The management of intestinal obstruction

The treatment of strangulation obstruction is always operative. The treatment of simple mechanical obstruction may be non-operative or operative. If it fails to improve after 48 hours of non-operative treatment, operate. The detailed indications for operating are listed below. Operate at the optimum moment after you have rehydrated a patient, but don't operate if his condition is hopeless.

Rehydrate him rapidly over a few hours, as in Section 15.3. of Primary Anaesthesia. If you rehydrate him energetically, you should be able to operate within 4 hours, and certainly within 6 hours. If you suspect strangulation obstruction, try to operate within one hour, and rehydrate him as best you can before doing so. If he is conscious with a normal blood pressure and is passing urine, he is probably fit for operation.

At the same time suck the fluid and gas from his dilated stomach and upper small gut. This will stop him vomiting, and may reduce his distension. Most importantly, it will reduce the danger that he will aspirate his stomach contents when he is anaesthetized.

When you have resuscitated him, he may improve so much that you may wonder if he really needs a laparotomy. So, decide if he wants one or not, before you resuscitate him! If he has improved so much after resuscitation that you really do wonder if he needs a laparotomy, try clamping his nasogastric tube to see if he distends again.

Fig. 10-8 NASOGASTRIC SUCTION. A, pass a large (16 Ch) nasogastric tube and aspirate it with a 20 or 50 ml syringe half- hourly. Meanwhile, let it syphon freely into a drip bag beside the patient's bed. Cut off the corner of the drip bag to let the air out. B, if you don't have an electric sucker, you may find this apparatus useful. X and Y are two jerricans with pipes and taps soldered in. Water flows from X to Y creating a negative pressure in X. When X is empty, X and Y are reversed. Z collects the fluid and measures the flow. After Les Agr[ac]eg[ac]es du Pharo, ''Techniques El[ac]ementaires pour M[ac]edecins Isol[ac]es', Fig. 168. Diffusion Maloine, with kind permission. Your first task is to save his life, so do an operation which will achieve this. In desperate cases, removing the underlying cause is a secondary consideration, and may have to wait until later. Sometimes, you can remove the cause quite easily: for example, you may be able to cut some easier adhesions. Don't do complicated operations which need much dissection.

Open his abdomen with the greatest possible care[md]you can so easily perforate his gut, and flood his abdomen with faeces. Distended loops of gut will bulge through the incision. Deliver them on to the surface, and don't go pawing around in the depths of his wound[md]they will continually obscure your field.

Because distended loops of gut are so difficult to work with, you will have to decide if you are going to decompress them. Doing so makes distended gut much easier to handle, and makes the abdomen easier to close. The danger of decompression is that it inevitably contaminates the peritoneum a little, unless you use the retrograde method. But carefully opening distended gut with the proper precautions causes much less contamination than an uncontrolled burst[md]which is the probable alternative. So, if gut is greatly distended, decompress it. If it is only moderately distended, don't.

There are four ways to decompress a patient's gut; surgeons vary as to which they like:

(1) You can push the fluid and air back up his gut into his stomach, between your fingers, starting distally. The anaesthetist then removes it through the nasogastric tube. This may be the best method, but be sure that the suction through the nasogastric tube is working properly, or your patient may aspirate the fluid! Only use other methods if this fails.

(2) You can use a specially prepared spinal needle. This will remove gas, but is soon blocked by food particles when you try to remove liquid. A spinal needle is especially useful for the sigmoid colon and the caecum, which are often distended with gas. Its advantage is that there is no need to insert a purse string round it.

(3) You can use a Savage decompressor, which is a long tube with a trocar, which you push into the patient's gut through a purse string suture, and then suck out fluid and gas through a side tube. If it blocks, leave it in and clear it with its trocar. You can decompress a long length of gut by ''skewering' it over the decompressor.

(4) You can insert a Yankauer sucker through a purse string suture. This has a nozzle with several holes. It blocks less easily than a needle, but the risks of a spill are greater. It always blocks eventually. Removing it, unblocking it, and reinserting it may be necessary, but is likely to cause a spill.

