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Sonographic Evaluation of the Acute Abdomen
Sandra Hagen-Ansert, B.A., RDMS, RDCS
Chair, Diagnostic Medical Sonography
Baptist College of Health Sciences
Memphis, Tennessee
Table of Contents
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Sonographic Evaluation of the Acute Abdomen
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Name the etiologies of the acute abdomen
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Describe the clinical signs and symptoms in the patient with an acute abdomen
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Name the common causes of pain in the following areas of the abdomen: central, right and left hypochondrium, and right iliac
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Know the pertinent patient history factors in the acute abdomen
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List the sonographic findings and differential diagnosis of the acute abdomen
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The onset of abdominal pain is a common condition which demands an expedient diagnosis and treatment plan. If a patient presents in the emergency room with severe abdominal pain, the clinician must have a defined pathway outlined in order to make a differential diagnosis. It becomes important to not only narrow the differential diagnosis to one primary choice, but also to determine if the patient is a surgical candidate. The general rule for abdominal pain is: the majority of severe abdominal pains, which appear in previously healthy patients and last for at least six hours, may require surgical intervention. Emergent problems such as appendicitis, perforated ulcer, intestinal obstruction, or other obstructive problems may require immediate surgical intervention. The purpose of this article is to present an overview of the etiology, clinical signs and symptoms, and diseases that fall under the "acute abdomen" as the disease may present to the sonographer.
The etiology of the acute abdomen may arise from any of the following causes:
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Infection: bacterial or chemical
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Traumatic: blunt or penetrating
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Congenital: atresia, hernia, malrotation of the bowel
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The bacterial infectious category of causes for an acute abdomen would include such conditions as acute appendicitis, diverticulitis, or pelvic inflammatory disease. The chemical infectious category would include the perforation of an ulcer with peritoneal inflammation and reaction.
Penetrating trauma to the abdomen from an automobile accident, gunshot or stab wounds may be the cause for an acute abdomen with a sudden increase in intraperitoneal fluid and blood in the peritoneal cavity.
Obstructive bowel conditions would comprise the mechanical causes of an acute abdomen. Such conditions as intussusception of the bowel, malrotation of the gut with volvulus, or incarcerated hernia may represent a mechanical obstruction.
A thrombus or embolism in the mesentery would represent a vascular cause for an acute abdomen. As the blood supply is interrupted secondary to an infarct, tissue necrosis develops with resulting gangrene of the bowel.
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The key finding in the patient with an acute abdomen is abdominal pain. The increased pain makes it difficult for the clinician to adequately examine the patient to be certain of an intra-abdominal lesion which may be present and causing the symptoms. As with many conditions in medicine, the patient may bear the abdominal pain throughout the day with the hope it may subside; however in the case of an acute abdomen, the pain increases with time and the patient must receive immediate medical attention to find the source of the pain.
The diagnosis of the origin of the pain may be difficult to assess because of the sympathetic nervous chain and transmitted signals from the related muscles to the nerve centers. A knowledge of muscular anatomy may help the clinical differential diagnosis as the muscles may be directly or indirectly irritated by the inflammatory process. Careful attention to the diaphragm, psoas, quadratus lumborum, erector spinae, lateral abdominal, rectus, pyriformis, and obturator internus muscles is important in understanding the origin of pain.
For example, a subphrenic or hepatic abscess may radiate to the diaphragm and shoulder area. A patient with appendicitus may present with pain near the psoas muscle that only receives relief when the thigh is extended on the affected side. A patient with pelvic inflammatory disease may have pain in the obturator internus muscle with referred pain to the hypogastrium. A gastric ulcer may rupture and the fluid impinge on the diaphragm which may irritate the phrenic nerve and cause radiating pain to the shoulder.
