The general method for an acute abdomen

Unlike the chest, which seldom needs surgery, the abdomen often does. It does so because the gut it contains can obstruct, perforate, or strangulate, and so allow the organisms inside it to infect the peritoneal cavity. Infection can also reach the peritoneum from the gall-bladder or the female genital tract. These events are the common causes of an ''acute abdomen'. Unless you operate on a patient within a few hours of admission he stands a good chance of dying.

Pain is the main symptom of an acute abdomen. If he was previously well, and has had an abdominal pain for more than 6 hours which is not accompanied by severe diarrhoea or urinary symptoms, the chances are that he has an acute abdomen. If peritonitis is the cause, his abdomen will become tender and rigid early, and distend late. If his large gut is obstructed, his abdomen will distend early, and become tender late. If his gut is obstructed high up, frequent vomiting predominates.

Although the frequency of the many causes of an acute abdomen differs from one developing country to another, their pattern is similar, and differs from that of the industrial world: (1) Small gut obstruction is more common (10.3). (2) Large gut obstruction is much more likely to be due to sigmoid volvulus than to carcinoma of the colon. (3) Tenderness in the right lower quadrant can be caused by amoebiasis, by caecal tuberculosis, or by a ''helminthoma', as well as by appendicitis. (4) Generalized peritonitis can be caused by a typhoid perforation, a leaking liver abscess, or perforation of the gut by Ascaris. (4) You are unlikely to see diverticulitis, Crohn's disease, or acute abdomens due to vascular disease.

As always, but particularly with an acute abdomen, there is no substitute for a careful history and a full examination[md]the commonest mistake is to leave out some of the essential parts of both. A patient's history should suggest the diagnosis, and examining him should merely confirm or refute it. When you decide to operate, don't do so merely on the diagnosis of an ''acute abdomen', but on its most likely cause, with a list of possible alternatives, based on as much evidence as you can find. His early symptoms and signs will be more distinctive than his later ones, when he has deteriorated towards the common pattern of generalized peritonitis.

Abdominal pain is usually his presenting symptom, and if only you can interpret this, you have gone a long way towards finding its cause. It can be of at least three kinds: (1) A colicky pain due to obstruction at various levels in his gut, which he feels in the positions shown in Fig. 10-1. His colic comes in waves or spasms. Often, he moves about restlessly. (2) A sharp continuous pain due to inflammation of his parietal peritoneum. (3) An agonizing continuous pain due to ischaemia of his gut. Pain may also be referred from the diseased area to the other parts of the body that are derived from the same segment. For example, he may refer pain from his gall-bladder to below his right scapula; pus or blood under his diaphragm may give him a pain in his shoulder. He can have pain of more than one kind. For example, when the lumen of his appendix is obstructed, he has central abdominal pain of type (1), but as soon as the peritoneum over it becomes inflamed, he has pain of type (2) in his right iliac fossa. If it becomes gangrenous, he has ischaemic pain of type (3).

Vomiting in the form of a single initial vomit, is usual in most kinds of acute abdomen, so it is little help in diagnosis. It has few special features, except in intestinal obstruction, when its nature will give you some indication of the level of the obstruction (10.3). He vomits most frequently and profusely when his small gut is obstructed, but he may not vomit at all if the obstruction involves his large gut, especially if it is not strangulated. If his vomit is faeculuent (smelling like faeces), his small gut has been obstructed for some time.

Constipation varies according to the level of the obstruction. If he has large gut obstruction (or ileus) he has absolute constipation, and passes no faeces or flatus. Obstruction high in his small gut does not cause constipation.

Abdominal tenderness is a sign that the peritoneum underneath the tender area is inflamed or irritated. The tenderness may be localized, as in early appendicitis, or generalized, and is not easy to evaluate, because his tolerance to your examining hand depends so much on how stoical he is. The parietal peritoneum of the pelvis does not share a common innervation with the abdominal wall, so he, or more usually she, can have pus in the pelvis with little abdominal tenderness or rigidity.

