This is a basic article for medical students and other non-radiologists
Obstetrics and Gynaecology imaging for students curriculum represents a core set of common pathologies seen on the wards, in theatre and in the emergency O&G patient.
Fundamental to most imaging of the O&G patient is an un...
The OEIS complex refers to the combined occurence of:
bladder exstrophy / cloacal exstrophy
an imperforate anus
and spinal anomalies: e.g
The estimated occurrence is at around 1-200,000 to 400,000 live births 1,8.
An omphalomesenteric duct cyst is a type of true umbilical cord cyst.
The omphalomesenteric duct serves as a communication between the midgut and yolk sac In early embryonic life and usually obliterates between the 9-18th week of gestation. The omphalomesenteric duct cyst is an embry...
Oro-facial-digital syndromes (OFDS) are a generic name for a variety of genetically heterogeneous disorders that result in malformations of the mouth, teeth, jaw, facial bones, hands, and feet.
There are several (at least 13 2 ) recognised subtypes which include:
OFDS type I: G...
An ovarian adenofibroma is a type of ovarian epithelial tumour. Many authors however overlap this entity with an ovarian cystadenofibroma and consider these tumours are often as part of a adenofibroma - cystadenofibroma spectrum.
Adenofibromas are benign compound tumours composed of ...
The ovarian artery is a paired structure and is the main gonadal artery in females.
The ovarian artery arises anterolaterally from the aorta just inferior to the renal arteries and superior to the inferior mesenteric artery.
Descends caudally in the retroperitone...
Ovarian borderline mucinous cystadenomas are a subtype of ovarian mucinous tumours and, as the name stands, are intermediate between mucinous cystadenomas and mucinous cystadenocarcinomas.
They account for ~ 10-15% of all ovarian mucinous tumours.
They are microscopica...
The most commonly adopted ovarian cancer staging system is the FIGO staging system. The most recent staging system is from 2014 1:
CT is considered the best imaging modality for staging ovarian cancer. 4.
stage I: tumour limited to the ovary or fallopian tube
tumour limited to o...
Ovarian carcinoid tumours are very rare sub type of ovarian tumour. They are usually classified under ovarian germ cell tumours (monodermal teratoma 5). The term carcinoid tumour of the ovary can be used to described primary ovarian carcinoid tumours or metastatic carcinoid tumours to the ovary....
An ovarian choriocarcinoma is a rare sub type of ovarian germ cell tumour.
They account for less than 1% of ovarian tumours.
In pre-menarchal patients, the tumors manifest with iso-sexual precocity (approximately 50% of cases) and other symptoms associated...
Ovarian cysts are commonly encountered in gynaecological imaging, and vary widely in aetiology, from physiologic, to complex benign, to neoplastic.
Small cystic ovarian structures should be considered normal ovarian follicles unless the patient is pre-pubertal, post-menopausal, pregnant, or the...
An ovarian cystadenocarcinofibroma (CACF) is an extremely rare ovarian tumour. The tumour has a fibrous component is considered as the malignant counterpart of an ovarian cystadenofibroma (CAF) 1. There is very little literature on the imaging findings of these.
An ovarian cystadenofibroma (CAF) is a relatively uncommon benign epithelial ovarian tumour where the fibrous stroma remains a dominant component of the neoplasm. As a group they are thought to represent ~1.7 % of all benign ovarian tumours 3.
Although generally classified as an epit...
Ovarian cystadenoma is a broad term given to a certain types of ovarian epithelial tumours. This can include
ovarian serous cystadenoma
ovarian borderline serous cystadenoma
ovarian mucinous cystadenoma
ovarian borderline mucinous cystadenoma
Ovarian cystic neoplasms can be either benign or malignant and can arise from epithelial, stromal, or germ cell components. In general, the risk of malignancy in unilocular cystic tumours <10 cm in women over the age of 50 years is thought to be low 3-4.
ovarian mature cystic teratoma
Ovarian dysgerminomas are a type of germ cell tumour of the ovary. They are the most common malignant germ cell tumours of the ovary and are thought to account for ~1% of all ovarian neoplasms 5.
