This takes several forms[md]you will see the first one in children, and the others in adults: (1) All over the world a child's ileum may telescope into his caecum and colon and cause an ileocaecal or ileo-colic intussusception. These are the common types, and there is no point in trying to make a fine distinction between them. In some areas this also happens in adults (Uganda, and Natal). (2) An adult's caecum can intussuscept into his ascending colon. This is the caeco-colic variety, which is common in the Ibadan area of Nigeria. (3) Amoebiasis or a tumour of the colon at any age can cause it to intussuscept into itself (colo-colic, rare). (4) Rarely also a tumour of the ileum can cause it to intussuscept into itself (ileo-ileal). The relative frequency of these varieties differs considerably from one area to another. In the industrial world intussusception of any kind is rare in adults.

The danger of any intussusception is that the patient's gut may strangulate[md]usually the inner part (intussusceptum), but occasionally also the outer one (intussuscipiens). Intussusception is thus always a strangulation obstruction, or is potentially so. But remember that: (1) The signs of peritoneal irritation are initially absent, because the gangrenous intussusceptum is covered by the initially normal intussuscipiens. (2) Intussusception may occur backwards, because gut contractions may be reversed (unusual).

The childhood type of intussusception presents with symptoms of intestinal obstruction and can take two forms: (1) Primary intussusception has a shorter history and is less likely to present with abdominal distension and a palpable mass. (2) Secondary intussusception follows diarrhoea, with or without vomiting and dehydration; it has a longer history and is more likely to present with a mass and distension. Blood and mucus are commonly passed rectally in both types, with the result that intussusception is often misdiagnosed as ''diarrhoea'.

In the developed world the child is usually between 6 months and 2[1/2] years; in the developing world he may be as old as 7 or 8. He draws up his knees in spasms of colicky pain. He vomits, and may pass ''red currant jelly' stools. You can usually feel a sausage-shaped abdominal mass in the line of his transverse and descending colons, above and to the left of his umbilicus, with its concavity directed towards his umbilicus. His right lower quadrant feels rather empty. His abdomen is seldom much distended, so that the mass is usually quite easy to feel. Rarely, it is hidden under his right costal margin, or is in his pelvis, where you may be able to feel it bimanually. Sometimes, the apex of the intussusceptum presents at his anus, or you may feel it rectally, and see blood and mucus on your finger afterwards. If you do see a mass at his anus, be careful to distinguish an intussusception from a rectal prolapse (22.9).

The clue is to find a shifting mass, which moves as his intussusceptum forces its way down his gut, and then returns to its starting point. Occasionally, a child's intussusception reduces itself, so that his symptoms come and go spontaneously.

The adult type of intussusception may be ileo-colic, caeco-colic or colo-colic. In the caeco-colic type the apex of the intussusception is that part of the patient's caecum which is opposite his ileo-caecal valve. His ileum is drawn up into his caecum, and with it, his appendix, but they seldom strangulate.

Colicky pain usually starts suddenly, but its onset may be gradual. At first, the obstruction is not complete, his abdomen is not markedly distended, and he may have diarrhoea, with or without the passage of bloody mucus. Feel for a sausage-shaped mass in his epigastrium in the line of his colon. During an episode of colic the lump hardens, and you may be able to hear a chorus of obstructive bowel sounds as it does so.

At operation, you should be able to reduce about 80% of intussusceptions by gentle manual reduction. If you fail you can: (1) Do a resection and anastomosis; often this need only involve part of the lesion. The danger, when you do it, is that he may die from peritonitis if you fail to remove all nonviable gut. (2) You can exteriorize the lesion, close the abdominal incision, and then resect his gangrenous gut to make an ostomy, which will have to be closed later, hopefully by an expert. By doing this, you may avoid contaminating his peritoneal cavity and improve his chances of survival. Don't try to reduce an intussusception with a barium enema.

Exteriorization is is a messy but life-saving procedure. In the ileo-colic type of childhood intussusception, you have first to mobilize the child's gut, so that you can bring his strangulated terminal ileum, his caecum, and his ascending colon out to the surface (his ileum has a mesentery, so that it is already more or less ''mobilized'). To do this you have to free up his ascending colon, and carefully tie off the vessels which supply the part you are going to exteriorize. When you have done this, he will find himself with a temporary ileostomy, but you will have saved his life. You will however have to replace the quantities of fluid he loses from his stoma, and, if possible, refer him to have this closed. Or, you will have to close it yourself by crushing the spur between the two loops of his gut (9.5).

