Surgical Assessment of the Abdomen

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chapter 12 Surgical Assessment of the Abdomen

Michael Giacomantonio

When unsure of the diagnosis, take the history again.

When you examine the abdomen of an infant or child, you need a clear understanding of the anatomic structures and physiologic phenomena involving the abdomen and its contents. In addition, special clinical skills are required to evaluate a child of any age with abdominal distress.

Abdominal symptoms can be manifestations of clinical problems that originate outside the abdomen, including various systemic and thoracic conditions (e.g., lower lobe pneumonia). Applying your knowledge methodically to the evaluation and management of a child with abdominal distress should allow you to diagnose most conditions correctly.

This chapter highlights clinical situations with which you should be familiar and offers some practical insights that should help you acquire the necessary clinical skills to evaluate a child with abdominal distress. It also includes selected topics that are encountered as part of the thorough evaluation of the abdomen and its related anatomical areas.

The history is ultimately the story of the pathophysiology of the problem.

Clinical Conditions by Typical Age of Occurrence

Abdominal problems in the newborn

Most neonatal abdominal problems develop as a result of adapting to extrauterine life. Therefore, rather than defining the neonatal period as the first month corrected for gestational age, defining it as the first month of life ex-utero is more appropriate.

Necrotizing Enterocolitis

In necrotizing enterocolitis (NEC), which is a potentially serious disorder, a sequence of events combine in newborns (usually in those who are premature) to stress the infant bowel. Under stress of any kind, blood is shunted from less vital to more vital organs, threatening the infant’s gastrointestinal (GI) tract (the autonomic stress reflex). The tiny, highly reactive vessels of the GI tract allow the stress reflex to shunt blood away from the infant gut, particularly in the ileocecal region (furthest from the central vascular system), causing ischemic injury of the bowel to occur. This process, in turn, exposes deeper layers of the bowel wall to the enteric contents. The combination of ischemic injury and contamination by bowel contents can lead to bowel wall infection, progressive transmural injury, and, ultimately, necrosis and perforation. When the infant is fed, the added metabolic demands of digestion on an already ischemic bowel can further aggravate mucosal injury and accelerate the cascade of bowel wall injury. Premature infants are especially vulnerable to this sequence of events.

Feeding a stressed premature infant is a set-up for necrotizing enterocolitis.

Understanding the threat of this triad (i.e., prematurity, feeding, and stress) is essential when trying to prevent progression to severe bowel injury and perforation. The earliest clinical signs are those of bowel dysfunction, that is, unexpected abdominal distention and feeding intolerance. Plain abdominal radiographs may show early evidence of ileus, which should trigger an aggressive effort to prevent progression by putting the gut to rest, that is, by stopping feeding, initiating nasogastric decompression, and administering a broad-spectrum antibiotic. If the subtle early signs of ileus are missed and ischemic mucosal injury leads to sloughing and bleeding, bloody bowel movements may be seen, and with further progression, transmural injury and perforation can occur. Early transmural injury may be accompanied by pneumatosis intestinalis (air within the bowel wall), which can be seen on plain abdominal radiographs. Serial radiography may identify further signs of progression. Unremitting sepsis and bowel perforation are indications for surgical intervention.

While managing infants with NEC usually involves neonatologists and pediatric surgeons, general pediatricians and family physicians may be involved in the care of such infants. Awareness of the threat, timely evaluation, and intervention can make a big difference in the outcome.

Malrotation

Malrotation can occur when the midgut fails to position itself normally within the abdomen. As a result, the retroperitoneal attachments of the midgut, which usually extend from the fourth part of the duodenum to the ileocecal area, are narrow, resulting in close approximation of the duodenum and cecum. This phenomenon allows the midgut to hang from its pedicle at the level of the second part of the duodenum. This pedicle includes the cecum, duodenum, and superior mesenteric vessels. Midgut ischemia can be life-threatening.

Early in its progression, a volvulus, twisting around the second part of the duodenum, will lead to both duodenal and vascular obstruction, which is venous at first and later arterial, resulting in bilious vomiting—the typical presenting clinical feature. Progressive volvulus will cause venous obstruction first and then arterial obstruction, with subsequent clinical features of discomfort. At first, an affected infant may show no discomfort other than bilious vomiting, but that single feature demands immediate action. Plain abdominal radiographs may show no abnormality early in the process. However, an experienced pediatric radiologist looking specifically at the proximal duodenum may recognize the volvulus, which typically appears as a corkscrew type of partial duodenal obstruction. If this critical feature is missed, contrast in the more distal upper small bowel may appear entirely normal, and the diagnosis may be missed.

Malrotation with midgut volvulus requires urgent surgical intervention to untwist the bowel and separate the duodenum and ileocecal area sufficiently to minimize the risk of an anatomic pedicle at the mesenteric vessel level that could lead to recurrence of the volvulus.

Bilious vomiting in a newborn demands a full explanation.

Duodenal Atresia/Stenosis

Duodenal atresia or stenosis are simply different degrees of the same abnormality. They usually occur at the level of the ampulla of Vater and are thought to be a result of compromised development of the segment of the duodenum where the ventral anlage of the pancreas develops and rotates to join its posterior segment. Thus, it can occur in association with an annular pancreas, resulting in a partial or complete duodenal obstruction. The annular pancreas in this situation is incidental and not clinically significant. A significant proportion of affected infants also have Down syndrome (trisomy 21). Prenatal diagnosis of both conditions is now possible.

Postnatally, duodenal stenosis or atresia causes feeding intolerance and vomiting, which may be bilious or nonbilious, depending on where the obstruction is in relation to the ampulla of Vater. Diagnosis is usually made with a radiograph of the abdomen with the infant upright, demonstrating the classic “double-bubble” sign. This sign is the result of dilation of both the stomach and the proximal duodenum, each being partially filled with fluid, and thus demonstrating two air fluid levels. Immediate surgical correction is required.

