Postoperative Abdominal Complications on CT: A Review

 

Postoperative Abdominal Complications on CT: A Review

 

Introduction & Importance of CT

 

Postoperative complications after abdominal surgery are common and require accurate diagnosis.

Computed Tomography (CT) is the primary imaging modality for evaluation [PubMed 37024236, PubMed 19752834].

CT guides crucial management decisions: conservative vs. interventional vs. surgical treatment [PMC4956629].

Challenge: Differentiating expected postoperative changes from true pathology is key [PMC4330234].

 

General Considerations - Timing & Comparison

Timing is Crucial:

    Early post-op: Expect small fluid/gas collections; typically regress [PubMed 19752834].

    Persistent/increasing findings are concerning.

   Free air (esp. after laparoscopy) should decrease over time [PMC4330234].

Comparison Scans:

    Essential to compare with baseline/previous studies.

    Helps track evolution of findings [PMC4330234].

 

 General Considerations - CT Protocols

 

Modality: Multidetector CT (MDCT) preferred [PMC4330234].

Contrast:

IV Contrast: Venous phase often sufficient for infection/collections [PMC4330234]. Arterial phase for active bleed/vascular issues.

Delayed Phase: Essential for urinary leaks (CT Urography) [PMC6176303, OUP Urinoma].

Oral/Rectal Contrast: Selective use for bowel evaluation, suspected leaks [PMC7289697].

 

 

 

Complication: Hemorrhage & Hematoma

Clinical Clues: Early post-op, hemodynamic instability, ↓Hb, drain output.

CT Findings:

Active Bleeding: Contrast extravasation ("blush") [PMC4956629].

 Hematoma: Collection, often near surgical bed. Acutely hyperdense on non-contrast CT. Density decreases over time.

 

Complication: Abscess / Infection

Clinical Clues: Fever, ↑WBC, localized pain, purulent drainage (often 5-7+ days post-op) [PMC4330234].

CT Findings:

    Low-attenuation fluid collection [PMC5510129].

    Rim Enhancement: Often thick, irregular (key feature) [ResearchGate Neck Abscess].

    Gas bubbles / Air-fluid level (highly suggestive) [PMC5510129].

    Surrounding fat stranding / inflammation [PMC5510129].

    Differentiation from simple fluid/hematoma is critical.

collection (left) following appendicitis (right) surgery

 

Complication: Anastomotic Leak

Clinical Clues: Fever, tachycardia, pain, ileus, change in drain output (feculent, urine, bile), ↑WBC (often 5-10 days post-op) [PMC7289697].

CT Findings:

    Extraluminal Gas: Near anastomosis, more than expected/increasing [PMC7289697].

    Extraluminal Contrast: Specific sign if oral/rectal/delayed IV contrast used [PMC7289697].

    Adjacent Fluid Collection/Abscess: Common finding [PMC7289697].

    Wall thickening / Inflammation at anastomosis [PMC7289697].

 

 

 

 

 

 

 

Complication: Bowel Obstruction

Clinical Clues: Nausea, vomiting, distension, cramping pain, obstipation.

CT Findings (Ileus):

CT Findings (Subacute obstruction):

CT Findings (Mechanical Obstruction):

    Dilated proximal bowel (>3 cm SB) / Collapsed distal bowel [AJR Gastric Carcinoma Resection - afferent loop].

    Clear Transition Point [AJR Gastric Carcinoma Resection - afferent loop].

    Identify cause: Adhesions (most common late cause), hernia, etc. [PubMed 19752834, PMC4729712].

   Ileus: Diffuse dilatation, no transition point (common early).

ILEUS

subacute obstruction

Post op adhesion (usually delayed)

Complication: Bowel Obstruction - Worrisome Signs

Closed-Loop Obstruction:

     Bowel obstructed at two points.

    High risk of ischemia/strangulation [PMC4729712].

    Look for C/U-shaped loops, radial configuration, whirl sign.

Signs of Ischemia:

     Bowel wall thickening.