Rebound tenderness is tested for by pressing firmly and steadily on a patient's abdomen for a minute or two, and then releasing your hand suddenly. If he finds this agonizingly painful, the sign is positive. It is an uncomfortable and not a very reliable sign, and is most useful when pressure applied in one place causes rebound pain in another. For example, if pressure in his left lower abdomen causes pain in his right lower abdomen, it suggests appendicitis (Rovsing's sign). Many surgeons use light percussion, which is more accurate and much less cruel than rebound tenderness.

Guarding is another sign that a patient's peritoneum is inflamed, but you must examine him gently, so that the contraction of his muscles is involuntary rather than voluntary.

Rigidity of the abdominal wall can be of any degree, from none to ''boardlike'. Gastric and duodenal exudates produce the most marked rigidity, pus is more variable, and blood may produce almost none, especially when it seeps up from the pelvis.

If he is in very severe pain, a judicious dose of morphine will: (1) improve his shock, (2) reduce his pain, (3) make him more comfortable and better able to give a history, and (4) prevent him immediately guarding his abdomen whenever you touch it, so that his physical signs become more localized.

The common mistakes are: (1) Not to ask the right questions properly and methodically. (2) Not to examine him carefully and systematically. (3) Not to make and record a diagnosis and a differential diagnosis. (4) Not to admit him and monitor him carefully, if there is any chance that he might have an acute abdomen. (5) To forget that many medical conditions, especially pneumonia (by causing diaphragmatic pain), can mimic an acute abdomen. (6) To forget that age and sex can profoundly influence the probability of a particular diagnosis. Children for example are more likely to have intussusception, or a gut obstruction by Ascaris. (7) To fail to make adequate allowance for the late case whose history is obscured, whose mind is clouded, and whose signs are altered. (8) To forget the ''silent interval' between the immediate chemical peritonitis of a perforated peptic ulcer and the delayed onset of bacterial peritonitis (11.2). (9) To forget that in advanced peritonitis ''septic shock' (53.4) may prevent a patient from showing the signs you expect. (10) Finally, worst of all, not to go and see a patient with a suspected abdominal emergency immediately.

KOFI, a little boy of 6 months, was taken to hospital with vomiting, abdominal pain and some blood and mucus in his stools. After several days treatment for gastroenteritis he was becoming steadily worse, so his parents took him in the bus many miles to the teaching hospital. There he was found to have intussusception, and eventually recovered after a long illness. LESSON In children the occasional acute abdomen is easily missed among many cases of gastroenteritis. Vomiting and pain with no diarrhoea, or only perhaps some blood and mucus, should make you suspicious. Fig. 10-1 THE SITES OF ABDOMINAL PAIN. (1) Lesions in a patient's stomach, duodenum, gall-bladder, and pancreas cause pain in his epigastrium. (2) Lesions from his duodenum down to the middle of his transverse colon cause pain in the middle of his abdomen. (3) Lesions from that point onwards cause pain in his lower abdomen. (4) The pain of biliary colic is primarily epigastric or in his right hypochondrium, but may be referred under the angle of his right scapula. (5) Ureteric colic is frequently referred to the testicle on the same side. (6) Pain from his kidney and pancreas may be referred to his back. (7) Pain from the uterus and rectum may be referred to the sacral area. (8) Pain from the ]]diaphragm is frequently referred to the shoulder. After Silen S, ''Cope's Early Diagnosis of the Acute Abdomen', (15th edn, 1979) Figs. 2 and 3, OUP, with kind permission.

THE GENERAL METHOD [s8]FOR AN ACUTE ABDOMEN[md]ONE Base your diagnosis on as many items of information as possible. The explanations given for a particular sign or symptom are suggestions only.

HISTORY ONSET. [f41]''How did your pain start?'' (if it woke the patient at night it is probably serious). ''Did it start with an injury?'' (quite a minor one can rupture the spleen). ''Was it so severe that you collapsed or fainted?'' (a perforated peptic ulcer, a ruptured ectopic pregnancy, and acute pancreatitis can all present like this).

PAIN. Form a detailed picture of this, and expect it to have more than one component.

''Did the pain start suddenly or slowly?'' (suddenly, suggests a perforated duodenal ulcer).