Intestinal Atresia

Intestinal atresia is thought to result from an in-utero vascular accident in a mesenteric segment of the bowel beyond the duodenum, causing loss of a segment of bowel, with sealing of the ends of the remaining bowel. A membrane may develop between the proximal (obstructed) segment and distal (unused) bowel segment. In severe cases, the vascular insult can result in loss of a significant segment of bowel between the proximal (atretic) and distal (unused) bowel. When this phenomenon occurs in utero, continuing fetal bowel function leads to bulbous distention of the proximal obstructed segment. The infant presents with abdominal distention, with or without bilious vomiting. Plain abdominal radiographs demonstrate obstruction and a bulbous proximal dilated bowel. Management is surgical, anastomosing the proximal dilated and distal unused segments to restore bowel continuity. The outcome varies but is usually favorable, depending on the amount of bowel lost.

Meconium Ileus

Meconium ileus is a congenital small bowel obstruction caused by plugging of the distal small bowel with meconium. Most infants with meconium ileus are found to have cystic fibrosis on subsequent investigation or neonatal screening. Such infants present with signs of distal bowel obstruction—that is, abdominal distention and possibly bile-stained vomiting. Plain abdominal radiographs demonstrate the obstruction. Management may be nonsurgical if it is possible to promote (with contrast enemas) the wetting and loosening of the meconium plug to allow its spontaneous passage. If the promotion of spontaneous passage is not possible, surgical intervention is required.

Hirschsprung Disease

Hirschsprung disease results from incomplete development of the distal enteric nervous system in the large bowel. The result is an absence of peristalsis and loss of reflex relaxation of the distal affected bowel, creating a functional partial large bowel obstruction. The rectum is the usual area involved, but it can extend to include the sigmoid or more proximal colon. In extreme cases, it can involve most of the colon. Histologically, there is an absence of ganglion cells in the affected bowel, and thus the disorder also is referred to as aganglionosis. The usual clinical presentation includes failure to pass meconium during the first 2 days of life in an otherwise normal full-term infant, with subsequent evidence of partial or complete distal bowel obstruction.

Failure to pass meconium spontaneously within the first few days of life should raise concerns of possible aganglionosis.

When Hirschsprung disease is suspected, a contrast enema should be performed, in which one looks specifically for an inverse ratio between the diameter of the rectum and that of the sigmoid colon. Normally, the rectal diameter is larger than that of the more proximal sigmoid colon; that is, the normal rectosigmoid ratio is greater than 1. (Note that the contrast enema must be done with isotonic [NOT hyperosmotic] contrast material, because instillation of hyperosmotic material into a colon that cannot evacuate may draw fluid into the colon, causing severe hypovolemia.)

Diagnosis is confirmed by a distal rectal biopsy to demonstrate the absence of ganglion cells and the presence of hypertrophied nerves.

Management requires distal intestinal decompression, resection of the aganglionic segment of distal bowel, and anastomosing the proximal (normally innervated) bowel to the area just above the anus.

Imperforate Anus

Imperforate anus is part of a spectrum of anal maldevelopment. In its mildest form, anal stenosis can occur. In its most severe form, the anus is absent. In embryologic development, the most distal (endodermal) portion of the GI tract blends precisely within the complex anal muscular apparatus (a product of the ectodermal layer). If the GI tract does not end precisely within the anal muscular structures, it usually ends in a fistulous tract anterior to its normal relationship to the anus. The more anterior the fistula, the more severe the maldevelopment. In male infants, such a fistula can occur at the anterior aspect of the anal dimple, anteriorly along the perineum, or internally, along the posterior aspect of the urologic structures, such as the posterior urethra or even higher. In female infants, the fistulous opening can occur, as in male infants, along the perineal raphe or along the posterior aspect of the vagina. The most common fistula in female infants is at the posterior fourchette of the vagina, just distal to the hymenal ring.

As with any embryologic event that compromises normal development, more than one system may be involved. Thus, imperforate anus may occur in association with a constellation of abnormalities, referred to as the VACTERL syndrome, a mnemonic for Vertebral, Anal, Tracheal, Esophageal, Renal and Radial Limb syndrome. Therefore, any infant with imperforate anus must be carefully assessed for associated abnormalities.

The outcome for such infants is usually good, although reconstruction can compromise anorectal function. Most children who have had surgical correction require bowel management programs to assist with evacuation and fecal continence. Aggressive bowel management can help minimize the social stigmata of fecal incontinence.

Careful inspection of the anal and perineal area of newborns is an important part of the newborn’s initial examination.

Omphalocele

An omphalocele results from a failure of complete closure of the abdominal wall around the umbilical structures. Small omphaloceles represent incomplete closure of the abdominal wall so that an amniotic membrane remains at the umbilical site from which the umbilical vessels extend. Surgical repair is easily accomplished.

Larger (giant) omphaloceles also represent incomplete closure of the abdominal wall, with the central area having an amniotic covering from which the umbilical vessels emanate. In giant omphaloceles, the amniotic membrane covers a significant portion of the central abdominal cavity. In infants with a giant omphalocele, it is believed that the abdominal wall, although seemingly fully developed, is inadequate to contain the otherwise normal abdominal viscera. Management often requires a staged repair.

Here, too, it is important to look for associated congenital abnormalities, particularly in the cardiovascular system.

Outcome depends on the size of the omphalocele and/or associated anomalies. Infants with giant omphaloceles may require multiple interventions, and prognosis is more guarded.

Gastroschisis

Gastroschisis represents an in utero developmental defect in which a significant portion of midgut, including small bowel and proximal colon, extrudes through the abdominal wall to the right of the umbilical cord.