They are rare ovarian tumours that occur predominantly in young women (majority occur...
Ovarian ectopic pregnancies are rare (1-3%) when compared to other types of ectopic pregnancy such as tubal ectopic.
Risk factors include pelvic inflammatory disease, IUCD use and endometriosis. Pathogenesis is debated and lies between:
fertilisation of the ovum in th...
Ovarian embryonal carcinomas are rare and malignant germ cell tumours of the ovary.
It is found predominantly in children and adolescents (average age 14 years).
Precocious puberty or menstrual irregularity occurs in 60% 2. The tumor can secrete B-hcG and/o...
Ovarian fibromas are a benign ovarian tumour of sex cord / stromal origin. Although fibromas account for ~4% of all ovarian neoplasms, they are the most common sex cord ovarian tumour.
Fibromas occur at all ages but are most frequently seen in middle-aged women.
Ovarian fibromatosis (OF) refers to a rare benign phenomenon where there is tumour-like ovarian enlargement due to diffuse ovarian fibrosis.
It may have a predilection towards younger pre-menopausal females (age range around 13-39 years) with a mean age of presentation of 25 years...
Ovarian fibrosarcoma is a malignant mesenchymal fibroblastic tumour of the ovary that has multiple mitotic figures which is the most important factor in histopathological diagnosis (4 or more mitotic figure per 10 high power fields).
Ovarian fibrosarcoma is a very rare malignant ...
Ovarian fibrothecomas comprise tumours in the spectrum of ovarian sex cord / stromal tumours where there are components of both an ovarian fibroma and an ovarian thecoma.
Most occur in adult women, with ~66% in postmenopausal women. Although they account for ~1% of all ovarian tu...
An ovarian follicle (also known as a Graafian follicle in its mature state) is the basic unit of female reproductive biology and is composed of roughly spherical aggregations of cells. It contains a single oocyte.
An ovarian follicle can be initiated to grow and develop, culminating in ovulati...
An ovarian follicular cyst is type of simple physiological ovarian cyst.
The terms "ovarian cyst" and "ovarian follilcular cyst" are often used interchangeably. These two terms describe lesions >3 cm, and it is important to differentiate them from an "ovarian follicle" which is <3 ...
Ovarian hyperstimulation syndrome (OHSS) is a complication of ovarian stimulation treatment (ovarian induction therapy) for in vitro fertilisation. Rarely, it may also occur as a spontaneous event in pregnancy (see spontaneous ovarian hyperstimulation later in the article).
The clinical syndrom...
Ovarian hyperthecosis (OHT) is a condition where there is a presence of luteinized thecal cells within a hyperplastic ovarian stroma.
Clinical manifestations include hyperandrogenism, obesity, hypertension, and impaired glucose tolerance. Virilization has been reported to...
A hypointense ovarian lesion on T2 weighted MRI is usually a sign of benignity. The low signal is considered to be due to fibrosis and blood products 1.
Lesions that can give this appearance include 1:
Ovarian lymphoma can refer to
primary involvement of the ovaries with lymphoma (i.e. primary ovarian lymphoma): very rare
secondary ovarian involvement of the ovaries with generalised lymphoma (i.e. secondary ovarian lymphoma): more common scenario
Mucinous cystadenocarcinoma of the ovary is a rare malignant ovarian mucinous tumour. This type can account for 5-10% of all ovarian mucinous tumours. It is a type of ovarian epithelial tumour.
Retrospective studies have suggested that many mucinous carcinomas initially diagnosed as...
Mucinous cystadenoma of the ovary is at the benign end of the spectrum of mucin-containing epithelial ovarian tumours.
The estimated peak incidence is at around 30-50 years of age.
They comprise approximately 80% of mucinous ovarian tumours and 20-25% of all benign ovarian tumou...