''Where is the pain and where did it start?'' If it is epigastric or subumbilical, it is probably from his small gut or appendix. If it is hypogastric, it is probably from his large gut. If it started ''all over'' his abdomen, think of a perforated peptic ulcer, or a ruptured ectopic pregnancy, or a pyosalpinx in a woman. If it is his loin and is referred to his testis, it is probably ureteric pain, perhaps caused by a stone.

''What is it like?'' (a throbbing pain or a constant ache suggests an inflammatory process, such as an appendix abscess). Burning or boring? (peptic ulcer, pancreatitis). Coming and going in waves or spasms? (colic). If it is colicky, how long do the spasms last, and is there complete relief between them?

''How long did it last?'' A patient with biliary colic may be free of pain between attacks.

''Has it moved?'' (if it started in his umbilical region and moved to his right iliac fossa, suspect appendicitis).

''Does your pain spread anywhere?'' To the testis of the same side? (ureteric colic). To the top of the shoulder? (a perforated peptic ulcer, a subphrenic or liver abscess, diaphragmatic pleurisy, gall-stones, a ruptured spleen, sometimes peritonitis). To the middle of the back? (peritonitis).

''What makes your pain better?'' Lying absolutely still? (peritonitis). Walking bent forwards? (appendicitis). Lying with your knees flexed? (inflammation in contact with the psoas muscle, such as appendicitis, or a psoas abscess).

''What makes it worse? Breathing, coughing, moving, drinking, eating, opening your bowels, or passing urine?'' Breathing aggravates the pain of pleurisy, peritonitis, a peritoneal abscess, abdominal distension due to intestinal obstruction, cholecystitis, etc. Dysuria may be caused by pyelitis, a stone, acute hydronephros, a pelvic abscess close to the bladder, or an appendix abscess irritating the right ureter. Dysuria and fever? (pyelonephritis).

VOMITING. [f41]''Tell me about the vomiting'' It started with the pain but is now less? (perforated peptic ulcer: persistent vomiting is rare in patients who have perforated a peptic ulcer). Severe and persistent? (strangulation of the small gut, acute pancreatitis). At the height of the pain? (intestinal or renal colic).

''What is the association between the pain and the vomiting?'' In an acute abdomen the vomiting almost always comes after the pain. Vomiting before the pain suggests gastroenteritis. Vomiting sudden and soon after the pain? (strangulation or obstruction of the upper small gut, a stone in the ureter or bile duct). Vomiting about 4 hours after the pain? (obstruction of the ileum, appendicitis). Vomiting many hours after the onset of the pain, or no vomiting? (large gut obstruction).

''How frequent is the vomiting?'' It usually varies directly with the acuteness of the condition. Vomiting mild, absent, or late? (many acute abdomens, including large gut obstruction and a ruptured ectopic).

If he has pain but no vomiting, suspect that: (1) The cause is outside his gut, as in salpingitis, a tubo-ovarian abscess, or a haemoperitoneum. (2) He may have a high threshold to vomiting[md]if so anorexia and nausea are important.

''What is his vomit like?'' Stomach contents, perhaps mixed with bile? (acute gastritis). Greenish jejunal contents (the colics). Frequent retching but little vomiting? (torsion of a viscus). First his gastric contents, then bilious, then greenish-yellow, then faeculent? (small gut obstruction).

PREVIOUS HISTORY. [f41]''Have you ever had a pain like this before?'' Minor attacks of pain like the present one but less severe? (intussusception, obstruction, appendicitis, etc). Pain when hungry relieved by food? (duodenal ulcer). Pain in the epigastrium or right hypochondrium irregularly related to meals? (gall-stones).

BOWELS. [f41]''Have you noticed any change in your bowels, have they been normal?'' If they are usually regular, constipation for several days is important. Hypogastric pain and diarrhoea with mucus, followed by hypogastric tenderness and constipation? (pelvic abscess). Diarrhoea, colic, fever? (gastroenteritis). ''Red currant jelly' stools? (intussusception). Frequent bloody stools? (amoebic colitis). Worms? (Ascaris obstruction).

