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Common problems in acute care surgery Common problems in acute care surgery Document Transcript

  • 19L.J. Moore et al. (eds.), Common Problems in Acute Care Surgery,DOI 10.1007/978-1-4614-6123-4_2, © Springer Science+Business Media New York 2013Introduction and EpidemiologyAbdominal pain is one of the most common reasons for vis-its to the emergency room. Although for the majority ofpatients, symptoms are benign and self-limited, a subset willbe diagnosed with an “acute abdomen,” as a result of seriousintra-abdominal pathology necessitating emergency inter-vention [1].An expeditious workup is necessary when evaluatingpatients presenting with acute abdominal pain to determinethe most likely cause of their symptoms and determinewhether or not emergent operative intervention is necessary.The most appropriate therapy should then be initiated withthe patient’s clinical status optimized. The workup shouldfirst include a thorough but efficient acquisition of thepatient’s history and physical examination followed by thejudicious use of laboratory and radiologic studies. The eval-uation of patients with acute abdominal pain can pose adiagnostic challenge for physicians as patients may presentwith atypical symptoms that interfere with the usual patternrecognition that often guides decision making. These atypi-cal presentations may help account for the over 25% ofabdominal pain cases labeled as “nonspecific” or “undiffer-entiated” [1].Additionally, physicians must take into account thepatient’s age and gender, as conditions associated with theacute abdomen may vary accordingly. Specifically, gastroen-teritis, acute appendicitis, and abdominal trauma are com-mon causes of the acute abdomen in children and youngadults [2], whereas biliary disease, intestinal obstruction,diverticulitis, and appendicitis are among the most commoncauses in middle-aged adults and the elderly [3]. Furthermore,pelvic pathology accounts for approximately 12% of acuteabdominal pain presentations and should therefore be con-sidered when evaluating female patients [1].Finally, there are a variety of nonsurgical causes ofabdominal pain that are cardiovascular, metabolic, and toxicin origin that should be considered when evaluating thesepatients.Clinical PresentationA thorough, yet expeditiously obtained, history and physicalexam are paramount to developing the differential diagnosisfor patients presenting with an acute abdomen. Various labo-ratory and imaging studies may subsequently be used asadjuncts to help guide decision making.HistoryWhen obtaining a patient history, the physician should avoidquestions that are leading and should focus on details of thepain. This includes information on the onset, character, dura-tion, and location of pain as well as the presence of radiationof pain.Regarding onset, pain that develops suddenly may be sug-gestive of a perforated viscus or ruptured abdominal aorticaneurysm (AAA). Pain that gradually worsens over time maybe the result of conditions characterized by the progressivedevelopment of infection and inflammation such as acuteappendicitis and cholecystitis.With regard to character, pain described as “burning” mayimplicate the pain of a perforated peptic ulcer while a “rip-ping” or “tearing” sensation typically represents the pain ofan aortic dissection. Pain that is intermittent or colicky shouldbe distinguished from pain that is continuous in nature.Colicky pain is typically associated with obstructive pro-cesses of the intestinal, hepatobiliary, or genitourinary tract,while pain that is continuous is usually the result of underlyingThe Evaluation of the Acute AbdomenAshley Hardy, Bennet Butler, and Marie Crandall2A. Hardy, M.D. • B. Butler, B.S. • M. Crandall, M.D., M.P.H.(*)Department of Surgery, Northwestern University Feinberg Schoolof Medicine, 676 N. St. Clair, Suite 650, Chicago, IL 60611, USAe-mail: mcrandall@northwestern.edu
  • 20 A. Hardy et al.ischemia or peritoneal inflammation. The latter may occurprimarily or following an initial episode of colicky pain whenan obstructive process is complicated by the development ofischemia. Examples of this include cases of biliary colic thatprogresses to acute cholecystitis or an incarcerated loop ofintestine that becomes strangulated and ischemic.The location of pain is important to consider as variouspathologic conditions tend to occur in specific regions orquadrants of the abdomen (Fig. 2.1a, b). Therefore, if thephysician is knowledgeable of the disease processes thatcause pain in these areas, they may be able to significantlynarrow down their differential. This holds true for those withthe understanding that certain conditions may result in painthat radiates or is referred to an area beyond the site of dis-ease due to shared innervation. Classic examples of thisinclude biliary pain that is referred to the right subscapularregion, the pain of acute pancreatitis that radiates to the back,and genitourinary pain that radiates from the flank down tothe groin. Finally, it is important to note any chronologicalvariation in the pain as this may provide helpful clues to thediagnosis. One of the best examples of this is in the case ofacute appendicitis, in which pain is initially perceived in theperiumbilical region before localizing to the right lowerquadrant (RLQ). This phenomenon reflects the transitionfrom visceral to parietal pain as appendiceal inflammationprogresses to involve and irritate the peritoneal lining.The majority of patients presenting with acute abdominalpain have associating symptoms (e.g., nausea, vomiting,diarrhea, constipation, hematochezia) that are often helpfulin making a