In infants with gastroschisis, the bowel is at risk of injury from exposure to amniotic fluid and from twisting of the bowel at its mesentery. Fortunately, vascular compromise is rare; however, inflammation of the bowel is common because of exposure within the amniotic fluid.

The clinical priority is to protect the bowel with gauze soaked in saline solution, covering it with a plastic membrane to minimize evaporative heat and water loss. The infant usually is placed on the right side, because the defect typically is to the right of the umbilical cord, and the bowel is propped up to avoid traction at the mesentery. The infant will require transfer to an appropriate facility for evaluation and surgical intervention. Prenatal diagnosis of this condition is now possible, with transfer of the expectant mother for delivery at a facility that can provide appropriate care for the infant.

The outcome is usually favorable if the bowel has not been significantly compromised. Most affected infants have some swelling of the bowel due to inflammation caused by exposure within the amniotic fluid. Resolution of edema and inflammation usually occurs over a few days following repair of the defect. In a few infants, however, inflammatory injury of the bowel can be sufficiently severe that functional bowel loss can be a significant threat. Associated anomalies with gastroschisis are no more common than in the general population.

Inguinal Hernias

Inguinal hernias are not uncommon in neonates, especially in premature infants and in male neonates. These hernias result from persistent patency of the processus vaginalis and often are asymptomatic. Premature infants with an inguinal hernia that remains asymptomatic often can wait until they are older to have the hernia repaired when administration of an anesthetic is less of a risk. The risk of postanesthetic apnea is a very real concern in newborn infants, especially premature infants, and this risk persists until after approximately 3 months corrected gestational age.

Asymptomatic hernias in neonates should be left alone and repaired electively after 3 months corrected gestational age.

Symptomatic hernias, that is, those causing irritability and those that include episodes of incarceration, demand more urgent attention.

In a premature infant it may be difficult to determine whether a hernia is causing discomfort, but when an inguinal hernia is present, it is reasonable to question if it is an aggravating factor. If the baby seems completely comfortable in spite of what looks like a large hernia, it is best to wait until the optimal time for repair (i.e., after 3 months corrected gestational age). Do not reduce an asymptomatic distended scrotum and inguinal area repeatedly. This procedure will cause unnecessary discomfort, and the hernia often reappears immediately after reduction.

On the other hand, if the baby seems symptomatic—for example, showing unexplained irritability—then reduction is appropriate. When incarceration occurs, careful reduction is absolutely required, and surgical repair is urgent.

Pyloric Stenosis

Pyloric stenosis is caused by hypertrophy of the pyloric musculature, resulting in partial gastric outlet obstruction. It has a tendency toward familial occurrence. Most affected infants present clinically between the third and fifth week of life with “spitting up” that progresses to projectile vomiting of nonbilious material in an otherwise healthy infant.

Emesis of chloride-rich gastric contents, combined with the inability to consume an adequate amount of fluid, can lead to dehydration and metabolic alkalosis due to the hypochloremia. Thus hypochloremic metabolic alkalosis with possible hypokalemia and paradoxical aciduria are typical of this condition.

Diagnosis can be confirmed unequivocally by palpating the thickened musculature that feels like an olive in the upper abdomen to the right of the midline, which is best palpated from the infant’s left side. The “olive” often can be difficult for inexperienced clinicians to palpate, and because modern abdominal ultrasound technology is so accurate with regard to diagnosis of pyloric stenosis, it frequently is used to confirm the diagnosis.

Following correction of fluid and electrolyte disturbances, treatment is by surgical pyloromyotomy. The thickened musculature is divided along its entire length to relieve the luminal obstruction. This procedure allows the pylorus to relax, and when healing is complete, the muscle often returns to a normal state, as does gastric function.

Umbilical Hernia

The presence of an umbilical hernia is common in perfectly normal infants. Spontaneous closure usually occurs during the first few years of life, even for large hernias. Therefore, surgical intervention should be deferred, at the very least until 2 to 3 years of age. If there is any evidence of closure occurring during that time, an even longer period of observation is advisable. This approach is safe because incarceration of an umbilical hernia is exceedingly rare. In the uncommon event that surgical repair is required, it is usually carried out before the child is school aged.

Umbilical hernias are asymptomatic, and incarceration is exceedingly rare.

Umbilical Granuloma

Umbilical granulomas are common in newborns and usually resolve spontaneously. If an umbilical granuloma persists, topical application of silver nitrate produces a chemical cauterization and desiccation. The granuloma is the result of residual umbilical cord tissue that persists after the cord separates. It can be a nuisance because the drainage that occurs can be somewhat purulent. Occasionally, such granulomas increase in size beyond the usual couple of millimeters in diameter to more than a centimeter in diameter. Larger granulomas may require excision, but even these usually disappear with repeated topical applications of silver nitrate.

Persistent granulomas ultimately epithelialize to result in a tiny umbilical nodule at the base of the umbilicus. These nodules rarely increase in size and may result in an umbilical epidermoid inclusion cyst that requires surgical excision. Tiny persistent epithelial nodules at the base of the umbilicus should be left alone.

Occasionally, an umbilical granuloma will resist efforts at silver nitrate cauterization. Such a granuloma should be carefully evaluated because it may, in fact, represent a persistent ectopic (usually intestinal) mucosa rather than a granuloma, related to incomplete disappearance of the vitelline duct. Such a persistent mucosa demands careful evaluation to assess whether any deeper associated connections exist, such as an (uncommon) omphalomesenteric duct. A persistent mucosa ultimately will require excision; otherwise, it will continue to produce serous or mucous drainage.

Perianal Abscess

A perianal abscess is not uncommon during the first few months of life and is not associated with any underlying pathology. It is thought to occur from infection of a perianal gland.

