Background Although, transsphenoidal (TSS) approach has largely been accepted as the gold standard for excision of sellar lesions, access via this approach may be limited by many vital surrounding neurovascular structures including internal carotid arteries. Injury to these structures during surgery usually has devastating consequences. The inter-carotid distance (ICD) and sellar turcica shape are some of the important aspects of the sellar region neuroanatomy that must be understood in the planning and safe execution of the TSS approach. Objectives This study assessed the sellar turcica shape and measured ICD in normal adults in Enugu Nigeria using magnetic resonance images and compared them with pituitary macroadenoma patients with the aim of determining how the presence of a macroadenoma affects these anatomical structures Methodology Magnetic resonance images of thirty-four patients with pituitary macroadenoma and one hundred subjects with normal sellar morphology were assessed prospectively. The sellar shape was determined by measuring the sellar angle on midline sagittal T1 images. These shapes were classified as prominent shape with sellar angle < 900, curved shape with angle 90 -1500 and flat shape with sellar angle > 1500. The ICD was measured at two levels on axial and coronal T2 MR images; ICD 1 at the laceral segment of ICA after exiting the carotid canal and ICD 2 at the mid-portion of the cavernous segment. Comparisons of the sellar turcica shape and ICD were made between the two groups using the Chi-Square test and independent sample t-test respectively. Tumour dimensions were also determined on T1 contrast images and correlated with the ICD. Results The prominent sellar shape was the most frequently occurring shape among patients with pituitary macroadenoma compared with normal subjects (55.9% vs 24.0%, p = 0.001). In the same vein, ICD was significantly wider in the macroadenoma patients in all the segments of ICA measured compared with normal subjects, with a weak positive correlation between tumour dimensions and the ICD. On the other hand, the study found the curved sellar shape to be the predominant shape among the normal subjects. Conclusion Sellar turcica shape and inter-carotid distance differ significantly between patients with pituitary macroadenoma and normal subjects. Whereas, the prominent shape is predominant in the patients with macroadenoma, who also have significantly wider inter-carotid distances, normal subjects tend to have more of the curved sellar type. Keywords Sellar turcica shape; inter-carotid distance; sellar angle; pituitary macroadenoma