Central Abdominal Pain
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Obstruction of the small intestine
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Right Hypochrondriac Pain
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Hydatid disease of the liver
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Left Hypochondriac Pain
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Rupture of inflammed diverticulum
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Leakage of splenic artery aneurysm
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Spontaneous rupture of spleen
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Several factors are important to know to help define the cause of the acute abdomen:
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Present physical condition
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Other diagnostic examinations the patient may have recently had performed
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The age of the patient helps to define the nature of the disease. A child under two may appear with acute intussusception, whereas appendicitis is more common in the younger adolescent. An obstruction of the large intestine is more common in patients over forty years of age. Acute pancreatitis or perforated ulcer is more often seen in the adult patient. Cholecystitis or a twisted ovarian cyst may be seen in the younger child, but is more commonly seen in the adult.
The present condition considers many factors: the exact time of onset, whether the pain is gradual or acute, and the specific character of the pain. The clinician should note if the pain has shifted over time. The presence of fever may indicate an infectious process. Nausea and vomiting should be documented as to the time it occurred in relation to the pain (before, same time as, or after the pain) and how often the vomiting has occurred.
Perforation of a gastric or duodenal ulcer or acute pancreatitis may cause the patient to faint if the pain is intense enough. On the other hand, many cases of intestinal obstruction appear with a gradual onset of pain.
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Significant past history would include previous diseases or conditions that may have caused surgical intervention. The patient’s loss of appetite or symptoms of indigestion should be noted. The external appearance of jaundice, weight loss, and fatigue may indicate gastrointestinal or gallbladder disease.
It is the responsibility of the sonographer to understand the patient’s past history, clinical signs and symptoms, and to find out if the patient has had previous diagnostic examinations prior to performing the sonographic procedure. This approach will enable the sonographer to look specifically for the differential diagnosis of the acute abdomen.
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Frequently, the patient experiences a recent history of indigestion or gastritis a few days prior to the attack of appendicitus. Bowel habits may be irregular, with either constipation or diarrhea, especially in adolescents. A patient who presents with acute appendicitis may have clinical findings of intense pain that may begin in the epigastric or umbilical area and move towards the right iliac area, with eventual extension throughout the abdomen.
Nausea, vomiting, and fever are usually present in the early stages of the attack, with subsequent loss of appetite. The degree of nausea and the frequency of vomiting depend on the amount of distention of the inflamed appendix and the reflex nervous susceptibility of the patient.
The critical element causing inflammation of the wall of the appendix is bacterial invasion. The usual bacteria organisms are colon bacilli and streptococci, two organisms which are commonly found in the intestinal tract.
Fever may be initially be present, but usually develops within twenty-four hours, followed with an elevated white blood count, which probably means that peritonitis has already begun. Extreme local tenderness, rigidity, or distention of the abdomen is usually experienced. When the appendix is acutely inflamed gaseous distention of the cecum may be present. This localized distention is due to the excessive formation of gases by the bacterial decomposition of the cecum and appendix.
Symptoms of Acute Appendicitis
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Pain, epigastric with extension into the right iliac fossae
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Nausea and vomiting, acute loss of appetite
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Rigidity of muscles may be present
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Most surgeons want to operate within the first twenty-four hours from the onset of pain to avoid the onset of perforation and peritonitis. There are two reasons which may explain why cases are operated on later than this time period. Either the patient may not present with acute symptoms or the symptoms are atypical.
Common conditions that may simulate acute appendicitus include but are not limited to: cholecystitis or perforated gallbladder, inflamed duodenal ulcer, perinephric abscess, renal infection, Meckel’s diverticulum, intestinal obstruction, ectopic pregnancy, or ovarian torsion.
Sonographic Findings in Acute Appendicitis:
The right lower quadrant is scanned with and without graded compression to see if the area of the appendix compresses or remains swollen secondary to inflammation. The total diameter of the appendix measures at least 7mm to 10mm. The distinction of the stratification of the wall layers are altered and inhomogeneous. A "target-like" appearance of the appendix is noted in the transverse views. The typical target lesion consists of a hypoechoic fluid-distended lumen with a hyperechoic inner ring that represents the mucosa and submucosa layers. The outer hypoechoic ring represents the muscularis externa. No peristaltic movement of the bowel is seen in acute appendicitus.