The clinical course is variable, with the transient appearance of an otherwise asymptomatic “lump” in the perianal area or development of a frank abscess that then drains either internally or externally.

If an abscess occurs, application of warm compresses usually is all that is required. If spreading cellulitis is a concern, a broad-spectrum antibiotic is indicated. On rare occasions, incision and drainage may be required.

If a perianal abscess drains externally, a fistula-in-ano may develop. If that occurs, expectant management is usually all that is required. Resolution may be slow over a number of months; nonetheless, a fistulotomy usually is not required.

Both perianal abscess and fistula-in-ano usually are best treated nonoperatively.

Infants (up to 3 years of age)

Intussusception

Intussusception occurs when a proximal segment of bowel is telescoped by peristalsis into a distal segment, causing partial bowel obstruction. Intussusception can occur at any age, but most cases occur between 3 months and 3 years of age. The most common site involved is the ileocecal area, where the lymphatic tissue of the terminal ileum can become swollen, causing protrusion of the overlying mucosa into the lumen. This site acts as a lead point for ileocolic or ileo-ileocolic intussusception. The intussuscepted bowel becomes engorged with blood because of partial venous obstruction; mucosal sloughing can occur thereafter. Typically the child presents with severe, colicky abdominal pain due to a combination of traction on the intussuscepted bowel and partial obstruction. Later, blood mixed with mucous may be passed by way of the rectum or seen on a digital rectal examination.

Early in the clinical course of intussusception, the clinical examination may be normal, but eventually a sausage-shaped mass may become palpable, usually in the right upper quadrant. In the absence of a palpable mass, a digital rectal examination may be done to look for the presence of blood on the examining finger. This mucous has been described as “red currant jelly” stool.

Rectal examinations are rarely indicated in infants. However, when intussusception is suspected, a careful digital examination may demonstrate bloody mucus that has not yet passed.

Plain abdominal radiographs may suggest the possibility of an intussusception if they demonstrate a paucity of gas in the right lower quadrant. However, a more precise diagnostic tool is abdominal ultrasonography. If the ultrasound examination results are inconclusive and the diagnosis remains in question, a contrast enema is used for diagnosis. If the baby does not have evidence of peritonitis, the contrast enema can be used, with a carefully controlled head of pressure as a therapeutic enema to effect hydrostatic reduction. This procedure should be done by experienced practitioners who are aware that an excessively aggressive effort at reduction can lead to colonic perforation. A large proportion of intussusceptions, if diagnosed early, can be reduced by contrast enema. If hydrostatic reduction is not possible, surgical reduction is necessary.

Undue delay in diagnosis may lead to loss of viability of the intussuscepted bowel, in which case surgical reduction may not be possible, necessitating resection of the infarcted segment.

Any intussusception that is reduced successfully by either method may be at risk for recurrence, which usually occurs shortly after the initial presentation. Therefore, a period of observation following reduction is appropriate. When reduction is successful, symptoms disappear rapidly.

Most intussusceptions occur spontaneously, that is, without a clearly defined lead point. The second most common cause of intussusception is a Meckel diverticulum, the inversion of which can serve as the lead point with intussusception into the more distal small bowel (ileo-ileal intussusception), causing partial or complete small bowel obstruction. While ultrasonography can confirm the diagnosis, contrast enema will show a normal colon. In such cases, surgical reduction is required.

Meckel diverticulum represents a persistent remnant of the omphalomesenteric duct. It occurs in about 1% of individuals but is usually asymptomatic. A small percentage of Meckel diverticula contain an ectopic gastric mucosa, which may produce acid and pepsin and cause ulceration of the contiguous normal ileal mucosa of the diverticulum. As with any ulcer, this can lead to blood loss. The classic presentation is of a child with no abdominal symptoms who becomes pale because of a low hemoglobin level and passes wine- or maroon-colored blood by way of the rectum. This presentation is virtually diagnostic of Meckel diverticulum. A technetium scan can confirm the diagnosis, because technetium is taken up by gastric mucosa. The scan is considered positive if, in addition to the stomach demonstrating activity, a separate patch of activity is seen elsewhere in the abdomen. Management requires surgical resection of the Meckel diverticulum, but a negative scan in the context of a classic presentation does not exclude the need for surgical intervention.

Meckel diverticulum also can present as a bowel obstruction caused by the intussusception; alternately, a persistent band (also an omphalomesenteric remnant) attached to the diverticulum may act as a fulcrum for a volvulus or a band, under which a segment of bowel can be trapped. As with any unexplained bowel obstruction, surgical intervention is required.

Finally, a Meckel diverticulum can present clinically by mimicking appendicitis. Here, too, surgical resection is required.

Rectal Prolapse

Rectal prolapse is not uncommon in toddlers and is thought to occur in those who have a limited rectal shelf at the level of the puborectalis muscle. The resulting relatively straight direction between the anal opening and the sigmoid above allows intussusception of both rectal and sigmoid tissue when the infant strains to defecate. Rectal prolapse can occur with relatively little straining. (The very first appearance of a rectal prolapse in an apparently healthy child can be a relatively scary event for parents.)

When an infant presents with rectal prolapse, a careful history and clinical examination are needed to exclude any associated pathology. Cystic fibrosis, in particular, is associated with an increased incidence of rectal prolapse. One should seek signs or symptoms suggestive of that condition by carefully obtaining a history.

A carefully conducted digital rectal examination is necessary to ensure that the prolapse is not associated with other rectal or pelvic pathology, such as a pelvic mass.