diagnosis. Chronology of nausea is important toconsider as vomiting that occurs after the onset of abdominalpain is more likely to be surgical in nature as a result of med-ullary vomiting centers that are stimulated by pain impulsestraveling via secondary visceral afferent fibers. Additionally,constipation or obstipation may point towards an intestinalobstruction, while diarrhea (especially if bloody) is associ-ated with gastroenteritis, inflammatory bowel disease, andintestinal ischemia.Aggravating or alleviating factors may also provide diag-nostic clues. Depending on the underlying etiology, patientsmay maintain certain positions to help alleviate their pain.For example, patients with peritonitis may find some reliefwhen lying still with their knees bent, while patients suffer-ing from a bout of acute pancreatitis prefer to sit upright andlean forward. The effect of food is also important to consideras eating may alleviate the pain of a peptic ulcer while wors-ening the pain of an intestinal obstruction, acute cholecysti-tis, or acute pancreatitis [4, 5].The patient’s past medical and surgical histories may alsohelp to narrow down the differential. A remote history ofabdominal surgery may indicate that intestinal obstructionsecondary to adhesive disease is the source of a patient’scomplaints. Furthermore, it is important to consider theimpact that coexistent medical conditions, such as diabetes,chronic obstructive pulmonary disease, and atherosclerosis,may have on patient outcomes. The fact that elderly patientsare more likely to have significant comorbidities places themat increased risk for end organ damage incited by gastroin-testinal emergencies [6].Physicians should also take into account the effects ofmedication use. Anticoagulants may predispose to the devel-opment of rectus sheath hematomas and precipitate the gas-trointestinal bleeding that is a component of the patient’sunderlying illness or complicating the patient’s postopera-tive or posttreatment course. Chronic use of nonsteroidalanti-inflammatory drugs (NSAIDs) may also promote bleed-ing episodes along with the development of peptic ulcer dis-ease (PUD) and its complications.A detailed social history should also be obtained to deter-mine if there is any significant history of tobacco, alcohol, orillicit drug use, as such behaviors can be a source of thepatient’s symptoms as well as complicate the patient’s hospi-tal course. Notably, a history of cocaine abuse may pointtowards a diagnosis of mesenteric ischemia as the underlyingreason for the patient’s symptoms.The social history should consist of a detailed gyneco-logic history, including the date of the last menses, the pres-ence of any vaginal bleeding or discharge, and any history ofunprotected sexual activity or intercourse with multiple part-ners. Such information could indicate pregnancy complica-tions, salpingitis or pelvic inflammatory disease, and othergynecologic conditions as the cause of the patient’s acuteabdominal complaints. Physicians should also take note ofany history of recent travel to implicate infectious entero-colitis. Any exposure to environmental toxins should bedetermined, as lead and iron poisoning are two well-known,extra-abdominal sources of acute abdominal pain [4, 5].Finally, the patient’s family history may ascertain whethera patient’s symptoms are hereditary in origin, as seen in thecase of inherited hypercoagulable states, which can causeacute mesenteric ischemia secondary to mesenteric venousthrombosis.Physical ExamExamination of the patient presenting with acute abdominalpain should initially begin with overall appearance of thepatient and vital signs. Patients who appear diaphorectic,pale, and anxious often suffer from a condition of vascularorigin, including dissecting AAA, mesenteric ischemia, oratypical angina. The patient who is lying particularly still onthe exam table often has peritonitis from perforated viscus orpancreatitis. Vital signs should always be interpreted know-ing the status of the patient’s pain, or the influence of anyhome medications (beta blockers masking tachycardia, for
  • 212 The Evaluation of the Acute AbdomenFig. 2.1 (a) Common causes of the acute abdomen based on quadrant. (b) Common causes of the acute abdomen based on region. Illustrationscourtesy of Briana Dahl
  • 22 A. Hardy et al.example). Severity of systemic illness can be graded basedon the degree of tachypnea, tachycardia, febrile or hypother-mic response, and relative hypotension. Further examinationof the lungs and heart could reveal signs representing pri-mary cardiac disease or new-onset arrhythmias, which couldlead to mesenteric embolic disease. The remainder of a com-plete physical examination should proceed expeditiously sothat attention can be focused on the abdomen.Examination of the abdomen should comprise foursequential components: inspection, auscultation, percussion,and palpation. The exam should include all areas of the abdo-men, flanks, and groins.InspectionInspection is the initial step of the abdominal examinationand consists first of a general assessment of the patient’soverall state followed by focus on the abdomen. Patientswith peritonitis tend to lie still with their knees flexed asdoing so provides some alleviation of their pain. Uponcloser inspection of the abdomen, one should note thepresence of prior surgical scars, abdominal distension orvisible peristalsis, any obvious masses suggestive of anincarcerated hernia or tumor, or erythema or ecchymosessecondary to traumatic injury or hemorrhagic complica-tions of acute pancreatitis. Caput medusa may indicateliver disease.Auscultation of the abdomen should be performed nextand involves listening for the presence or the absence ofbowel sounds, for the characteristics of those sounds, and forthe presence of bruits. Although this step may be the leastvaluable overall, as bowel sounds may be completely normalin patients with severe intra-abdominal pathology, it mayFig. 2.1 (continued)