     Submucosal edema (Target sign).

     Lack of mural enhancement.

    Pneumatosis intestinalis (intramural gas).

     Portal venous gas.

    Requires urgent attention!

 

Complication: Urinoma / Urinary Leak

Clinical Clues: Post GU/Gyn/Pelvic surgery. Flank/abdominal pain, mass, fever, drain output (urine), ↑Creatinine [PMC6176303, OUP Urinoma].

CT Findings:

     Peri-nephric or pelvic fluid collection [OUP Urinoma].

    Key: Extravasation of IV contrast into the collection on DELAYED images [PMC6176303, OUP Urinoma].

    May see associated hydronephrosis.

 

 Complication: Retained Foreign Body (Gossypiboma)

Clinical Clues: Often delayed presentation (weeks/months/years). Pain, infection, obstruction, fistula, or incidental finding.

CT Findings:

    Soft-tissue mass [AJR Retained Sponges].

    Spongiform / Whorled pattern with trapped gas bubbles [AJR Retained Sponges, AJR Retained Sponge Diagnosis].

    Radiopaque Marker: Diagnostic if present (check scout images!) [AJR Retained Sponges].

    May have enhancing capsule (granuloma) or associated abscess [AJR Retained Sponges, AJR Retained Sponge Diagnosis].

    Can mimic tumor, abscess, hematoma.

 

Complication: Wound Issues

Clinical Clues: Incisional pain, erythema, discharge, palpable fascial defect.

CT Findings:

    Infection: Subcutaneous/intramuscular fluid collections +/- gas near incision [ResearchGate CT diagnosis].

    Hematoma: Collection within wall layers.

    Dehiscence: Fascial layer separation +/- herniation [ResearchGate CT diagnosis, PubMed 19752834].

 

 Conclusion

 

CT is Essential: The cornerstone for diagnosing postoperative abdominal complications [PubMed 37024236].

Context Matters: Integrate imaging findings with clinical picture and surgical history.

Know Normal vs. Abnormal: Familiarity with expected post-op changes is vital [PMC4330234].

Comparison

Accurate Reporting: Precise description and addressing the clinical question guides appropriate management.

 

 

 

References

 

PubMed 37024236: Complications after abdominal surgery. Radiologia (Engl Ed). 2023.

PubMed 19752834: [Postoperative imaging of the peritoneum and abdominal wall]. J Radiol. 2009.

PMC4956629: Multidetector CT... ventral hernia repair. Insights Imaging. 2016.

 PMC4330234: Pictorial review... laparoscopic appendectomy. Insights Imaging. 2015.

PMC6176303: Urinoma: Prompt Diagnosis and Treatment... Cureus. 2018.

OUP Urinoma: Abdominal urinoma after oncologic gynaecological surgery. Postgrad Med J. 2022.

PMC7289697: Normal and Abnormal Postoperative Imaging Findings after Gastric... Surgery. Korean J Radiol. 2020.

ResearchGate Neck Abscess: CT differentiation of abscess and non-infected fluid... Acta Radiol. 2013.

PMC5510129: CT findings... postoperative abdominal infection patients with pancreatic carcinoma. Pak J Med Sci. 2017.

PMC4729712: Imaging the postoperative patient: long-term complications... Insights Imaging. 2016.

AJR Gastric Carcinoma Resection: CT Findings... After Gastric Carcinoma Resection. AJR Am J Roentgenol. 2002.

Radiopaedia SBO: Small bowel obstruction | Radiology Reference Article | Radiopaedia.org (Summarizes findings from multiple sources).

 AJR Retained Sponges: Imaging of Retained Surgical Sponges... AJR Am J Roentgenol. 2003.

AJR Retained Sponge Diagnosis: Retained surgical sponge: diagnosis with CT and sonography. AJR Am J Roentgenol. 1988.

 ResearchGate CT diagnosis: CT diagnosis of postoperative abdominal complications. Abdom Imaging. 2004.