When a prolapse in a toddler is unassociated with any other pathology, it usually is a self-limited problem. Measures to minimize straining with bowel movements, patience, and reassurance will allow spontaneous resolution of most cases of rectal prolapse, although resolution may take many months. Children who strain excessively with bowel movements should be treated for constipation. The most important intervention required is strong reassurance of the parents. Most prolapses will reduce spontaneously, but they can be frequent, which can be disconcerting to parents. Occasionally, parents have to manually reduce a prolapse that does not reduce spontaneously.

When rectal prolapse is associated with a neurologic injury or when additional conditions, such as autism, are present, surgery may be a more appropriate option than expectant management.

Rectal prolapse in otherwise normal toddlers is rarely, if ever, a surgical problem.

Colonic Pseudoobstruction (with Gastroenteritis)

Colonic pseudoobstruction during a viral illness is a dramatic but uncommon occurrence. Colonic pseudoobstruction has many potential causes, including neurologic disease and ingestion of antiperistaltic medication, but most cases occur in otherwise normal children during a viral illness. If you have ascertained that there are no aggravating factors, such as medication, then time and patience are all that are required in addition to general care.

True colonic obstructions are rare in infants and children with normal anorectal development and previously normal colonic function. Contrast enemas cause discomfort and are unnecessary. Even if the colonic distention looks dramatic—and while there may be some benefit to placement of a nasogastric tube to try to minimize the consequences of further swallowed air—there is rarely any benefit from placement of a rectal tube. Time, observation, and reassurance are usually all that is required.

Epigastric Hernia

Epigastric hernia is a congenital defect of the linea alba along the line between the umbilicus and the xiphoid, usually in the lower third of the linea alba (above the umbilicus). These hernias typically present as a recurrent lump with a palpable tiny defect or as a small lump of preperitoneal fat protruding through and trapped by a tiny midline defect. There is little change in size over time and rarely any associated discomfort.

These defects do not resolve spontaneously. Surgical intervention is not urgent, although time may lead to the accumulation of more and more fat in the tiny defect, leading to a significant subcutaneous lump. Surgical repair is usually advised for the sole reason of minimizing progression to a cosmetically more significant lesion.

Diastasis Recti

Diastasis recti is not a pathological entity. The broad angles of the subcostal margins in infants are such that the rectus muscles in infants can be widely separated in the upper abdomen, creating a broad linea alba that can be relatively thin, allowing a ventral ovoid bulge between the umbilicus and xiphisternum with straining. This bulge is of no clinical significance; in time, with growth, gradual approximation of the rectus muscles occurs and it disappears.

Swallowed Foreign Objects

When infants and children swallow foreign objects, they can become lodged in the esophagus and may need to be removed. In the most common clinical situation, the child swallows a small foreign object (most often a coin) that gets stuck in the upper esophagus and cannot be “milked” by esophageal peristalsis beyond the aortic arch. When this situation occurs, esophagoscopy and removal are usually appropriate.

If an ingested small foreign body passes into the distal esophagus and is asymptomatic, a short period of observation may be appropriate, because foreign bodies that descend that far often pass into the stomach and ultimately through the full length of the GI tract. For most such objects, continued observation is not required. An exception is the ingestion of a watch battery, which can undergo corrosion of its seals, releasing harmful material into the stomach. If a watch battery has not passed beyond the stomach within a short (1- to 2-day) period, endoscopic removal should be considered.

Evaluation for small ingested foreign objects usually is done by radiography. Posteroanterior (PA) and lateral chest radiographs for the esophagus and PA and lateral upright abdominal films for small objects beyond the esophagus are usually all that is required. If the object is not radiopaque—for example, if the object is plastic—and the child’s symptoms suggest it is lodged in the esophagus, esophagoscopy for retrieval is indicated. If the youngster is completely asymptomatic and the object is not seen on radiograph, observation alone is required, without additional imaging. If a watch battery is in the stomach and is being followed, repeat plain films of the abdomen over the next day or two can ensure that it has passed beyond the stomach. Most other small foreign bodies in the stomach will pass spontaneously without symptoms, and thus there is no need for serial imaging.

Long objects and sharp pins are reasonable exceptions and may require formal follow-up and/or possible removal.

Ingested coins that pass into the stomach may remain lodged in the stomach for weeks before passing safely through the GI tract.

School-aged children

Appendicitis

Appendicitis can occur at any age, but it presents most frequently during late childhood and early adolescence. The pathophysiology of appendicitis is thought to be an obstructed or partially obstructed appendix, causing stasis in the distal appendiceal lumen and an infection that progresses from intraluminal to transmural. The cause of the obstruction may be a fecalith but often is speculated to be a mucosal or submucosal swelling of an unknown cause. Without treatment, appendiceal infection and inflammation can lead to increased pressure within the appendiceal lumen. Tension within the appendiceal wall can produce a mural transudate, then a transmural exudate. Ultimately, with increased pressure and appendiceal wall tension, mural necrosis and perforation can occur, with release of the infected appendiceal contents into the peritoneal cavity.

This sequence of events has clinical correlates at each stage. Piecing together the clinical observations in correct temporal order usually allows for an accurate diagnosis. Clinically, the following sequence occurs:

1. An unspecific gastrointestinal disturbance correlates with the early phase of obstruction of the appendiceal lumen.

2. Transmural inflammation leads to progression of the nonspecific abdominal disturbance to frank abdominal pain.

3. Continued increase of intraluminal pressure and mural tension lead to progressive GI disturbance and upset, causing nausea and vomiting.

4. Further progression of inflammation allows transudate and then exudate into the tissues surrounding the appendix, leading to progressive localization of the abdominal discomfort to the right lower quadrant (the location of the appendix). Palpation of the abdomen at this stage will demonstrate involuntary guarding due to parietal peritoneal inflammation. A leukocyte count after pain appears should demonstrate evidence of the mobilization of white blood cells (WBCs), that is, an increase in the total WBC count and/or the band count. It is highly unlikely that neither the WBC count nor the band count will be increased if inflammation is well established.

