Medical Case: Acute abdominal pain in a young adult

A 39-year-old man presents to the emergency department with acute abdominal pain, anaemia, and diarrhea: what diagnosis lies behind this condition?

A terrible tummy ache during holiday time

On 25 July 2021 at 2:00 p.m., Lucas, a 39-year-old man, presented to the Emergency Department with acute abdominal pain. The pain had been present intermittently for approximately two days. Since the previous night, he had experienced several episodes of diarrhea. Lucas reported no known medical conditions and no current medication use.

Physical examination

The patient was 176 cm tall, weighed 76 kg (BMI 24.54 - within normal range).

The abdomen was soft and non-tender on palpation. Murphy’s sign was negative, and there were no signs of acute or chronic appendiceal inflammation. No palpable masses were detected, and examination of the umbilical and inguinal regions revealed no hernias.

Medical History

Lucas maintained a healthy lifestyle: he was a vegetarian, did not smoke, consumed alcohol occasionally (beer once a week at the pub), denied drug use, and engaged in moderate physical activity. He underwent a tonsillectomy in childhood and a trabeculectomy for glaucoma at age 21. He reported no other hospitalizations or chronic illnesses.

The patient reported no major diseases among family members.

Imaging

Laboratory findings

Value Results
HGB 9.2 g/dl
RBC 4.65 x 10⁶/ul
HCT 30.6%
MCV 65.8 fl
MCH 19.8 pg
MCHC 30.2 g/dl
RDWCV 19.5%
WBC 7.53 x10³/ul
Neutrophil 5.5 x10³/ul (73.6%)
Lymphocyte 1.3 x10³/ul (16.8%)
Monocyte 0.6 x10³/ul (7.8%)
Eosinophil 0.1 x10³/ul (1.2%)
Basophil 0.0 x10³/ul (0.6%)
PLT 374 x10³/ul
PDW 18 fl
MPV 8.7 fl
Amylase 44 mU/ml
Alkaline Phosphatase 57 mU/ml
Total bilirubin 0.48 mg/dl
GGT 29 mU/ml
Acetylcholinesterase 8519 mU/ml
GPT 11 mU/ml
 LDH 188 mU/ml
CK 140 mU/ml
Glucose 113 mg/dl
Sodium 138 mEq/l
Potassium 3.78 mEq/l
Calcium 9.2 mg/dl
Urea 27 mg/dl
Creatinine 1.04 mg/dl
GFR 90 ml/min/1.73m

Electrocardiogram

The electrocardiogram performed in the emergency room was normal.

Clinical and diagnostic approach

The ER physician called the on-call abdominal surgeon for a consultation. The surgeon decided to admit Lucas for further diagnostic workup and closer observation.

Transfer to Surgery

At 7:00 p.m. on 25 July, a nasogastric tube was placed to decompress the stomach and drain excess gastric contents. The patient was kept nil per os (NPO). Supportive therapy included intravenous fluid replacement and gastroprotective medication.

On 26 July a follow-up abdominal X-ray showed the presence of the nasogastric tube with an apex at the level of the gastric fundus. No free air was evident subdiaphragmatically. The number of air-fluid levels appeared reduced compared to the previous day's check-up. Remaining findings were unchanged. The patient reported marked improvement in abdominal pain symptoms. Blood tests on 26 July confirmed microcytic anaemia. Liver, pancreatic and renal function were normal.

On 27 July the patient reported no abdominal pain. The patient fed freely, was apyretic, abdominal examination showed nothing significant. Bowel function was normal, with normally formed and colored stools.


Did you guess correctly?

Why is each answer plausible?

A. Measurement of anti-tissue transglutaminase IgA and total serum IgA

This is a reasonable and non-invasive first step in a patient with persistent microcytic anemia and intermittent gastrointestinal symptoms. Celiac disease often presents with iron-deficiency anemia and can be subclinical. However, it rarely causes acute abdominal pain or subocclusive patterns on imaging. In this case, although celiac disease remains a differential diagnosis, it would not fully explain the radiological findings.

B. Fecal calprotectin and targeted intestinal ultrasound

Crohn’s disease can present with intermittent abdominal pain, subocclusive episodes, and anemia due to chronic inflammation or malabsorption. Fecal calprotectin is a useful non-invasive marker of intestinal inflammation, and intestinal ultrasound is increasingly used in inflammatory bowel disease assessment. While appropriate in certain contexts, these tests may not detect a neoplastic process or mechanical obstruction.

