Abdominal pain is discomfort in the abdominal cavity. Symptoms accompanying abdominal pain may include belching, nausea, vomiting, rumbling and gurgling noises, and flatulence (wind).
Mild abdominal pain is common and is often due to excessive alcohol intake, eating unwisely, or an attack of diarrhoea. Pain in the lower abdomen is common during menstruation but may occasionally be due to a gynaecological disorder such as endometriosis (in which fragments of uterine lining are present in abnormal sites within the abdomen).
Cystitis (inflammation of the bladder) is another common cause of pain or discomfort in the lower abdomen. Bladder distension due to urinary obstruction may also cause abdominal pain.
Abdominal colic is the term used for pain that occurs every few minutes as one of the internal organs goes into muscular spasm. Colic is an attempt by the body to overcome an obstruction such as a stone or an area of inflammation. The attacks of colic may become more severe and may be associated with vomiting (see abdomen, acute).
A peptic ulcer, which is associated with an increase in the amount of acid formed in the stomach, often produces recurrent gnawing pain.
Other possible causes of abdominal pain are infection, such as pyelonephritis (infection of the kidneys) and pelvic inflammatory disease (infection of the internal female reproductive organs), and ischaemia (a lack of blood supply), as occurs when a volvulus (twisting of the intestine) obstructs blood vessels. Tumours affecting an abdominal organ can cause pain.
Abdominal pain may also have a psychological cause, such as anxiety.
For mild abdominal pain, self-treatment measures, such as a wrapped hot-water bottle or a milky drink, are often effective. Pain due to peptic ulcer can be temporarily relieved by consuming food or by taking antacid drugs. Abdominal pain that is not relieved by vomiting, persists for more than six hours, or is associated with sweating or fainting requires urgent medical attention. Urgent attention is also necessary if pain is accompanied by persistent vomiting, vomiting of blood, or passing of bloodstained or black faeces. Abdominal pain that is accompanied by unexplained weight loss or changes in bowel habits should always be investigated by a doctor.
Investigations and diagnosis
The doctor makes a diagnosis of abdominal pain based on a physical examination and a detailed description of the patient’s symptoms. Investigation of severe abdominal pain may also include blood tests, imaging tests such as ultrasound scanning, and endoscopy (examination of a body cavity using a flexible viewing tube) in the form of laparoscopy (viewing the abdominal cavity), gastroscopy (viewing the stomach and duodenum), or colonoscopy (viewing the large intestine).
The complaint of abdominal pain is probably one of the more common surgical complaints of patients attending both an outpatient clinic and also as an emergency at hospital. The assessment of abdominal pain will be discussed as for ‘acute abdominal pain’, but the underlying history-taking and examination should be the same for both the ‘elective’ and the ‘emergency’ patient. All the organs contained in the abdomen, pelvis and retroperitoneum can be the cause of abdominal pain. However, one must not forget that acute abdominal pain can also be caused by some acute medical problems (porphyria, diabetic ketoacidosis, etc.) in addition to both acute cardiac and pulmonary disorders.
Medical causes of abdominal pain
- Diabetic ketoacidosis
- Pain arising from the heart or lungs
Understanding the mechanism behind the distribution of pain fibres within the abdomen and retroperitoneum helps to explain the clinical symptoms and signs of the acute abdomen. The parietal peritoneum lines the abdominal wall, and the visceral peritoneum invests the viscera. The parietal peritoneum is innervated by the relevant somatic nerves through spinal nerves in the distribution of the overlying dermatomes: the xiphisternum at the level of T4, the umbilicus at T8 and the inguinal ligament at T12. Pain is sharply localised to the point of inflammation of the parietal peritoneum. For example, an acutely inflamed sigmoid colon from diverticulitis causes irritation to the overlying parietal peritoneum, and pain is then localised to the left iliac fossa.
The viscera and visceral peritoneum is innervated by the autonomic nervous system with pain travelling back to the spinal cord along sympathetic fibres. However, the pain is localised or referred to the equivalent somatic distribution of that nerve root (from T1 to L2). This pain is therefore deep, poorly localised and usually associated with sympathetic symptoms such as sweating and nausea. The gastrointestinal tract is divided embryologically into the foregut, midgut and hindgut, each arising with its own blood and nerve supply. Pain from the foregut is localised to the epigastrium, from the midgut to the peri-umbilical region and from the hindgut to the lower abdomen (Table 1).
