Peritonitis

The area of a patient's peritoneal cavity is three times that of his skin, and is a huge area to become infected. So it is not surprising that the mortality from peritonitis is about 10%, even in good units.

Bacteria, both aerobic and anaerobic, can reach the peritoneum from inside the gut (often), from an outside wound (occasionally), or from the blood-stream (rarely). Peritonitis can also follow a laparotomy if this is carelessly done. It is particularly likely to complicate: a strangulated obstruction of the gut (10.3), appendicitis (12.1), a penetrating abdominal injury (66.2), pelvic sepsis in a female (PID, 6.6), a septic Caesarean section (6.7), a perforated peptic ulcer (11.2) or typhoid ulcer (31.8), the breakdown of an anastomosis, especially of the unprepared large gut, where this has not been protected by a proximal colostomy, amoebic colitis (31.11), the torsion of an ovarian cyst (20.7), acute cholecystitis (13.3), pancreatitis (13.9), or the rupture of a liver abscess (31.12). Sometimes, there is no cause (''primary' peritonitis). The frequency of these causes differs geographically, so find out what the common causes are in your area.

You can reduce the risk of death from peritonitis if you: (1) Operate early[md]before a patient is very ill. (2) Take the necessary precautions to minimize the infection of his peritoneal cavity, when you do any laparotomy. So handle his tissues gently, anastomose his gut carefully, pack away potentially infected areas, control bleeding meticulously, and give him perioperative antibiotics when these are indicated (2.9).

Peritonitis develops through several stages, which need different treatment:

(1) Disease in an organ before the peritoneum over it is infected. For example, a patient may have the symptoms of peptic ulceration, appendicitis, or of typhoid fever, but no involvement of his peritoneum. At this stage, you may be able to treat the underlying disease and prevent peritonitis.

(2) Localized peritonitis. With proper treatment this localized peritonitis may resolve, and he may recover. A mass may form, but the toxic features of an abscess will not have appeared.

(3) Abscess formation around the organ responsible for the infection. Pus forms, but this is sealed off from the rest of his peritoneal cavity by loops of gut which are stuck to one another by a fibrinous exudate. His abscess may resolve, as an appendix abscess often does, or it may spread, as is common with a perforated duodenal or typhoid ulcer. The mass is bigger than in stage (2) above, and he now has toxic symptoms.

(4) Spreading peritonitis which may become generalized. If spread is incomplete, multiple abscesses form in his peritoneal cavity, particularly in his pelvis and under his diaphragm. If he is unlucky, all his abdominal organs are bathed in pus. If you operate and wash the pus out of his peritoneal cavity, more abscesses may form postoperatively.

Gut which is surrounded by pus usually develops ileus (10.13). If his peritonitis becomes generalized, his abdomen becomes silent and distends, as his gut fills with fluid and dilates. This fluid, and that which is lost into his peritoneal cavity, depletes his circulation, so that his blood volume, his blood pressure, and his urine output all fall, and his pulse rate rises. As peritonitis advances, his peripheral circulation fails, and he may develop septic shock (53.4).

Take a careful history. Ask for the symptoms of any underlying disease which may have caused peritonitis, such as previous dyspepsia, or a fever that may be typhoid. In a woman, enquire for symptoms suggesting PID (6.6).

Ask about pain. The pain of peritonitis is constant and is made worse by deep breathing, by coughing, and by movement. A patient with peritonitis is weak and thirsty, anorexic and nauseated. He vomits, and may have diarrhoea or be constipated.

The signs of peritonitis vary with the state of the disease: (1) An early sign is the failure of his abdomen to move as he breathes. (2) His abdomen is tender. This tenderness is localized at first, then regional, and finally general. It is usually worse where the disease started. (3) Feel for muscle guarding, progressing to rigidity. If peritonitis is advanced, there is no need to test for rebound tenderness[md]it is painful and unhelpful. But if peritonitis is localized, rebound tenderness is a good indication as to which parts of his peritoneum are involved and which are not. (5) Listen for decreased or absent bowel sounds. (6) Look also for distension, eventually becoming tympanitic, as ileus develops. You will soon find that the intensity of a patient's signs is little guide to the nature of the fluid inside his abdomen. Gastric, bilious, and pancreatic fluids produce the most tenderness; pus, urine, and especially blood are more variable, and may cause almost none. Even faecal contamination produces no peritoneal signs at first.

