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Internal MedicineGastroenterologyAbdominal masses and pelvic masses
Gastroenterology6 min readUpdated February 2, 2026

Abdominal masses and pelvic masses

Introduction

The evaluation of abdominal and pelvic masses is a frequent and critical clinical scenario encountered in Canadian medical practice. For the MCCQE1, candidates are expected to demonstrate the CanMEDS Medical Expert role by formulating a broad differential diagnosis based on anatomical location, patient age, and clinical presentation.

Understanding the epidemiology specific to the Canadian population (e.g., prevalence of colorectal cancer, AAA screening guidelines) is essential for high performance.

CanMEDS Corner

Health Advocate: Recognize barriers to screening (e.g., rural access to ultrasound or colonoscopy) and apply Canadian Task Force on Preventive Health Care (CTFPHC) guidelines appropriately.
Leader: Practice resource stewardship by ordering the most cost-effective and sensitive initial investigations (e.g., Ultrasound vs. CT).

Anatomy and Quadrant-Based Differential Diagnosis

A systematic approach based on abdominal quadrants is the most effective strategy for the MCCQE1.

Right Upper Quadrant (RUQ)

  • Liver: Hepatomegaly (Hepatitis, NAFLD, CHF), Hepatocellular carcinoma, Metastases, Abscess.
  • Gallbladder: Hydrops, Carcinoma (rare), Abscess.
  • Kidney: Hydronephrosis, Polycystic kidney disease, Renal cell carcinoma (RCC).
  • Colon: Hepatic flexure tumour.

Clinical Approach: The MCCQE1 Framework

Follow these steps to maximize your score on Clinical Decision Making (CDM) cases.

Step 1: Focused History

Elicit “Red Flags” and constitutional symptoms.

  • Timeline: Acute vs. Chronic.
  • Constitutional: Fever, night sweats, significant weight loss (suggests malignancy).
  • GI Symptoms: Change in bowel habits, hematochezia, melena, jaundice, early satiety.
  • Gyn/GU: Post-menopausal bleeding, hematuria, urinary retention.
  • Risk Factors: Smoking (AAA, bladder Ca), Alcohol (Liver), Family History (Lynch syndrome, BRCA).

Step 2: Physical Examination

Perform a systematic abdominal exam.

  • Inspection: Distension, scars, caput medusae.
  • Auscultation: Bruits (renal/aortic), bowel sounds.
  • Percussion: Shifting dullness (ascites), tympany (obstruction).
  • Palpation: Define mass characteristics:
    • Size, Shape, Consistency (hard vs. cystic)
    • Mobility (moves with respiration?)
    • Pulsatility (expansile vs. transmitted)
    • Tenderness
  • DRE (Digital Rectal Exam): Mandatory for pelvic/GI masses.
  • Pelvic Exam: Speculum and bimanual exam for females.

Step 3: Initial Investigations

Choose investigations based on the most likely differential.

  • Labs: CBC (anemia), Electrolytes, Cr/BUN, LFTs, INR/PTT.
  • Tumour Markers: Only if specific malignancy suspected (e.g., CA-125 for ovarian, CEA for colon, AFP for liver/testicular). Note: Not for screening.
  • Urinalysis: Hematuria/infection.

Step 4: Diagnostic Imaging

  • Ultrasound (US): First-line for RUQ, Pelvic, and Pulsatile masses (AAA).
  • CT Abdomen/Pelvis: Best for characterizing masses, staging malignancy, and evaluating retroperitoneum.
  • MRI: Problem-solving (e.g., liver lesions, indeterminate renal masses, local staging of rectal/gyn Ca).
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Red Flags necessitating urgent referral or imaging:

  • Unintentional weight loss >5-10% of body weight.
  • Pulsatile abdominal mass (suspected AAA).
  • Post-menopausal bleeding (Endometrial Ca).
  • Iron deficiency anemia in a male or post-menopausal female (Colon Ca until proven otherwise).
  • Virchow’s Node (Left supraclavicular lymphadenopathy).

Canadian Guidelines and Screening

Knowledge of CTFPHC (Canadian Task Force on Preventive Health Care) guidelines is high-yield for the MCCQE1.

1. Abdominal Aortic Aneurysm (AAA)

  • Definition: Aortic diameter >3.0 cm.
  • Screening Guideline: One-time screening with abdominal ultrasound for men aged 65 to 80.
  • Rationale: Reduces mortality from AAA rupture.
  • Women: Screening not routinely recommended (lower prevalence).