When you have decompressed a patient's obstructed and distended gut, you will have to: (1) Find the obstruction. (2) Decide if his gut is strangulated or not. (3) Resect strangulated gut, if you find it. Having resected it, what you should do next will depend on whether it is large or small gut: (a) If it is his small gut you can anastomose its ends. (b) If it is his large gut you can: (i) Anastomose its ends and do a proximal protective colostomy (9.5). (ii) Exteriorize its ends and do a double-barrel colostomy. (iii) Bring the proximal end to the surface as a colostomy, and close the distal end (Hartmann's operation).

If you cannot anastomose gut, you can bring both ends to the surface as a colostomy, as in Figure 9-13, and refer him. This is more practical with the large gut; if you do it with small gut, his fluid losses will be so high that you will have to refer him within a few hours.

If you fail to resect and anastomose (or exteriorize) gut when it is not viable, he will certainly die of peritonitis.

DON'T OPERATE IF HE IS MORIBUND

THE MANAGEMENT [s8]OF INTESTINAL OBSTRUCTION PREOPERATIVE PREPARATION NASOGASTRIC SUCTION. Pass a nasogastric tube of a suitable size, and aspirate it regularly (4.9). Make sure it reaches the patient's stomach, and be sure it is draining properly. Suck efficiently to remove air and fluid before operating. Suck by syphoning the fluid into a bag, and sucking every 15 to 30 minutes with a syringe. Empty his stomach thoroughly, and then instil 30 ml of magnesium trisilicate mixture before induction.

INSERT AN INDWELLING CATHETER if he is very ill, and measure his urine volume hourly. If he is not very ill, its risks may outweigh its advantages. If an adult passes 35 to 60 ml per hour, his kidneys are being adequately perfused, and his blood volume is becoming normal. For a man Paul's tubing is acceptable.

SET UP A CVP LINE, if you can do so (A 19.2).

RESUSCITATION [s7]FOR INTESTINAL OBSTRUCTION This is critical. If he is severely dehydrated, and you fail to resuscitate him, he will probably die. If his obstruction has lasted longer than 24 hours, he is sure to be dehydrated, especially if he has been vomiting profusely, and his abdominal signs are unimpressive, indicating that his obstruction is probably high in his small gut. Start a fluid balance chart (A 15.5), and rehydrate him as in (A 15.3). Here are some rough rules, which give him rather more fluid than is given in Primary Anaesthesia (A 15.3). They assume that he is a 60 kg adult[md]modify them according to his actual weight.

Either: (1) Give him the first half of his deficit as Ringer's lactate or saline and the second half as alternate bottles of this and 5% dextrose. Fluid replacement is more important than potassium replacement (except in pyloric stenosis, which produces a specific metabolic defect, see Section 11.6). In late cases add 10 mmol of potassium to each 500 ml bottle after the first two. Or, (2) if you don't trust your nurses with strong potassium solutions, give him half-strength Darrow's solution (K 17 mmol/litre) every second bottle.

If he is thirsty, and his lips and tongue are dry, he is mildly dehydrated, and needs at least 4 litres of fluid.

If he also has sunken eyes and loss of skin elasticity, he is moderately dehydrated,, and needs about 6 litres.

If he also has oliguria, anuria, hypotension, and clammy extremities, he is severely dehydrated and needs about 8 litres.

If he is also weak and disorientated, he has probably lost more than 8 litres. Don't be afraid to give him up to 4 litres over one hour.

If he is elderly or has cardiac problems, watch his lung bases for crepitations, and his jugular venous pressure or his CVP.

If his gut strangulates, its veins block before its arteries, so that he loses blood into the lumen. He may need blood, about 2 units per metre of strangulated gut. If he was anaemic before he became obstructed, he also needs blood; but his main need is for water and electrolytes. Remember the danger of HIV. If an adult is sufficiently ill to need blood he needs at least 2 units.

If you have corrected his hypovolaemia as shown by an adequate urine output, or a normal CVP, but he is still hypotensive, he is probably in septic shock (53.4).

ANTIBIOTICS. Give him perioperative antibiotics (2.9). Give him chloramphenicol 500 mg intravenously, followed by an equal dose 6-hourly; and give him metronidazole 7.5 mg/kg 8- hourly. If you give it rectally give 1000 mg.