Ovarian mucinous tumours are a subgroup of ovarian epithelial tumours. They represent ~20% of all ovarian tumours and ~10% of all malignant ovarian tumours. They are subdivided according to their malignant potential and clinical behaviour into:
ovarian mucinous cystadenoma
ovarian borderline m...
Ovarian serous cystadenocarcinoma is an ovarian epithelial tumour at the malignant end of the spectrum of ovarian serous tumours.
They account for the largest proportion of malignant ovarian tumours 1, representing over 50-80% of all malignant epithelial ovarian tumours 4. The pre...
Ovarian serous cystadenomas are a type of benign ovarian epithelial tumour at the benign end of the spectrum of ovarian serous tumours.
Serous cystadenomas account for ~60% of ovarian serous tumours 1. They are the commonest type of ovarian epithelial neoplasm. The peak incidence ...
Ovarian serous neoplasms are the commonest subtypes of the epithelial ovarian tumours, being more prevalent than the mucinous ovarian tumours. They are subdivided according to their malignant potential and clinical behaviour into:
benign serous cystadenoma / serous cystadenofibroma
Ovarian Sertoli-Leydig cell tumours (SLCT), also known as an ovarian androblastomas, are a subtype of ovarian sex cord-stromal tumour.
They are rare and only account for ~0.5% of all ovarian tumours. While they can present at any age, they typically present <30 years old, with a m...
Ovarian teratomas is the most common group of ovarian germ cell tumours.
They can be divided into 3 main sub types
mature ovarian teratoma
immature ovarian teratoma
struma ovarii tumour
Ovarian thecomas are benign ovarian tumours of sex cord / stromal (mesenchymal) origin. They are thought to account for approximately 0.5-1% of all ovarian tumours. As ovarian thecomas secrete oestrogen, they are described as functional ovarian tumours.
They typically present in o...
Ovarian torsion, also sometimes termed adnexal torsion or tubo-ovarian torsion, refers to rotation of the ovary and portion of the fallopian tube on the supplying vascular pedicle.
It can be intermittent or sustained and results in venous, arterial and lymphatic stasis. It is a gynaecological ...
Ovarian transposition is a surgical procedure in which the ovaries are displaced from the pelvis before pelvic radiation therapy in order to protect them from radiation injury.
It is performed in premenopausal women with a variety of pelvic malignancies (e.g cervical cancer, rectal cancer, and ...
Ovarian tumours are relatively common and account for ~6% of female malignancies. This article focuses on the general classification of ovarian tumours. For specific features, refer to the subarticles.
Primary ovarian tumours
Surface epithelial-stromal ovarian tumours (60-...
There are several ovarian tumours associated with endometrial thickening and is often due to oestrogenic effects of the ovarian tumour.
Such tumours include:
ovarian epithelial tumours
endometroid carcinoma of the ovary
may have synchronous endometrial carcinoma or endometrial hyperplasia, p...
Ovarian vein syndrome is a relatively rare condition where a dilated ovarian vein causes notching, dilatation, or obstruction of the ureter. This is usually secondary to varicoses of the ovarian vein or ovarian vein thrombosis and occurs at the point where the ovarian vein crosses the ureter.
Ovarian vein thrombosis (actually most often a thrombophlebitis) occurs most commonly in postpartum patients and can result in pulmonary emboli. A presentation is usually with acute pelvic pain in the postpartum period, then termed puerperal ovarian vein thrombosis or postpartum ovarian vein th...
Ovarian yolk sac tumours, also known as endodermal sinus tumours, are a type of ovarian germ cell tumours.
Ovarian yolk sac tumour is a rare malignant ovarian germ cell tumour that usually occurs around the second decade of life. It is considered the most common malignant germ cel...
The ovaries are paired female gonads of the reproductive and endocrine systems. They lie within the ovarian fossa on the posterior wall of the true pelvis.
The ovaries are ovoid in shape and measure approximately 1.5-3.0 cm x 1.5-3.0 cm x 1.0-2.0 cm (length x width x thickness) ...