C. Stool culture and ova/parasite testing

Given the recent onset of diarrhea, an infectious etiology is worth considering, especially in younger patients. However, the absence of fever, systemic inflammation, or leukocytosis, along with the presence of anemia and radiological signs of subocclusion, make this option less likely to provide the full diagnostic picture in this case.

D. Discharge with dietary advice and outpatient follow-up

In a patient with resolving symptoms and stable vital signs, this option might seem safe. However, the persistence of unexplained anemia and recent subocclusive symptoms require further investigation before discharge. Premature reassurance could delay the diagnosis of serious underlying conditions.

E. Abdominal ultrasound and CT scan with and without contrast medium

Advanced imaging is fully justified in this clinical scenario. The combination of persistent microcytic anemia, intermittent abdominal pain, and radiological signs of subocclusion raises concern for a possible structural lesion, including neoplasms such as small bowel adenocarcinoma, lymphoma, or GIST. Ultrasound is a low-risk, first-line tool, and CT with contrast offers detailed anatomical information. Even in the absence of classic cancer risk factors, this diagnostic step is appropriate and often decisive.

Outcome

The patient’s wife, who is a physician, questioned the surgical team regarding the lack of investigations to determine the cause of her husband’s abdominal pain and microcytic anemia. She expressed concern that the management was limited to simple observation without any diagnostic workup. She also asked why an abdominal ultrasound had not yet been performed. The surgical team remained convinced that the symptoms were due to a non-specific abdominal colic.

Following his wife’s advice, Lucas decided to leave the hospital. He was discharged against medical advice. The discharge diagnosis was non-specific abdominal colic, and he was advised to rest, maintain adequate hydration, follow a light diet, and undergo outpatient hematologic evaluation to investigate the microcytic anemia.

On 30 July, Lucas underwent an abdominal ultrasound at another facility, which revealed a heterogeneous hypoechoic lesion in the right flank, located at the level of the hepatic flexure of the colon, measuring approximately 5 cm in diameter, with marked vascularization.

On 3 August, a contrast-enhanced CT scan of the abdomen confirmed the presence of a pathological concentric wall thickening (“apple core” lesion) of the hepatic flexure, extending for approximately 5 cm.

On 10 August, a colonoscopy was performed, revealing a stenosing neoplastic lesion at the hepatic flexure, non-traversable by the colonoscope. Biopsies were taken from the lesion.

On 18 August, the patient underwent a laparoscopic right hemicolectomy for colonic adenocarcinoma.

The correct answer is E:

Abdominal ultrasound and CT scan with and without contrast

Despite the patient's young age, lack of family history, and healthy lifestyle, the persistence of microcytic anemia and the subocclusive pattern on abdominal X-ray warranted further investigation to exclude a neoplastic process. Small bowel tumors — including adenocarcinomas, gastrointestinal stromal tumors (GISTs), and lymphomas — may present with nonspecific symptoms such as intermittent pain, bloating, or chronic anemia due to occult bleeding. They are often diagnosed late because early signs can mimic benign or functional disorders.

In this case, abdominal ultrasound was a reasonable and accessible first-line test that could have been performed in the Emergency Department. It is non-invasive, radiation-free, and can detect masses, lymphadenopathy, or wall thickening. However, it may miss deeper or subtle lesions.

CT scan with and without contrast medium remains the gold standard for evaluating structural causes of intestinal subocclusion, detecting intraluminal or extraluminal masses, and assessing surrounding tissue involvement. In this patient, it was the key step that led to the correct diagnosis.

Why cancer should be considered even in young, healthy patients

At first glance, cancer may seem unlikely in a 39-year-old man with a vegetarian diet, no smoking or alcohol abuse, no family history of malignancy, and a physically active lifestyle. However, age is not an absolute protection. Healthy habits reduce risk but do not eliminate it, and persistent symptoms justify escalation. In particular, iron-deficiency anemia in a male patient, combined with signs of partial bowel obstruction, should always raise concern. Even if symptoms resolve with supportive care, the underlying cause must be investigated.