Or, give him gentamicin 2[nd]5 mg/kg daily in divided doses 8-hourly. Or, give him penicillin 1 megaunit 6 hourly, and streptomycin 0.5 g 12-hourly, and metronidazole 8-hourly. If he is to have a long-acting relaxant, start the gentamicin or the streptomycin postoperatively, before he leaves the theatre (A 14.3). Much better, give him something else that can be started preoperatively.

THE NON-OPERATIVE TREATMENT [s7]OF INTESTINAL OBSTRUCTION INDICATIONS. Obstruction due to: (1) A mass of Ascaris worms. (2) Plastic tuberculous peritonitis. (3) A localized inflammatory mass, such as an appendix mass, a pyosalpinx, or PID. (4) A pelvic abscess which can be drained rectally or vaginally. (5) Some patients with adhesions[md]see Section 10.7. (6) Typhoid fever causing partial mechanical obstruction or ileus (not uncommon).

CAUTION ! Non-operative treatment is never indicated if there is even a suspicion of strangulation obstruction.

METHOD. Continue nasogastric suction and intravenous infusions. Observe him carefully. Measure his girth. If you ''suck and drip him' for more than a few days, try to add at least 8.5 MJ (about 2000 kcal) of energy to his daily intake. If possible, give this as 50% dextrose into a central vein (A 19.2).

Signs of improvement are: (1) Reduction in the gastric aspirate. The normal minimum is 500 ml of clear light-green fluid, which is the volume excreted into an unobstructed stomach. (2) A reduction in his girth. (3) Return of his bowel sounds to normal. (5) Less pain. (6) Finally, he passes flatus and stools.

THE OPERATIVE TREATMENT [s7]FOR INTESTINAL OBSTRUCTION EQUIPMENT. A general set (4.12). A large (2 mm) spinal needle attached to a glass connector with a piece of rubber tubing, as in Fig 10-9. A Savage decompressor.

ANAESTHESIA. The aspiration of stomach contents is his major risk. Nasogastric suction reduces it, but does not remove it. Intubate him using cricoid pressure (A 16.5). Make sure that repeated attempts are made to empty his stomach every 15 minutes before the operation. Even aspirating air reduces the risk. Instil 30 ml of magnesium trisilicate mixture into his stomach before you induce him.

INCISION. A right paramedian or a midline incision is usually best, one-third above his umbilicus and two-thirds below it. Start with a 10 cm incision and enlarge it up or down as necessary. You will probably find that his posterior rectus sheath and his peritoneum will appear as two distinct layers, now that his abdominal wall is distended. Have moist packs (laparotomy pads) ready. Put them into warm water and then wring out most of the fluid. Use them: (1) to cover any gut that bulges out of the wound, (2) to wall off any fluid that spills.

If he has an old scar, a loop of gut may have stuck to its under side, so open his abdomen at one end of it, as in Section 9.2. This is safer than making a parallel incision, which may lead to necrosis of the abdominal wall between the two incisions.

If he has a strangulated external hernia, make the appropriate incision (Chapter 14).

CAUTION ! (1) Open his abdomen with the greatest care as in Figure 9-2. Distended loops of gut will be pressing up against it, and the smallest nick of a scalpel will go straight through them. You can so easily cut the thin wall of his distended colon and cause a fatal peritonitis. (2) Note which parts of his gut are distended; you will need to know this later, to decide where the obstruction is.

HANDLING HIS GUT. If it is very distended, decompress it before you do anything else. If it is less distended, use a moist swab to lift the dilated loops gently out on to the surface of his abdomen.

CAUTION ! (1) Handle them with the greatest care. They can easily tear. If you handle them roughly you will prolong the period of postoperative ileus. Be especially careful of his caecum. It is often greatly thinned, and if it does burst, soiling will be particularly dangerous. (2) Don't let loops of his gut get dry[md]cover them with moist packs. (3) If they are heavily laden with fluid, ask your assistant to support them.