In infancy and adolescents, the appendix may become decompressed after perforation and the inflammatory process may not wall off or form a well-defined abscess, as is typically seen in the adults. Supplemental findings such as free abdominal fluid with debris or thickening of the adjacent abdominal wall may suggest appendicitis.
The progression of acute appendicitus with rupture may lead to the development of gangrene. The appendix lumen may distend and fill with fluid secondary to a appendicolith (which may or may not be calcified). The diameter of the inflammed appendix extends from 11 to 19 mm.
Perforation of the appendix occurs when the wall of the appendix ruptures and an abscess or fluid collection develops in the right lower quadrant and/or pelvis. The appendix itself may be difficult to see with the pocket of abscess surrounding it. If seen, the wall shows asymmetrical thickness and inflammed mesenteric nodes may be present.
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The anatomical relationship of the pancreas to its surrounding structures is an important factor in understanding the consequences of pancreatic disease. The gland is retroperitoneal in close relationship with the celiac plexus. The head is surrounded by the duodenum, while the tail lies in close proximity to the hilum of the spleen. Acute forms of inflammation of the pancreas are due to infection which may lead to severe hemorrhage of the gland with extension into the retroperitoneal cavity.
An acute attack of pancreatitis is usually related to biliary tract disease and alcoholism. Other causes include trauma, inflammation from an adjacent peptic ulcer, abdominal infection, vascular thrombosis, or drugs. It usually affects males under the age of forty, and is more common in obese people.
The process of inflammation and destruction of the pancreas may be severe. Damage to the acinar tissue and duct system results in exudation of pancreatic juice into the interstitium of the gland, leakage of secretions into the peripancreatic tissues, or both. After the acini or duct is disrupted, the secretions migrate to the surface of the gland. The common course is for fluid to break through the pancreatic connective tissue layer and thin posterior layer of the peritoneum and enter the lesser sac.
Symptoms
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Fainting may occur when pain is intense
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Pain begins in epigastrium, with extension to back and groin
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Epigastric tenderness & rigidity
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Jaundice present when head of pancreas compresses CBD
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The pancreatic juice enters the anterior pararenal space by breaking through the thin layer of the fibrous connective tissue, or the fluid might migrate to the surface of the gland and remain within the confines of the fibrous connective tissue layer. Collections of fluid in the peripancreatic area generally retain communication with the pancreas. A dynamic equilibrium is established so that fluid is continuously absorbed from the collection and replaced by additional pancreatic secretions. The drainage of juices may cease as the pancreatic inflammatory response subsides and the rate of pancreatic secretions return to normal. The collections of extra-pancreatic fluid should be reabsorbed or, if drained, should not recur with recovery of proper drainage through the duct.
Acute pancreatitis most commonly mistaken for a perforated gastric or duodenal ulcer. The milder cases may be mistaken for appendicitis. If distention is present, intestinal obstruction may be included in the differential. Acute cholecystitis and biliary colic may simulate the symptoms of pancreatitis.
Sonographic Findings in Acute Pancreatitis:
In the early stages of acute pancreatitis, the gland may not show swelling. When swelling does occur, the gland is hypoechoic to anechoic because of the increased edema within the lobulations of the gland and the congestion of the vessels. The borders may be somewhat indistinct but usually remain regular with smooth lobulations. On the longitudinal scan, the swollen head of the pancreas may compress the inferior vena cava. The pancreatic duct may be enlarged secondary to inflammation, spasm, edema, swelling of the papilla, or pseudocyst formation.
Complications of acute pancreatitis may lead to hemorrhagic pancreatitis, phylegmon formation, abscess, or pseudocyst formation.