Table 1 Embryological division of the gastrointestinal tract
Duodenum – first and second parts
Duodenum – third and fourth parts
As a result, early inflammation of a mobile part of the viscera, such as the appendix/small bowel, which does not result in parietal peritoneal inflammation, produces referred pain in the peri-umbilical pain region. As the inflammation reaches the parietal peritoneum, the pain localises to that dermatome, as supplied by the somatic nerve supply. In the case of the appendix, this will obviously be the right iliac fossa. Another example of referred pain occurs when the diaphragm is irritated. As the nerve supply comes from the phrenic nerve (C3, 4, 5), the pain is localised to those dermatomes supplied by the equivalent somatic nerves, and pain may be felt in the region of the shoulder (Summary box 56.4).
Pain due to parietal peritoneal inflammation may also radiate back or forwards along the line supplied by the somatic nerve, as is seen in acute cholecystitis, when pain spreads from the right subcostal region around to the back.
Inflammation of the retroperitoneal structures, such as the pancreas and kidney, causes irritation of the somatic spinal nerves, producing back pain. Similarly, an inflamed retrocaecal appendix will irritate the ilio-psoas muscle, producing pain in the right loin at times, especially when the psoas muscle is stretched. Of course, most causes of abdominal pain will incorporate both visceral and parietal pain, producing a picture that changes as the inflammation increases and spreads. This evolving picture may be picked up within the history-taking process or subsequently by regular and repeated review of the patient. Pain from small bowel obstruction will usually be central and colicky in nature but, as the obstructed loop becomes ischaemic and starts to inflame the overlying peritoneum, the pain will become continuous, more widespread and be associated with signs of ‘peritonitis’ (see below).
The history of abdominal pain associated with specific disorders
Inflammation and infection
Common intra-abdominal inflammatory conditions include acute appendicitis, acute cholecystitis, acute diverticulitis, acute pancreatitis, acute salpingitis (pelvic inflammatory disease) and mesenteric adenitis. The pain is initially often very non-specific, gradually increasing in intensity over a period of several hours or even days (Summary box 56.5; Fig. 56.2). Other conditions that cause abdominal pain through this mechanism include infarction (which may initially present as obstruction, see below) and haemorrhage, where the intraperitoneal blood irritates the parietal peritoneum.
Perforation of an abdominal viscus usually results in the sudden onset of severe abdominal pain (Fig. 56.3). Identifying the viscus in question may be determined by a history of preceding abdominal symptoms or illness, such as constipation or peptic ulcer disease. In the early stages, the site of maximum tenderness may also indicate the organ that has perforated (upper or lower abdomen), but generalised peritonitis usually follows very quickly as the intra-abdominal structures have not had time to try and ‘wall off’ the diseased organ, as often occurs in ‘inflammatory’ conditions. The most common organs that perforate (excluding the appendix) are the stomach and duodenum (from peptic ulcer disease) and the colon (from diverticular disease or severe constipation). Of course, the endpoint of many of the conditions that produce visceral inflammation is perforation but, generally, these patients present with symptoms of the underlying disease first, rather than the short severe presentation associated with a sudden perforation (Summary box 56.6).
Obstruction of any hollow viscus within the abdominal cavity usually causes acute abdominal pain. Obstruction of all viscera except the gall bladder tends to produce colicky pain (Fig. 56.4), while obstruction of the gall bladder (inaccurately termed ‘biliary colic’) usually presents with a more acute continuous type of pain, often punctuated by acute exacerbations, and is similar to that of inflammation, but may have a slightly quicker onset. Colicky pain classically resolves between short-lived episodes, and it is only when underlying inflammation or infection sets in that a more continuous background element to the pain is introduced. This can of course represent the development of a serious complication (such as ischaemia of the bowel) and, therefore, its recognition by the emergency surgeon is crucial to prompt treatment.
Specific characteristics of ‘abdominal pain’
The site, onset, character and duration of the abdominal pain provide important pointers to the diagnosis. Radiation of the pain, progression or alteration of its site or character, factors that aggravate the pain or relieve it and any associated symptoms are also helpful in refining the diagnosis. The site of the abdominal pain is usually related to one of nine areas (Fig. 56.5). These regions are demarcated by the mid-clavicular lines in the vertical axis and by the transpyloric and transtubercular lines in the horizontal axis. Figure 56.5 also indicates some of the common organs and pathological processes that commonly cause pain experienced in these regions.
