**Core Concept**
Splenectomy, or the surgical removal of the spleen, is a procedure that can be life-saving in specific clinical scenarios. The spleen plays a crucial role in filtering the blood, storing red blood cells, and housing a significant portion of the body's lymphocytes. However, in certain conditions, the spleen can become damaged or dysfunctional, leading to a need for its removal.

**Why the Correct Answer is Right**
The correct answer is related to the management of hereditary spherocytosis, a genetic disorder characterized by the production of abnormal, sphere-shaped red blood cells. These cells are more prone to premature destruction in the spleen, leading to anemia and other complications. Splenectomy can significantly improve the quality of life for patients with hereditary spherocytosis by removing the source of red blood cell destruction.

**Why Each Wrong Option is Incorrect**
* **Option A:** Splenectomy is not the primary treatment for portal hypertension, although it may be used as a last resort in certain cases. The primary treatment for portal hypertension involves endoscopic and pharmacological interventions to reduce pressure in the portal vein.
* **Option B:** Splenectomy is not typically performed for the treatment of splenic injuries, as this can lead to long-term immunosuppression and increased susceptibility to infections. Conservative management and supportive care are usually preferred for splenic injuries.
* **Option C:** Splenectomy is not a common treatment for autoimmune hemolytic anemia, as this condition often requires immunosuppressive therapy to manage the underlying autoimmune process.

**Clinical Pearl / High-Yield Fact**
Splenectomy can lead to increased susceptibility to infections, particularly those caused by encapsulated bacteria such as Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis. Patients who have undergone splenectomy should receive routine vaccinations and take prophylactic antibiotics to prevent these infections.

**Correct Answer: D. Hereditary spherocytosis**