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Hemorrhagic Phlegmon: One of the complications of acute pancreatitis results in inflammation of the surrounding tissues of the peripancreatic area. These tissues may be edematous with hypoechoic sonographic features, or they may be a more complex striated pattern with hemorrhage.
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Pseudocyst of the Pancreatic Tail: Longitudinal scan of the left upper quadrant demonstrates a pseudocyst formation near the tail of the pancreas. The mass is anterior to the left kidney and contains debris located near the posterior of the pseudocyst. A smaller daughter cyst is seen anterior to the larger pseudocyst.
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When a patient presents with acute abdominal pain and distention mesenteric thrombosis or peritonitis should be considered. An acute blockage of the mesenteric arteries or veins by an embolus, thrombus or tumor invasion may be difficult to separate from that of intestinal strangulation. If mesenteric thrombosis is the cause, the extent of bowel involvement and distension of the abdomen is usually greater than with other causes.
Sonographic Findings in Mesenteric Ischemia and Thrombosis:
Specific imaging of the area of bowel ischemia is difficult to perform with realtime sonography. However Doppler ultrasound may be useful to evaluate the celiac and superior mesenteric arterial vessels in the upper abdomen. If ischemia is present, the sonographer may see retrograde perfusion of the hepatic artery through the superior mesenteric artery. The peak systolic velocity greater than 160 cm/sec in the celiac trunk indicates more than fifty percent stenosis during the fasting state.
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A dissecting aneurysm is applied to a medical condition in which an erosion of the inner lining of an artery through which the blood escapes into the substance of the wall of the artery and courses along within its substance parallel to the main stream, splitting the arterial wall in its middle muscular coat. The aorta may dissect at its root, near the aortic cusps, and extend into the ascending aorta to the arch, descending aorta, and into the abdominal aorta. This is the most dangerous type of dissection, especially if the dissection spirals around the aorta, cutting off the supply of blood to the carotid, brachiocephalic, and subclavian vessels. The second type of dissection begins at or below the level of the left subclavian artery and extends downwards into the descending and abdominal aorta. The third type of dissection begins at the lower end of the descending aorta and extends into the abdomen. This type may be critical if the dissection cuts off the renal arterial supply to the kidneys.
A dissecting aortic aneurysm may cause unbearable severe thoracic pain that radiates to the neck or through to the back. Gradually the pain extends into the abdomen with tenderness and rigidity of the abdominal wall. It may simulate a perforation of a peptic ulcer, mesenteric thrombosis, or hemorrhagic pancreatitis.
Dissection of the aorta may be secondary to cystic medial necrosis or Marfan’s disease, or hypertension. Cystic medial necrosis leads to a weakening of the arterial wall. Individuals with Marfan’s syndrome have characteristic features that include extreme height with double jointed extremities. Marfan’s syndrome is a progressive stretching disorder that may exist in the arterial vessels, particularly in the aorta. The disorder causes abnormal dilation and weakening of the walls which can lead to dissection or rupture.
Sonographic Findings in Aortic Dissection:
A dissecting aneurysm may be detected by transesophageal echocardiography or abdominal ultrasound. The patient may have a history of a thoracic or abdominal aortic aneurysm. If the patient presents with sudden, excruciating chest pain radiating to the back, the suspicion of a dissection should be ruled out immediately. If the patient is stable, the sonographer should look specifically for signs of a dissection: the false parallel channel, the "flap" at the site of the itimal tear, and irregular assymetric plane of enlargement.
The transesophageal echocardiogram is best to image the origin of the dissection in the thoracic cavity. The intimal flap is seen in at least two views, the presence of pericardial effusion may be detected, and the amount of aortic insufficiency may be documented with color and spectral Doppler.
False positive diagnostic information may be seen if the aorta has calcified atheromatous plaque (causing shadowing and a break in the intimal wall) or reverberation echoes from the aneurysmal ascending aorta.