  • 232 The Evaluation of the Acute Abdomennonetheless provide some information that assists thephysician in making a diagnosis. For example, the absenceof bowel sounds may point towards a paralytic ileus,while ones that are high pitched in nature or rushed mayindicate the presence of a mechanical bowel obstruction.Finally, bruits that are detected on the abdominal examsuggest the presence of turbulent flow, which is often thecase for arterial stenoses.PercussionNext, percussion is utilized to assess for any dull masses,pneumoperitoneum, peritonitis, and ascites. A largely tym-panic abdomen may indicate the presence of underlyingloops of gas-filled bowel typical of intestinal obstructions ora paralytic ileus. If findings of tympany extend to include theright upper quadrant (RUQ) however, it may be suggestive offree intraperitoneal air. Lastly, percussion can be used todetect ascites by the presence of shifting dullness or by thegeneration of a fluid wave. Percussion may be all that is nec-essary to elicit pain in the patient who has peritonitis, forwhom further palpation should be deferred.PalpationPalpation is the final, critical step as it enables the physi-cian to better define the location and severity of pain andconfirm any findings made on other aspects of the physicalexam. Palpation should always commence away from thearea of greatest pain to prevent any voluntary guarding,which should be distinguished from the involuntary guardingthat accompanies peritonitis. Palpation can produce varioussigns commonly associated with specific disease processes.These include Murphy’s sign, characterized by an arrestin inspiration upon deep palpation of the RUQ in patientswith acute cholecystitis, and Rovsing’s sign, observedmany times in patients with acute appendicitis in whichpain is elicited at McBurney’s point upon palpation of theleft lower quadrant. Additionally, pain felt with hyperex-tension of the right hip, or iliopsoas sign, may indicate thepresence of a retrocecal appendix, while a pelvic locationof the appendix may be suspected in patients exhibitingObturator sign, or pain created with internal rotation of aflexed right hip.It is essential that all patients presenting with acuteabdominal pain undergo a digital rectal exam as it may revealthe presence of a mass, the focal tenderness of a periappen-diceal or peridiverticular abscess, and the presence of grossor occult blood. Finally, a pelvic examination should be per-formed in female patients presenting with lower quadrantpain to discern whether their pain has a gynecologic orobstetric source like pelvic inflammatory disease or a rup-tured ectopic pregnancy. On exam, one should take note ofany vaginal bleeding or discharge and any adnexal or cervi-cal motion tenderness [4, 5].Diagnosis Including Use/Value of PertinentDiagnostic StudiesLaboratory StudiesVarious laboratory studies can be used as adjuncts to helpnarrow down the differential, or to confirm or rule out a diag-nosis. A complete blood count (CBC) with differential, forexample, may help detect or confirm the presence of aninfectious or inflammatory process by the demonstration ofleukocytosis and/or a left shift. The accompanying hemat-ocrit is also of value as it can provide information about one’splasma volume, altered in cases of dehydration and hemor-rhage. In addition, serum electrolytes, blood urea nitrogen(BUN), and serum creatinine may provide clues to the extentof any fluid losses resulting from emesis, diarrhea, and third-spacing as can lactic acid levels and arterial blood gases. Thelatter two tests may also help to confirm the presence of anyintestinal ischemia or infarction as well.Liver function tests (LFTs) can help in determiningwhether conditions of the hepatobiliary tract are the source ofthe patient’s symptoms, while measurements of serum amy-lase and lipase may implicate acute pancreatitis or its compli-cations as the cause. Physicians should be mindful of the fact,however, that serum amylase levels may also be elevated in avariety of other acute abdominal conditions including intesti-nal obstruction, mesenteric thrombosis, ruptured ectopicpregnancy, and perforated PUD to name a few [7].Urinary tests, namely, urinalysis, should be obtained inpatients presenting with hematuria, dysuria, or flank pain todetermine if their symptoms are genitourinary in origin. Urinesamples can also be used to perform toxicology screens in thosewhose abdominal pain is thought to be the result of long-stand-ing illegal drug use, as seen in the case of mesenteric ischemiathat occurs with chronic cocaine abuse. Finally, human chori-onic gonadotropin (Hcg) levels can help in determining whethercomplications of pregnancy, such as a ruptured ectopic preg-nancy, are to blame. Regardless of whether or not it is the sourceof the patient’s symptoms, Hcg levels should be obtained in allwomen of childbearing age as it may affect decision making,especially if additional studies or surgical intervention aredeemed necessary [4]. Finally, depending on the clinical situa-tion, blood may be obtained for typing and crossmatching.Radiologic StudiesRadiologic imaging plays a key role in the evaluation and man-agement of the acute abdomen (Table 2.1). Plain films, ultra-sound (US), computed tomography (CT), and magneticresonanceimaging(MRI)arethemostcommonimagingmodal-ities employed in the diagnostic workup of these patients.
