Normative values of the internal genital organs of the female pelvis in transvaginal and transabdominal ultrasound

Abstract

Aim: To conduct a systemic review of published data on reference values for both transabdominal and transvaginal ultrasound in gynecology. Materials and methods: Literature from 1970 to 2020 of reference values for the female pelvis in healthy subjects was reviewed. According to the determination of reference intervals for laboratory values reference values are generally determined using 95%-reference intervals and their associated 90%-confidence intervals. The list of articles was supplemented with extensive crosschecking of the reference lists of all retrieved articles. Results: A total of 33 studies were included and analyzed. The diagnostic performance of transvaginal ultrasound (TVUS) has a higher sensitivity and specificity than transabdominal ultrasound (TAUS) for high quality imaging of the uterus and the bilateral adnexa. The length of normal uterus is about 50-80 mm in fertile age. There is no consensus about the cut off value of the thickness of the endometrium in asymptomatic postmenopausal women, while a measurement of >5 mm and postmenopausal bleeding is suspect and requires further examination. The distribution of normal ovarian volumes is narrow with small volumes in postmenopausal women. Conclusion: Normal values are helpful in delimiting the pathological changes in the female pelvis. While sonomorphologic criteria are more important than the ovarian size for the assessment of ovarian masses and reference values of the uterus in adults have little impact on routine practice, normative values in pediatric patients are important for the detection of pathologies. Normative values of the internal genital organs in females are sufficiently validated; still further research is required to assess the role of normative values in routine clinical practice and in sonographic screening for endometrial and ovarian cancer.