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The most common place for an ectopic pregnancy to develop is in the ampullary portion of the Fallopian tube. Rarely it is found in the isthmus of the tube or cornu of the uterus. As the ectopic pregnancy grows, the tube distends with an eroding action of the villi leading to the thinning of the wall of the tube. Gradual oozing of blood occurs from the eroded area into the peritoneal cavity. Sometimes the ovum is expelled through the end of the tube into the peritoneal cavity by a process termed "tubal abortion", or the embryo may die in consequence of hemorrhage into the sac, or rupture of the sac into the lumen of the tube, and thus may be formed a tubal mole.
If the embryo lives, the primary rupture of the sac occurs usually within the first eight weeks. Rupture of the sac causes pelvic pain which subsides with the formation of blood clots in the pouch of Douglas. If the embryo continues to live after the primary rupture of the tube severe symptoms may be caused by a secondary rupture into the peritoneal cavity.
Symptoms of Ectopic Pregnancy
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Hypogastric pain & tenderness
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Passage of fetal membranes
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Sonographic Findings in Ectopic Pregnancy:
Pregnancy is clinically evident when the results of the pregnancy test, beta-HCG level, greater than 1,000 to 2,000 mIU/mL (IRP) is recorded. With the endovaginal transducer, the early intrauterine pregnancy may be seen as early as four weeks. The sonographer must determine if there is a pregnancy within the uterus or not. An empty uterus with an adnexal mass, and positive pregnancy test is very suspicious for an ectopic pregnancy with either transabdominal or endovaginal studies. A pseudogestional sac may be present in the uterus that appears as a parietal decidual reaction with an anechoic center secondary to bleeding. A corpus luteum within the ovary on the same side as the ectopic pregnancy may be seen in over fifty percent of patients.
Transabdominal Findings
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Corpus luteum within the ovary
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The endovaginal probe allows the sonographer to define the uterine cavity with greater clarity and to evaluate the adnexal area for the presence of an extrauterine mass, hematoma or clotted blood, free fluid, live embryo, or a hydro or hematosalpinx secondary to a ruptured tube. The uterine cavity may show a decidual cast with a hyperechoic endometrial thickening.
Endovaginal Findings
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Extrauterine gestational sac with/without embryo
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Doppler: high velocity, low-impedance flow surrounding mass
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Color Doppler may be useful, but not specific in the diagnosis of an ectopic pregnancy. If an adnexal mass is seen, the color flow would present as a high-velocity low-impedance flow around the extrauterine gestation. Other masses that may present with a low-impedance flow include a corpus luteum cyst, tuboovarian abscess, or a degenerating fibroid.
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Inflammation of the gallbladder is more common in middle aged fertile, obese females (4F: female, fertile, fat, forty). The inflammation may be acute, subacute, or chronic. The acute form is bacterial with pre-existing gallstones a common finding. The bacteria may reach the gallbladder via the blood stream or from the intestine by the common bile and cystic ducts or from the ulcerated duodenum either directly or by the portal vein. The inflammation begins with the gallbladder as it attacks the mucous membrane lining the interior and gradually working its way outwards until it is either stopped by cellular resistance or until it may perforate the wall of the gallbladder to cause peritonitis. Complications may occur according to the site of perforation.
Right Hypochrondriac Pain
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Cholecystitis or biliary colic
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Inflamed or leaking duodenal ulcer
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Rupture of gallbladder or biliary duct
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The symptoms of acute cholecystitis vary in each patient, therefore in making a diagnosis, the clinician must divide the symptoms into two primary groups: those in which there is no obstruction in the cystic duct, and those in which the cystic duct is obstructed by small gallstones or by a kink in the duct.
