33. Imaging modalities in obstetrics and gynecology

Obs and Gyn

Normal anatomy of the female pelvis –

1. Vagina
2. Endocervical canal
3. Uterus w/ body and fundus
4. Fallopian tubes
5. Ovaries

Dx’s:

1. US – Evaluates pelvic pain, masses, polycystic ovaries, amenorrhea, dysmenorrhea (painful menses), delayed menses and can be used for screening.
2. a. Transabdominal – though the abdo wall, pt has a full bladder to aid visualisation as there it acts as an acoustic window to the deeper structure. Uses a low freq probe and done in late pregnancy. Top pic

1. b. Transvaginal – through the vagina. Bladder should be empty. Uses high freq sound waves and done in early pregnancy. Image is 180 degrees. Bottom pic

2. CT w/ or w/o contrast – Lower diagnostic value. Not used routinely for Dx due to radiation so is not done unless vital or the benefits overcome the harm to the foetus (mothers’ condition is more important – done in emergencies like rupture of fallopian tube or ovarian cyst, ectopic pregnancy, haemorrhage) but is the only way to image the finer structures. Used for TNM staging, see infiltration of tumours in lower GI to genitals.

3. MRI – Has higher soft-tissue contrast than CT so has more accurate characterisation of the pelvis. Used for assessment of acute pelvic pain or uterine a. embolus, dx of adenomyosis, stage endometrial/ cervical cancer and see workup for surgery of pelvic floor prolapse. MRI shown here on the left. Can also do foetal MRI (below) in the 2^{nd}/ 3^{rd} trimester to evaluate abnormalities in brain, spine and body and confirm an US diagnosis.

4. Hysterosalpingography w/ contrast– Contrast introduced through the cervical canal. This is an X-ray → visualising the lumen of the uterine cavity, fallopian tubes and part of the cervical canal.

5. Sonogram – Foetal US using sound waves to determine presence of embryo/ foetus after 5 weeks (gestational sac first sign of pregnancy – shown as an oval a-echogenic formation in the uterine body shown on the right →) or multiple pregnancies, duration of pregnancy, dx of congenital anomalies, location and growth of foetus, location of placenta and evaluates amniotic fluid. (Poly-/ hydramnios). It is a safe, non-invasive, precise and inexpensive. It is a dynamic real time method that can detect foetal RR, HR and vascular pulsation. Can also measure the skull’s biparietal diameter (BPD) and head circumference. →

Types:

1. a. Transvaginal (early pregnancy)
2. b. Transabdominal
3. c. Doppler US
4. d. 3D- US
5. e. Tissue harmonic imagine

Types of breast tissue: