Abdominal Mass History Taking OSCE — Site, Differentials, and Red Flag Symptoms

Why This Station Is Tested

Abdominal mass history taking tests your ability to take a systematic, differential-driven history for a classic surgical/medical presentation. It appears frequently in OSCE finals because it covers multiple systems simultaneously — GI, urological, gynaecological, and lymphatic — and requires you to demonstrate clinical reasoning through your questioning.

Opening the History

Standard opening applies: introduction, consent, open question. For abdominal mass, the key opening is:

*"I understand you've noticed a lump in your abdomen. Can you tell me about it in your own words — when did you first notice it?"*

SOCRATES for the Mass

Differentials by Site

Associated Symptoms to Ask

GI symptoms: change in bowel habit (constipation, diarrhoea, rectal bleeding, melaena), dysphagia, nausea, vomiting, jaundice

Urological: haematuria, frequency, nocturia, poor stream (bladder/prostate/renal)

Gynaecological (if female): last menstrual period, abnormal bleeding, pelvic pain, pregnancy test

Constitutional red flags: weight loss (malignancy), night sweats (lymphoma, TB), fever (abscess, lymphoma, infection), fatigue

Vascular: pulsatile quality, back pain (AAA — leaking or expanding)

Past Medical History, Drug History, Family History

• PMHx: previous malignancy (liver mets, recurrence), IBD, polycystic kidney disease, cirrhosis
• DHx: immunosuppressants (lymphoma risk), alcohol (hepatomegaly, cirrhosis)
• FHx: colorectal cancer (Lynch syndrome, FAP), ovarian cancer (BRCA), renal cancer

Social History

• Smoking (colorectal, renal cell, bladder carcinoma risk)
• Alcohol (hepatomegaly, cirrhosis, hepatocellular carcinoma)
• Travel (amoebic liver abscess, schistosomiasis with hepatosplenomegaly)

Investigations to Mention

"To investigate further, I would request: FBC (anaemia of chronic disease), LFTs, Ca-125 (if ovarian suspected), CEA, AFP (hepatocellular), PSA (prostate), urinalysis, abdominal ultrasound as first-line imaging, followed by CT abdomen/pelvis with contrast for characterisation."

Frequently Asked Questions

"How do you differentiate an epigastric mass from an AAA in a history?"

A pulsatile, expansile epigastric or para-umbilical mass in a man over 65 with cardiovascular risk factors (smoking, hypertension, hyperlipidaemia) should immediately raise concern for an abdominal aortic aneurysm (AAA). Key history features: the mass is present at rest and does not vary with meals; it may be associated with poorly localised back or loin pain (expanding or leaking); there may be a family history of AAA. In contrast, a gastric or pancreatic mass may be associated with early satiety, weight loss, epigastric pain radiating to the back (pancreatic), or dysphagia. In an OSCE, stating "I would not palpate this mass forcefully given the risk of AAA" demonstrates clinical awareness.

"What are the red flags that make you suspect malignancy in an abdominal mass history?"

The combination of features most strongly suggesting malignancy are: unintentional weight loss (>5% body weight in 3 months), night sweats, persistent fatigue, a new palpable mass that is hard or irregular, associated change in bowel habit lasting more than 4 weeks, rectal or urinary bleeding, dysphagia, or jaundice. A personal or family history of colorectal, ovarian, or renal cancer significantly raises the index of suspicion. These findings collectively should trigger an urgent 2-week wait (2WW) referral. In an OSCE, listing specific red flags rather than saying "I'd be worried about cancer" demonstrates systematic clinical thinking.

"Why is the last menstrual period the first question to ask a woman presenting with a lower abdominal mass?"

In any woman of reproductive age presenting with a lower abdominal or pelvic mass, the first question after the site is the last menstrual period, because pregnancy — including ectopic pregnancy — must be excluded immediately. An enlarged uterus from pregnancy, a gravid uterus with a fibroid, or an ovarian mass from corpus luteum of pregnancy are all common. More critically, an ectopic pregnancy presenting as an adnexal mass with pain is a surgical emergency. A positive pregnancy test fundamentally changes the differential and management pathway. Candidates who miss this question in a female patient with a pelvic mass lose marks in both history and management domains.

"What is the difference between a right iliac fossa mass due to Crohn's disease vs appendix mass?"

Both present with a right iliac fossa mass but have different histories. An appendix mass follows an episode of acute appendicitis that has partially resolved — there is usually a preceding history of central colicky pain migrating to the RIF, fever, anorexia, and nausea that settles but leaves a palpable mass (a phlegmon or abscess around the appendix). Crohn's disease presents with a longer history: episodic colicky abdominal pain, diarrhoea (often with blood or mucus), weight loss, perianal disease (fistulae, fissures, skin tags), and extraintestinal features (uveitis, erythema nodosum, arthropathy). A RIF mass in Crohn's represents thickened terminal ileum and surrounding mesenteric inflammation.

"What investigations would you request for a palpable right upper quadrant mass?"

For a right upper quadrant mass the first-line investigation is liver ultrasound (differentiates hepatomegaly, solitary liver lesion, gallbladder pathology, and can detect ascites). Blood tests: FBC (anaemia of chronic disease, thrombocytopenia in cirrhosis), LFTs (pattern: hepatocellular vs cholestatic), GGT, albumin, coagulation. If liver metastases are suspected: CEA (colorectal), Ca 19-9 (pancreatic/biliary), AFP (HCC), Ca-125 (ovarian). If HCC is suspected: AFP, hepatitis B and C serology, viral load. CT abdomen with contrast characterises the lesion further and assesses for distant spread. MRI liver is used for further characterisation of focal liver lesions.

"What is the significance of a left iliac fossa mass that moves with respiration?"

An abdominal mass that moves with respiration is attached to or derived from an intra-abdominal organ that moves with the diaphragm — specifically the liver, spleen, gallbladder, or kidneys. A left iliac fossa mass that descends on inspiration and has a smooth upper border with the examiner unable to palpate above it is more consistent with splenomegaly than a renal or colonic mass. A left iliac fossa mass that is fixed (does not move with respiration) is more likely to be sigmoid colonic (carcinoma or diverticular mass) or retroperitoneal. Distinguishing these on history requires asking about symptoms of splenic pathology (left shoulder tip pain from diaphragm irritation, easy bruising, infections in hyposplenism).

Related guides: Abdominal Examination OSCE · How to Take an Abdominal History OSCE · Jaundice History OSCE · Lower GI Bleeding OSCE · Ascites Examination OSCE