**Core Concept**
Cytomegalovirus (CMV) infection is a common complication in immunocompromised patients, particularly those undergoing organ transplantation. CMV can cause a wide range of symptoms, from mild to severe, and can affect various organs, including the gastrointestinal (GI) system.

**Why the Correct Answer is Right**
CMV infection can cause GI ulcers and hemorrhage due to its tropism for the epithelial cells of the GI tract. CMV can lead to direct damage to the mucosa, resulting in ulceration and bleeding. This is a well-documented complication of CMV infection, particularly in immunocompromised patients. The virus can also cause inflammation and necrosis of the GI mucosa, leading to symptoms such as diarrhea, abdominal pain, and bleeding.

**Why Each Wrong Option is Incorrect**
**Option A:** Intra-abdominal abscess is not a direct sequela of CMV infection. While CMV can cause inflammation and tissue damage, it is not typically associated with the formation of abscesses.

**Option B:** Pyelonephritis is a type of urinary tract infection that can occur in patients with kidney disease, but it is not a direct sequela of CMV infection. CMV can cause kidney disease, but pyelonephritis is not a typical complication of CMV infection.

**Option C:** Cholecystitis is inflammation of the gallbladder, which is not typically associated with CMV infection. While CMV can cause a wide range of symptoms, cholecystitis is not a well-documented complication of the virus.

**Clinical Pearl / High-Yield Fact**
In immunocompromised patients, CMV infection can cause a range of GI symptoms, including diarrhea, abdominal pain, and bleeding. Early diagnosis and treatment of CMV infection are critical to prevent severe complications, including GI ulcers and hemorrhage.

**✓ Correct Answer: D. GI ulcers & hemorrhage**