A 34-year-old man comes to the emergency department reporting a 3-day history of left shou… — USMLE Step 2 CK

A 34-year-old man comes to the emergency department reporting a 3-day history of left shoulder pain, intractable hiccups, and persistent fevers. Fourteen days ago, he underwent an exploratory laparotomy, splenectomy, and distal pancreatectomy following severe blunt abdominal trauma sustained in a motorcycle collision. He was discharged on postoperative day 8. His current temperature is $39.0^\circ\text{C}$ ( $102.2^\circ\text{F}$ ), blood pressure is 122/76 mmHg, pulse is 112/min, and respirations are 22/min. Oxygen saturation is 96% on room air. Physical examination reveals decreased breath sounds at the left lung base. The abdomen is soft with mild tenderness in the left upper quadrant, but no rebound guarding is present. The surgical incision is well-healed without erythema or discharge. Laboratory studies show a leukocyte count of $18,200/\text{mm}^3$ . A chest radiograph demonstrates a left-sided pleural effusion and atelectatic changes at the left lung base. Which of the following is the most appropriate next step in management?

Computed tomography scan of the abdomenAnswer
B
Diagnostic thoracentesis
C
Intravenous piperacillin-tazobactam and observation
D
Computed tomography pulmonary angiography
E
Chlorpromazine administration

Answer

Computed tomography scan of the abdomen

This patient's clinical picture is highly suspicious for a left subphrenic abscess. He underwent surgery involving the spleen and pancreas, which are located in the left upper quadrant, predisposing him to localized fluid collections in this space. The collection of infected fluid beneath the diaphragm leads to diaphragmatic irritation. This irritation triggers intractable hiccups (diaphragmatic spasm) and refers pain to the left shoulder (Kehr sign) via the phrenic nerve, which shares cervical nerve roots (C3-C5) with the supraclavicular nerves that innervate the shoulder. Furthermore, severe subdiaphragmatic inflammation commonly causes a sympathetic (reactive) pleural effusion and basilar atelectasis on the ipsilateral side. The most appropriate next step in management is to obtain a computed tomography (CT) scan of the abdomen. This will confirm the presence, size, and exact location of the abscess and allow for planning of percutaneous drainage, which is the definitive treatment.

Step-by-Step Solution

Analyze the patient's presenting symptoms and surgical history.

The patient has late-onset postoperative fever, left shoulder pain, intractable hiccups, and a recent splenectomy and distal pancreatectomy.

Identifying the timing and specific symptoms relative to the type of surgery narrows down the differential diagnosis of postoperative complications.

Connect the specific symptoms (shoulder pain, hiccups) to an anatomical source.

Hiccups indicate diaphragmatic irritation. Left shoulder pain is referred pain from the diaphragm via the phrenic nerve (Kehr sign).

Understanding referred pain pathways pinpoints the pathology to the left subdiaphragmatic (subphrenic) space.

Evaluate the chest radiograph findings in the context of the physical exam.

The left-sided pleural effusion and atelectasis are sympathetic reactions to the underlying subdiaphragmatic inflammation, not primary lung pathology.

Intra-abdominal abscesses frequently cause reactive thoracic symptoms that can mislead clinicians away from the true source.

Determine the diagnostic test of choice.

Computed tomography (CT) of the abdomen is selected to visualize the suspected left subphrenic abscess.

CT is the gold standard for identifying intra-abdominal fluid collections and can simultaneously be used to guide percutaneous drainage.

Key Concept

Patients who develop fever, leukocytosis, hiccups, and referred shoulder pain (Kehr sign) several days after abdominal surgery should be suspected of having a subphrenic abscess. An abdominal CT scan is the diagnostic modality of choice.

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