Trisomy 13 syndrome is a rare disorder that carries a high mortality rate due to abnormal prenatal development resulting in serious birth defects. Although genitourinary malformations are commonly seen in trisomy 13 syndrome, to our knowledge, the association of cloacal exstrophy with trisomy 13 has been extremely rarely reported. Herein, a newborn with trisomy 13 syndrome having multiple congenital anomalies, including cloacal exstrophy, is presented, and the importance of structural anomalies of the neutrophilic leukocytes on a blood smear in supporting diagnosis of trisomy 13 is discussed.