2. Colorectal Cancer (CRC)

  • Screening Guideline: Asymptomatic adults aged 50 to 74.
  • Modality: Fecal Immunochemical Test (FIT) every 2 years OR Flexible Sigmoidoscopy every 10 years.
  • Symptomatic Mass: Diagnostic Colonoscopy (not screening).

3. Ovarian Cancer

  • Guideline: No routine screening recommended for the general population (CA-125 and Transvaginal US have high false-positive rates and do not reduce mortality).

4. Cervical Cancer

  • Guideline: Routine screening (Pap test) every 3 years starting at age 25.

Key Clinical Entities

Abdominal Aortic Aneurysm (AAA)

  • Risk Factors: Smoking (strongest), Male, Age, HTN, Atherosclerosis.
  • Presentation: Asymptomatic (incidental), pulsatile mass, back pain.
  • Rupture Triad: Hypotension + Pulsatile Mass + Back/Flank Pain.
  • Management:
    • <5.0 cm: Surveillance US (frequency depends on size).
    • >5.5 cm (men) or >5.0 cm (women) or Rapid expansion (>0.5 cm/6mo): Surgical repair (EVAR or Open).

Colorectal Carcinoma

  • Right-sided (Cecum/Ascending): Occult bleeding, iron deficiency anemia, fatigue. Mass often palpable.
  • Left-sided (Sigmoid/Rectum): Obstruction, change in bowel habits, “pencil stools”, frank blood.
  • Diagnosis: Colonoscopy with biopsy.

Uterine Fibroids (Leiomyomata)

  • Epidemiology: Very common benign monoclonal tumours.
  • Presentation: Menorrhagia, pelvic pressure/pain, “lumpy-bumpy” uterus on exam.
  • Management: Observation if asymptomatic. Medical (OCP, GnRH agonists) or Surgical (Myomectomy, Hysterectomy, Embolization) for symptoms.

Mnemonics for MCCQE1

To help remember the causes of abdominal distension/masses:

The 6 F’s of Abdominal Distension

  • Fat (Obesity)
  • Fluid (Ascites)
  • Flatus (Gas/Obstruction)
  • Fetus (Pregnancy)
  • Feces (Constipation)
  • Fatal Growth (Tumour)

Key Points to Remember for MCCQE1

  1. Iron Deficiency Anemia: In an adult male or post-menopausal female, this is GI malignancy until proven otherwise. Do not just treat with iron; investigate the GI tract.
  2. Pulsatile Mass: Do not palpate vigorously. Order an urgent Ultrasound if stable. If unstable (hypotension), go directly to the OR (if known AAA) or FAST scan/CT if diagnosis unclear but patient stable enough.
  3. Sister Mary Joseph Nodule: Palpable nodule at the umbilicus representing metastasis from a pelvic or abdominal malignancy (often gastric or pancreatic).
  4. Courvoisier’s Sign: Palpable, non-tender gallbladder with jaundice suggests malignancy (pancreatic head), not gallstones.
  5. Pediatrics: A flank mass in a child is likely Wilms Tumour (nephroblastoma) or Neuroblastoma. Wilms tumour typically does not cross the midline; Neuroblastoma does.

Sample Question

Scenario: A 68-year-old male presents to his family physician for a routine health maintenance visit. He has a history of hypertension controlled with amlodipine and has smoked 1 pack of cigarettes daily for 40 years. He has no specific complaints. On physical examination, his BMI is 28 kg/m². Abdominal examination reveals a non-tender, pulsatile mass in the epigastrium, slightly superior to the umbilicus. The mass is estimated to be approximately 4 cm in width. Peripheral pulses are intact.

Which one of the following is the most appropriate next step in the management of this patient?

Choose an answer, then check it against the explanation.

References

  1. Canadian Task Force on Preventive Health Care. (2017). Recommendations on screening for abdominal aortic aneurysm in primary care. CMAJ.
  2. Medical Council of Canada. (2023). MCCQE Part I Clinical Decision Making and Multiple Choice Question Objectives.
  3. Toronto Notes. (2024). Gastroenterology and General Surgery Sections.
  4. UpToDate. (2024). Clinical presentation, evaluation, and management of renal masses.
  5. Society of Obstetricians and Gynaecologists of Canada (SOGC). Clinical Practice Guidelines on Adnexal Masses.
Abdominal distensionAcute abdominal pain