Obtaining information on aggravating or relieving factors can be particularly helpful to the assessing surgeon. Pain made worse by moving and coughing suggests peritoneal inflammation ‘peritonism’, whereas pain which makes the patient roll around or double up is typical of ‘colic’ (Summary box 56.7). making a diagnosis, and information on the influence of movement, injury, position, food, antacids, vomiting, bowel action and micturition on the pain must always be sought. A history of previous trauma, however minor, may also be important. At the same time, it is important to ask about associated symptoms such as vomiting, diarrhoea, dysuria or a missed period that preceded or followed the onset of the pain as these may again provide important diagnostic clues.
As mentioned earlier, true colic is a gripping pain of sudden onset, which rapidly reaches a crescendo before equally swiftly dying away, usually completely. This description is true of intestinal and renal colic, but biliary colic is a misnomer (see above) as patients tend to complain of a continuous pain with exacerbations of severe pain. As already mentioned, strangulation should be suspected when intestinal colic alters to become a continuous pain.
Other common adjectives for abdominal pains include stabbing, wrenching, boring, burning and crushing, and these should all be taken into account with the other symptoms when trying to reach a diagnosis. Specific areas of radiation are characteristic of certain causes of abdominal pain and help to reach a diagnosis. Some of the classical sites of radiation are shown in Figure 56.6. Identification of the ‘best questions’ to ask is obviously important and, in his studies on acute abdominal pain, de Dombal revealed not only how important enquiry into factors aggravating the pain was, but also that this simple question was omitted in half the patients being questioned in a single hospital. Other surgical symptoms Although each is important in its own right, the other symptoms that cause a patient to be referred for surgical assessment, in either the elective or the emergency setting, do not present the complex pictures associated with ‘abdominal pain’ and can therefore be pooled together for the purposes of this chapter. Clearly, the individual chapters in this textbook will focus on the individual symptoms that are important to diseases of that organ. Common symptoms are:
- abdominal distension/bloating
- abdominal lumps/masses (including groin and scrotal lumps)
- weight loss/cachexia
- altered bowel habit and bleeding/mucous per rectum.
After taking a detailed history, the patient should be carefully examined. An abdominal examination must always be part of a ‘general’ examination, but must specifically include the general appearance of the patient, including cachexia, anaemia, pallor, cyanosis, jaundice, dehydration, fetor and pyrexia. In the acute setting, a rapid (and/or irregular) pulse and low blood pressure may be important.
The neck and chest should be examined next, looking especially for lymphadenopathy, breast tumours and signs of pulmonary disease, while examination of the cardiovascular system may reveal evidence of cardiac failure, valve disorders or peripheral vascular disease.
The abdominal examination is made easier by the preceding history, which should have alerted the clinician to the possible underlying differential diagnoses. However, the opportunity to identify additional findings, which might either confirm or refute these diagnoses, must not be missed by a less than thorough examination. In the assessment of the patient with acute abdominal pain, several good studies have demonstrated that examination, along with the patient’s distress, is facilitated by early administration of adequate analgesia. The old adage that analgesia should be withheld until a patient with acute abdominal pain has been assessed by the surgeon should be banished from every surgical textbook (Summary box 56.8).
The swellings caused by enlargements of the liver, spleen, kidneys and bladder or tumours of the bowel or ovary and other intraabdominal or retroperitoneal structures may all be visible on careful inspection. The expansile pulsation of an abdominal aneurysm may also be seen. All abdominal scars must be noted (and subsequently tested for an incisional hernia). Distension, which is usually caused by ascites, intestinal obstruction or a large intraabdominal tumour, might also be apparent. A careful inspection may also reveal skin eruptions (such as those caused by herpes zoster), distended veins from portal hypertension (or occlusion of the inferior vena cava) and visible peristalsis. The hernial orifices must be specifically inspected (and then examined) along with the male genitalia, looking especially for tenderness and masses within the scrotum.
Palpation of the abdomen should not be carried out until full inspection has been completed. An initial superficial examination might reveal specific sites of a mass or maximum tenderness, which can then be further evaluated by deeper palpation, if appropriate (in the case of pain) (Summary box 56.9).