If you nick only the seromuscular wall of a loop of gut, leave it alone. Close a deeper injury with a purse string suture, or by sewing it up transversely in two layers, while trying to keep spills to a minimum. If you do soil his gut with faeces, suck them out immediately. Irrigate his peritoneal cavity thoroughly two or three times with liberal amounts of warm saline, preferably with tetracycline (2.9), and then suck this out.

Fig. 10-9 DECOMPRESSING OBSTRUCTED GUT. A, using a needle. Note the glass tube, so that you can see what you are sucking. B, using a Yankauer sucker held in with a purse string suture. C, by retrograde stripping between your index and middle finger. D, E, and F, Savage's decompressor. G, and H, using a Foley catheter. Blow up its bulb after introducing it. Then milk the bulb along the gut. I, a rubber ''fish' to prevent gut getting in the way of an abdominal incision while you close it. Many surgeons think that C, if it works, is the best, and if C fails they use D. The idea of the Foley catheter was kindly contributed by Georg Kamm.

DECOMPRESSION [s7]FOR INTESTINAL OBSTRUCTION Be safe, and decompress a patient's gut if there is any risk of rupturing it, if gets in your way unduly, or if it prevents your closing his abdomen. Decompress it after you have brought it out of the wound, and closed it off well with packs, so that fluid will not soil his peritoneal cavity if it bursts.

If his caecum is distended, needle it, or decompress his transverse colon.

If his distension is mainly gaseous, as in the colon, needle that. You can also needle loops of small gut containing gas and fluid, provided you do it ''above the water line'.

RETROGRADE DECOMPRESSION is the method of choice, provided his gut is not too oedematous and friable. It is useful for his entire small gut and for much of his large gut, if his ileocaecal valve is incompetent. Start at his jejuno-ileal junction, and milk the contents proximally between your straight index and middle fingers. You may need some firm pressure on his proximal jejunum. When you have emptied enough fluid out of his jejunum, strip the fluid from his ileum into it and repeat the process. As you decompress, ask the anaesthetist to keep aspirating fluid from his stomach.

A SPINAL NEEDLE is only useful in the colon. Pack this off well. Push the needle through a taenia coli, and advance it longitudinally between the muscle coats for 3 cm. Then angle it inwards through the circular muscle to reach the lumen. Keep its point in the gas and clear of the fluid. If it blocks, pinch the rubber tube, then pinch it again distally. This should provide enough pressure in the needle to free it. If you insert the needle obliquely, there is no need to close the hole, which should not leak.

A YANKAUER SUCKER does not have a trocar, so it is difficult to use without spilling. Insert a purse string suture round the chosen site. Nick the seromuscular layer with a scalpel, raise it up and make the final incision through the mucosa. Then rapidly plunge the sucker through into the patient's gut, and close the purse string. Manipulate the sucker within his gut; eventually, the holes will plug up and you will have to withdraw it.

CAUTION ! When you have inserted a sucker, don't remove it unless you have to. If you have to remove it to clear it, pack off the peritoneal cavity to avoid spillage, and discard any contaminated ''lap pads'.

TO USE A SAVAGE DECOMPRESSOR insert a purse string suture on the antemesenteric border of his gut. Make an enterotomy incision in the centre of this, and push the decompressor with its trocar through. Withdraw the trocar and close the proximal opening of the decompressor with its threaded cap. With your thumb on the vent to control the degree of suction, start sucking out gas and fluid.

Pass the decompressor proximally and distally, carefully threading the distended loops of gut over it as you suck. To minimize clogging the holes, remove your finger from the vent from time to time. This will reduce the suction and let the food particles fall away. Or, more effectively, reintroduce the trocar.

When you have decompreessed enough gut (there is no need to decompress it all), remove the decompressor, close the purse string, and put it in the ''dirty basin'. Reinforce the purse string with a second layer of sutures, 3 mm beyond the first, going through the seromuscular layer only.

Alternatively, use a standard abdominal sucker. This is not so good, because it does not have a side tube, and blocks more easily.

TO USE A FOLEY CATHETER make a purse string suture and an enterotomy incision as above. Insert the catheter (with its side holes cut close to the balloon) connected to the sucker. Suck his gut empty. Then blow up the balloon and ''milk' it along his gut, sucking as you go. If it blocks, inject some saline and start again. Withdraw it, sucking as you go, then close the purse string.