COLIC, AN ABDOMINAL MASS, AND DIARRHOEA?[md]THINK OF INTUSSUSCEPTION! Fig. 10-12 INTUSSUSCEPTION. A, B, and C, stages in the development of the common ileo-colic intussusception in children. D, squeeze the colon that contains the leading edge of the intussusception. In practice the caecum does not move quite as far as is shown in C, because it is fixed to the posterior abdominal wall. E, don't try to reduce an intussusception by pulling. Partly after Ravitch et al., ''Paediatric Surgery', Fig 93-3. Yearbook Medical, with kind permission. Hulme-Moir I, ''Paediatric Intussusception in Moshi'. Tropical Doctor 1979;2:114[nd]118.

INTUSSUSCEPTION Follow the general method for gut obstruction in Section 10.4. Correct the patient's fluid and electrolyte deficit, and pass a nasogastric tube. Treat any medical complications vigorously[md]pneumonia, malaria, measles, gastroenteritis, and convulsions.

CHILDHOOD [s7]ILEO-CAECAL INTUSSUSCEPTION X-RAYS. You will see the ordinary signs of any small gut obstruction[md]a dilatated gut with fluid levels. There are also some other more specific but rather difficult ones: (1) An empty right iliac fossa with no caecal gas shadow. (2) A soft tissue mass. (3) A ''ground glass' appearance to the child's abdomen, especially on the right, due to exudate.

MANUAL REDUCTION. Make a short right paramedian incision, insert two fingers, and feel for the mass. Retract the edges of the wound and try to lift out the mass. Look at it to see which way the intussusception goes, backwards or forwards.

If the outer layer of the intussusception looks viable, try to reduce it by manipulation. If it is not viable proceed immediately to exteriorize it, as described below, or to resection and anastomosis, if you have had some experience of bowel surgery.

If the intussusception has not gone beyond his splenic flexure, manual reduction should not be too difficult. But if it has reached his sigmoid colon, or if it has lasted more than 24 hours, you may have trouble.

Using a thick, moist gauze ''lap pad' between the thumb and index finger of your right hand, apply gentle pressure to the part of his colon which contains the leading edge of the intussusception. Reduce it from its apex proximally. Use the gauze to transmit the pressure to as wide an area of his gut as you can. Squeeze it gently, so as to make the mass go proximally. Be patient, and change the position of your squeezing hand as necessary. The intussusception will usually reduce itself quickly.

Manual reduction will be most difficult near the end, and the seromuscular layers of his gut usually split. Persist up to a point. Abandon reduction if: (1) Splitting becomes deep. (2) You cannot reduce his intussusception any further. (3) You see a necrotic area of gut (the intussusceptum) emerging proximally.

If you split the serous and muscular coats of the last few centimetres of the child's gut as you reduce it, don't worry. This usually happens. Provided his mucosa is intact and his gut is not gangrenous, it will heal.

CAUTION ! (1) Do all the reduction by squeezing. (2) Don't pull the proximal end. (3) Try to reduce the last dimple, or the intussusception may recur. (4) Make sure the apex is viable, because this is the part which is most likely to become gangrenous.

If, after manual reduction, any part of his terminal ileum, caecum, or ascending colon is gangrenous, exteriorize them. If you are inexperienced, this is probably safer than trying to do an end-to-side anastomosis[md]you will probably contaminate the peritoneal cavity if you try, and the tissue will probably not hold your stitches.

EXTERIORIZATION [s7]FOR INTUSSUSCEPTION Examine the proximal and distal ends of his strangulated gut to find parts which you are sure are healthy. Protect the area with carefully applied towels. Apply Babcock forceps or a silk ligature to healthy gut at least 3 cm away from either end of the gangrenous area.

TO MOBILIZE THE CHILD'S ASCENDING COLON stand on his left side and ask an assistant to retract the right side of the wound, so as to expose his caecum and ascending colon. Use a pair of long blunt-tipped dissecting scissors to incise the peritoneal layer 2 cm lateral to his ascending colon. Free his colon as in Fig. 66-20 using the ''push and spread technique' (4-8). Put a moist pack over his colon and draw it towards you, so as to stretch his peritoneum in his right paracolic gutter.