  • 24 A. Hardy et al.While plain films are less sensitive and specific comparedto CT scanning, it is often the initial imaging study performedin patients presenting with acute abdominal pain. The advan-tages of their use include their rapidity and universal avail-ability. Although patients are subject to ionizing radiationexposure, the dose is significantly lower than that of CTscans [8]. Plain films can be of greatest utility in patientssuspected of a perforated viscus by the detection of a pneu-moperitoneum, or the presence of free air beneath the righthemidiaphragm, as well as those with a suspected intestinalobstruction by the presence of dilated loops of bowel andair-fluid levels.The advantages of abdominal US include the lower costand the lack of ionizing radiation exposure [9], which isadvantageous for the pediatric population and pregnantwomen. In addition, abdominal US is the imaging modalityof choice for those patients presenting with suspected hepa-tobiliary pathology, with a sensitivity of 88% and specificityof 80% in the diagnosis of acute cholecystitis [10]. Featuressuggestive of acute cholecystitis on US include the presenceof gallstones, gallbladder wall thickening, pericholecysticfluid, and an elicited Murphy’s sign (Fig. 2.2).If an obstetrical or gynecologic condition is suspectedas the source of a patient’s acute abdominal pain, pelvicand transvaginal US are the preferred imaging modalitiesto assess the uterus and adnexal structures. The presence offree fluid and an empty uterus on US in the setting of apositive pregnancy test is strongly suggestive of a rupturedectopic pregnancy [11] while an enlarged and edematousovary with an absence of blood flow is characteristic of atorsed ovary.The CT scan has sensitivity of 96% overall for diagnos-ing most causes of the acute abdomen, compared to a 30%sensitivity for plain films [8]. As a result, the number ofCT scans performed for patients presenting with acuteabdominal pain has increased by 141% between 1996 and2005 [12]. CT scanning has had a significant impact on thediagnosis of acute appendicitis as it has decreased the neg-ative appendectomy rate from 24 to 3% [13]. Findingsdiagnostic of appendicitis on CT scan include an enlarged,nonopacified appendix, appendicoliths, and adjacent fatstranding while the presence of an abscess, phlegmon, andextraluminal gas points towards appendiceal perforation(see Fig. 2.2).Table 2.1 Diagnostic imaging strategies and treatment options for common causes of acute abdominal pain based on age and genderImaging strategy Treatment optionsChildren/young adultsAcute appendicitis US, CT Appendectomy (laparoscopic or open); percutaneous abscess drainageGastroenteritis None Supportive careFunctional constipation XR Manual or pharmacologic fecal disimpactionIntussusception XR, US, contrast enema Contrast enema; operative reduction; resection of ischemic or perforated bowelAbdominal trauma FAST, DPL, CT Exploratory laparotomy; IROlder adults/elderlyAcute cholecystitis US Cholecystectomy (laparoscopic or open); percutaneous cholecystostomyIntestinal obstruction XR, CT Supportive care; exploratory laparotomy with adhesiolysis, resectionof ischemic bowelPerforated peptic ulcer XR, CT or UGI with H2Osoluble contrastPatch closure with Helicobacter pylori treatment if hemodynamic instabilityDiverticulitis CT Supportive care; percutaneous abscess drainage; resection of involved bowelAcute appendicitis CT Appendectomy (laparoscopic or open); percutaneous abscess drainageAcute pancreatitis US, CT Supportive care; IR or operative pseudocyst drainage; debridement of infectednecrosisMesenteric ischemia CTA, MRA Supportive care; IR; operative bypass, thrombectomy, resectionof ischemic bowelWomenAcute appendicitis in pregnancy US, CT, MRI Appendectomy (laparoscopic or open)Acute cholecystitis in pregnancy US Cholecystectomy (laparoscopic or open)Ectopic pregnancy US Linear salpingostomy or salpingectomy (laparoscopic or open)Ovarian torsion US Ovarian detorsion, possible oophorectomy (laparoscopic or open)Pelvic inflammatory disease US, MRI, CT Supportive care; percutaneous or operative drainageof abscessUS ultrasound, CT computerized tomography, XR plain radiography, FAST focused abdominal sonography for trauma, DPL diagnostic peritoneallavage, UGI upper gastrointestinal series, IR interventional radiology, CTA, CT computerized tomographic angiography, MRA magnetic resonanceangiography, MRI magnetic resonance imaging
  • 252 The Evaluation of the Acute AbdomenAlthough MRIs provide excellent visualization of theintrabdominal organs without the need for ionizing radiation,their cost and lack of universal availability make them lessideal for use in the evaluation of the acute abdomen [14]. Inaddition, some patients have contraindications to undergoingan MRI or are simply unable to tolerate the test because ofclaustrophobia. MRI, however, may be of utility for pregnantwomen in the setting of acute abdominal pain with equivocalUS findings [15].Diagnostic LaparoscopyDiagnostic laparoscopy may be of utility in the evaluation ofacute abdominal pain, especially in situations in which theunderlying etiology remains unclear despite a thorough clin-ical evaluation and radiologic imaging. The advantages ofdiagnostic laparoscopy include its ability to make a definitivediagnosis in 90–98% of cases and determine whether furtherintervention is necessary [16, 17]. A resultant decrease in theFig. 2.2 Algorithm for the treatment of the acute abdomen