As his peritonitis advances, he becomes febrile, apprehensive, dehydrated, and hypotensive. His pulse is fast, his breathing is shallow and his facies Hippocratic (pinched, drawn and grey). Finally, he dies in peripheral circulatory failure.

Often, all you will know before you operate is that he has peritonitis, without knowing why. Try to to establish how advanced it is. A laparotomy is usually mandatory but, as you will see below, there are some indications for non-operative treatment. If you are uncertain about these in a particular case, you would be wise to operate.

Aim to: (1) Resuscitate him by treating his dehydration for 2 or 3 hours before you operate (A 15.3). (2) Treat the cause of his peritonitis, for example by closing his perforated peptic ulcer (11.2), by removing his appendix (12.1), or by resecting and anastomosing his gangrenous small gut (9.3). (3) Remove the pus in his peritoneum (if his peritonitis is generalized), by thorough lavage, and then leave some tetracycline solution in his peritoneal cavity. This will reduce the danger of abscesses forming in his peritoneum later, and will increase his chances of recovery.

You are often in a serious dilemma, when you drain an abdomen for peritonitis. If the pus is thin and adhesions few and light, there is no problem. But if loops of his gut are firmly stuck together, how radical should you be? If you don't separate them enough, you will leave pockets of pus behind. If you separate too vigorously, you risk stripping off the muscle layer or opening his gut[md]a real disaster, because a fistula will probably follow (9.14). This is difficult surgery, and there is no easy answer; only experience will teach you. You feel you cannot win, yet you will have to! Sometimes you will fail, and have to reopen his abdomen.

About 5 days after the operation his tachycardia should subside, his temperature should settle and his bowel sounds should return. When this happens the volume of his nasogastric aspirate will decrease, his abdominal distension will go down and he will start to pass flatus. If he survives the first 10 days, he will probably live.

His postoperative course is likely to be stormy. It may be complicated by paralytic ileus (10.13), the formation of more abscesses (6.3), Gram-negative septicaemia (53.4), intestinal obstruction (10.13), or extreme nutritional deficiency (9.11). One of the greatest dangers is a faecal fistula (9.14). If you separate the adhesions between the loops of his gut too roughly, you may: (1) open it and have to repair it immediately, or (2) strip part or all of its muscular coat and weaken it, so that it breaks down later to form a fistula (9.14).

Fig. 6-3 THE PERITONEAL CAVITY. In generalized peritonitis this fills with pus. A, the posterior abdominal wall showing the lines of peritoneal reflection after removal of the liver, spleen, stomach, jejunum, ileum, and the transverse and sigmoid colons. Organs on the back of the abdominal wall are seen through the posterior parietal peritoneum. B, a longitudinal section of the abdomen.

1, the anterior superior subphrenic space. 2, the anterior inferior subphrenic space. 3, the lesser sac. 4, coils of jejunum. 5, the transverse colon. 6, the great omentum. 7, coils of ileum. 8, the bladder. 9, the rectum. 10, the mesenteric artery. 11, the duodenum. 12, the pancreas. 13, the liver. 14, the stomach. 15, the left triangular ligament of the liver. 16, the oesophagus. 17, the upper recess of the omental bursa (lesser sac). 18, the lienorenal ligament. 19, the root of the sigmoid colon. 20, the root of the mesentery. 21, the cut edge of the lesser omentum. 22, the ascending colon. 23, the descending colon. 24, the duodenum.

GENERALIZED PERITONITIS This extends the general method for a laparotomy in Section 9.2. For tuberculous peritonitis see Section 29.5.

