DrPak Senior Member
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    I should have made clear this was a USMLErx question, not one on the boards. I missed the diagnosis because I thought with Hirschsprungs a DRE wouldn't have resulted in a gush of anything, so I crossed that option out.

    @felipe5, I don't think there is any tonicity to the aganglionic segment. It's already stretched, so a finger stretching it a bit more shouldn't have made the difference b/w no stool and a gush of stool.
     
  6. Actually in kids with Hirschsprungs there's anal sphincter HYPERtonicity. That's because the main function of the nerves that are missing to the sphincters is inhibition (and relaxation).

    So doing a DRE will stretch out the sphincter and open the flood gates as it were.
     
  7. trudub

    trudub Senior Member
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    Yep, the aganglionic segment is constricted due to the lack of inhibitory neurons. Manually stretching the anus starts a local reflex arc that allows relaxation of the aganglionic segment and voila, out it comes.
     

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