  • 26 A. Hardy et al.negative laparotomy rate—and the fact that if further treatmentis indicated that many acute abdominal conditions can betreated laparoscopically—equates to a decrease in morbidityand mortality, a shorter length of stay, and decreased hospitalcosts [16].Therapeutic OptionsIn the evaluation of patients presenting with acute abdominalpain, the physician must first determine whether operativeintervention is necessary, and if so, whether it should be pur-sued on an immediate or emergent basis versus urgently orwithin a few hours of a patient’s arrival. Treatment algo-rithms are beneficial in helping to make such decisions (seeFig. 2.2). In some cases, a short delay to fully correct anyfluid and electrolyte abnormalities may prove to be beneficial,whereas in others, immediate operative intervention is neces-sary for stabilization of a patient’s condition. This holds truein the presence of peritonitis, a pneumoperitoneum, intesti-nal ischemia or infarction, and continued hemodynamicinstability despite aggressive resuscitative measures.Specific treatment strategies for the acute abdomen arelargely dependent upon the underlying etiology (seeTable 2.1). In the case of acute appendicitis, patients shouldreceive antibiotics and undergo urgent removal of theirappendix through either an open or laparoscopic approach,unless their condition is complicated by a perforation with anassociated abscess or phlegmon, for which initial nonopera-tive therapy with interval appendectomy is employed.For those presenting with acute pancreatitis, however,treatment is largely supportive and includes bowel rest,aggressive fluid and electrolyte repletion, pain control, anti-biotic therapy, and nutritional support. Surgery is reservedfor the management of complications that may occur subse-quently, including the development of infected pancreaticnecrosis and large, symptomatic pseudocysts.Lastly, for patients whose conditions do not warrant emer-gent surgery, but in whom the underlying etiology remainsuncertain, treatment options include diagnostic laparoscopyas previously discussed or observation with frequent moni-toring of their hemodynamic status and serial abdominalexaminations. Studies have demonstrated that observation inproperly selected patients is safe without an increased risk ofcomplications [18].Special Patient PopulationsThe Acute Abdomen in the Extremes of AgeAbdominal pain is one of the most common complaintsamong elderly patients presenting to the emergencydepartment [19]. As the presentation is often different thanwhat is seen in younger patients, the ability to accuratelydiagnose the underlying cause of their abdominal complaintscan be challenging. Elderly patients may lack the febrileresponse, leukocytosis, and severity of pain expected in thosesuffering from serious intra-abdominal pathology as a resultof the age-dependent decline in immune function [20] alongwith a well-documented delay in pain perception [21].The atypical presentation commonly seen in these patientsmay also be attributed to the effects of other, coexistingmedical conditions and medications. For example, betablockers may blunt the normal tachycardic response to acuteabdominal processes while nonsteroidal agents and acet-aminophen may prevent the development of a fever. Finally,diagnostic accuracy may be difficult to achieve because ofthe inability to obtain an adequate history from elderlypatients with memory and hearing deficits. Combined, thesefactors contribute to the increased incidence of complica-tions and increased morbidity and mortality observed inelderly patients presenting with acute abdominal pain. Forexample, although the incidence of acute appendicitis islower in this population compared to their younger counter-parts, the rate of perforation is significantly higher, reachingalmost 70% in some series [22]. Furthermore, complicationsof acute cholecystitis occur in more than 50% of patientsaged 65 or older [23].Although on the opposite end of the age spectrum, thediagnosis of the acute abdomen in children can be equally aschallenging, particularly in children who are preverbal oruncooperative. Further adding to the difficulty is the fact thatthe etiologies of abdominal pain in children can range fromtrivial (e.g., constipation) to potentially life-threatening (e.g.,malrotation with midgut volvulus) with little to no differencein their presentation [24]. As a result, there are higher ratesof misdiagnosis and complications in the pediatric popula-tion as well. In fact, the rate of perforation in childhood casesof acute appendicitis is 30–65%, which is significantly higherthan what is reported for adults [25].Overall, physicians should be mindful of the potentialchallenges posed to them in the evaluation of acute abdomi-nal pain in these extremes of age and adjust their diagnosticapproach accordingly.The Acute Abdomen in ImmunocompromisedPatientsThe ability to make the diagnosis of an acute abdomen isoften challenging for those patients who are immunocom-promised as a result of conditions such as cancer requiringchemotherapy, transplantation, human immunodeficiencyvirus/acquired immunodeficiency syndrome (HIV/AIDS),renal failure, diabetes, and malnourishment to name a few.
