**Question:** Teunissen's classification is used in classification of congenital anomalies of:

A. Antenatal, Neonatal, and Postnatal (ANN)
B. Antenatal and Neonatal (AN)
C. Antenatal and Neonatal (AN) without A and Neonatal (NN)
D. Antenatal and Neonatal (AN) without Postnatal (PN)

**Correct Answer:**

D. Antenatal and Neonatal (AN) without Postnatal (PN)

**Core Concept:**

Teunissen's classification is a method used to categorize congenital anomalies based on the timing of their occurrence during gestation. It divides the anomalies into four groups:

1. Antenatal (A): anomalies detected before birth (ultrasound or amniotic fluid analysis).
2. Neonatal (N): anomalies detected within the first 28 days of life.
3. Postnatal (P): anomalies detected after the first 28 days of life.
4. Antenatal and Neonatal (AN): anomalies detected before birth and within the first 28 days of life.

**Why the Correct Answer is Right:**

Teunissen's classification is appropriate for option D because it accounts for both antenatal and neonatal periods, two crucial phases of fetal and neonatal development. This classification is widely used in clinical practice to determine the timing of the anomaly's presentation and guide appropriate interventions, investigations, and management.

**Why Each Wrong Option is Incorrect:**

A. ANN (ANN) refers to the timing of the anomaly, but it does not clearly differentiate between antenatal and neonatal periods, making it less specific.
B. AN (AN) is also used to describe the timing of the anomaly, but it omits the neonatal period, which is crucial for management decisions.
C. AN (AN), excluding neonatal period, is similar to option D but includes the neonatal period, making it redundant.

**Clinical Pearl:**

Understanding Teunissen's classification is essential for healthcare professionals to accurately diagnose, manage, and follow-up congenital anomalies. This classification system aids in determining the need for antenatal and neonatal interventions, such as early ultrasound screening, close surveillance, and early intervention, respectively.