Clinical Characteristics of the Acute Abdomen Since pain is the most prominent presenting complaint in a patient with an acute abdomen, it is important to know the origin, location, radiation and character of abdominal pain in order to understand its significance. The perception of abdominal pain is first visceral and then becomes somatic. The abdominal viscera and the visceral peritoneum receive sensory fibers via the sympathetic chain from T5 through L3. The sensory supply to the viscera is sparse and visceral pain is vague and poorly localized. The alimentary tract from the esophagus to the anal canal is insensitive to many stimuli which produce intense pain in other structures. The gut can be biopsied, crushed or cauterized without pain. If the bowel or any other hollow viscus is distended or if its muscle coat goes into spasm, however, pain is felt. The cause of visceral pain is tension in the muscle fibers produced by stretching of the wall, spasm of the muscle or stretching of the capsule of the organ. Violent peristaltic contractions occur in an attempt to force luminal contents through an obstruction. Pain associated with obstruction is severe and cramping in nature, but intermittent, with pain-free intervals and is called colic. Ischemia of visceral muscle gives rise to pain because the gut loses motility and becomes distended. Visceral pain of ischemic origin is caused most often by strangulation of the bowel in hernia or volvulus. A less frequent cause is acute mesenteric thrombosis. The parietal peritoneum which lines the abdominal cavity and the interior surfaces of the diaphragm derives sensory fibers from the somatic nerves T6 through L1. When the parietal peritoneum is irritated, somatic pain results. Somatic pain is with localized tenderness and spasm of the muscle groups supplied by the dermatome of origin of the pain stimulus. For example, the right lower quadrant (RLQ) pain, tenderness and muscle spasm associated with appendicitis is caused by inflammation of the contiguous RLQ parietal peritoneum. The abdominal signs in perforated peptic ulcer, on the other hand, are generalized because diffusion of highly acid fluid throughout the peritoneal cavity causes intense irritation of all the parietal peritoneal surfaces. Pain experienced at a site other than that stimulated but in somatic zones supplied by the same or adjacent segments of the spinal cord is called referred pain. Visceral pain is referred to three zones located in the midline of the abdomen. The localization of abdominal pain indicates which organs may be involved. Epigastric pain is associated with structures innervated by T6-T8, the stomach, duodenum, pancreas, liver, biliary tree and associated parietal peritoneum. Periumbilical pain is related to innervation from T9 to T10 and includes the small intestine, appendix, and upper ureters. Hypogastric pain has its origin in structures innervated by Tll and T12, the colon, bladder, lower ureters and uterus. The pattern of radiation of pain may provide important clues as to its origin. For example, pain which initially is located in the periumbilical area and then moves to the RLQ occurs with appendicitis, whereas pain in the epigastrium which radiates to the tip of the right scapula is frequently found with acute cholecystitis. Such shifting or radiation of pain to a localized site with local tenderness and muscle spasm denotes local inflammation of the parietal peritoneum and suggests a circumscribed inflammatory process. The pain of renal colic usually is felt in the flank and radiates towards the groin on the same side. Pain that involves the entire abdomen almost immediately after onset is usually due to flooding of the peritoneal cavity with an irritating fluid from a perforated ulcer, or from blood and chorionic tissue in a ruptured ectopic pregnancy. A general rule to follow is that the majority of severe abdominal pain occurs in patients who have enjoyed fairly good health and which persists as long as six hours is caused by diseases requiring surgical intervention. Obviously, there are always exceptions to any rule. View attachment 16485 Other features of pain and associated GI symptoms which may provide important clues as to cause are listed below in tabular form with some examples of each. Type of onset sudden - rupture of viscus, mesenteric thrombosis gradual - cholecystitis, appendicitis Quality dull - initial epigastric pain of appendicitis sharp - renal or biliary colic or obstruction of gut aching - pelvic inflammatory disease pleuritic - intensified by breathing lancinating - acute pancreatitis tearing - dissecting aneurysm Intensity severe - rupture of viscus or blood in the peritoneal cavity moderate - RLQ appendiceal mild peptic ulcer, without perforation Temporal features continuous - acute pancreatitis pulsatile - abdominal aneurysm colicky - lumen obstruction, intermittent severe pain with pain-free intervals frequency & duration transient pain of short duration which does not recur is usually insignificant. The longer the duration the more likely a surgical condition. Factors which intensify or relieve pain relation to meals - peptic ulcer pain relieved by food, cholecystitis pain aggravated by fatty meal posture jack-knifing - leg drawn up to decrease peritoneal irritation in suppurative appendicitis motion - any movement causes intense pain in generalized peritonitis and the patient lies motionless Associated nausea and vomiting nausea & vomiting - reflex, or irritative non-specific vomiting occurs in many conditions. In surgical disease such as acute appendicitis, anorexia always occurs and vomiting, if it occurs, usually follows abdominal pain rather than preceding it, as in gastroenteritis. Repeated vomiting of large amounts occurs in gut obstruction, is often bile stained and may become fecal. Protracted vomiting time - early in high GI obstruction; late in low GI obstruction character of vomitus - blood - bleeding ulcer bile stained - obstruction below ampulla of Vater fecal - intestinal obstruction, mechanical or with paralytic ileus; copious amount Diarrhea most common with acute gastroenteritis or food poisoning, but it may occur with appendicitis or other focal inflammatory lesions of the gut Constipation or obstipation With complete small bowel obstruction - unrelenting constipation (obstipation) after fecal material below obstruction has been passed. Progressive constipation with carcinoma of the large bowel. Gas stoppage with decreased or absent bowel sounds - paralytic ileus All of the patient's symptoms must be carefully considered and analyzed, especially with regard to organs most likely to give rise to acute conditions. Extraabdominal conditions which simulate the acute abdomen arise most often in the heart, lungs, urinary tract and female reproductive organs. The age and sex of the patient will provide helpful leads as to which conditions responsible for a "hot belly" are most likely, outlined below: Age - newborn - congenital anomalies, gut atresia, imperforate anus, malrota2ion, diaphragmatic hernia Neonatal - hypertrophic pyloric stenosis (males), megacolon, hernia Later infancy - intussusception Childhood and young adults - hernia, appendicitis - most common but can occur at any age Young adolescent females - "mittelschmerz" - rupture of graafian follicle with LLQ or RLQ abdominal pain occurring in the middle of the menstrual cycle. Females - gallbladder - female, fair, fat, forty ectopic pregnancy pelvic inflammatory disease Males - peptic ulcer Advancing age - mesenteric thrombosis or embolus often after myocardial infarction, large bowel neoplasms, diverticulitis Past history of disease or abdominal operation abdominal scars, adhesions - intestinal obstruction peptic ulcer - possible perforation chronic cholecystitis or biliary colic - acute cholecystitis Physical Examination Careful and complete data collection by history and physical exam is the prime diagnostic aid to avoid errors of omission and to separate those conditions which require immediate surgery from those which require watchful expectancy, or those which require medical rather than surgical management. Often the patient's condition is such that extensive laboratory investigation requiring many hours would compromise the patient's life and thus the outcome often depends on a precise and detailed history and physical examination. A complete general physical examination provides essential data for making the diagnosis, determining the urgency of the condition, assessing the patient as an operative risk, and making a sound management plan. First, the patient is surveyed rapidly for fever and/or evidence of shock, hemorrhage, anemia, dehydration or cardiac decompensation. When necessary, if the patient is severely ill and/ or shocked, resuscitative treatment should be started immediately and a detailed history and examination deferred temporarily. On observation of the patient, the severity and character of the pain may be apparent. Temperature, pulse, respiration and blood pressure are recorded, providing a base line for later observation. Complete and systemic examination of all organ systems is done next, usually deferring abdominal rectal and pelvic examination until last. It is important that the heart and lungs be carefully examined, not only to determine if an extraabdominal cause for abdominal pain is present, but to determine whether the patient is in satisfactory condition for surgery if this is indicated. The abdominal examination, including pelvic and rectal, provides information which indicates the type and degree of the intraabdominal process on which the diagnosis can be based and the recommendation for or against surgical intervention determined. The abdomen must be exposed completely for examination. The patient should be in a comfortable supine position with the knees slightly flexed to relax the abdominal musculature, and the examiners hand should be warm. A calm sympathetic approach and gentleness in examination on the part of the practitioner are very helpful. The patient is asked to point with one finger to the area of greatest pain, and the examiner should be especially gentle when studying these areas. Inspection of the abdomen may reveal significant surgical scars. Auscultation of the abdomen is performed next. The intestine is quite sensitive to touch, and peristaltic bowel sounds can be best evaluated by listening to the abdomen before palpating it. Auscultation is most helpful in determining functional activity of the bowel. When alterations in bowel sounds occur in association with other changes, they have clinical significance. Decrease in gastrointestinal motility and function is part of the reaction to local and general stress. For example, an acute fracture of the femur will cause a paralytic ileus and a silent abdomen, as will generalized peritonitis. The inhibition generally does not persist and, after several