Overlapping fetal fingers is an antenatal ultrasound observation where the fetal fingers are seen to overlap each other. It may be seen seen with a concurrent clenched fetal hand. If the hand is clenched typically the 2nd finger is seen to overlap the 3rd 4.
a well re...
P16 is a widely used immunohistochemical marker. It can be expressed in other neoplasms and in several normal human tissues. It can play an important role gynaecological malignancy and is a surrogate marker for HSIL's (high-grade squamous intraepithelial lesions). It has been applied to facilita...
Pallister-Killian syndrome (PKS) is an extremly rare chromosomal anomaly.
It may be more prevalent in woman of advanced age 4.
It is a polymalformative complex with tetrasomy of isochromosome 12p although many cases are mosaic.
The majority of cases are th...
A papillary serous carcinoma of the cervix (PSCC) is an uncommon histological type of cervical cancer. It is considered a sub type of adenocarcinoma of the cervix.
Accodring to some studies, there was a bimodal age distribution, with one peak occurring before the age of 40 years ...
Papillary serous carcinoma of the endometrium is an uncommon histological subtype of endometrial carcinoma accounting for only 5-10% of all such tumours 2. It is considered type II endometrial adenocarcinoma and has a clinically aggressive form with an early extension of the tumour via Fallopian...
Papillary squamous cell carcinoma (PSCC) of the cervix is a distinct subtype of squamous cell carcinoma of the cervix.
These tumours are characterised by a papillary architecture containing fibrovascular cores and moderate to severe dysplasia without any of frank keratinization and k...
The parametrium is a band of fibrous tissue that separates the supravaginal portion of the cervix from the bladder. It extends on to its sides and laterally between the layers of the broad ligaments.
The uterine artery and ovarian ligament are located in the parametrium.
The parametrium is imp...
Paraovarian cysts (POCs) are remnants of Wolffian duct in the mesosalpinx that do not arise from the ovary. They account for ~10-20% of adnexal masses 3-4.
They typically occur in women at the ages of 20-40 years old.
Most are asymptomatic, although patient...
Paraovarian cystadenoma is a usually benign adnexal tumour that does not arise from the ovary. There is an association with Von Hippel Lindau syndrome.
typically seen as a unilateral cystic adnexal lesion
may be a simple cyst, or contain solid nodular ...
A parasitic leiomyoma is a considered a type of extra-uterine leiomyoma and presents as peritoneal pelvic benign smooth-muscle masses separate from the uterus.
It likely originates as a pedunculated subserosal leiomyoma that twists and torses from its uterine pedicle. The contact wi...
The paraurethral ducts (or Skene ducts) drain the paraurethral glands of the female urethra. There is one duct, draining each gland, on each side, just proximal to the external urethral meatus.
paraurethral duct cyst
paraurethral duct abscess
Paraurethral duct cysts are retention cysts that form secondary to inflammatory obstruction of the paraurethral (Skene) ducts in females.
The cysts are lined by stratified squamous epithelium due to their origin from the urogenital sinus.
Partial hydatidiform mole is a type of hydatidiform mole, which in turn falls under the spectrum of gestational trophoblastic disease.
Clinical signs and symptoms such as abdominal pain, cramps of the lower abdomen and vaginal bleeding during pregnancy are common but non...
Parturition-induced pelvic instability is a rare condition seen in women following vaginal delivery.
The incidence of symphyseal rupture after vaginal delivery ranges from one in 600 to one in 30,000 deliveries 1.
Predisposing factors include multiparity, complicated delivery, ...
Patau syndrome (also known as trisomy 13) is considered the 3rd commonest autosomal trisomy.
This along with Down syndrome (T21) and Edward syndrome (T18) are the only three trisomies to be compatible with extrauterine life. However, few infants live more than a few days.
A pelvic abscess refers to a walled-off collection of pus in the pelvis.
