Why do you palpate before percussion?

General management

Abdominal examination may reveal a mass. Sigmoidoscopy and sometimes faecal occult blood testing (stool guaiac), MRI, ultrasound, barium enema (Fig. 7.8) and colonoscopy may be required. Methylated septin 9 (SEPT9), a plasma test to screen for colorectal cancer, has a sensitivity and specificity similar to those of stool guaiac or faecal immune tests (immunochemical faecal occult blood test).

Surgical resection is the usual treatment. Spread is frequently to the liver. The 5-year survival rate is overall about 30% (Ch. 22). Radiother-apy may be useful for dealing with pain from recurrences. Chemotherapy may be used in advanced cancer: capecitabine, irinotecan, oxaliplatin, raltitrexed and possibly cetuximab. Serial monitoring for serum carcino-embryonic antigen or serum or faecal M2-pyruvate kinase (M2-PK) antigen may help detect recurrences (Ch. 22). Metastatic carcinoma may be treated with bevacizumab, cetuximab or antiangiogenesis agents, such as aflibercept, in combination with chemotherapy.

Abdominal Examination

The abdominal examination begins with a visual inspection of the abdomen and inguinal region for scars (due to prior surgeries or trauma), asymmetry (suggesting a mass or organomegaly), distention (due to obesity, ascites, or intestinal ileus or obstruction), prominent periumbilical veins (suggesting portal hypertension), or hernias (umbilical, ventral, inguinal). The examination proceeds with auscultation followed by percussion, and it ends with light and deep palpation.

In patients without abdominal pain, auscultation of bowel sounds to assess intestinal motility has limited usefulness and may be omitted. Percussion may be performed before or in conjunction with light and deep palpation. Initial cursory light percussion across the upper, mid-, and lower abdomen is useful to denote areas of dullness and tympany, as well as to elicit unanticipated areas of pain or tenderness before palpation. More extensive percussion provides limited but useful information about the size of the liver and spleen, gastric or intestinal distention, bladder distention, and ascites (Chapters 148 and 156Chapter 148Chapter 156). Gentle, light palpation promotes abdominal relaxation and allows the detection of muscular resistance (guarding), abdominal tenderness, and superficial masses of the abdominal wall or abdomen. Deeper palpation of the abdominal organs (liver, spleen, kidneys, aorta) and abdominal cavity may detect enlargement or abnormal masses. Superficial or deep masses should be assessed for size, location, mobility, content (solid, liquid, or air), and the presence or absence of tenderness. The consistency of a patient's response to palpation with and without distraction is particularly useful in those with suspected chronic functional abdominal discomfort. Superficial masses include hernias, lymph nodes, subcutaneous abscesses, lipomas, and hematomas. Deep abdominal masses may be caused by neoplasms (liver, gallbladder, pancreas, stomach, intestine, kidney), abscesses (appendicitis, diverticulitis, Crohn's disease), or aortic aneurysms.

Examination of the right upper quadrant should assess the liver size, contour, texture, and tenderness. Liver size is crudely estimated by percussion of the upper and lower borders of liver dullness in the midclavicular line. Liver contour and tenderness are best assessed during held inspiration by deep palpation along the costal margin. Examination of the left upper quadrant is useful to detect splenomegaly (Chapter 171), although a normal-sized or even an enlarged spleen often cannot be detected. Percussion in the left upper quadrant near the tenth rib (posterior to the midaxillary line) may detect splenic dullness that is distinct from gastric or colonic tympany. The tip of an enlarged spleen may be palpated during inspiration if the examiner supports the left costal margin with the left hand while palpating below the costal margin with the right hand. Ascites should be suspected in a patient with a protuberant abdomen and bulging flanks. To screen for ascites, percussion of the flanks should be performed to assess the level of dullness. If the level of flank dullness appears to be increased, the most sensitive test for ascites is to check for “shifting” dullness when the patient rolls from the supine to the lateral position.