As you incise his peritoneum, draw his entire colon medially, from his caecum to his hepatic flexure. Use a ''swab on a stick' to push away any structure which sticks to its posterior surface[md]especially his duodenum and his ureter, which runs downwards about 5 cm medially to his colon, and which you should identify and preserve.

As you lift his caecum and ascending colon medially, you will see his ileocolic vessels which supply them. Hold up his colon and try to see them against the light.

Make windows in his peritoneum on the medial side of his colon, and clamp the branches of these vessels, one by one, 3 cm medial to the wall of his colon. Insert two haemostats through each window and cut between them, leaving a cuff of tissue distal to the proximal hamostat. Then tie the vessels held in each haemostat with No. 1/0, 2/0 or 3/0 chromic catgut or silk, depending on the size of the child. Tie them twice on the proximal side for safety.

If you cannot find the blood vessels because strangulation has altered his anatomy, lift up his colon and apply haemostats to the mesentery close to the wall of his colon. Cut between them and his colon, until it is completely free.

Apply haemostats to the mesentery of his ileum 2 cm from his gut, and cut between them until you reach healthy gut supplied by a visibly pulsating vessel. Raise his greater omentum towards his head, and use scissors to separate the filmy adhesions between it and his hepatic flexure.

Mobilize his hepatic flexure under direct vision. Cut peritoneum only and draw the flexure downwards and medially. Free his colon from his duodenum with ''a swab on a stick'.

You should now be able to lift his strangulated gut out of the wound, free of all its peritoneal, mesenteric, and vascular attachments. As you lift it up, make sure that there is healthy gut above skin level at both ends.

TO MAKE THE COLOSTOMY if possible, use a separate incision for the bowel and thread it through, as in Fig. 9-19. This is much better than exteriorizing his gut through the paramedian incision, which is an alternative.

Make a transverse colostomy incision, as in Fig. 9-19. Bring the healthy parts of his ileum and colon together, and thread them through this incision.

Alternatively (and less satisfactorily), bring them out at the top of his paramedian incision.

In either case, bring his ileum and colon together to form a double-barrelled colostomy-cum-ileostomy. Apply a series of seromuscular sutures for about 5 cm. Attach the joined parts of his ileum and his colon to the cut edges of his peritoneum. Three sutures on each side will probably be enough.

CAUTION ! (1) Check again that viable gut extends 2 cm above his skin. (2) Make sure that there is no tension on his ileum or colon inside his abdomen.

Close his abdominal wound including his skin. Make sure you have not closed it too tightly round his gut. Can you easily slide a finger down beside it?

Place two clamps across each end of his exteriorized gut. Cut between the two clamps and leave the two proximal clamps on. Secure them in place with strapping, or suture the mucosa to the skin at this stage.

POSTOPERATIVELY, remove the two clamps on his abdominal wall 24 hours later. By this time the two ends of his gut should have sealed to his skin enough to prevent contamination.

There are several ways you can manage his ileostomy, either alone or in combination: (1) You can fit him with a standard ileostomy bag. (2) You can use the makeshift bag in Fig. 9-16. (3) You can protect his skin with zinc oxide cream, barrier cream, or karya gum powder, which will help to protect his skin. Change his dressings frequently. (4) You can give him codeine to slow down peristalsis, so that he forms a semisolid stool. (4) You can nurse him in a prone position with his hips and chest supported on several pillows so as to allow the contents of his ileum to discharge by gravity, as in Fig. 9-13.

Refer him rapidly[md]if possible within 48 hours[md]for careful electrolyte control, and for elective surgery to restore the continuity of his gut. Manage his fluid losses as best you can meanwhile (A 15.5).

If you cannot refer him, wait 2 to 3 weeks[md]if he survives this long[md] and apply a clamp to the spur between the two loops of gut, as in G, Fig. 9-19. This will cause pressure necrosis, so that the contents of his gut can pass from his ileum to his colon.

RESECTION AND ANASTOMOSIS [s7]FOR INTUSSUSCEPTION The most suitable kind of anastomosis depends on the type of intussusception.

For an ileo-colic lesion, do an end-to-side anastomosis (9.4).

For an ileo-ileal lesion do an end-to-end anastomosis (9.3).

For a colo-colic lesion do an end-to-end anastomosis (9.3), with a proximal colostomy (9.5).