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Emergency and Acute Medicine – Diverticulitis
Basics
Description
Diverticulitis results from micro- or macroscopic perforation of a colonic diverticulum. The condition is classified as uncomplicated in approximately 75% of cases and complicated in the remainder. Its incidence is increasing worldwide, and obesity is a recognized risk factor.
Etiology
Fecal material may become trapped within a diverticulum and harden to form a fecalith, leading to increased intraluminal pressure. Progressive erosion of the diverticular wall causes inflammation, focal necrosis, and eventual perforation.
Microperforation leads to uncomplicated diverticulitis, characterized by colonic wall thickening and surrounding inflammatory changes, such as fat stranding on computed tomography.
Macroperforation results in complicated diverticulitis, which may include abscess formation, bowel obstruction, fistula formation after recurrent attacks, and peritonitis. Colovesical fistula is the most common fistula type and presents with dysuria, urinary frequency, urgency, pneumaturia, and fecaluria.
Diagnosis
Signs and symptoms
Symptoms typically evolve over several days, and nearly half of patients report prior similar episodes. Left lower quadrant abdominal pain occurs in about 70% of cases in Western populations, whereas right lower quadrant pain is more common in Asian patients. Pain is often initially vague before localizing. Associated symptoms include nausea, vomiting, constipation, diarrhea, and urinary complaints.
On examination, patients may have low-grade fever and left lower quadrant tenderness, with an occasional palpable mass representing a phlegmon. Abdominal distension and variable bowel sounds may be present. Rectal tenderness with heme-positive stool can occur, although massive rectal bleeding is rare. Peritoneal signs suggest perforation. Elderly, immunocompromised patients, or those on corticosteroids may have minimal findings.
Essential workup
Initial evaluation includes complete blood count and urinalysis. Blood cultures and lactate levels are obtained if sepsis is suspected. Computed tomography of the abdomen and pelvis is the preferred diagnostic modality, as it confirms diverticulitis, assesses severity, and identifies alternative diagnoses. Intravenous and oral or rectal contrast enhance diagnostic accuracy, while barium contrast should be avoided when perforation is suspected. Plain abdominal and chest radiographs may identify free air or obstruction.
Diagnosis tests and interpretation
Leukocytosis is common but not universal. Urinalysis may reveal sterile pyuria, and the presence of colonic bacteria suggests a colovesical fistula. Imaging findings on CT include colonic wall thickening greater than 5 mm, pericolic fat inflammation, and abscess formation. CT-guided percutaneous drainage of localized abscesses may avoid surgery. Endoscopy is not required during the acute phase, though rigid sigmoidoscopy may help exclude alternative diagnoses. Ultrasonography can identify wall thickening or abscesses but is operator dependent. Barium enema is reserved for post-resolution evaluation to exclude malignancy or fistula.
Differential diagnosis
Consider colon carcinoma with perforation, ischemic or infectious colitis, appendicitis, inflammatory bowel disease, irritable bowel syndrome, gynecologic pathology, pancreatic disease, pelvic inflammatory disease, peptic ulcer disease, and renal colic.
Treatment
Prehospital care
Initial management includes intravenous fluid administration.
Initial stabilization and therapy
Resuscitate with isotonic fluids, institute bowel rest with nothing by mouth or clear liquids, and place a nasogastric tube if persistent vomiting or bowel obstruction is suspected.
Emergency department treatment and procedures
Uncomplicated diverticulitis is usually managed medically, though up to 30% of patients may eventually require surgery. Complicated diverticulitis often requires percutaneous drainage or surgical intervention. Analgesia may include anticholinergics such as dicyclomine for colonic spasm or opioids for severe pain, avoiding opioids in unstable patients.
Antibiotics should cover gram-negative aerobic and anaerobic organisms. Mild uncomplicated cases may be treated as outpatients with oral regimens such as amoxicillin-clavulanate or trimethoprim-sulfamethoxazole plus metronidazole. Inpatient regimens include third-generation cephalosporins with metronidazole, beta-lactam/beta-lactamase inhibitor combinations, or carbapenems for severe disease.
Emergent surgery is indicated for generalized peritonitis due to perforation. Elective surgery may be considered after recurrent attacks, fistula formation, obstruction, or failure of medical therapy. Percutaneous drainage is appropriate for well-circumscribed abscesses.
Medication
Common agents include amoxicillin-clavulanate, trimethoprim-sulfamethoxazole, ciprofloxacin, metronidazole, third-generation cephalosporins, beta-lactam/beta-lactamase inhibitors, and carbapenems, selected according to disease severity and patient factors.
Follow-up and disposition
Admission criteria
Hospitalization is indicated for intractable pain or vomiting, high fever, peritonitis, failure of outpatient therapy, severe disease on imaging, significant leukocytosis, immunocompromised status, recurrent episodes, major comorbidities, extremes of age, or diagnostic uncertainty.
Discharge criteria
Patients with mild disease, minimal comorbidities, and ability to tolerate oral intake may be discharged with close follow-up.
Follow-up recommendations
Patients should begin with clear liquids and advance diet as symptoms improve, usually within three days. They should seek care for worsening pain, fever, or inability to tolerate oral intake. Colonoscopy or contrast studies are recommended after recovery to exclude malignancy. Avoidance of seeds and nuts is not required.
Pearls and pitfalls
Computed tomography distinguishes uncomplicated from complicated diverticulitis and guides management. Most uncomplicated cases do not progress to complicated disease, and multiple attacks do not necessarily predict worsening severity. Severe findings on initial imaging are associated with higher risk of treatment failure and complications.