X-RAYS. Take an erect and a supine film. Look for: (1) free air under the patient's diaphragm. (2) Gas and fluid filled adjacent loops which appear to be separated, due to the exudate between them. (3) Distended loops of gut; to recognize the different levels of the gut radiologically, see Section 10.4 and Figs. 10-6 and 10-7.

BLOOD COUNT. He is likely to have a leucocytosis of more than 15,000 [gm]l. If his haematocrit is over 50% he has lost much extracellular fluid and needs Ringer's lactate.

ASPIRATION. If you suspect acute pancreatitis (13.9), confirm it by aspirating his peritoneal cavity with a needle, and if this is negative do a peritoneal lavage (66.1).

RESUSCITATION. The need for this varies:

If his peritonitis is early, and his general signs are minimal, he does not need resuscitation.

If his pulse is rapid and his blood pressure low, delay operation for a few hours (never more than 6) while you resuscitate him (A 15.3). Give him intravenous Ringer's lactate or saline (an adult may need several litres). If possible, measure his CVP and keep it at 6[nd]8 cm of water (A 19.2). Monitor his hourly urine output (A 15.5) and keep a fluid balance chart. Catheterise his bladder. Operate as soon as his pulse rate falls, his blood pressure rises, and his peripheral circulation improves.

If signs of peripheral circulatory failure do not respond to generous resuscitation, he will probably die, whatever you do. You may be wise not to operate.

If he is confused, severely hypotensive, and hyperventilating, with a fast pulse, and warm pink extremities, or cold clammy ones, he is in septic shock. Treat him as in Section 53.4. If you can, drain the septic focus. Timing is important: he must be fit enough to withstand the operation, so overcome shock, and then do the simplest possible operation.

THE NON-OPERATIVE TREATMENT [s7]OF PERITONITIS INDICATIONS. You have got to be very sure about these: (1) Acute pancreatitis. (2) Some cases of typhoid peritonitis (31.8). (3) Peritonitis which is mainly pelvic. You can feel an inflammatory mass vaginally or rectally. Drain this pus vaginally after confirming it by aspiration (16.6), or rectally in a male (uncommon). (4) Pus which is mainly under the diaphragm (6.4). (5) Peritonitis which has been confirmed by aspiration (66.1), but the patient is too ill to withstand laparotomy. Delay operation until he has improved.

METHOD. Start antibiotics and nasogastric aspiration as described below and give him intravenous fluids (A 15.3, 15.5). Give him nothing by mouth. Be sure to correct potassium deficiency (A 15.3). Continue nasogastric suction and intravenous fluids until he shows signs of recovery (his bowel sounds return, there is less aspirate, and he passes flatus).

LAPAROTOMY [s7]FOR PERITONITIS NASOGASTRIC ASPIRATION. Insert a nasogastric tube (4.9).

ANTIBIOTICS are unnecessary if he has: (1) Acute pancreatitis. (2) A perforated gastric or duodenal ulcer (unless you see him late when peritonitis has developed, 11.1). (3) Appendicitis causing only localized peritoneal infection. Otherwise, give them.

If he has generalized peritonitis, take blood cultures (if possible) before you give him antibiotics. You have a good chance of isolating the organisms responsible. When the sensitivity tests come back, adjust his antibiotics accordingly. Meanwhile, give him the perioperative antibiotics, as in Section 2.9. Chloramphenicol or a cephalosporin, and metronidazole are likely to be the practical ones. Give him chloramphenicol 6-hourly, at first intravenously, later orally; and metronidazole 8-hourly, the first two doses intravenously if possible and rectally later. For tetracycline instillation, see below.

CAUTION ! If he is to be given a relaxant, don't give him an aminoglycoside antibiotic unless you have an experienced anaesthetist[md]it may prolong the paralysis (A.14.2 to 14.4). These include gentamicin (especially), kanamycin, streptomycin, and amikacin.

EQUIPMENT. A general set (4.12). Several litres of warm saline or Ringer's lactate. To warm them, see below.

INCISION. As soon as he is draped, and anaesthetized, and his abdomen is relaxed, palpate it (10.1). Unless you have good indication for making another incision, make a median or a right paramedian one, centred on his umbilicus.

For a list of some of the things you might find on opening his abdomen, see Section 10.2. We assume here that he has localized or generalized peritonitis, with pus and fibrinous exudate everywhere. First, take a specimen for culture and sensitivity.

Break down adhesions with the greatest possible care. Only break down light ones with your fingers. If they are dense, define them carefullly, and cut them with scissors, or, better (if you are experienced) with a fine scalpel (10-11). If you are rough, you increase the chances of a faecal fistula.

If peritonitis is widespread, search systematically until you can find its cause. Be guided as to where it might be by: (1) His history. (2) The nature of the exudate. (3) The place where pus and exudate are most intense. (4) The density of the adhesions; the densest ones may indicate the origin of the infection.

CAUTION ! (1) Suck out all free pus before you start. (2) You must have good exposure[md]see Section 9.2. (3) If you find localized pus, try to minimize its spread around his peritoneum! (4) You face the dilemma described above[md]when to divide adhesions and when not to.

MANAGING THE UNDERLYING CAUSE. First, you will have to find it, and this may not be easy. Look for appendicitis (12.1), PID (6.6), a perforated peptic ulcer (11.2), strangulation obstruction (10.3), and signs of typhoid fever (multiple lesions in his distal small gut, 31.8). In most cases of typhoid, you will probably have decided not to operate. If your search produces something that you can do easily, without breaking down too many protective adhesions, such as removing a gangrenous appendix when the tissues are not too friable, or an infected ovarian cyst, do it. If you cannot find a cause after a full laparotomy, lavage his peritoneum and instil tetracycline. Play safe: he is desperately sick, and you must not risk complications.

If he has a hole in his large gut, repair it and make a proximal defunctioning colostomy (9.5).

If he has a hole in his rectum, do a proximal colostomy or a Hartmann's procedure (9.6).

If a dilated loop of gut ''disappears' into an inflammatory mass that might be tuberculosis, or a sealed-off perforation, don't try to dissect out the mass. Bypass it (29.5). This will keep risk to a minimum, relieve incipient obstruction, and allow the inflammation to subside. If you can easily biopsy the mass, do so. Usually, plan to re-operate and resect the lesion 3 to 6 months later.

If he has a perforated peptic or typhoid ulcer, oversew it and apply an omental graft (11.2).

LAVAGE. If he has generalized peritonitis, lavage his peritoneal cavity with saline. If his peritonitis is localized this may only spread the infection, so don't lavage. Sometimes, you can safely wash out only the pelvis.

Tip in several litres of warm saline or Ringer's lactate with 1 g of tetracycline (oxytetracycline may be cheaper) to the litre, slosh it around with your hand, and suck it out until the fluid which returns is clear. You may need 8 to 10 litres. Usually 3 or 4 are enough. Wash out his upper abdomen, his paracolic gutters, his infracolic area and his pelvis. Mop his peritoneum dry. Finally, leave a litre of warm tetracycline solution in his peritoneal cavity.

To warm the saline, put the bag or bottle in a basin of hot water and warm it to blood heat, feeling its temperature with your hand. If you have no saline you will have to use water, but the last instillation containing the antibiotic should be saline, or some other isosmotic fluid.

CLOSURE. Close his abdomen with interrupted through-and- through sutures of stout monofilament nylon or steel deep to the skin (9.8). Leave his skin unsutured for delayed closure.

DRAINS. Generalized peritonitis and multiple intra- abdominal abscesses cannot be drained adequately, because the area to be drained is too large: so wash out the pus, instil tetracycline, and don't insert drains.

It may be appropriate to drain a localized abscess[md]a pelvic abcess (vaginally in a female or rectally in a male), or a single intra-abdominal abscess. Abdominally, use wide bore tube drains; rectally, use corrugated rubber (4.10).

CAUTION ! If you instil tetracycline, don't insert drains, or it will all flow out!

