Imaging in Obs & Gynae Flashcards
Use of imaging in Obs and Gynae
Confirm or refute a provisional diagnosis
Determine the extent of disease
Assess response to treatment
Most common imaging method used in Obs and gyane
Ultrasound
Other imaging methods used in obs and gynae
CT
MRI
X-ray screening fluoroscopy – e.g. hysterosalpingograms (HSG)
Functional imaging – PET-CT
Indications for using radiology?
Diagnosis of pelvic pain – cause?
Assessment of pelvic masses
Investigation of abnormal menstrual bleeding
Assessment of patients with post-menopausal bleeding
Investigation of infertility
Interventional radiology – fallopian tube recanalisation, uterine artery embolisation
Benefits of US
Relatively cheap
Safe – no ionising radiation
Provides very good definition of different pelvic organs
Can be used in the clinic as an adjunct to pelvic examination
What are the two main ultrasound techniques used?
TRANSABDOMINAL - first line
TRANSVAGINAL - well tolerated
Often both techniques are used at the same time
What is good practice during a trans-abdominal ultrasound?
To perform a brief assessment of the upper abdomen in order to:
- ensure that there is no hydronephrosis
- detect early ascites
- ensure that the pelvic abnormality is not secondary to upper abdominal pathology
Why must the patient have a full bladder during US?
The urine-distended bladder acts as an “acoustic window”
A distended bladder displaces gas-filled bowel loops out of the pelvis (bowel gas scatters the ultrasound beam and degrades image quality)
Advantages of trans-abdominal US
Safe
Readily available
No ionising radiation and therefore ideal for children and women of reproductive age
Disadvantages of US
difficult to obtain good images in obese patients and in patients where there is gaseous distension of the bowel
Operator dependent
It is difficult to produce exactly the same images every time the patient attends and this means ultrasound is not often used for assessing the response to cancer treatment
What is an important landmark to note during TA US
iliac artery and vein
It will help locate the ovaries
Trans Vaginal scan
Probe goes in much closer proximity to organs of interest so the view is better
Patient needs a full badder for TV US - True or False
False
Full bladder is uncomfortable for patient during TV scan
Advantages of TV scan
Good depiction of pelvic organs
Disadvantages of TV scan
More invasive procedure
Not suitable for individuals who have not been sexually active
Can sometimes just demonstrate “the tip of the iceberg” and may not depict the full extent of large pelvic masses (ideally transvaginal scan should follow a transabdominal scan which allows better overview)
What is the second-line investigation in patients with acute abdo pain?
CT scan
Uses of CT scan
Assess post-surgical complications – e.g.small bowel obstruction secondary to adhesions, post-operative collections/abscesses etc.
Staging of gynaecological malignancy, especially ovarian and endometrial cancers
Assessing response to treatment in patients after chemotherapy +/- radiotherapy
Advantages of CT scan
Quick
The entire chest abdomen and pelvis can be assessed on one scan
Modern multiple detector row (“multislice”) scanners produce very thin slices and images can be manipulated to produce coronal and sagittal reformats, as well as the axial source images
Disadvantages of CT scanning
High radiation dose (equivalent to about 160 chest x-rays) with a significant dose delivered to the ovaries
Therefore used sparingly in children and patients of reproductive age
Does not provide optimal depiction of different pelvic organs (MR is better at providing good tissue resolution)
How does MRI work?
Uses radiofrequency energy rather than ionising radiation
It is possible to alter the time between transmitting the RF signal and receiving the RF signal from the patient and this leads to scans with different characteristics – e.g. T1- and T2-weighted scans
T2 - more fluid sensitive - organs or structures containing fluid will be bright
T1 - Fat, protein, blood appear dark
Advantages of MRI
Provides an excellent depiction of pelvic organs
No ionising radiation and is therefore suitable for children and women of reproductive age
Can give some idea about the composition of soft tissue masses – e.g. do they contain fluid, fat, blood etc ?
MRI is safe during pregnancy except during ____?
1st trimester
Disadvantages of MRI
Time-consuming
Poor depiction of lung parenchyma – a CT scan should be performed if there is query about pulmonary metastases
Not tolerated if patients have claustrophobia
Contra-indicated in patients with: pacemakers, many artificial metallic heart valves, nerve stimulators, cochlear implants etc etc.
Uses of MRI in Gynae patients
Cancer staging – especially cervical cancer
Further evaluation and characterisation of adnexal and uterine masses, where pelvic ultrasound or other imaging have not provided a diagnosis
Evaluation of patients with sub-fertility – are there are contributory anatomical variations?
MR of the pituitary gland is performed in patients with suspected prolactinoma