A mass arising within the anterior abdominal wall will usually be mobile with the patient relaxed. On contracting the abdominal wall muscles (such as by lifting the legs in the straight position), lumps superficial to the abdominal wall muscles will become more obvious, those attached to the deep fascia will become less mobile, whereas those arising within the muscle layer will become fixed and less obvious. Lumps arising deep to the abdominal wall (i.e. within the peritoneal cavity or retroperitoneum) will usually become impalpable on tensing the anterior abdominal wall muscles. Intraperitoneal lumps will usually have some degree of mobility, even if only movement on respiration (i.e. liver and spleen), depending on which organs are involved. Retroperitoneal masses are usually fixed, although an enlarged kidney may be ‘ballotable’.
Guarding and rebound tenderness
In the presence of abdominal pain, the degree of abdominal wall rigidity and involuntary guarding should be assessed. Guarding represents contraction of the abdominal wall muscles over the area of pain. This might occur ‘voluntarily’ when the patient wishes to avoid the pain from examination, or ‘involuntarily’ when the muscles go into spasm as the inflamed viscus touches the parietal peritoneum, resulting in a reflex spasm contracting the overlying abdominal wall muscles. The presence of rebound tenderness indicates underlying peritoneal inflammation and is best examined using percussion, although pain on coughing is also indicative of rebound tenderness. When the underlying peritoneal inflammation becomes generalised, the abdomen becomes ‘board-like’ to palpation, and selective tenderness can no longer be elicited. This sign represents widespread involuntary guarding. Specific pain due to abdominal wall tenderness is apparent as an increase in pain at the point of maximal abdominal tenderness when the abdominal muscles are contracted.
The presence of fluid within the peritoneal cavity may be suspected from clinical examination, but will usually require confirmation by either ultrasonography or computerised tomography (CT). Percussion of the abdomen in a patient with significant ascites will reveal dull flanks and a resonant central area, where the bowels ‘float’ on the underlying fluid. If the patient is asked to turn onto their side, the area of dullness will move downwards over their abdominal wall, while the area of resonance will ‘float’ to the flank of the side facing upwards (Summary box 56.10).
In the assessment of a patient with any gastrointestinal symptoms, a rectal examination is required and, if there is suspicion of underlying anorectal disease, this should be followed by a proctoscopy and sigmoidoscopy. A stool sample for occult blood should also be obtained where possible. However, the role of the rectal examination in assessment of the acute abdomen has changed over the last decade following a large study from Edinburgh, which demonstrated that, in patients with right iliac fossa pain (i.e. suspected appendicitis), no further additional information was obtained if rebound tenderness had already been demonstrated. However, when a gynaecological diagnosis is suspected, or needs to be excluded, a gentle pelvic examination should be carried out (Summary box 56.11).
Listening to the noises emanating from within the abdominal cavity requires experience, and interpretation is highly subjective. However, additional useful information can be obtained in relation to the characteristic bowel sounds produced by intestinal obstruction (gurgling and high pitched) and the total absence of bowel sounds found in patients with a severe generalised peritonitis or a postoperative paralytic ileus. Abdominal bruits associated with underlying vascular disease may also be detected (Summary box 56.12). Specific signs There are a number of specific ‘named’ signs that are still used to describe specific abdominal conditions, and these are described in Table 56.2.
Observation and review
In the case of acute abdominal pain, there is a group of patients in whom, after full clinical assessment, the admitting surgeon considers that the need for an urgent operation is uncertain. This is probably the most difficult group to deal with compared with those in whom an urgent operation is either clearly required, or clearly not required, and undoubtedly the one in which the majority of errors occur. Further expeditious investigations are obviously essential in this group. However, while these are taking place, a period of observation with regular review is essential, and the benefits have been clearly reported on several occasions by surgeons from Aberdeen. This has now become an integral part of the early management of patients with acute abdominal pain and has been further highlighted by a recent prospective trial of CT in the investigation of abdominal pain. In this study, the presumed diagnosis was recorded on admission and at 24 hours, with a further review at 6 months. Only 50% of diagnoses on admission were correct at 6-month follow-up, but 76% of the diagnoses at 24 hours were correct. This included patients in the CT arm and the standard treatment arm.