Aim and background: Mature cystic teratomas (MCTs) are common germ cell tumors in women of reproductive age, but they are relatively rare during pregnancy. In some cases, these teratomas can transform into a rare variant known as parasitic teratomas. This happens when the teratoma depends on a nearby organ or tissue for its blood supply and nourishment, often due to insufficient blood flow. This fascinating phenomenon highlights the complex interactions within the body and the unexpected challenges that can arise during pregnancy. Case description: This paper discusses a noteworthy case of an asymptomatic parasitic teratoma discovered incidentally during a cesarean section. A significant aspect of this case is the absence of the left fallopian tube and ovary, which adds a unique dimension to the patient's clinical presentation. We detail the case of a 32-year-old woman, gravida 4 para 3, who was 38 weeks and 5 days pregnant. Her obstetric history included a fourth-degree obstetric anal sphincter tear (OASIS), necessitating an emergency lower segment cesarean section. During the procedure, a cystic tumor measuring 5 cm by 5 cm, filled with hair and sebum, was identified at the ureterovesical fold. Fortunately, the newborn was delivered with an acceptable Apgar score. Upon exteriorizing the uterus, the absence of the left fallopian tube was noted, while the right ovary and fallopian tube appeared normal. Histopathological analysis of the cystic tumor confirmed it as an MCT, with no evidence of immature components, somatic malignancy, or other germ cell tumors. Conclusion: This case presents a rare opportunity to investigate the diagnosis of a parasitic teratoma during pregnancy, an occurrence that is infrequently observed in clinical practice. The potential risks to both the mother and fetus, including torsion and rupture, are considerable. The management of parasitic teratomas typically necessitates surgical intervention, with the timing being critical. When a tumor is identified during a cesarean section, as in this case, the immediate priority is to ensure the safe delivery of a healthy infant, followed by a thorough assessment of the tumor. In conclusion, this unique case underscores the rarity of diagnosing such conditions during pregnancy and emphasizes the necessity for comprehensive care and ongoing follow-up for both the mother and her newborn.