POSTOPERATIVE CARE [s7]FOR PERITONITIS FLUID BALANCE. Continue to ''suck and drip' him (9.9, A 15.5), and keep an accurate fluid balance chart. The common error is not to give him enough fluid.

Nasogastric suction. If he has had generalized peritonitis, he is sure to get ileus; suction will reduce his distension. You may suck out 2 to 6 litres of fluid a day. Replace it with 0.9% saline or Ringer's lactate in addition to his standard requirements (A 15.5).

Intravenous fluids. Manage his fluid balance as in Section A 15.5. For maintenance an adult needs at least a litre of 0.9% saline, or Ringer's lactate, and 2 litres of 5% dextrose in 24 hours. Be sure to monitor his urine output (if possible 2- hourly for the first 48 hours). After the initial period of up to 48 hours, when you expect his urine output to fall, keep his urine output above 1 ml/kg/hour. Replace all losses as appropriate (A 15.5). If his initial resuscitation was inadequate, he may still have a deficit to make up.

Potassium supplements. Don't forget these (A 15.5), especially if there is a large volume of gastric aspirate. Start them when his postoperative diuresis begins.

He may be acidotic. There are several ways you can correct this. You can: (1) Give him 200 ml of 8.4% sodium bicarbonate (200 mmol). Or, give him 500 ml of 4.2% sodium bicarbonate (250 mmol). (2) Give him a litre of 1/6 molar lactate. (3) Give him adequate intravenous fluids and let his kidneys correct his acidosis. If his condition is poor, use (1) or (2), and repeat them daily.

Blood. If he bled during the operation, and this loss was not replaced, replace it now.

POSTOPERATIVE ANTIBIOTICS. If he had generalized peritonitis, continue the same antibiotics you gave him preoperatively for 5 to 7 days. Be guided by his clinical response, rather than by the sensitivities reported by the laboratory. If he has not improved after 3 days change them.

OTHER MEASURES. Examine him carefully each day for complications. Watch his temperature chart, his general state of alertness, his abdominal girth, his bowel sounds, and the volume of his gastric aspirate.

DIFFICULTIES [s7]WITH PERITONITIS These are many, and include septic shock (53.4), which can develop postoperatively.

If you CANNOT FIND A CAUSE FOR PERITONITIS, remember that PRIMARY PERITONITIS without any obvious cause does exist and is not uncommon in Africa. Bacteria may have arrived in the bloodstream as part of a septicaemic or pyaemic process. It is a diagnosis of exclusion, so make sure there is no perforation in any part of the gut, no PID or external injury etc.

If he DOES NOT IMPROVE, he may have residual sepsis and need a further laparotomy.

If his ABDOMEN DISTENDS and the volume of his gastric aspirate remains high (or he vomits), either the normal short period of ileus is continuing, or his gut is obstructing, see Section 10.13.

If his WOUND BECOMES INFECTED and breaks down, see Section 9.12. This is rare if you use non-absorbable sutures and close all the layers of his abdomen, except his skin (which should be left open for delayed closure), as a single layer. If you use absorbable sutures and close his abdomen layer by layer, wound breakdown is more likely.

If FEVER CONTINUES he may have a postoperative urinary or chest infection, or any of the abscesses in Section 6.3.

If he has DIARRHOEA, especially with the passage of mucus, suspect a pelvic abscess (6.5).

If FAECES START TO DISCHARGE FROM THE WOUND or a drain, he has a faecal fistula (not uncommon), so see Section 9.14. This is usually due to stripping some of the muscular coat of his gut, as you separate adhesions, and weakening it so that it breaks down later. If the fistula persists, it may produce disastrous fluid losses and severe wasting. Finding and closing it will be very difficult, so manage him non-operatively at first. If his gut is not obstructed distally, his fistula may close spontaneously. If it fails to close, refer him if you can. Try to avoid a fistula by only dividing light adhesions with your fingers. Define all other adhesions clearly, and divide them with scissors or a scalpel. Don't use diathermy close to his gut.