# Situation: A 55-year-old woman weighing 70 kg is recovering from an open abdominal operation done under general anesthesia. She has no drug allergies and no history of sleep apnea. On the first postoperative day her temperature is 37.9 °C (100.2 °F). Breath sounds are clear and equal to both bases, her respiratory rate is 16/min, her oxygen saturation is 98% on room air, and she uses her incentive spirometer every hour. The incision is dry without redness, her urine is clear, and her calves are soft and nontender. Her family asks why she has a fever. Which explanation is MOST accurate?

> source: MyMerci (mymerci.kr)  
> url: https://mymerci.kr/pages/nclex_q.php?qn_id=629674  
> language: ko  
> subject: Nursing Practice III — Care of Clients with Problems in Surgery, Oxygenation, Fluid and Electrolytes, Infectious, Inflammatory and Immunologic Response, Cellular Aberrations

## 문제

Situation: A 55-year-old woman weighing 70 kg is recovering from an open abdominal operation done under general anesthesia. She has no drug allergies and no history of sleep apnea.

On the first postoperative day her temperature is 37.9 °C (100.2 °F). Breath sounds are clear and equal to both bases, her respiratory rate is 16/min, her oxygen saturation is 98% on room air, and she uses her incentive spirometer every hour. The incision is dry without redness, her urine is clear, and her calves are soft and nontender. Her family asks why she has a fever. Which explanation is MOST accurate?

## 보기

1. It is an early sign of infection at the incision site
2. It comes from dehydration during the preoperative fast
3. It is an inflammatory response to surgical tissue injury **✔ 정답**
4. It reflects atelectasis from shallow breathing after anesthesia

**정답: 3**

## 해설

A mild fever in the first 48 hours after surgery is usually the body's inflammatory response to tissue injury. Persistent or later fever needs evaluation for wound infection, pneumonia, urinary tract infection, line infection, deep vein thrombosis, or leak. The findings given show no sign of those causes.

## 심화 해설

Why the fever is most likely benign

A temperature of 37.9 °C (100.2 °F) on the first postoperative day is a low-grade fever. In the first 48 to 72 hours after surgery, this pattern most often represents the body’s normal inflammatory response to surgical tissue injury. Tissue cutting, cautery, suture placement, and the early phases of wound healing release cytokines and other inflammatory mediators that reset the hypothalamic set point slightly upward. This is a physiologic, noninfectious fever, not an automatic sign of infection.

A mild fever up to 101.5 °F (38.6 °C) within the first 48 to 72 hours after routine surgery typically reflects normal healing processes, including inflammation, wound repair, fluid shifts, or effects of anesthesia. The patient’s temperature is below that threshold, which supports a benign explanation.

Why the other options are less accurate

The clinical findings do not point to any of the usual infectious or mechanical causes. The incision is dry and without redness, so an early wound infection is unlikely. Breath sounds are clear and equal, the respiratory rate is 16/min, oxygen saturation is 98% on room air, and the patient is using her incentive spirometer every hour, which argues against significant atelectasis or pneumonia. Urine is clear, making a urinary tract infection less likely. The calves are soft and nontender, so deep vein thrombosis is not suggested. Dehydration from the preoperative fast is not a primary driver of a low-grade fever in this setting.

Key point! In clean and clean-contaminated surgery, noninfectious fever is more frequent than infectious fever. A prospective study of elective orthopedic and urologic surgery found that 81% of postoperative fevers were noninfectious.

How to apply this at the bedside

The timing of fever matters more than the number alone in the early postoperative period. A fever in the first 48 hours is usually inflammatory. A fever that appears later, persists beyond 72 hours, or rises above 38.6 °C (101.5 °F) should prompt a focused evaluation for wound infection, pneumonia, urinary tract infection, line infection, deep vein thrombosis, or anastomotic leak.

| Timing | Most likely cause | Nursing response |
| --- | --- | --- |
| First 48–72 hours, low-grade | Inflammatory response to tissue injury | Monitor, encourage pulmonary toilet, no routine extensive workup |
| After 72 hours or high-grade | Infection, DVT, leak, line infection | Focused assessment and diagnostic evaluation |

Watch out! The “101.5 Rule” is a clinical shorthand, not a diagnostic test. A patient can have a serious infection with a lower temperature, especially if immunocompromised or older. Always correlate the fever with the physical examination and the postoperative day.

The findings given show no sign of wound infection, pneumonia, urinary tract infection, deep vein thrombosis, or leak. The fever is best explained by the normal inflammatory healing response after open abdominal surgery.

## 임상 시나리오

Postoperative Fever: First 48 HoursBenign inflammatory response vs. infectious causes
A low-grade fever below 38.6 C (101.5 F) within the first 48 to 72 hours after surgery most often reflects the body's normal inflammatory response to surgical tissue injury. Cytokines released from tissue cutting, cautery, and suture placement reset the hypothalamic set point slightly upward.

Assess for infectious or mechanical causes only when fever is persistent or occurs later. Key findings that rule out common causes here: dry incision without redness (no wound infection), clear breath sounds with 98% oxygen saturation (no atelectasis or pneumonia), clear urine (no UTI), and soft nontender calves (no DVT).

CautionDo not reflexively order infectious workup for early low-grade fever. Evaluate for wound infection, pneumonia, UTI, line infection, DVT, or anastomotic leak if fever persists beyond 72 hours or rises above 38.6 C.

## 핵심 개념

- **postoperative fever** — Elevated temperature after surgery; within first 48-72 hours often benign inflammatory response
- **inflammatory response** — Cytokine-mediated physiologic reaction to tissue injury causing mild temperature elevation
- **atelectasis** — Alveolar collapse from shallow breathing; unlikely here given clear breath sounds and normal oxygenation
- **incentive spirometry** — Breathing exercise device to prevent atelectasis and pneumonia after surgery
- **low-grade fever** — Temperature below 38.6 C (101.5 F) typically reflecting normal healing processes

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