CT of the abdominal cavity and pelvis

Diagnosis of purulent complications of diverticular disease

Diverticular disease may lead to the formation of abscesses, which are classified by their localization into three types:

1. Pericolic abscess. Forms directly in the area of the ruptured diverticulum. It is usually localized in the intestinal mesentery or may be covered by the mesentery itself and the tissues of the anterior abdominal wall.
2. Pelvic abscess. Differs in that its walls are formed by the tissues of the bowel itself, the walls of the lesser pelvis, and at least one of the pelvic organs.
3. Distant abscess. This type includes interloop abscesses located outside the pelvic cavity, as well as any abscesses found in other anatomical regions of the abdominal cavity.

Diagnostic imaging and staging

To establish the disease stage, current TNM classifications and WHO systems are used. The diagnostic workup requires a comprehensive approach utilizing instrumental methods for various anatomical regions:

• Abdomen and retroperitoneal space: comprehensive ultrasound, as well as CT or MRI of the abdominal organs, is performed.
• Chest: chest radiography and/or CT is used.
• Breasts: bilateral mammography is performed, which may be supplemented by MRI.
• Lymphatic system: ultrasound of regional areas (axillary, supraclavicular, and infraclavicular lymph nodes) is performed.
• Lesser pelvis: ultrasound is the baseline method.

If internal organ involvement is suspected, for example, during the progression of Sézary syndrome, CT of the chest, abdomen, retroperitoneal space, and pelvic organs is indicated (level of recommendation evidence — C).

Pelvic organ assessment

The baseline examination method is comprehensive pelvic ultrasound, including both transabdominal and transvaginal approaches.

This examination is indicated for absolutely all female patients to provide a detailed evaluation of the anatomical and functional state of the uterus and its appendages (level of evidence reliability — 5).

In complex diagnostic situations, the method is replaced or supplemented by magnetic resonance imaging. Pelvic MRI is strictly recommended for differential diagnosis, as well as in unclear cases with clinical or sonographic suspicion of uterine and appendage malformations.

Morphological verification of findings

Any suspicious lesions (altered lymph nodes, tumor nodes, metastases) identified on diagnostic imaging are subject to biopsy followed by pathomorphological examination.

The obtained surgical or biopsy material undergoes immunohistochemical (IHC) examination to determine:

• Expression of estrogen (ER) and progesterone (PR) receptors.
• Proliferative activity index (Ki-67 marker).
• Expression of HER2/neu. If necessary, results are confirmed by in situ hybridization methods (FISH or CISH).

What else to study on this topic

• Features of performing in situ hybridization (FISH, CISH) to confirm HER2/neu
• Principles of staging according to TNM and WHO classifications
• Specifics of comprehensive pelvic ultrasound (transvaginal and transabdominal)
• Ultrasonic anatomy of regional lymph nodes
• Clinical presentation and progression of Sézary syndrome

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.