hours or days, sounds will be heard again as bowel function resumes following appropriate treatment. Bowel sounds in established mechanical obstruction may be striking. The sounds are loud, booming, rhythmical, and synchronous with colicky pain. As the bowel becomes distended, the sounds become more high pitched and take on a tinkling quality. Borborygmi is the term applied to the very hyperactive bowel sounds associated with mechanical obstruction. Early in bowel obstruction peristaltic activity can be very vigorous. In time, however, the obstructed bowel fatigues and bowel motility decreases, resulting in hypoactive or absent bowel sounds as distention-inhibition and vascular impairment of the intestine develop. The next step is systematic palpation of the abdomen with light pressure (to a depth of about 1 cm) beginning at a distance from the area of maximal tenderness and alternately testing and comparing each side with the opposite side, while observing the patient closely for wincing or other evidence of pain. The entire abdomen is palpated systematically for areas of tenderness, muscle spasm, or presence of masses. Any specific areas which may appear abnormal should be retested and re-evaluated. Deep palpation, again done gently, gives more information about deep tenderness or the nature, size, and consistency of any lesion or mass. On deeper palpation the examiner advances the probing fingers deeper into the patient's abdomen when the patient inspires, as this maneuver tends to relax the musculature of the abdominal wall. When muscle spasm and tenderness are very marked, deep palpation is quite painful, uninformative and unnecessary. Persistent localized tenderness, point tenderness , is the most important sign of peritoneal inflammation. In acute appendicitis, when point tenderness is definite, it is an indication for surgery. Rebound tenderness may be demonstrated when pain is experienced on sudden release of deep pressure. Information concerning a localized area of peritoneal irritation may also be obtained by having the patient rise on his toes and come down suddenly on his heels, identifying where pain is felt. This is the so-called "jarring test" and it is said to be more objective than the rebound test. Percussion of the abdomen is helpful in demonstrating gas or fluid in hollow organs or in the free peritoneal cavity. When the abdomen is enlarged and hyperresonant, intestinal distention or pneumo-peritoneum should be considered. Free fluid within the peritoneal spaces is demonstrated by testing for a fluid wave and shifting dullness. In ascites, bulging in the flanks may be observed. Dullness to percussion can be helpful in determining the size of an enlarged spleen or liver or a solid tumor mass. The physical examination must include rectal palpation in the male and pelvic and rectal examination in the female. Fecal impaction, pelvic abscess, and neoplasms may produce signs of intestinal obstruction. When an inflamed appendix lies low in the pelvis, there may be rectal tenderness or a palpable pelvic mass in the absence of abdominal signs. Disease of the female pelvic organs may produce acute abdominal conditions. Bimanual pelvic examination may reveal a tubal or ovarian mass, exquisite tenderness on movement of the cervix, or bloody or purulent cervical discharge, suggestive of acute pelvic complications. If physical findings are equivocal, the patient should be reexamined at frequent intervals until a diagnosis can be made and/or proper management of the patient determined. Laboratory Tests Urgency of acute abdominal conditions usually precludes prolonged investigation. There are only a few specific tests or examinations which may be relied upon to give clear cut answers to the exact cause of the acute condition. Urine and blood should be examined routinely. Pus or blood in the urine suggest disease of the urinary tract and can also result from an inflamed appendix lying in proximity to the ureter or bladder. In dehydration the specific gravity of the urine may be increased, and the red cell and hemoglobin values increased as a result of hemoconcentration. The total leukocyte count and percentage of polymorphonuclear cells are usually elevated in acute inflammatory conditions, whereas early in the course of intestinal obstruction there may be no significant alterations. Conditions in which tissue necrosis occurs, as in a strangulated intestinal obstruction, are generally associated with a marked polymononuclear leukocytosis. With acute appendicitis, the leukocytosis isn't great unless you already have a perforated appendix. The serum amylase test is essential when the possibility of acute pancreatitis exists. This possibility should be kept in mind in all patients with acute severe upper abdominal pain. Serum amylase values in excess of 500 units are significant and levels of 1500-2000 units or more are not unusual in the early stages of severe acute pancreatitis. Certain tests are indicated when extraabdominal conditions are suspected as the cause of an acute abdomen. These include blood and urine sugar determinations in diabetic keto- acidosis, hemoglobin electrophoresis in possible sickle cell crisis, chest x-ray in pneumonia, EKG in coronary artery disease, and lead levels in children with pica and anemia with an eye to chronic lead poisoning. Serum electrolytes to determine the degree of dehydration and electrolyte imbalance should be done when fluid loss has been significant.