Absence of any of the aforementioned significant features (i.e., abdominal pain, nausea, vomiting, involuntary right lower quadrant guarding, and abnormal WBC count) and any deviation from the expected temporal sequence of symptoms suggests caution in concluding that the patient has appendicitis.

The temporal sequence of clinical events is important in suggesting appendicitis.

Appendicitis is often considered in the differential diagnosis of a child or adolescent who presents with abdominal pain. A complete history and physical examination should determine whether the abdominal pain is consistent with a clinical diagnosis of appendicitis or with an alternative diagnosis. If the history, physical examination, and WBC count are inconclusive, imaging, including abdominal plain films and/or abdominal ultrasound, can help determine the likelihood of appendicitis. In very early stages, if the diagnosis remains inconclusive, a period of observation often is very useful in confirming or rejecting the diagnosis. The nature of appendicitis suggests that the pathophysiology will continue if there is no definitive treatment. By contrast, transient GI disturbances, such as viral infections, should abate spontaneously without definitive treatment. The time frame from early appendicitis to perforation is such that, if careful observation and repeated reexamination over several hours increase the clinical suspicion of appendicitis, definitive treatment can be arranged.

This approach to the child with suspected appendicitis rarely fails to resolve the question. A computed tomography (CT) scan may be helpful but should be reserved for those few cases that cannot be resolved by other means, because it exposes the child to significant radiation, with the attendant increased risk of future malignancy. In fact, ample evidence exists that careful repeated clinical evaluation produces diagnostic accuracy equivalent or superior to most imaging procedures. Therefore, if time, patience, and repeated clinical assessment carry lower risk than unnecessary radiation exposure, the clinical approach represents a higher standard of practice.

Mittelschmerz (Midcycle) Pain

Mittelschmerz or (menstrual) midcycle pain typically presents in a young female adolescent who has started ovulation and who reports acute lower abdominal pain associated with varying degrees of GI upset about 2 weeks after her last menstrual period. The pain is typically of acute onset, preceding other symptoms. A complete blood cell count (CBC) may show a mildly elevated WBC count. Obtaining an inadequate history from such patients could easily lead you to mistakenly conclude that the likely diagnosis is appendicitis.

Midcycle rupture of the ovum-containing follicle may be accompanied by bleeding within or from the ovary. The combination of the traumatic rupture, followed by the presence of the follicular contents and blood, causes acute onset of pain and possible peritoneal findings on clinical examination.

Midcycle pain is common in female adolescents.

Understanding the pathophysiology and timing of events reported in the history, without the presence of other significant clinical features, should allow a safe conclusion as to the cause of the abdominal pain. Reasonable reassurance and observation should be the next step. Ultrasonography to look for evidence of pelvic fluid and absence of any other significant ovarian pathology, such as torsion of the ovary, can be valuable. The associated distress may be significant and may merit a period of observation in the hospital with bed rest, bowel rest, mild analgesics, and intravenous fluids. Repeated clinical evaluation to observe the expected evolution of the signs and symptoms is all that is required. The usual clinical course is stabilization or resolution of the pain during the next 1 to 2 days with no progression of systemic signs and symptoms, as would occur with a missed diagnosis of appendicitis. Failure of the expected clinical evolution should lead you to reconsider the diagnosis.

Torsion of Ovary

All female adolescents, especially young girls, are at risk of ovarian torsion. The cause is usually unknown, but some episodes are associated with the development of large cysts that create the mechanical circumstances for torsion of a relatively large mass on a relatively narrow pedicle. Torsion can occur in premenstrual girls. Without that knowledge, unwary clinicians may ignore this possibility.

Torsion of ovary is easily missed and should be considered in the differential diagnosis when the ovary is considered the seat of abdominal pain.

The presentation usually consists of an ill-defined, relatively acute onset of lower abdominal pain that persists. There is no correlation with the menstrual cycle. The severity of pain is quite variable. This discomfort often is not associated with other significant symptoms and can easily be underappreciated.

For the young girl who presents with lower abdominal pain that is not easily explained, in whom ovarian-based pathology is considered in the differential diagnosis, pelvic ultrasonography can be very useful to identify the swollen ovary on the involved side and possibly even to demonstrate compromised blood flow. In the absence of an ultrasound facility, a careful rectal examination may reveal a pelvic mass. Performing a bimanual examination in a young virginal girl without causing unreasonable discomfort is difficult and yields limited information.

Torsion of the ovary is a surgical emergency.

Biliary Tract Disease

As with adults, biliary tract disease in children and adolescents is usually related to gallstones. Whereas gallstones once occurred rarely and in most cases were related to hemolysis that resulted in bilirubin stones, nowadays most gallstones are cholesterol-based. As with adults, laparoscopic cholecystectomy is used to manage gallstones in children and adolescents.

Great caution should be used in considering biliary dyskinesia when recurrent epigastric or right upper quadrant pain occurs in children. Often more harm is done by pursuing such a diagnosis or by intervening rather than offering reassurance after careful evaluation if no other significant pathology is evident. Even if biliary dyskinesia were to be missed, it likely would be self-limited, with no sequelae.

Pancreatitis

Pancreatitis in children is uncommon and thus is not often considered when a child presents with abdominal pain. Gallstone-based pancreatitis and congenital (often metabolic) causes must be considered in the differential diagnosis.

The diagnosis of pancreatitis is made with serial assessment of serum (amylase and lipase). Abdominal ultrasound may help evaluate pancreatic swelling and identify pseudocysts.

Pancreatitis often is self-limited and resolves with bowel rest. Pseudocysts are uncommon but also are self-limited in most cases.