Measure the fluid you have aspirated to see how much he has lost.

ON OPENING THE ABDOMEN [s7]IN INTESTINAL OBSTRUCTION Here are some of the many things you might find, either immediately, or after a careful search.

If there is straw-coloured fluid in his abdomen, he has probably only got a simple obstruction.

If the fluid is very dark and foul-smelling, his gut has probably necrosed and strangulated, or recently perforated.

If pus is present, he has an inflammatory lesion somewhere.

If loops of his gut are red and congested, peritonitis is present.

If they are dusky and plum-coloured, they are strangulated[md]see below.

If a huge purple mass fills his abdomen, it is likely to be a strangulated sigmoid volvulus.

If most of his small gut is deeply congested and haemorrhagic, it has probably undergone volvulus.

FINDING THE CAUSE [s7]OF INTESTINAL OBSTRUCTION First decide if the obstruction is proximal or distal to his caecum. In the developing world obstruction is more common proximal to the caecum than distal to it. Your task will be easier if you decompress his gut and then lift as many of its loops on to his abdominal wall as you can. Protect them by wrapping them in a moist ''lap pad' or in a sterile plastic bag.

If his caecum was distended when you opened his abdomen, the obstruction is distal to it, so feel his upper rectum and sigmoid. Then raise the left side of the incision and feel his descending colon. Then feel his splenic flexure, his transverse colon, his hepatic flexure, and his ascending colon.

If his caecum was collapsed, the obstruction must be in his small gut. First look for a strangulated hernia by palpating his hernial orifices from inside his abdomen[md]you should have examined them earlier from outside. If these are clear, ask your assistant to retract the right side of the lower end of the wound. Pick up the last loop of his ileum, start at his ilio-caecal junction, and run his small gut through your fingers, loop by loop, and then return it to his abdomen. Try to handle only collapsed gut distal to the obstruction, and not fragile distended gut proximal to it. The place where collapsed gut meets distended gut is the site of the obstruction.

If you find a loop which feels ''tethered', and you cannot lift it into view, it is probably the site of the obstruction. Expose this area well, by appropriate retraction, by packing gut away, and by lengthening the incision.

If you cannot find a collapsed loop, withdraw the distended loops and explore his pelvis and right iliac fossa.

If the obstruction is be difficult to find, remember that it is more likely to be in his small gut.

If you are not sure if a piece of gut is large or small, remember that large gut has taenia coli running over its surface.

If you don't know which piece of gut is proximal and which is distal, pass your hand down to the root of his mesentery, and remember that it runs obliquely downwards from left to right.

If you really are lost as to which way the gut goes, you have no alternative except to deliver the obstructed loops until you reach his duodenum proximally, or the obstructed focus distally.

CAUTION ! Don't try to rely on the standard differences between ileum and jejunum. Obstructed gut loses some of its characteristic features.

If you cannot find the cause of the obstruction, and yet his gut is grossly distended, decompress it[md]if you have not already done so[md]and search its length again.

IS HIS GUT VIABLE? Decide this by the criteria in Section 9.3 and Figure 9-8.

SPECIAL METHODS. See elsewhere for: obstruction due to bands and adhesions (10.7), inguinal hernias (14.6), femoral hernias (14.7), other hernias (Chapter 14), ascariasis (10.6), intussusception (10.8), volvulus of his small gut (10.9), sigmoid volvulus (10.10), volvulus of his caecum (10.11), and abdominal tuberculosis (29.5).

CLOSING THE ABDOMEN [s7]AFTER INTESTINAL OBSTRUCTION Do this with particular care[md]a ''burst abdomen' is a major risk (9.13). Distension may also recur, hopefully only temporarily. Remember to bring his omentum down over his gut to separate it from his abdominal wall[md]this will often prevent adhesions, and is especially important if you have done an anastomosis.

Close his abdomen by Everett's or Goligher's methods in Section 9.8.

If his abdomen is difficult to close, decompress his small gut into his stomach, and again empty it by aspiration through his nasogastric tube. If necessary use the ''fish' in Fig. 10-9; and see Section 9.8.

