**Core Concept**
Genital tuberculosis is a form of extrapulmonary tuberculosis that affects the reproductive organs. It usually spreads from a primary site of infection, typically the lungs, through the hematogenous route.

**Why the Correct Answer is Right**
The most common mode of dissemination of genital tuberculosis is through the hematogenous route, where the bacteria are carried by the bloodstream from the primary site of infection. This route is favored by the presence of Caseating granulomas, which are characteristic of tuberculosis and facilitate the spread of the bacteria. The hematogenous spread often occurs via the Batson's vertebral plexus, a valveless venous plexus that connects the pelvic organs to the spine, allowing the bacteria to reach the genital organs.

**Why Each Wrong Option is Incorrect**
**Option A:** Lymphatic spread is not the primary mode of dissemination for genital tuberculosis.
**Option B:** Direct extension from an adjacent infected organ is possible but not the most common route.
**Option C:** Contiguous spread from the gastrointestinal tract is unlikely, as the bacteria would need to cross the peritoneal cavity to reach the genital organs.

**Clinical Pearl / High-Yield Fact**
Genital tuberculosis often presents with symptoms such as pelvic pain, infertility, and amenorrhea, and can be diagnosed through imaging studies and biopsy. It is essential to consider tuberculosis in the differential diagnosis of genital tract abnormalities, especially in regions with high prevalence.

**Correct Answer: D. Hematogenous spread.**