View Full Version : Congenital Megacolon (Hirshsprung’s disease)(Etiology-Clinical picture-Investigations-Treatment)

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05-03-2008, 05:12 AM
m Definition:
It is a condition with great dilatation and hypertrophy of the colon in absence of organic obstruction.
m Aetiology:
Congenital absence of parasympathetic ganglion cells from the wall of colonic segment ® Collapsed segment with absence of peristaltic waves ® functional obstruction.
m Pathology:
* Proximal
* Distal
* At the site:
- Common to be from the rectosigmoid junction to the anal canal but the aganglionic segment may extend to involve the whole colon.
- The aganglionic segment is collapsed causing functional obstruction. The proximal segment will be dilated and distended with faecal matter.
m Clinical Picture:
- Male > Female, 1st baby, +ve family history.
- Constipation: the infant pass stool once / week.
- Abdominal distention.
- Audible & visible peristalsis.
- Retarded growth and toxaemia. (Fusiform infant)
D.D: Causes of abdominal distention in infants:
1- Congenital megacolon.
2- Wilm's tumour.
3- Ganglion neuroma.
1- P.R. examination:
Anal canal ® free from fissures and excoriation.
Rectum ® empty & collapsed and grips the examining fingers.
Sometimes the megacolon occurs in cases with normal ganglionic colon (Idiopathic megacolon) It is due to painful lesion in the anal canal e.g fissure.
P.R . ® Anal sphincter ® spastic and painful.
Rectum ® full of faeces.
Also it usually occurs in older age groups.(Adult or aquired megacolon)
2- Rectal biopsy:
The rectosigmoid junction is devoid of Meissner and Auerbach's nerve plexus = aganglionic segment.(The most diagnostic investigation)
3-Barium enema:
Colon is hugely distended with funnel shaped termination.
1- In infants colostomy is done to bypass obstruction and to help in preparation of the colon till the age of 2 years (become able to withstand major surgery).
2- After 2nd years or in older children:
The colon is prepared for few days then resection of the aganglionic segment is done.
· The Operations:
1- Swenson's operation.
2- Duhamel's operation.
3- Soave's operation.
4- Lynn's operation.

1) Swenson's Operation

- It is a rectosegmoidectomy by pull through method.
- Combined abdomino-anal approach is done.
Disadvantage: The rectal sensation will be lost.® patient can't regulate defecation by his own desire

2) Duhamel's Operation

- Abdominal incision, dissection of the colon to peritoneal reflection where the rectum is divided just above th aganglionic segmet and the distal end of the stump is closed.
- Dissection of the rectum from the sacrum is done, then the colon is anastomosed with post wall of the rectum.
- After crushing of the spurr, rectal sensation is preserved in ant. wall of the rectum.
Disadvantage: pelvic disssection leads to denervation of the seminal vesicle and urinary bladder resulting in impotence and incontenence.

3) Soave’s operation

- To avoid dissection in the pelvis, the colon is pulled through the rectum "after dissection of rectal mucosa" to be anastomosed with the anal canal (enclosed within the muscular cuff of the rectum So, it preserve rectal sensation)

4) Lynn's operation
Simply it is a myotomy or better called myectomy of the spastic segement through the anus.It has limited indications.

F N.B. In preparattion of the colon for surgery or barium enema ® saline is used instead of water to avoid great absorption of huge colon ® over hydration (water in toxication) ® pulmonary oedema.

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