Introduction: Compression of the median nerve in pregnancy is thought to be due to fluid retention within the carpal tunnel space. We aim to discover the cause of carpal tunnel syndrome (CTS) in pregnancy using high resonance ul- trasonography. Methods: This is a cross-sectional study where obstetric patients were screened for CTS and subjected to a non invasive ultrasonic imaging. Results: A total of 63 patients were seen with 25 diagnosed to have CTS (39.7%) and 38 patients had none (60.3%) based on a screening tool. Age ranged from 20-42 years old with the highest range in the 28-30 year old group (34.9%). In patients with CTS, the cross sectional area of the median nerve inside the tunnel was a mean of 0.908 cm ie larger, while non-CTS patients had a mean of 0.797 cm inside the tunnel. The transverse carpal ligament (TCL) measured a mean of 0.0988 cm in the CTS group (ie thinner) and 0.1058 cm in the non-CTS group. Median nerve mobility at equal to or less than one tendon width was 80% in pregnant women with CTS and 92.1% for those without. No fluid was present within the carpal tunnel of all patients. The results were sta- tistically not significant. Conclusion: Ultrasonographic evidence in pregnant women with CTS shows a larger median nerve, a more mobile median nerve and a less thick transverse carpal ligament. There is absence of fluid retention and synovitis ruling out extrinsic compression of the median nerve as cause of CTS in pregnancy.