Some of the causes include:
pelvic inflammatory disease (tubo-ovarian abscess)
iatrogenic e.g. post surgical
inflammatory bowel disease
pelvic actinomycosis infection
Pelvic actinomycosis infection is rare but serious infection caused by Actinomyces sp, an opportunistic gram-positive bacteria usually introduced by foreign bodies specially IUCDs, surgery, or trauma. It generally falls under the broader spectrum of pelvic inflammatory disease.
A dedicated pelvic MRI protocol is very useful for imaging assessment of cervical carcinoma.
Although the FIGO is a clinical staging, the 2009 revised FIGO staging encourages the use of MRI to complement clinical staging.
Imaging is optimally performed after three hours of fasting...
Pelvic congestion syndrome (some prefer pelvic venous insufficiency 9) is a condition that results from retrograde flow through incompetent valves in ovarian veins. It is a commonly missed and potentially-treatable cause of chronic abdominopelvic pain.
It tends to be more common ...
Pelvic inflammatory disease (PID) is a broad term that encompasses a spectrum of infection and inflammation of the upper female genital tract, resulting in a range of abnormalities.
The highest incidence is seen among sexually-active women in their teens, with 75% cases being und...
Pelvic lipomatosis or pelvic fibrolipomatosis represents excessive deposition of fat in pelvis due to overgrowth of adipose cells leading to compression of pelvic organs.
The condition usually presents in patients 20-50 years of age. The condition is predominantly (2/3 of cases) s...
Pelvic masses in females carry a broad differential diagnosis:
benign adnexal cyst: 34%
pelvic malignancy: 14%
pelvic inflammatory disease: 8%
Extra-gynaecological masses, e.g. colorectal carcino...
A dedicated MRI protocol is crucial for accurate MRI evaluation of endometrial carcinomas.
Imaging is optimally peformed after 3 hours of fasting to reduce bowel peristalsis and following administration of an anti-peristaltic agent unless contra-indicated.
Supine position using a pelvic phased...
It is important to have a systematic way of approaching a case with pelvic pain in the exam.
Most examinations are performed using ultrasound. Always say that you would further assess the uterus with 3D ultrasound. You may also say that in my department we would perform a sonohysterogram. Only...
Evaluation of known endometriosis with MRI requires a slightly different protocol to a routine pelvic MRI (see Pelvic MRI protocol: routine), and should probably be reserved for known cases of endometriosis rather than for the assessment of pelvic pain.
IV (or IM) Buscopan® is administered to r...
Pelvic ultrasound is usually the initial modality for imaging gynaecologic pathology, including acute pelvic pain and chronic pelvic pain. The exam normally involves two components: a transabdominal (TA) evaluation and a transvaginal (TV) / endovaginal (EV) evaluation.
Normal ultrasound anatomy...
The term pelvis can refer to either the bony pelvis or the pelvic cavity.
The bony pelvis is formed by the sacrum and coccyx and a pair of hip bones ("ossa coxae"), which are part of the appendicular skeleton. Its primary function is the transmission of forces from the axial skelet...
Perigestational haemorrhage refers to haemorrhage that occurs around the fetus during the gestational period. The spectrum of haemorrhage includes:
chorionic haemorrhage: caused by the separation of the chorion from the endometrium
subchorionic haemorrhage: most common type, occurs between th...
Getting a film with perigestational haemorrhage in the exam is one of the many exam set-pieces that can be prepared for.
Transabdominal and transvaginal pelvic ultrasound show an anteverted uterus with an intrauterine gestational sac. MSD is 20 mm in TV study with a single, live e...
Perinatal lethal hypophosphatasia (PLH) is the most severe form of hypophosphatasia. If untreated, it is lethal in all cases.
The estimated incidence is at ~1:100,000 live births.
As with all hypophosphatasia cases, this is due to a mutation in chromosome 1q3...
The perineum is a diamond shaped region below the pelvic diaphragm and is divided by an imaginary line drawn between the ischial tuberosities into anteriorly the urogenital triangle and posteriorly the anal triangle.
The perineum is bounded by the pubis anteriorly, the ischial tu...