''When did you last pass a motion, and what was it like?'' He may pass two or more stools after the onset of a complete small gut obstruction. In complete low large gut obstruction, he passes no flatus or stools.

PERIODS. (1) ''When was your last period?'' (2) ''Was it before or after the normal time?'' (3) ''Was the loss more or less than usual?'' (4) ''Has there been any slight loss since your last period?'' Last period late or scanty? (ectopic pregnancy). One to three periods missed, followed by a small dark loss? (subacute bleed from an ectopic). Last period painful, and not accustomed to dysmenorrhoea? (threatened abortion, salpingitis).

CAUTION! (1) Always ask the four questions above with care. The question ''Are your periods normal'' is not enough. (2) Occasionally, a patient's periods may be normal in an ectopic pregnancy.

OTHER SYMPTOMS. Enquire about appetite, swallowing, weight loss, fever, and changes in girth. Weight loss or general deterioration in health? (abdominal tuberculosis, etc). Severe illness with fever? (typhoid perforation). Increase in abdominal girth, or change in the fit of his clothes? (ascites).

THE GENERAL EXAMINATION [s7]OF AN ACUTE ABDOMEN GENERAL CONDITION. His general condition may be surprisingly normal, even though he has an acute abdomen. Is he well or badly nourished, bright and moving about? If he is limp, lethargic, and slow to respond, suspect toxaemia, septicaemia, or shock. If he is both lethargic and restless, suspect cerebral hypoxia, due to hypovolaemia. Look at his tongue and his conjunctivae, and smell his breath.

His face may be characteristic later on when his disease is advanced. If the face of a a Caucasian is pale and livid and his brow sweating, or an African or Indian goes mildly grey, suspect a perforated peptic ulcer, acute pancreatitis, or a strangulated gut. Deathly pale with gasping respiration? (ectopic pregnancy with severe bleeding). Gaze dull and face ashen? (severe toxaemia). Eyes sunken, tongue and lips dry, and skin elasticity reduced? (dehydration, intestinal obstruction). Nose and hands cold? (hypovolaemia, peripheral circulatory failure).

His pulse may be normal early on, even if he has an acute abdomen. The trend in his pulse is important in deciding if he has some serious abdominal condition, especially an abdominal injury (66.1). Tachycardia? (late peritonitis, strangulation of the gut). The pulse of typhoid fever is no longer slow after the ileum has perforated.

His attitude in bed may be characteristic. Restless? (severe colic or haemorrhage). Knees drawn up to relax the tension on his abdomen? (extensive peritonitis). Only changes his position in bed with pain and difficulty? (peritonitis, perforated gastric ulcer). Lies still with his hips and knees flexed? (generalized peritonitis). Right knee flexed (appendix or psoas abscess). Constantly moving around? (ureteric colic). Straight one minute and doubled up the next? (intestinal or biliary colic).

His respiration rate will help you to decide if his condition is abdominal or thoracic. If his respiration rate is twice normal, he probably has pneumonia. Shallow and occasionally grunting respiration? (peritonitis, especially of his upper abdomen). Rapid and shallow? (shock). Look at a child's nose; if his alae nasi are moving, he has pneumonia. Listen to his chest.

His temperature may be normal, especially in intestinal obstruction. Severe fever from the onset? (typhoid, basal pneumonia, pyelonephritis).

SIGNS OF DEHYDRATION. If his small gut is obstructed he will become dehydrated rapidly.

ABDOMEN. Ask him to point to where the pain started, to where it is now, and to where it is worst.

Look at his abdomen. Is its contour normal? If it is severely distended, is this due to gas, fluid, or a tumour? If necessary, test for shifting dullness.

Does his abdomen move freely as he breathes? Peritonitis anywhere may splint all or part of it, and stops the normal movement that accompanies breathing. Reduced or no movement in the lower abdomen? (PID, appendicitis).

Can you see visible peristaltic waves? Watch for at least one measured minute in a good light from a low angle. If so, he is either very thin or a neonate, in which case they are normal, or he has pyloric stenosis, or small gut obstruction.

Look at his groins[md]his central abdominal pain may be due to an obstructed hernia. Are there any old operation scars? If so, adhesions may be causing his symptoms.