  • 272 The Evaluation of the Acute AbdomenAs a result of their body’s inability to launch a fullinflammatory response, these patients may have a delayedonset of fever and other typical symptoms, experience lesspain, and have an underwhelming leukocytosis [4]. As aresult, a diagnosis may not be made until the development ofoverwhelming sepsis, multisystem organ failure, and death.It is also important to consider that these patients may sufferfrom a variety of atypical infections—including ones that areviral (in particular, cytomegalovirus and Epstein–Barr virusinfections), mycobacterial, fungal, and protozoal in origin—thatmay affect the pancreas and hepatobiliary, and gastrointestinaltracts. Furthermore, neutropenic enterocolitis is a commonsource of acute abdominal pain in patients with bone marrowsuppression secondary to chemotherapy [26]. As a result ofthese challenges unique to this subset of patients, physiciansshould have a high index of suspicion for an acute abdominalprocess if such patients present with persistent abdominal com-plaints even if seemingly mild in intensity. These patients shouldundergo prompt diagnostic imaging and the possibility of oper-ative intervention should be considered early on.The Acute Abdomen in the Critically IllThe acute abdomen in the critically ill presents a diagnosticchallenge as even the history and physical exam are oftenunattainable or unhelpful, especially in those patients whoare obtunded, sedated, or intubated. Physicians should there-fore have a high index of suspicion and develop a strategythat will allow them to diagnose and treat acute abdominalillnesses in a timely fashion.Physicians should initially take note of any recent abdomi-nal surgery, the sudden onset of abdominal pain or distension,as well as any changes in laboratory studies or hemodynamicstatus as indicated by changes in vital signs, an increase involume requirements, and the need for pressors.If not contraindicated because of hemodynamic instabil-ity or physical constraints, radiologic imaging should beobtained to search for evidence of an acute abdominal pro-cess. As is the case for patients who are not critically ill, thesensitivity and specificity for diagnosing certain conditionsmay vary amongst imaging modalities.If contraindicated, however, but clinical suspicion is high,then emergent laparotomy is indicated. If there are stilldoubts however, a less invasive technique such as diagnosticperitoneal lavage (DPL) may be used to assist in decisionmaking. The advantages of DPL include the ability to per-form the test at the bedside and the fact that it preventedunnecessary laparotomy in more than 60% of patients in asmall series [27, 28]. Overall however, CT is the imagingmodality of choice for most intra-abdominal processes,unless a biliary process is suspected for which US is the mostsensitive and specific [10].An acute abdominal condition of the biliary tract morecommonly observed in the critically ill is that of acute acal-culous cholecystitis. Although the exact etiology is unclear,biliary stasis and gallbladder ischemia with resultant bacte-rial colonization have been implicated in its development[29]. Such a scenario is common in critically ill patientswho are typically not enterally fed and who are hemody-namically unstable.Acalculous cholecystitis tends to have a more fulminantcourse and is therefore characterized by increased rates ofgallbladder perforation and gangrene [29]. While cholecys-tectomy is the treatment of choice for this condition, forpatients who are critically ill and unable to undergo surgery,percutaneous cholecystostomy is therapeutic until thepatient is able to undergo cholecystectomy at a later time.Approximately 90% of patients experience significantimprovement after percutaneous cholecystostomy [30].Another acute abdominal process more prevalent in thecritically ill population is that of abdominal compartmentsyndrome (ACS), which often occurs in the setting of abdom-inal sepsis coupled with aggressive fluid resuscitation [31].Characterized by an increased intra-abdominal pressure(IAP) of 20 mmHg or higher, ACS can progress to hemody-namic compromise (due to impaired venous return),difficulties with ventilation and oxygenation (a result of ele-vated airway pressures), and oliguria (secondary to impairedvenous return and renal vein compression) [32]. Treatmentinvolves emergent abdominal fascial decompression.The Acute Abdomen in the Morbidly ObeseIt is often more challenging to diagnose the acute abdomenin morbidly obese patients as a result of the subtle changes invital signs, atypical symptoms, and underwhelming physicalexam findings these patients often present with. A mildlyelevated heart rate, fever, nausea, and malaise may be theonly indications to the presence of a serious intra-abdominalprocess. This is further complicated by the constraints cre-ated by an obese body habitus that make performing a physi-cal exam and interpreting any exam findings more difficult.By the time the patient is found to have peritonitis, it is oftena late finding with the patient at significant risk for the sub-sequent development of abdominal sepsis, multisystem organfailure, and death [33].Physicians should also be aware of the fact that an obesebody habitus may result in imaging studies being unattain-able or more difficult to interpret. Weight limits may rendersome morbidly obese patients from being eligible to undergoCT or MRI scanning and large amounts of subcutaneous fatcan result in poor radiographic and sonographic imagequality [34]. As a result of these challenges, a high index ofsuspicion should be employed when making treatment