Primary Symptoms of Acute Cholecystitis
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Vomiting, nausea, loss of appetite
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Abdominal tenderness & muscular rigidity
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Distention of right colon
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No Obstruction in the Cystic Duct. The bacteria attack the mucous membrane which responds by excreting an excessive amount of thick mucus that distends the gallbladder until the distention causes pain (which may be felt in the epigastrium). This pain is the first symptom and may cause a positive Murphy’s sign when the gallbladder area is palpated. This pain may be followed by nausea, vomiting, or a complete loss of appetite. The distended gallbladder may be palpated as a mass in the right upper quadrant. As the patient stands, the distended gallbladder becomes unable to expel the thick mucus through the cystic duct which causes further distention and pain radiating to the epigastrium. This causes the patient to lie down and the gravity effect helps the distended gallbladder to then empty gradually through the cystic duct and the pain is relieved.
In the next few hours, the bacteria may irritate areas surrounding the gallbladder as they erode the gallbladder wall. Acute cholecystitis with perforation is very painful as the infection enters into the peritoneal cavity.
Obstruction of the Cystic Duct. The most common cause of obstruction of the cystic duct is from a small gallstone that occludes the lumen of the duct. If the stone passes through the cystic duct, into the common duct and eventually into the duodenum, the biliary colic will subside. However, if the stone remains in the cystic duct, inflammation leading to a subacute infection of the gallbladder may result with resultant peritonitis.
Sonographic Findings in Acute Cholecystitis. If the patient has acute tenderness over the area of the gallbladder this indicates a positive sonographic Murphy’s sign. Principle criteria of acute cholecystitis include the visualization or nonvisualization of the gallbladder and the presence or absence of stones. The additional sonographic criteria are a thickened gallbladder wall (over 3mm) with edema. This edema is characterized by a diffuse striated hyperreflective wall thickening, hazy wall delineation, and gallbladder distension. In addition, there is a lucent layer within the thickened gallbladder wall that represents edema and necrosis. The gallbladder may be distended with or without sludge or evidence of cholelithiasis (stones obstructing the cystic duct are present in over 80% of patients ). The shape of the gallbladder becomes rounded and tense appearing with the transverse diameter larger than the transverse kidney (or greater than 5cm). If the wall has perforated, an irregular collection of hypoechoic echoes will surround the area of the gallbladder that indicates abscess.
Click on image to view full size
 |  |  | | Acute Cholecystitis: Transverse and longitudinal scans of the right upper quadrant demonstrate a complex echo pattern in the area of the gallbladder, inferior to the right lobe of the liver, and anterior to the right kidney and inferior vena cava. Pericholecystic fluid and abscess formation is one of the complications of acute cholecystitis. | Acute Cholecystitis: Longitudinal scan of a distended acalculous gallbladder (hydrops), with wall thickening, edema, and sludge. |
 | Bowel Obstruction: Longitudinal scan of the lower abdomen reveals multiple distended loops of bowel. Fecal material and air pockets are seen throughout the dilated bowel loops. Mural thickening and edema of hausstra are seen to invaginate the distended bowel. |
Sonographic Findings in Intussusception:
An abdominal mass may be palpable. In children with classic symptoms of colicky abdominal pain, vomiting, and bloody stools, in whom there are no peritoneal symptoms or fever, preliminary abdominal radiographs followed by a barium or air enema are rapidly undertaken for both diagnostic confirmation and to attempt therapeutic reduction. Failure to reduce an intussusception mandates immediate surgical intervention. Likewise, in patients with a classical clinical presentation of intussusception who have developed fever and peritoneal signs, surgical intervention is indicated. In patients with more vague clinical presentation, in whom intussusception remains suspect, an ultrasound examination is a helpful diagnostic undertaking.
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Trauma to the abdomen may result from non-penetrating injuries (heavy vehicle running over the abdomen), external trauma to the abdomen (abdominal blow from a kick, punch, or fall), or from a surgical trauma. Any injury of the abdominal wall may be accompanied by serious internal trauma to the organs without any visible sign of injury to the abdominal wall.