If you have had to resect gut, or his peritoneum has been soiled, wash out his peritoneal cavity with warm saline or Ringer lactate, and instil tetracycline (6.2).

If there has been significant soiling, leave the skin edges unsutured for delayed primary closure (9.8).

POSTOPERATIVE CARE [s7]FOR INTESTINAL OBSTRUCTION Continue nasogastric suction until he is passing flatus, his distension is becoming less, his bowel sounds are returning, and you are aspirating 400 ml or less of light-green fluid, which is his normal gastric secretion. Continue to keep an accurate fluid balance chart. Measure his urine output, and when necessary his CVP.

An adult in the tropics loses at least 3 litres of fluid a day (skin 1000 ml, lungs 500 ml, urine 1500 ml). Replace this with one litre of 0.9% saline and 2 litres of 5% dextrose. In a hot humid environment increase these volumes by 50% after the first 24[nd]48 hours. Monitor his urine output: he should be passing at least 1500 ml by the third postoperative day.

Replace the fluid you aspirate from his stomach as in Section A 15.5. You can usually replace it with 0.9% saline or Ringer's lactate.

As soon as his postoperative diuresis starts (at 24[nd]60 hours) replace the potassium he loses. His basic needs are about 40 mmol/24 hours. But if he still needs intravenous fluids after 48 hours, he may need up to 80 mmol of potassium a day, depending on the volume of secretions he has lost (A 15.1). Give it to him, either as a solution of 1 mmol/ml added to his intravenous fluids, or as Darrow's solution (K 34 mmol/litre) or as half- strength Darrow's.

If he has been very ill he may have a postoperative diuresis[md]see Section 53.3.

DIFFICULTIES [s7]WITH INTESTINAL OBSTRUCTION If he is obstructed clinically, and yet you CANNOT FIND ANY CAUSE FOR THE OBSTRUCTION, the only useful thing to do may be to decompress his gut. He may have one of three kinds of pseudo-obstruction. (1) You may see many short (2 cm) intense spasms of his ileum, making it narrow like string, with gross dilatation in between. Try giving him pethidine. (2) His ileum may be distended down to its last metre or so, after which it gradually returns to its normal size. (3) You may see his colon hugely distended without any cause. Look for a retroperitoneal carcinomatous mass in the region of his pancreas, and remember the possibility of uraemia and Hirschprung's disease. Dilate his anus by Lord's procedure (22.5).

If you DON'T KNOW WHAT TO DO about an obstruction, and the situation looks very complex, one contributor advises you to consider bypassing the obstruction by anastomosing a distended to a collapsed loop. Or, if you cannot do this, to bring out the proximal loop of gut as an ileostomy, and then to refer him rapidly.

If his large or small gut is not viable, but you CANNOT DO AN ANASTOMOSIS, exteriorize it. Bring it out through a stab wound which is big enough to accommodate it. Stitch its margins, at a point where it is healthy, to the skin of his wound, so that it won't slip back inside. Close your laparotomy wound carefully. He now has an ileostomy of rather generous proportions, sticking out of a short wound in his flank. Either, cut off the non-viable bowel about 3 cm from his skin to form a double barrelled ileostomy, or refer him to an expert, as soon as you see he is going to survive the procedure. He will loose large volumes of small gut contents, which will have to be replaced[md]so referral is urgent! See Fig. 9-13.

If his BOWEL SOUNDS DO NOT RETURN, the fluid you aspirate does not decrease, and he becomes more distended, paralytic ileus is developing[md]see Section 10.13.

If he has DIARRHOEA postoperatively, don't be alarmed. This is common after any operation to relieve intestinal obstruction: it is a sign of recovery and usually clears up spontaneously. Measure his stools and replace them litre for litre with Ringer's lactate or normal saline with added potassium (A 15.5).

Fig. 10-10 INTESTINAL OBSTRUCTION caused by [f10]Ascaris [f11]worms. This is a lateral X-ray in the supine position. Note the fluid levels and gas-filled coils of gut. In the film from which this was drawn worms could easily be seen, but not quite as clearly as this! Typically, they are coiled in a mass, like ''Medusa's head'. Kindly contributed by John Maina.