Case Author(s): Brock G. McDaniel, M.D. and Keith C. Fischer, M.D. , 02/26/03 . Rating: #D3, #Q3

Diagnosis: Pelvic Abscess

Brief history:

20-year-old male who is status post fall with pelvic pain. The patient subsequently developed leukocytosis and Staphylococcus aureus bacteremia.

Images:

24 hour delay- Anterior image

View main image(iw) in a separate image viewer

View second image(iw). Increased intensity (24 hour delay)-Anterior Image

View third image(ct). Pelvic CT

View fourth image(ct). Pelvic CT

Full history/Diagnosis is available below


Diagnosis: Pelvic Abscess

Full history:

20-year-old male who presented to the emergency department four days after slipping on ice with complaints of stabbing pelvic pain which he rated as 10/10. He subsequently developed Staphylococcus aureus bacteremia. A previous CT (not shown), performed at the time of initial presentation (one week prior to the In-111 WBC), demonstrated possible thickening of the urinary bladder wall and adjacent soft tissues on the right. The patient had pyuria, suprapubic pain and leukocytosis at that time.

Radiopharmaceutical:

.459 mCi In-111 labeled autologous leukocytes i.v.

Findings:

The In-111 labeled leukocyte study demonstrates subtle increased uptake within the right anterior hemipelvis, which correlates well with the CT findings of asymmetric thickening of the right lateral wall of the urinary bladder and/or adjacent soft tissues.

A follow-up pelvic CT, performed the next day, demonstrates a new fluid collection which has developed in the right perivesicular region and rectus sheath. Both collections showed rim enhancement consistent with loculated abscesses.

Discussion:

Labeled leukocytes migrate to sites of infection and inflammation. For bacteremia, In-111 labeled leukocytes is the preferred method of abscess localization by scintigraphy. Tc-99m labeled leukocytes can be substituted for In-111 leukocytes, but can be less sensitive because the labeled cells are almost all neutrophils and delayed images cannot be performed. In cases of inflammatory bowel disease, Tc-99m labeled leukocytes is superior to In-111 leukocytes because early images can give a more accurate map of the imflamed bowel prior to the whicte blood cells sloughing nto the bowel lumen. If the study must be performed portably (i.e. intubated ICU patient), Tc-99m labeled leukocytes is the only choice.

This case is a good example of how subtle the findings can be. Only after adjusting the intensity setting is the abnormality clearly seen.

Followup:

The patient was placed on intravenous Oxacillin and shortly thereafter, defervesced with decreasing leukocytosis and resolution of his suprapubic pain. The regions were not drained because of the patientís remarkable improvement following antibiotic therapy. A PICC line was placed and the patient was discharged to home with instructions for an additional 4 weeks of intravenous antibiotics.

Differential Diagnosis List

Infectious enteritis/colitis, ischemic enteritis/colitis, GI bleeding, swallowed labelled white blood cells from an upper or lower respiratory tract infection.

ACR Codes and Keywords:

References and General Discussion of Indium -111 WBC Scintigraphy (Anatomic field:Gasterointestinal System, Category:Inflammation,Infection)

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Case number: iw014

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