Feel his abdomen. First relax it by flexing his hips. If necessary, ask an assistant to support his flexed knees. Your hand must be warm, gentle, patient, and sensitive. Use light palpation first to test for muscle rigidity and spasm, and localize the tenderness. Then, if necessary use deep palpation.

Lay your hand flat on his abdomen, and keep your fingers fully extended as you feel for tenderness. Avoid the painful area, and start feeling his abdomen as far from it as you can (Don't worry if he tells you it is the wrong place!). Move towards this slowly. Where is the area of greatest tenderness? It will be easier to find if there is no guarding, and is a useful clue to the organ involved. In his right iliac fossa? (appendicitis). In his flank? (renal suppuration). Suprapubically in a woman? (PID). Superficial induration and tenderness? (pyomyositis of the abdominal wall).

Can you feel any masses? In his right iliac fossa? (appendix mass, amoebiasis, a mass of Ascaris worms)

Is his abdomen soft, or firm and rigid, or do his muscles only contract when you move your fingers towards them? Abdomen rigid like a board? (generalized peritonitis, especially that due to perforated peptic ulcer). How widely distributed is this rigidity? If rigidity is due to pleural pain, you can overcome it by continuous pressure on his abdomen, and the pain is not usually increased. But if he has disease in his abdomen, his pain gets worse as you press (confirm pneumonia by listening to his chest).

CAUTION ! A patient may show very little rigidity if: (1) His perforation occurred about 6 hours ago, so that his immediate rigidity has had time to go, and secondary bacterial peritonitis has not yet had time to develop. (2) He is very fat and flabby, and his muscles are thin and weak. (3) He is very toxaemic and ill. (4) He is very old or immunosuppressed. (5) A woman is pregnant.

Feel his loins. Press your fingers forwards under his ribs. Resistance and tenderness without swelling? (an inflammatory focus). Now put your other hand in front of his loin, ask him to take a deep breath, and feel for an abnormal swelling moving between your two hands as he breathes (pyo- or hydronephros).

Fig. 10-2 THREE TESTS. A, the iliopsoas test. Ask the patient to flex his hip against the resistance of your hand. If he feels pain, there is inflammation in relation to his psoas muscle. B, the obturator test. Flex his hip to 90[de] and gently rotate it internally and externally. If this causes pain, there is inflammation in relation to his obturator muscle. C, the fist percussion test. Percuss gently with your fist over his chest wall. On the right a sharp pain indicates an inflammatory lesion of his diaphragm or liver; on the left one of his diaphragm, spleen, or stomach. Kindly contributed by Jack Lange.

The iliopsoas test is only indicated if he is not very ill, and does not have generalized peritonitis. Lie him on the opposite side, and extend his thigh on the affected side to its fullest extent. If this is painful, there is some inflammatory lesion near his psoas muscle (appendix abscess, iliac abscess, pyomyositis of his iliopsoas). This test is less useful if his anterior abdominal wall is rigid.

The obturator test. If rotating his flexed thigh so as to stretch this muscle causes pain, there is pus or perhaps a haematocoele (in a woman) in contact with the surface of the patient's obturator internus.

The fist percussion test. Percuss gently with your fist over his chest wall. On the right a sharp pain indicates an inflammatory lesion of his diaphragm or liver; on the left one of his diaphragm, spleen, or stomach. This sign is often positive in acute hepatitis.

Percuss for liver dullness in his right nipple line from his 5th rib to below his costal margin. If he is resonant here, or in his axillary line (and his abdomen is not distended, and his liver is not atrophic), there is probably free gas in his peritoneal cavity.

Listen to his abdomen. Decreased or absent bowel sounds? (peritonitis or ileus from some other cause). Loud peristaltic rushes? (gastroenteritis). A rush of high-pitched tinkling bowel sounds, coinciding with worsening of his abdominal pain? (obstruction[md]this is a very important sign, see Section 10.3).

THE HERNIAL SITES. Feel both his femoral and inguinal openings, his umbilicus, and any old incisions.