Abdomen

The abdominal examination begins with observation of the configuration, fullness, and movement with respiration of the abdominal wall. Major abdominal wall abnormalities such as omphalocele, gastroschisis, prune belly syndrome, and bladder extrophy will be obvious on initial inspection in the delivery room and may be diagnosed prenatally. A small omphalocele may produce only a slight widening of the umbilicus and proximal part of the umbilical cord (Fig. 25.18). If such an omphalocele is not detected postnatally before the umbilical cord is clamped and cut, the intestine within it may be damaged. Counting of the umbilical vessels is best done in the delivery room on the freshly cut cord.

The abdomen of the newborn ranges from flat to moderately protuberant, with substantial variation depending on feeding and the passage of gas and meconium. A markedly distended abdomen suggests the possibility of significant ascites, a large mass, or an intestinal obstruction. A proximal obstruction (e.g., esophageal or duodenal atresia) does not cause abdominal distention. A sunken or scaphoid abdomen may be seen in the newborn with respiratory distress caused by a diaphragmatic hernia.

The umbilicus should be inspected for meconium staining, signs of infection, visible discharge of urine caused by a patent urachus, and the rare occurrence of pallor and edema. At 1–2 days after birth, slight redness of the periumbilical skin is common, because of irritation from the cord clamp, and needs to be distinguished from an omphalitis or cellulitis. Bowel sounds should be auscultated before one proceeds to palpate the abdomen if the newborn is asleep or resting quietly.

Palpation should initially be gentle and superficial, to detect any signs of tenderness and the presence of an enlarged liver or spleen. Tenderness must be distinguished from the tendency of the newborn to stiffen the abdominal muscles in reaction to the touch of the examiner's fingers, which are usually colder than the newborn's skin. If the examiner's fingers remain in gentle contact within the same spot, the temperature difference quickly dissipates, and the baby will usually relax and allow the examiner to proceed without struggle. In the healthy newborn, the liver edge may be at or slightly above the right costal margin or palpable 1–2 cm below it. The spleen is rarely palpable unless it is enlarged. Gentle palpation of the lower abdomen can detect an enlarged bladder, which is the most common cause of a midline abdominal mass in newborns. Deep palpation to detect small masses or enlargement of the kidneys is most easily done soon after birth, before significant feeding, and when the newborn is quiet. However, a satisfactory examination can be done even in a crying newborn by one keeping the fingers in position and gradually increasing the depth of palpation each time the newborn briefly relaxes the abdominal muscles while taking a breath between cries. It is helpful to support the flank with one hand while palpating the abdomen to detect the kidney with the other or to palpate the abdomen with the thumb while supporting the flank with fingers of the same hand.

Percussion of the abdomen is not particularly helpful in routine examination, but it can sometimes help to define the boundaries of an enlarged liver or bladder.

Tenderness and Muscle Guarding

On routine abdominal examination, an area of maximal tenderness often is elicited in the area of McBurney point, which is located two-thirds of the distance along a line from the umbilicus to the right anterior superior iliac spine. If the appendix is in a high retrocecal position or is entirely within the true pelvis, point tenderness and muscle rigidity might not be elicited. In high retrocecal appendicitis, tenderness may occur over a large area, and there may be no signs of muscle rigidity. In pelvic appendicitis, neither tenderness nor muscle guarding may be present. Both signs are often lacking or only minimally expressed in the aged population.

Signs of peritoneal inflammation or irritation in the right lower quadrant are also helpful in the diagnosis of acute appendicitis and can be demonstrated by many methods. Asking the patient to cough or bounce on the heels elicits this type of pain in 85% of patients. Rebound tenderness is elicited by the sudden release of abdominal palpation pressure. Rovsing sign—pain elicited in the right lower quadrant with palpation pressure in the left lower quadrant—is a sign of acute appendicitis. Muscle guarding, manifested as resistance to palpation, increases as the severity of inflammation of the parietal peritoneum increases. Initially, there is only voluntary guarding, but this is replaced by reflex involuntary rigidity.

What is the purpose of palpation?

Why is it important to use palpation as part of the assessment process?