**Question:** The first to appear in a cause of acute intestinal obstruction is

A. Abdominal pain
B. Nausea and vomiting
C. Passage of flatus and feces
D. Diarrhea

**Core Concept:** Acute intestinal obstruction is a condition in which there is a sudden onset of mechanical or chemical blockage in the gastrointestinal tract, leading to impaired intestinal motility and transit. It can be categorized into three types: mechanical, toxic, and obstetric.

**Why the Correct Answer is Right:** In the context of acute intestinal obstruction, the correct answer (B) is related to the early clinical manifestations. The obstruction leads to impaired intestinal motility and transit, affecting the absorption and transit of fluids and electrolytes. As a result, patients may experience nausea, vomiting, and potentially develop dehydration.

**Why Each Wrong Option is Incorrect:**

A. **Abdominal pain:** Although abdominal pain can be present in acute intestinal obstruction, it is not the first symptom to appear. The described sequence of symptoms in intestinal obstruction is nausea and vomiting followed by abdominal pain.

C. **Passage of flatus and feces:** This option is incorrect because it describes the later symptoms that occur after the obstruction has already started. The passage of flatus and feces typically occurs when the obstruction resolves.

D. **Diarrhea:** Diarrhea is not the first symptom in acute intestinal obstruction. In fact, it is often absent or present as constipation due to impaired transit and absorption.

**Clinical Pearl:** A thorough understanding of the sequence of symptoms can help in making an early clinical suspicion of acute intestinal obstruction, enabling prompt evaluation and treatment.

**Correct Answer:** B. Nausea and vomiting