Peritoneal inclusion cyst (PIC) (also known as a peritoneal pseudocyst and benign cystic mesothelioma) is a type of cyst-like structure that appears in relation to the peritoneum and results from a non-neoplastic reactive mesothelial proliferation.
Peritoneal inclusion cysts occur...
There are several peri-urethral cystic lesions. These include:
female genitourinary tract:
Gartner duct cyst
epidermal inclusion cyst of the vagina
Skene duct cyst
Bartholin gland cyst
endometrial cyst of perineal - vulval - vaginal region
Perivascular epithelioid cells tumours (PEComas) are a group of related mesenchymal tumours and tumour-like conditions found in many locations. This group includes:
clear cell 'sugar' tumour of the lung
clear cell myomelanocytic tumour (CCM...
A persistent right umbilical vein (PRUV) is an uncommon vascular anomaly which is often detected in utero.
The estimated prevalence is ~2 per 1000 births 1,2.
In the normal situation, the right umbilical vein begins to obliterate in the ~4th week of gestation and disap...
It is important to have a systematic way of approaching a case with per vaginal bleeding in the exam.
intrauterine fetal demise
PET-CT is a combination of cross-sectional anatomic information provided by CT and the metabolic information provided by positron emission tomography (PET).
PET is most commonly performed with 2-[F-18]fluoro-2-deoxy-D-glucose (FDG). Fluorine-18 (F-18) is an unstable radioisotope and has a half-...
Phocomelia is an extremely rare congenital skeletal disorder that characteristically affects the limbs. It can affect either the upper limbs or lower limbs or both. Phocomelia is also a descriptive term to describe the characteristic limb anomalies occurring with its associated conditions.
Physiological gut herniation is a natural phenomenon that occurs in early pregnancy. It usually occurs from around 6-8 weeks up until 12-13 weeks in-utero, after which the bowel returns to the abdominal cavity.
It occurs as a result of the bowel (particularly ileum) growing faster ...
Physiological pelvic intraperitoneal fluid refers to the presence of a small volume of free fluid in the pelvis, particularly the pouch of Douglas. It occurs in young females of reproductive age and can be a mimic of traumatic free fluid in abdominal trauma.
Unfortunately, pelvic free fluid may...
Getting a film with placental abruption (premature separation of placenta from uterus) in the exam is one of the many exam set-pieces that can be prepared for.
Transabdominal and transvaginal pelvic ultrasound show a single live fetus with gestational age of 27 weeks. The cervix i...
Placental calcification has been considered a manifestation of “ageing” of the placenta. It commonly increases with gestational age.
Delayed placental calcification
Accelerated placental calcification
normal placental maturity
maternal thrombotic disorde...
Placental chorioangiomatosis is an extremely rare condition where numerous placental chorioangiomas involve the placenta. The individual chorioangiomas can be of varying size.
Recognised complications include
precipitation of fetal hydrops 2
fetal cerebral embo...
Placental fusion is a phenomenon that can occur in a twin pregnancy. This can occur to varying degrees. Determination of chorionicity on ultrasound can sometimes be difficult if there has been a placental fusion.
Placental grading (Grannum classification) refers to a ultrasound grading system of the placenta based on its maturity. This primarily affects the extent of calcifications. In some countries the use of placental grading has fallen out of obstetric practice due to a weak correlation with adverse ...
Placental infarction refers to a localised area of ischaemic villous necrosis. It is a significant cause of placental insufficiency.
A localized infarction can occurs in up to ~12.5% (range 5-20%) of all gestations.
It usually results from an interrupted maternal blo...
Placental mosaicism is a situation where there discrepancy between the chromosomal makeup of the cells in the placenta. According to one study fetal mosaicism was found in 50% of cases with placental mosacism. When the fetal cells are normal in chromosomal composition, this is then known as conf...
A placental septal cyst is a placental cyst typically located in the mid-placenta. It forms between the cotyledons of the placenta. The cysts contain gelatinous material and are usually 5-10 mm in diameter. They may be present in 10-20% of placentas from full term uncomplicated pregnancies.