  • 28 A. Hardy et al.decisions, in particular, whether to operate or not. Note thatwith the advent of laparoscopy and the development of bar-iatric laparoscopic ports and instruments less invasive mea-sures may be taken to both diagnose and treat the source ofthe patient’s symptoms [35].The Acute Abdomen in Pregnant PatientsWhen evaluating a pregnant patient who presents withabdominal pain, one must keep in mind that delays in diag-nosis and subsequent intervention can result in an increasedrisk of morbidity and mortality for both the patient and herunborn fetus.Delays in presentation, diagnosis, and treatment mayoccur because many of the presenting signs and symptomsmay mimic those normally observed in pregnancy, includ-ing abdominal pain, nausea, vomiting, and anorexia. Inaddition, vital signs and laboratory findings may be moredifficult to interpret as they are routinely altered in preg-nancy. There is notably a “physiologic anemia” in pregnancyin addition to mild leukocytosis. Additionally, there is typi-cally a 10–15 bpm increase in pulse rate as well as relativehypotension as a result of hormone-mediated vasodilation[36].The examining physician must also take into account thatthe presentation of certain disease processes and physicalexam findings may differ in the pregnant patient as a result ofthe upward displacement of the gravid uterus. A classicexample of this is seen in the case of acute appendicitis, inwhich tenderness may be palpated in the RUQ. Appendicitisis the most common nonobstetrical cause of the acute abdo-men, complicating 1 in 1,500 births [37]. Although the over-all incidence is similar to that of nonpregnant patients, therate of perforation is higher at approximately 25%, presum-ably due to delays in diagnosis and intervention. If and whenperforation occurs, the risk of both fetal and maternal mor-tality increases significantly [38].Delays may occur because of hesitancy on the part of thephysician to obtain certain radiologic studies like that ofplain films or CT scans due to the concerns of the radiationexposure associated with these modalities. Ultrasound istherefore used as the initial imaging study in most evalua-tions of the pregnant acute abdomen [39]. In addition to fetalevaluation, ultrasound is the imaging study of choice forassessment of the biliary tract, pancreas, kidneys, and adn-exa. In addition, multiple studies have shown that whenpaired with graded compression, ultrasound has a sensitivitybetween 67 and 100% and a specificity between 83 and 96%for diagnosing acute appendicitis in pregnancy [40].If the diagnosis remains uncertain, CT scan is an accept-able alternative means of imaging the pregnant abdomen ifused judiciously in order to minimize ionizing radiationexposure [41]. Although the estimated conceptus dose from asingleCTacquisitionis25mGy[42],asperthe1995AmericanCollege of Obstetricians and Gynecologists (ACOG) consen-sus statement, “Women should be counseled that X-ray expo-sure from a single diagnostic procedure does not result inharmful fetal effects. Specifically, exposure to less than 5 rad(50 mGy) has not been associated with an increase in fetalanomalies or pregnancy loss.”[43] Ultimately, the use of CTscans as a secondary imaging tool in pregnancy can lead to amore timely diagnosis of acute appendicitis resulting indecreased rates of perforation. This along with the decreasedrate of negative appendectomies observed in expectant womenundergoing US followed by CT scan [44] likely reduces therisk of mortality for both the mother and fetus significantly.MRI, which uses magnets instead of ionizing radiation,has also been shown recently to be of use in evaluatingabdominal pain during pregnancy when ultrasonagraphy wasdeemed inconclusive [15]. Despite this however, MRI is notalways readily available for emergent evaluations and theeffects of using gadolinium-based contrast, which crosses theplacenta, have yet to be determined and it is not approved foruse in pregnancy, unlike iodinated CT contrast agents [14].Once diagnosed, patients should undergo appendectomy.Despite initial concerns of the safety of such an approach,laparoscopy has been accepted as safe with the same advan-tages afforded for nonpregnant patients, including shorterhospitalizations and less narcotic medication needs [45]. Ofcourse certain precautions should be taken to ensure safety,including using an open Hasson approach to enter the abdo-men, a left tilted position, maintaining a CO2insufflation of10–15 mmHg, and monitoring fetal heart tones during theprocedure [46].After appendicitis, the next most common nonobstetriccause of acute abdominal pain are disorders of the biliarytract, notably acute cholecystitis and gallstone pancreatitis.The incidence of acute cholecystitis ranges from 1 in 6,000to 1 in 10,000 births [37]. Presenting symptoms, diagnosticworkup, and treatment are similar to their nonpregnant coun-terparts. As previously stated, laboratory values may bemore difficult to interpret, especially in the case of acutecholecystitis as white blood cell counts and alkaline phos-phatase levels are normally elevated during pregnancy [37].As is the case in nonpregnant patients, acute cholecystitis isusually treated conservatively early on with intravenous fluidhydration, bowel rest, pain control, and antibiotics. If thepatient fails to respond to medical management, then sur-gery is indicated. Failing to operate on these patients in atimely fashion significantly increases the risk of pretermlabor and fetal loss [47].Regardless of whether patients respond appropriately toconservative management, the majority of surgeons still rec-ommend surgery during pregnancy to prevent any recurrenceor any complications that may pose a threat to the fetus [47].