CAUTION ! (1) A hernia does not have to be tense, tender, or painful to be obstructed. (2) It may be small, especially if it is a femoral hernia[md]only a centimetre or two. (3) He may be quite unaware of it. (4) Femoral hernias are very easy to miss in fat patients. (5) Don't overlook a small umbilical hernia lying deep in fat, or think a lump is not a hernia because his symptoms are not very acute. (6) Has he ''pushed back a hernia recently'[md]he may have obstruction from ''reduction en masse'. (7) In a baby, it is not the bulging inguinal hernia which will strangulate, but the small slim one one containing only a thin loop of his tiny gut. It may only feel like slightly thickened cord and testicle, with reddening and oedema of his scrotal skin.

THE PELVIC CAVITY is just as important as the abdomen. You will find a vaginal examination more useful than a rectal one (except in a child). If necessary, do both.

Feel and percuss suprapubically, press deeply behind the patient's inguinal ligament and pubis. Feel for tenderness, muscular resistance, the mass of a pelvic abscess, a full bladder, or an enlarged uterus.

Never forget to examine the rectum. Lay him on his side or back. Press a well-lubricated finger as far up his anal canal as it will go. Feel for tenderness in all directions. Feel forwards, in a man for an enlarged prostate, a distended bladder, or enlarged seminal vesicles; and in a woman for swellings in her pouch of Douglas or displacements of her uterus. Feel upwards for a stricture, the ballooning of the anal canal below an obstruction, the apex of an intussusception, or the bulging of an abscess against the rectal wall. Feel laterally for the tenderness of an inflamed swollen appendix. Feel bimanually for a pelvic tumour or swelling, or for any fullness in the pouch of Douglas. Is there blood or mucus on your glove afterwards?

CAUTION ! It has been well said that ''If you don't put your finger in a patient's rectum, you will put your foot in it!''

OTHER SYSTEMS. Don't forget to listen to his chest, he might have a basal pneumonia. Examine his spine (spinal tuberculosis or a tumour can cause root pain felt in the abdomen). Feel for a stiff neck (meningitis can cause vomiting and abdominal pain).

SPECIAL METHODS. If you suspect intraperitoneal bleeding, do a four quadrant tap (66.1) or peritoneal lavage.

If the diagnosis of an acute abdomen is uncertain or examination is difficult, examining him under anaesthesia may help, especially to assess a mass in the pelvis. Be prepared to follow this by laparotomy, depending on your findings.

LABORATORY TESTS. Don't diagnose an acute abdomen until you have examined his urine. Red cells, pus cells, or sugar in it may alter your management completely. Also remember that uraemia can present as abdominal distension and vomiting, and diabetes as vomiting and abdominal pain.

CAUTION ! A normal white count never excludes any of the diseases that cause an acute abdomen.

X-RAYS must be good, because you are interested in gas shadows. Be selective, and look at the films yourself. Ask for: (1) A PA film of his chest to check his diaphragm and subphrenic area. (2) An erect and a supine film of his abdomen. If he cannot sit up (he usually can if you support him), take a left lateral decubitus film.

An erect normal film may show a gastric air bubble, perhaps a fluid level, gas in his colon, but none in his small gut except under the age of 2 years. His psoas shadows should be clear and his renal shadows well outlined.

Abnormal signs include: (1) A shadow caused by free air under his diaphragm (or his anterior abdominal wall in a decubitus film). If you see it, a hollow viscus has perforated. Free gas under the diaphragm is often better seen on an erect chest X-ray than on an abdominal one. (2) Fluid levels (usually multiple) due to intestinal obstruction (10-6). (3) Air in the small gut is always abnormal, except in a child under 2 years. (4) Displacement of normal gas shadows. A ruptured spleen may displace the shadow of a patient's splenic flexure downwards and medially. (5) Obliteration of his psoas shadow can be caused by bleeding from an injured kidney, pyomyositis of his psoas, a psoas abscess from a tuberulous spine, or a retroperitoneal abscess. (6) Look for the shadows of renal calculi along the lines joining the tips of the transverse processes of his vertebrae to his sacroiliac joints.

CAUTION ! The absence of free gas does not exclude a perforation, nor does the absence of fluid levels exclude an obstruction.