**Question:** A neonate presented with fever, lethargy, abdominal distension, vomiting and constipation. Clinically he was diagnosed as volvulus neonatorum with suspected perforation. Best investigation would be:

A. Abdominal ultrasound
B. Plain abdominal X-ray
C. Abdominal computed tomography (CT) scan
D. Small bowel follow-through (SBFT)

**Correct Answer:** D. Small bowel follow-through (SBFT)

**Core Concept:**
Volvulus neonatorum is a condition in which the intestine twists and compresses, leading to ischemia and potential perforation. In such cases, a suspect of bowel perforation necessitates a more detailed imaging study to evaluate the bowel wall, peritoneum, and surrounding structures.

**Why the Correct Answer is Right:**
Small bowel follow-through (SBFT) is the most appropriate investigation in this context because it provides detailed information about the small bowel's structure, peritoneum, and surrounding structures. It is particularly useful in assessing for signs of perforation or obstruction, which are crucial in the clinical scenario of neonatal volvulus with suspected perforation.

**Why Each Wrong Option is Incorrect:**

A. Abdominal ultrasound: Although ultrasound is useful in assessing abdominal pathology, it may not provide sufficient information regarding the small bowel wall, peritoneum, and surrounding structures as effectively as SBFT.

B. Plain abdominal X-ray: Plain abdominal X-ray is less sensitive for detecting bowel obstruction or perforation, as it lacks the ability to visualize the small bowel wall, peritoneum, and surrounding structures.

C. Abdominal computed tomography (CT) scan: While CT is a valuable imaging modality, it may not be readily available in all settings and may expose the neonate to ionizing radiation. In contrast, SBFT does not expose the neonate to radiation risks and provides similar information about the small bowel wall, peritoneum, and surrounding structures.

**Clinical Pearl:**
In neonates, SBFT is a valuable tool for assessing small bowel pathology, including volvulus with suspected perforation. It allows for detailed evaluation of the small bowel, peritoneum, and surrounding structures, and is often preferred over other imaging modalities due to its non-ionizing radiation exposure and availability in most pediatric settings. However, it is essential to consider alternative methods like ultrasound and CT if these modalities are readily available and pose no radiation risks to the neonate.