  • 292 The Evaluation of the Acute AbdomenIn fact, the rate of fetal demise with gallstone pancreatitis hasbeen reported to be as high as 60% [48]. As is the case withacute appendicitis, laparoscopic cholecystectomy has beendeemedsafetoperformduringpregnancywithoutanyincreasedrisk of morbidity or mortality to the mother or fetus [49].The Acute Abdomen from a Global PerspectiveThe acute abdomen can be especially concerning from aglobal health perspective. The low density of adequatelytrained physicians and quality treatment facilities in develop-ing countries means long delays between symptom onset andtreatment, resulting in worse outcomes [50, 51]. Proper man-agement of the acute abdomen in these regions may be fur-ther complicated by the lack of modern radiographic andother diagnostic modalities, which may render contemporarytreatment algorithms unusable. As a result, increased empha-sis should be placed on careful history taking and physicalexam skills. Findings of abdominal distension, abdominalmasses, deranged vital signs, guarding, and a positive vagi-nal/rectal examination have been associated with worse out-comes in these regions, warranting further investigation [52].In areas where advanced clinicians are unavailable, a stan-dardized questionnaire may help in establishing a differentialdiagnosis in patients presenting with acute abdominal pain.There is a lack of consensus on the overall incidence of theacute abdomen in the developing world, likely as a result of therange of locations which fall into this category (e.g., SoutheastAsia, Sub-Saharan Africa, and Central America) in addition tovarious socioeconomic, dietary, cultural, and environmentaldifferences. Despite this, some generalizations about the mostcommon causes of the acute abdomen in impoverished regionscan be made. Many are shared with those of developed nations,including acute appendicitis and intestinal obstruction, whichaccount for up to 25 and 35% of all cases, respectively [52].Other commonly shared causes of the acute abdomen includeacute cholecystitis, gynecological disorders (e.g., ectopic preg-nancy, uterine rupture, and tubo-ovarian abscesses), trauma(most commonly from gunshot wounds and car accidents),and perforated peptic ulcers [53, 54].In addition to these conditions, physicians in developingcountries must consider other exotic causes of acute abdom-inal pain, including typhoid enteritis, abdominal tuberculo-sis, and parasitic infections, which can themselves causeacute intestinal obstructions, appendicitis, cholangitis, andliver abscesses [55]. Typhoid, which usually presents withhigh fever, abdominal distension, and delirium, remainsendemic in impoverished parts of the world [56]. Causedby the bacterium Salmonella typhi, typhoid fever is trans-mitted through fecal contamination of food or water sup-plies. If not identified and treated in a timely fashion withthe appropriate antibiotics, typhoid can result in intestinalhemorrhage or perforation—two potentially fatal causes ofan acute abdomen requiring surgical intervention [56]. Inone series, typhoid fever complicated by ileal perforationwas diagnosed in 16% of patients in a region of West Africa,making it the second most common cause of the acuteabdomen [51].A large number of acute abdominal cases in developingcountries are caused by parasitic infections, which like thatof typhoid fever are typically acquired through fecal-oraltransmission. In one study originating from West Africa,some 4% of acute abdominal cases necessitating emergencysurgery were attributable to parasites [57]. The majority ofthese were secondary to infections with members of theamoeba family, which can cause colitis and hepatic abscesses,or Ascaris lumbricoides, a species of roundworms that caninvade and overwhelm the gastrointestinal and hepatobiliarysystems, resulting in intestinal obstruction, appendicitis, pan-creatitis, and cholecystitis [58]. In addition to emergent sur-gical intervention, patients should be treated with antiparasiticmedications to ensure complete eradication of disease.Overall, the acute abdomen poses diagnostic challengesunique to the developing world given the limited access toresources and personnel required to sufficiently treat patientswith potentially life-threatening abdominal conditions.Compounding this are the other exotic causes of acute abdom-inal pain prevalent in these regions that one must consider intheir workup. Therefore, in addition to enhancing access tohealthcare, health education, and sanitation, attention shouldbe placed on the development of adequate history taking andphysical exam skills to improve the outcomes of patients pre-senting with an acute abdomen in these regions of the world.Potential Complications and OutcomesThe outcomes of patients presenting with an acute abdomenare influenced by the underlying etiology of their symptoms,age, comorbid conditions, and the time to diagnosis andtreatment. In terms of etiology, one could assume that apatient with a noncontained hollow viscus perforation islikely to have higher rates of morbidity and mortality in theperi- and postoperative period compared to a patient present-ing with acute, nonperforated appendicitis. With regard toage and health status, diminished physiologic reserve and anincreased incidence of comorbidities place elderly patientsat an elevated risk of complications and death compared totheir younger counterparts. For example, the age-relateddecline in pulmonary function is associated with a prolongedneed for mechanical ventilation and an increased risk ofdeveloping ventilator-associated pneumonias [59]. Theseissues are compounded by the fact that elderly patients tendto have delays in diagnosis and treatment, further contribut-ing to their increased rates of morbidity and mortality. In the
  • 30 A. Hardy et al.case of perforated PUD, older patients who underwentsurgery more than 24 h after perforation were eight timesmore likely to die compared to those who were operated onwithin 4 h [60].Morbidly obese patients with an acute abdomen are alsoat an increased risk of poor outcomes due to atypical presen-tations and the challenges posed by their body habitus thatresult in treatment delays [33]. Even in cases where surgeryis indicated and performed in a timely manner, higher ratesof postoperative complications including surgical woundinfections and multisystem organ failure are experienced bymorbidly obese patients [61].In pregnant patients, the acute abdomen poses significantrisks to both the mother and fetus. Atypical presentationsand the inability to distinguish some acute abdominal symp-toms from those normally experienced during pregnancy canresult in treatment delays and an increased susceptibility forpreterm labor and fetal loss [38].In general, regardless of age or health status, patients pre-senting with an acute abdomen should undergo a thoroughyet expeditious evaluation to help establish a diagnosis andinitiate the therapeutic interventions necessary to help ensurepositive outcomes for these patients.References1. Kamin RA, Nowicki TA, Courtney DS, Powers RD. Pearls and pit-falls in the emergency department evaluation of abdominal pain.Emerg Med Clin North Am. 2003;21(1):61–72. vi.2. Leung AK, Sigalet DL. Acute abdominal pain in children. Am FamPhysician. 2003;67(11):2321–6.3. Hendrickson M, Naparst TR. Abdominal surgical emergencies inthe elderly. Emerg Med Clin North Am. 2003;21(4):937–69.4. Sabiston DC, Townsend CM. Acute abdomen. 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