Renal and Urologic Problems

Pyelonephritis, structural urologic anomalies such as obstruction at the ureteropelvic junction, and renal colic from the passage of stones are occasional causes of abdominal pain in children. These possibilities must be considered in children who present with unilateral colicky abdominal pain, especially if it is associated with flank tenderness and urinalysis abnormalities.

It is not uncommon for a child to present with acute abdominal and flank pain following a relatively low-impact trauma, such as a simple fall; this pain may be the first indicator of a previously unrecognized congenitally obstructed kidney. When hydronephrosis is present in such a child, even mild trauma can injure an already tense capsule and lead to significant pain and hematuria.

Urinalysis and abdominal ultrasonography will define most urologic causes of abdominal pain.

Significant hematuria following mild trauma may herald a previously unrecognized renal abnormality.

Presenting Clinical Features

Abdominal pain of extraabdominal etiology

Abdominal pain can be the presenting feature of various conditions that originate beyond the abdomen.

Pneumonia, especially in a lower lobe, may present with abdominal pain, often in the right lower quadrant. Relevant clinical features may include a history of a recent cough or cold, tachypnea, flaring of the alar nasi, abnormal auscultatory findings on the chest examination, and lack of involuntary guarding on an abdominal examination. Demonstration of pneumonia on a chest radiograph may explain the abdominal distress.

Parenthetically, it is worth noting that grunting respiration in infants, which is easily interpreted as evidence of respiratory disease, also is a classic presentation of significant abdominal distress, including peritonitis, in which the baby splints during inspiration due to significant abdominal pain. In such cases, the apparent respiratory findings originate within the abdomen.

Generalized viral illnesses often present with abdominal pain, and patients with such illnesses may have mesenteric and/or retroperitoneal adenopathy (often seen on ultrasound). Generalized viral illnesses may have a gastrointestinal component with right lower quadrant discomfort. As with pneumonia, involuntary guarding is rarely associated with generalized viral illnesses.

Two additional conditions may present with abdominal pain: incarcerated hernias and, in male patients, acute testicular pathology. Examination of the inguinal area should be part of every abdominal examination. An incarcerated hernia, especially in a younger child, can present with abdominal distress as the dominant feature, that is, without specific inguinal complaints. The presence of abdominal pain with or without emesis and the demonstration of an incarcerated hernia on examination demands reduction of the hernia and planning for subsequent surgical repair.

Just as an abdominal examination is incomplete without examination of the inguinal area in male patients, the abdominal examination must include examination of the scrotum. Acute testicular pathology, such as torsion of testicle in male adolescents, can present as referred pain to the abdomen. Careful examination of the scrotum is essential in all male patients with abdominal distress.

Bilious vomiting

When a patient presents with a history of vomiting, first ask whether it is bilious or nonbilious in color. If it is bilious in color, the next question is, “What color is the bile”? The presence of yellow-tinged emesis may not be a significant problem, whereas emesis that is frankly green is cause for concern.

Bile that leaves the biliary tract by way of the ampulla of Vater into the duodenum is green in color. When emesis is not associated with an obstruction (mechanical or paralytic) of the gastrointestinal tract, it is not uncommon for some duodenal content to reflux into the stomach in a small amount. The small amount of refluxed bile, mixed with gastric content, can be altered to a yellow color and contributes a yellowish tinge if emesis occurs. When a significant quantity of duodenal contents relfuxes into the stomach, the emesis remains frankly green, implying obstruction to normal gastrointestinal flow. Such obstruction can be mechanical in infants with malrotation or paralytic, as is seen in children with intraabdominal sepsis resulting from perforated appendicitis. Other signs and symptoms may hint at the cause of the green bile emesis; nonetheless, such emesis may be a presenting clinical feature. Even if no other signs or symptoms are present initially, careful reassessment of the child who presents with frankly green bilious emesis may uncover a significant cause. Malrotation is one example.

Acute abdominal pain

Because a period of observation and repeated clinical assessment often is required to elucidate the cause of a child’s abdominal pain, it can be tempting to try to take a shortcut to the diagnostic assessment by rushing to obtain imaging studies.

Using imaging technology to supplant clinical acumen just because it is readily available in many centers is one such shortcut, but it is not without risk. The most striking example is the excessive use of CT scans for children with abdominal pain because of their presumed high level of diagnostic accuracy. As noted earlier, CT scans expose children to very significant radiation, with possible significant future consequences in the form of malignancy risks years later. For most clinical pediatric problems presenting as an acute abdomen, a thoughtful clinical history and careful physical examination with the appropriate use of the CBC, abdominal plain film, and abdominal ultrasound can clarify most abdominal conditions with the same accuracy as a CT scan.

If good clinical acumen yields results comparable to those found with invasive or threatening tests, it represents a higher standard of clinical practice while achieving the same end.

Chronic abdominal pain

Chronic abdominal pain, which is more common in older children and adolescents than in younger children, can be a challenge to evaluate. Many serious disorders can present with chronic abdominal pain, including inflammatory bowel disease and certain neoplasms. But with significant illness, chronic abdominal pain often is not central and is rarely an isolated feature. When chronic, centrally located abdominal pain occurs in a growing child or adolescent without associated clinical symptoms, physical signs, interference in energy or activity, weight loss, or compromised growth, it is unlikely to be associated with serious underlying disease.

When a careful history and physical examination fail to suggest a worrisome condition, you will be faced with two options: either subject the child involved to a battery of baseline tests (which almost never yield diagnostic information!) or reevaluate the child repeatedly. Usually, reassurance and your willingness to reassess the child as often as necessary is the best approach to resolving the problem. The term “functional abdominal pain” has no real meaning and should be abandoned.

Chronic abdominal pain demands a thoughtful and thorough history and physical examination to demonstrate that organic pathology is unlikely.

