**Question:** Least likely to regress spontaneously is

A. Hirschsprung's disease
B. Congenital heart defects
C. Congenital hypothyroidism
D. Congenital cataracts

**Correct Answer:** D. Congenital cataracts

**Core Concept:** Regression of congenital anomalies is a process in which developmental abnormalities spontaneously improve or resolve in an infant. The term "regress" refers to the correction of these abnormalities without intervention, either through natural mechanisms or medical treatment.

**Why the Correct Answer is Right:** Congenital cataracts (option D) are a group of eye disorders that affect an infant's vision due to cloudiness in the lens of the eye. In most cases, congenital cataracts regress spontaneously, meaning they improve or resolve without surgical intervention. This is often because the lens fibers reabsorb the abnormal substance causing the cataract and the lens becomes clear again.

**Why Each Wrong Option is Incorrect:**

**A. Hirschsprung's disease:** This is a congenital disorder characterized by the absence of ganglion cells in the submucosal plexus of the large intestine. While Hirschsprung's disease can be treated with medications or surgery, it does not regress spontaneously in most cases.

**B. Congenital heart defects:** These refer to structural abnormalities of the heart present at birth. While some congenital heart defects may improve or resolve over time, many require intervention, such as surgery or medications. Therefore, they are less likely to spontaneously regress compared to congenital cataracts.

**C. Congenital hypothyroidism:** This refers to the abnormal development of the thyroid gland or thyroid hormones in an infant. Hypothyroidism is typically caused by genetic or iatrogenic factors and requires medical intervention in the form of thyroid hormone replacement therapy. Consequently, congenital hypothyroidism is less likely to regress spontaneously compared to congenital cataracts.

**Core Concept (Continued):**

In medical examinations, understanding the likelihood of spontaneous regression of congenital anomalies is essential for proper diagnosis, treatment, and prognosis. Adequate knowledge in this area helps physicians determine when to intervene and when to expect spontaneous improvement in the patient's condition.

**Why Each Wrong Option is Incorrect (Continued):**

**A. Hirschsprung's disease:** Although Hirschsprung's disease can be managed with medications or surgery, it rarely regresses spontaneously. In contrast, congenital cataracts are more likely to regress without treatment.

**B. Congenital heart defects:** Many congenital heart defects require surgical intervention or medications for management. Consequently, they are less likely to regress spontaneously compared to congenital cataracts.

**C. Congenital hypothyroidism:** As mentioned earlier, congenital hypothyroidism typically requires medical intervention with thyroid hormone replacement therapy. Due to the need for treatment, it is less likely to regress spontaneously compared to congenital cataracts.

**D. Congenital cataracts