Symptoms of Trauma to the Abdomen
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Shock is shown by pallor, weak pulse, sweating, shallow respiration, and cold extremities. These symptoms will subside unless there is an underlying serious injury. Injuries of the upper abdomen cause more serious shock than those of the hypogastric region. Renal contusions also cause severe shock. If the symptoms of shock persistent longer than six hours, hemorrhage or peritonitis should be considered.
The search for free fluid and hemorrhage in a patient with severe abdominal trauma may be handled by paracentesis, ultrasound, or CT evaluation.
Hemorrhage. The primary organs injured in the upper abdomen include the liver, spleen, and kidneys. The primary abdominal vessels are more likely to be injured by trauma directed against the central portion of the abdomen. When the liver and spleen are severely torn, the symptoms of shock and hemorrhage are extreme. If the tear is not as extensive, the patient may experience restlessness, pain, progressive pallor of lips and finger nails, increased pulse, and increasing dullness in the flank area. A tear in the spleen may give rise to pain in the left shoulder; subsequently, a tear in the liver may give rise to pain in the right shoulder.
Contusion or rupture of the kidneys frequently is accompanied by severe shock which may subside within two hours. The subsequent symptoms depend on the extent of the injury and the condition of the renal capsule. In patients where the capsule remains intact, hematuria, local tenderness, and renal colic due to the passage of clots down the ureter, comprise the symptoms. If the capsule is torn, a retroperitoneal hematoma is formed with a urinoma from the leakage of the extravasated ureter.
Sonographic Findings in Acute Trauma: The liver is the third most common organ injured in the abdomen after the spleen and kidney. Laceration of the liver occurs in 3% of trauma patients and is frequently associated with other injured organs. The need for surgery is determined by the size of the laceration, the amount of hemoperitoneum, and the patient’s clinical status. The right lobe is more affected than the left. Ultrasound may find indications of a tear, a fluid collection along the lateral, medial, or subdiaphragmatic margin of the liver, or other evidence of intraperitoneal fluid along the flanks. The characteristic of the hematoma will depend on the age of the bleed. Initially the bleed is hyperechoic with the red blood cells actively moving within the clot; after time, the lesion becomes sonolucent as the red cells resolve within the hematoma.
The spleen is frequently injured in patients who have received blunt trauma to the left upper quadrant. Rib fractures and left renal injuries often are accompanied by trauma to the spleen. The presence of a subcapsular hematoma may be seen to form along the lateral margin of the spleen. The exact area of the laceration is better defined by CT, as well as the extent of the hemoperitoneum.
Trauma to the kidney may result in the development of a subcapsular hematoma, renal contusion, or a small cortical laceration without caliceal disruption. The sonographer must carefully evaluate the renal contour and perinephric space to locate fluid or blood that may have collected around the renal capsule. Color Doppler and/or power Doppler is useful to evaluate the vascular supply of the kidney.
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In patients with hepatitis, a tenderness is felt all over the abdomen, including the lateral aspect and the right hypochondrium.
Clinical findings may be "flu-like" with gastrointestinal symptoms, including loss of appetite, nausea, vomiting, and fatigue. Jaundice may occur in severe cases. Lab values for liver function show an increased in SGOT, SGPT, and bilirubin levels.
In acute hepatits, damage to the liver may range from mild disease to massive necrosis and liver failure. The pathologic changes include the following: liver cell injury, swelling of the hepatocytes, and hepatocyte degeneration which may lead to cell necrosis; reticuloendothelial and lymphocytic response with Kupffer cells enlarging; and regeneration.
Sonographic Findings in Acute Hepatitis:
A decreased parenchymal echogenicity pattern may be seen within the liver capsule. The portal venule walls will illustrate increased brightness (known as the "starry sky" pattern). Edema and thickening of the gallbladder wall is often present. A hyperechoic fatty appearance is seen within the falciform ligament, ligamentum venosum, porta hepatis, and the periportal connective tissue. Hepatosplenomegaly is usually present with acute hepatitis.