Repeated clinical assessment serves two purposes: it lets you confirm your initial clinical impression and offers additional reassurance to the child and parents that an organic explanation is not being missed. It also can be very helpful to ask the parents and/or child what condition they are most worried about that the child might turn out to have. There may be family members who have had inflammatory bowel disease, cancer, or some other serious (or even life-threatening) condition, and unspoken fears of such conditions may exacerbate the child’s symptoms and the parents’ concern.

Abdominal masses

When you palpate a mobile, left lower quadrant mass in a child with a history of significant constipation, this mass usually represents a sigmoid colon full of stool. The presence of a palpable right upper quadrant sausage-shaped mass in a toddler presenting with severe episodic colic and “red currant jelly” stools supports a suspected diagnosis of intussusception.

Finding an unexpected abdominal mass is a different matter. Such masses may be cystic or solid and may represent benign congenital abnormalities or a solid tumor, but they are beyond the scope of this chapter.

Clinical Assessment of the Child with Abdominal Trauma

1. Gastric dilatation. Gastric dilatation is common in traumatized children and is likely due to swallowed air, aggravated by crying. Such gastric distention can be sufficient to confound the abdominal examination and can easily be misinterpreted as evidence of a significant underlying injury. In assessing any traumatized child with a distended or tender abdomen, a nasogastric tube should be placed early, before any imaging is done.

2. Solid viscus injury. Most solid viscus injuries (e.g., of the spleen, liver, or kidneys) can be managed nonoperatively. Hemodynamic instability is the dominant criterion for surgical intervention. Hemodynamic stability is defined as the ability to stabilize and maintain stability with blood transfusion requirements within one-half blood volume (40 ml/kg whole blood) within a 12-hour period. If the transfusion requirements are beyond one-half blood volume or the patient continues with signs of instability beyond the 12-hour period, surgical intervention may be necessary. Should stability be evident, most intraabdominal injuries go on to heal spontaneously, usually without sequelae. Such “conservative” management is actually anything but conservative. It requires dedicated, intense observation and monitoring, because missing any signs of deterioration that demand appropriate intervention can be lethal.

The timing of postinjury ambulation of patients with solid viscus injuries is somewhat arbitrary. Pain is a reasonable guide. When spontaneous pain resolves, regular ambulation is likely safe. Participation in non-contact sports can be resumed at about the 6-week period, with participation in contact sports being deferred until 3 months after the injury occurs.

3. Chance fracture. The use of seat belts has had a remarkable, positive impact on outcomes of motor vehicle accidents, especially with regard to head injury. Seat belt technology has improved, but simple lap seat belts are still common. Although lap seat belts save lives, they introduce their own problems; nonetheless, this is a reasonable trade-off for the decreased risk of head injury. When the lap seat belt is used, a severe deceleration event can lead to a triad of significant injuries:

• Hyperflexion of the spine at the seat belt level can occur, causing varying degrees of posterior spinous element disruption, ranging from mild posterior disruption of soft tissues to fracture and displacement of the posterior bony elements, threatening the integrity of the spinal cord. Such fractures must be looked for with appropriate imaging techniques when a seat belt injury is encountered.

• Trauma to the abdominal wall at the site of the seat belt can lead to injuries ranging from bruising to disruption of elements of the abdominal wall, leading to immediate or delayed herniation of abdominal viscera.

• Trauma to the underlying bowel can be sustained, either from (1) direct compression against the seat belt during deceleration (2) distraction of the tethering elements where the bowel is anchored or along its mesenteric attachments, leading to disruption of or devascularization of the attached bowel. The latter injury can take several days to become fully apparent because devascularized but intact bowel may not perforate until (ischemic) necrosis has been established. Therefore, serial evaluation and repeated imaging with plain abdominal radiographs are necessary when an underlying bowel injury is suspected but not immediately evident.

Prenatal Diagnosis

Regular use of prenatal ultrasound has led to a new era of prenatal diagnosis of a number of abdominal problems in unborn children. Identification of such problems has not had a significant impact on the outcome of management of most abnormalities identified, but it may allow expectant mothers and caregivers to be prepared for postnatal management. Problems such as an omphalocele, gastroschisis, and intestinal atresias rarely affect the mode of delivery or other obstetrical concerns. Therefore, the identification of such abnormalities has little immediate effect on the pregnancy or delivery. Temptation often exists to consider early delivery or delivery by caesarean section rather than vaginal delivery because it is speculated that these measures will provide improved protection for the infant. However, experience to date suggests that there is no measurable benefit from such intervention, and interfering with the normal course of pregnancy or delivery can create its own risks and concerns that are unacceptable if there is no ultimate benefit for either the baby or the mother.

While prenatal ultrasound screening has ushered in a new era of improved perinatal management, prenatal identification of abdominal abnormalities has provided more questions than benefits, often advancing the onset of parental anxiety about outcome even when a good outcome can be anticipated.

Summary

The surgical assessment of the abdomen in pediatric practice in particular demands commitment from the practitioner to demonstrate good clinical acumen if the highest standards of patient care are to be achieved. The subject matter is broad and varied with a significant overlap of presentation for a number of these disorders in patients who are often unable to express their complaints. A solid knowledge base and ability to use that in the conduct of a good history and physical exam are the main components of good clinical acumen, the performance of which not only heightens the probability of developing the correct clinical pathway for any particular patient, but also minimizes the chances for unnecessary and sometimes harmful tests and interventions. Future patients will benefit more from those students who understand the need to take time to learn the clinical acumen required to approach the problems listed in this chapter than from those students who simply see the above list of topics as information to commit to memory; and, those students that recognize the importance of developing good clinical acumen will be amply rewarded with the satisfaction that come with the highest standard of performance on behalf of their patients.

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Pediatric Clinical Skills