Pelvic floor dysfunction in the form of pelvic organ prolapse (POP) is a common gynaecological condition, especially in the elderly. Although the aetiology is poorly understood, several risk factors such as vaginal childbirth, chronically raised intra-abdominal pressure (such as asthma and chronic constipation), ageing, previous hysterectomy and connective tissue disorders are thought to play a role in the pathophysiology of POP. Studies have shown that vaginal childbirth can result in both gross and micro-architectural distortion/alteration of the pelvic floor musculature and is thus considered to play a major role in the development of POP. Although ethnicity has been proposed as a risk factor, there are limited studies on this subject. Recently, transperineal ultrasound (TPUS) has been used to study the structural integrity and the dynamic interaction between the pelvic organs and pelvic floor musculature. Using a specified methodology we intended to determine and compare pelvic floor morphology, namely pelvic organ descent and levator hiatal distensibility in a multi-ethnic South African population (Asian, Caucasian and Black) in both asymptomatic nulliparous and symptomatic multiparous women. Secondly we also intended to study the association between prolapse symptoms and functional anatomy of the pelvic floor, and finally to determine the impact of vaginal childbirth on the pelvic floor morphology 3-6 month postpartum. For all the studies women were recruited from the local nursing school, general gynaecology and tertiary urogynaecology clinic. Pregnant women were recruited from the district antenatal clinic. This cohort included only Black pregnant women. After informed consent all ultrasound volumes were acquired at rest, maximal pelvic floor contraction and Valsalva maneuver. Volumes were deindentified and analysed 6-8 weeks later using GE Kretz 4D View (GE Kretztechnik Gmbh, Zipf, Austria). In the nulliparous cohort, we found that Black South African women had greater pelvic organ descent on ultrasound and clinically and greater distensibility compared to South Asian and Caucasian women. Multivariate modelling revealed that Black 2 ethnicity remained a significant factor for pelvic organ mobility on clinical examination, (P=0.024). In women with symptomatic POP, there was significant variation in clinical prolapse stage, levator distensibility and pelvic organ descent in this racially diverse population presenting with pelvic organ prolapse, with South Asians having a lower avulsion rate than the other two ethnic groups (P= 0.014). As regards the association between prolapse symptoms and functional anatomy of the pelvic floor we found a significant association between awareness, visualization and/or feeling of a vaginal lump and abnormal pelvic floor functional anatomy, that is, hiatal ballooning and levator avulsion (all P< 0.05). The fourth part of the study included eighty four women who returned at a mean of 4.8 months postpartum. We found significant alteration in pelvic organ support and levator hiatal distensibility after vaginal delivery i.e. a significant increase in mean values from ante to postpartum measurements, more so for the vaginal delivery group. 15% of Black primiparous women sustained levator trauma after their first vaginal delivery. In conclusion, to the author‘s knowledge this is the first study on pelvic floor morphology in South African women. Contrary to previous publications inferring that Black women rarely develop PFD, we have shown that this particular ethnic group had significantly different pelvic floor dynamics than Caucasian and South Asian women for both nulliparous and multiparous symptomatic women. Levator trauma occurs in 15% of Black women after vaginal childbirth. / Thesis (PhD)--University of Pretoria, 2017. / Obstetrics and Gynaecology / PhD / Unrestricted