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Intussusception or invagination of the intestine is the most common abdominal emergency in children under two years. It consistutes 15 percent of all cases of intestinal obstruction. The problem occurs when the invagination of one portion of intestine prolapses into the portion next to it. The usual occurrence of intussusception of the bowel is in the ileocacal region, where the narrow ileum can readily enter the lax cecum, and in actual clinical experience this is the most common place for the condition to start.
There are three varieties of intussusception: enteric, enterocolic, and colic. Enteric is uncommon and occurs where the small intestine alone is involved. Colic involves only the colon and is not very common. The most common form is entercolic, where the end of the ileum is invaginated into the colon along with a portion of the mesentery. When this occurs, the messentery becomes constricted and later strangulated, which causes edema, intestinal hemorrhage and eventually gangrenous. The entercolic form is subdivided into ileocecal, in which the apex of the invaginated part is the ileocecal valve, and the ileocolic, in which a part of the gut near the end of the ileum forms the apex.
The cause of intussusception appears to be the presence of something in the intestine which provokes excessive peristalsis. Commonly it occurs in infants at weaning time as the infant begins to consume solid food. This undigested solid food causes increased peristalsis which irritates the bowel.
Symptoms of Intussusception
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Passage of blood and mucus per rectum
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Peritonitis (later stage)
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The onset of abdominal pain in the infant is usually seen with a fit of screaming. The legs are drawn up to the stomach as the pain corresponds to the violent peristaltic contraction of the gut. Blood and mucus passed through the rectum usually occurs within a few fours. The amount of blood and mucus may be slight. Vomiting may initially be severe until complete obstruction or peritonitis has developed. The area of intussusception occassionally may be palpated as a mass in the lower abdomen. Abdominal distension occurs with increased obstruction. Fever may appear with extreme cases of peritonitis and gangrene formation.
The patient is examined in the supine position. A survey of the entire abdomen is performed, followed by an examination focusing on the bowel using a high frequency transducer. The sonographic appearance of intussusception is of alternating hypoechoic and hyperechoic rings surrounding an echogenic center as seen in a short-axis view of the involved area. This is known as the doughnut or target sign. In the long axis, hypoechoic layers on each side of the echogenic center results in a pseudokidney or sandwich appearance. Free peritoneal fluid is not an uncommon finding with uncomplicated intussusception. Other conditions that can produce a target-like sonographic appearance include primary bowel tumors such as lymphoma, and inflammatory bowel disease.
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The evaluation of a patient with an acute abdominal pain requires the sonographer to have an understanding of the etiology and clinical signs and symptoms that may lead to the diagnosis of an acute abdomen.
The etiology (infection, traumatic, mechanical, vascular, or congenital) will help the sonographer evaluate specific areas within the abdomen to help the clinician arrive at the specific diagnosis for the patient. The clinical signs and symptoms provided by the patient and the clinician will help the sonographer examine certain areas of the abdomen which may assist the clinician in his/her final analysis of the patient. This review concentrated on the acute abdominal problems that confront the sonographer on a weekly basis. The ability of the sonographer to integrate clinical findings with abdominal sonographic imaging will lead to more efficient differential diagnostic information for the clinician to manage the patient.
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Cope, Sir Zachary, THE EARLY DIAGNOSIS OF THE ACUTE ABDOMEN, Oxford University Press, London, 1972.
Dahnert, Wolfgang, RADIOLOGY REVIEW MANUAL, 3rd ED., Williams & Wilkins, Baltimore, 1996.
Hagen-Ansert, Sandra L., TEXTBOOK OF DIAGNOSTIC ULTRASONOGRAPHY, 4th ED., Mosby, St. Louis, 1995.
Mittelstaedt, Carol A., GENERAL ULTRASOUND, Churchill Livingstone, New York, 1992.
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