Basics
Description
Diverticulitis results from micro- or macroscopic perforation of a colonic diverticulum. The condition is classified as uncomplicated in approximately 75% of cases and complicated in the remainder. Its incidence is increasing worldwide, and obesity is a recognized risk factor.
Etiology
Fecal material may become trapped within a diverticulum and harden to form a fecalith, leading to increased intraluminal pressure. Progressive erosion of the diverticular wall causes inflammation, focal necrosis, and eventual perforation.
Microperforation leads to uncomplicated diverticulitis, characterized by colonic wall thickening and surrounding inflammatory changes, such as fat stranding on computed tomography.
Macroperforation results in complicated diverticulitis, which may include abscess formation, bowel obstruction, fistula formation after recurrent attacks, and peritonitis. Colovesical fistula is the most common fistula type and presents with dysuria, urinary frequency, urgency, pneumaturia, and fecaluria.
Diagnosis
Signs and symptoms
Symptoms typically evolve over several days, and nearly half of patients report prior similar episodes. Left lower quadrant abdominal pain occurs in about 70% of cases in Western populations, whereas right lower quadrant pain is more common in Asian patients. Pain is often initially vague before localizing. Associated symptoms include nausea, vomiting, constipation, diarrhea, and urinary complaints.
On examination, patients may have low-grade fever and left lower quadrant tenderness, with an occasional palpable mass representing a phlegmon. Abdominal distension and variable bowel sounds may be present. Rectal tenderness with heme-positive stool can occur, although massive rectal bleeding is rare. Peritoneal signs suggest perforation. Elderly, immunocompromised patients, or those on corticosteroids may have minimal findings.
Essential workup
Initial evaluation includes complete blood count and urinalysis. Blood cultures and lactate levels are obtained if sepsis is suspected. Computed tomography of the abdomen and pelvis is the preferred diagnostic modality, as it confirms diverticulitis, assesses severity, and identifies alternative diagnoses. Intravenous and oral or rectal contrast enhance diagnostic accuracy, while barium contrast should be avoided when perforation is suspected. Plain abdominal and chest radiographs may identify free air or obstruction.
Diagnosis tests and interpretation
Leukocytosis is common but not universal. Urinalysis may reveal sterile pyuria, and the presence of colonic bacteria suggests a colovesical fistula. Imaging findings on CT include colonic wall thickening greater than 5 mm, pericolic fat inflammation, and abscess formation. CT-guided percutaneous drainage of localized abscesses may avoid surgery. Endoscopy is not required during the acute phase, though rigid sigmoidoscopy may help exclude alternative diagnoses. Ultrasonography can identify wall thickening or abscesses but is operator dependent. Barium enema is reserved for post-resolution evaluation to exclude malignancy or fistula.
Differential diagnosis
Consider colon carcinoma with perforation, ischemic or infectious colitis, appendicitis, inflammatory bowel disease, irritable bowel syndrome, gynecologic pathology, pancreatic disease, pelvic inflammatory disease, peptic ulcer disease, and renal colic.
Treatment
Prehospital care
Initial management includes intravenous fluid administration.
Initial stabilization and therapy
Resuscitate with isotonic fluids, institute bowel rest with nothing by mouth or clear liquids, and place a nasogastric tube if persistent vomiting or bowel obstruction is suspected.
Emergency department treatment and procedures
Uncomplicated diverticulitis is usually managed medically, though up to 30% of patients may eventually require surgery. Complicated diverticulitis often requires percutaneous drainage or surgical intervention. Analgesia may include anticholinergics such as dicyclomine for colonic spasm or opioids for severe pain, avoiding opioids in unstable patients.
Antibiotics should cover gram-negative aerobic and anaerobic organisms. Mild uncomplicated cases may be treated as outpatients with oral regimens such as amoxicillin-clavulanate or trimethoprim-sulfamethoxazole plus metronidazole. Inpatient regimens include third-generation cephalosporins with metronidazole, beta-lactam/beta-lactamase inhibitor combinations, or carbapenems for severe disease.
Emergent surgery is indicated for generalized peritonitis due to perforation. Elective surgery may be considered after recurrent attacks, fistula formation, obstruction, or failure of medical therapy. Percutaneous drainage is appropriate for well-circumscribed abscesses.
Medication
Common agents include amoxicillin-clavulanate, trimethoprim-sulfamethoxazole, ciprofloxacin, metronidazole, third-generation cephalosporins, beta-lactam/beta-lactamase inhibitors, and carbapenems, selected according to disease severity and patient factors.
Follow-up and disposition
Admission criteria
Hospitalization is indicated for intractable pain or vomiting, high fever, peritonitis, failure of outpatient therapy, severe disease on imaging, significant leukocytosis, immunocompromised status, recurrent episodes, major comorbidities, extremes of age, or diagnostic uncertainty.
Discharge criteria
Patients with mild disease, minimal comorbidities, and ability to tolerate oral intake may be discharged with close follow-up.
Follow-up recommendations
Patients should begin with clear liquids and advance diet as symptoms improve, usually within three days. They should seek care for worsening pain, fever, or inability to tolerate oral intake. Colonoscopy or contrast studies are recommended after recovery to exclude malignancy. Avoidance of seeds and nuts is not required.
Pearls and pitfalls
Computed tomography distinguishes uncomplicated from complicated diverticulitis and guides management. Most uncomplicated cases do not progress to complicated disease, and multiple attacks do not necessarily predict worsening severity. Severe findings on initial imaging are associated with higher risk of treatment failure and complications.
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